Introduction
Gnathostomata are the jawed vertebrates. (gnathos= "jaw" + (stoma)="mouth".
It comprises roughly 60,000 species. (99% of all living vertebrates).
Living gnathostomes have teeth, and paired appendages.
A horizontal semicircular canal is present in the inner ear.
Myelin sheaths is present on the neurons.
Adaptive immune system uses V(D) J recombination ( it is the mechanism of somatic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. VDJ recombination is the process by which T cells and B cells randomly assemble different gene segments – known as variable (V), diversity (D) and joining (J) genes – in order to generate unique receptors (known as antigen receptors) that can collectively recognize many different types of molecule. While Agnatha (petromyzon and hagfish) use genetic recombination in the variable lymphocyte receptor gene.
It is now assumed that Gnathostomata evolved from ancestors that already possessed a pair of both pectoral and pelvic fins.
In addition to this, some placoderms were shown to have a third pair of paired appendages, that had been modified to claspers in males and basal plates in females—a pattern not seen in any other vertebrate group.
It is believed that the jaws evolved from anterior gill support arches that had acquired a new role, being modified to pump water over the gills by opening and closing the mouth more effectively – the buccal pump mechanism.
Presence of Calcified, bony skull and vertebra are the characteristic features of Gnathostomata (fishes, amphibians, reptiles, birds and mammals).
Pelvic fins are situated just in front of the anus.
Interventrals and basiventrals present in the backbone. These are the elements of the backbone which lie under the notochord, and match the basidorsals and interdorsals respectively.
Gill arches which lie internally to the gills and branchial blood vessels, contrary to the gill arches of all jawless craniates, which are external to the gills and blood vessels.
A horizontal semicircular canal in the inner ear.
Paired nasal sacs which are independent from the hypophysial tube.
There are numerous other characteristics of the soft anatomy and physiology (e.g. myelinated nerve fibres, sperms passing through urinary ducts, etc.), which are unique to the gnathostomes among extant craniates, but cannot by observed in fossils.
Introduction:
Adaptation to environment is one of the basic characteristics of the living organisms. Living organisms are plastic and posses the inherent properties to respond to a particular environment.
It is a facet of evolution and involve structural diversities amongst living organisms that are heritable. Organisms exhibit numerous structural and functional adaptations that help them to survive as species and to overcome the tremendous competition in nature.
All classes of vertebrates have their representatives leading to partial or total aquatic life.
Water is a homogenous medium for animals.
As a medium, it is heavy in concentration than air.
Stable gaseous and osmotic concentration in a specific region.
Temperature fluctuation is minimum for a particular region.
Water bodies generally have very rich food resources.
Characters of an Aquatic Animal:
An aquatic animal should have the ability to swim to overcome the resistance of the surrounding medium.
Therefore, it should have a streamlined body with an organ or ability to float.
The animal should also have to overcome the problem of osmoregulation.
There are two types of animals living in the present day water, which have undergone aquatic adaptation.
According to their origin, they are primary and secondary aquatic animals.
Adaptations to water habitat are of two types:
Primary aquatic adaptations which includes primitive gill-breathing vertebrates (fishes); Those animals, whose ancestors and themselves are living in the water from the very beginning of their evolution, are called primary aquatic animals. In other words, primary aquatic animals never had a terrestrial ancestry. They exhibit perfect aquatic adaptations. All fishes are primary aquatic animals.
Secondary aquatic adaptations which are acquired as in reptiles, birds and mammals. Those animals whose ancestors were lung breathing land animals, migrated to the water for some reason and ultimately got adapted to live in aquatic habitat, are called secondary aquatic animals. Some of them live partially while others live totally in the water. All aquatic reptiles, aves and mammals are representatives of secondary aquatic animals. Amphibians are in a transitional form between primary and secondary aquatic life.
Sensory adaptations like, electroreception for electrolocation and electro communication, olfaction (vomeronasal system), balance (spatial orientation, movement perception), vision (cornea curvature, retinal topography), and hearing (acoustics, ear anatomy) under the underwater sound reception mechanisms in various aquatic amniotes are well developed.
INTRODUCTION
The term urogenital refers to something that has both urinary and genital origins. The word urogenital is used because the urinary and reproductive systems in males merge.
These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways (ex. urethra).
Kidneys and urinary ducts form the urinary system.
The Urinary system performs two important homeostatic processes like excretion and osmoregulation. This system is intimately associated both anatomically, and in terms of embryonic origin with the genital system.
The genital system includes the gonads which generate gametes and the genital ducts that serve as passages for the gametes.
Though functionally different the two organ systems the urinary and the genital system are treated together as the urino- genital system, since both develop from the same segmental blocks of trunk mesoderm or adjacent tissues and share many of the ducts.
Thus although the two systems have nothing common functionally they are closely associated in their use of common ducts and are studied under the broad heading of urinogenital system.
The function of the excretory system is crucial in considering the possible environment of the ‘vertebrate life ’. Several main functions can be attributed to all vertebrate excretory systems:
Excretion of nitrogenous waste products.
Maintaining homeostasis with regard to ions (i.e. salt balance).
Regaining valuable substances (glucose, salts, amino acids, etc.)
Maintaining a physiological osmotic value (i.e. water balance).
The excretory system is formed by a series of paired, segmental nephrons that begin with a nephrostome opening into the coelomic cavity.
A pair of glomeruli per segment, supplied by branches from the aorta, projects into the coelomic cavity close to these nephrostomes.
At a later stage of development, the glomerulus/nephrostome area becomes separated from the rest of the coelomic cavity by an epithelial fold.
The nephrons connect to a duct that is formed by caudal growth of the most anterior nephric tubules. These paired urinary ducts open near the anal region.
Introduction:
Adaptation to environment is one of the basic characteristics of the living organisms. Living organisms are plastic and posses the inherent properties to respond to a particular environment.
It is a facet of evolution and involve structural diversities amongst living organisms that are heritable. Organisms exhibit numerous structural and functional adaptations that help them to survive as species and to overcome the tremendous competition in nature.
All classes of vertebrates have their representatives leading to partial or total aquatic life.
Water is a homogenous medium for animals.
As a medium, it is heavy in concentration than air.
Stable gaseous and osmotic concentration in a specific region.
Temperature fluctuation is minimum for a particular region.
Water bodies generally have very rich food resources.
Characters of an Aquatic Animal:
An aquatic animal should have the ability to swim to overcome the resistance of the surrounding medium.
Therefore, it should have a streamlined body with an organ or ability to float.
The animal should also have to overcome the problem of osmoregulation.
There are two types of animals living in the present day water, which have undergone aquatic adaptation.
According to their origin, they are primary and secondary aquatic animals.
Adaptations to water habitat are of two types:
Primary aquatic adaptations which includes primitive gill-breathing vertebrates (fishes); Those animals, whose ancestors and themselves are living in the water from the very beginning of their evolution, are called primary aquatic animals. In other words, primary aquatic animals never had a terrestrial ancestry. They exhibit perfect aquatic adaptations. All fishes are primary aquatic animals.
Secondary aquatic adaptations which are acquired as in reptiles, birds and mammals. Those animals whose ancestors were lung breathing land animals, migrated to the water for some reason and ultimately got adapted to live in aquatic habitat, are called secondary aquatic animals. Some of them live partially while others live totally in the water. All aquatic reptiles, aves and mammals are representatives of secondary aquatic animals. Amphibians are in a transitional form between primary and secondary aquatic life.
Sensory adaptations like, electroreception for electrolocation and electro communication, olfaction (vomeronasal system), balance (spatial orientation, movement perception), vision (cornea curvature, retinal topography), and hearing (acoustics, ear anatomy) under the underwater sound reception mechanisms in various aquatic amniotes are well developed.
INTRODUCTION
The term urogenital refers to something that has both urinary and genital origins. The word urogenital is used because the urinary and reproductive systems in males merge.
These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways (ex. urethra).
Kidneys and urinary ducts form the urinary system.
The Urinary system performs two important homeostatic processes like excretion and osmoregulation. This system is intimately associated both anatomically, and in terms of embryonic origin with the genital system.
The genital system includes the gonads which generate gametes and the genital ducts that serve as passages for the gametes.
Though functionally different the two organ systems the urinary and the genital system are treated together as the urino- genital system, since both develop from the same segmental blocks of trunk mesoderm or adjacent tissues and share many of the ducts.
Thus although the two systems have nothing common functionally they are closely associated in their use of common ducts and are studied under the broad heading of urinogenital system.
The function of the excretory system is crucial in considering the possible environment of the ‘vertebrate life ’. Several main functions can be attributed to all vertebrate excretory systems:
Excretion of nitrogenous waste products.
Maintaining homeostasis with regard to ions (i.e. salt balance).
Regaining valuable substances (glucose, salts, amino acids, etc.)
Maintaining a physiological osmotic value (i.e. water balance).
The excretory system is formed by a series of paired, segmental nephrons that begin with a nephrostome opening into the coelomic cavity.
A pair of glomeruli per segment, supplied by branches from the aorta, projects into the coelomic cavity close to these nephrostomes.
At a later stage of development, the glomerulus/nephrostome area becomes separated from the rest of the coelomic cavity by an epithelial fold.
The nephrons connect to a duct that is formed by caudal growth of the most anterior nephric tubules. These paired urinary ducts open near the anal region.
Introduction
Ostracoderms (shell-skinned) are of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates.
They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago. They were quite abundant during the upper Silurian and Devonian periods. Most of fossils of Ostracodermi were preserved in the bottom sediments of freshwater streams.
However, the opinion is sharply divided as to whether their habitat was freshwater or marine.
The first fossil fishes that were discovered were ostracoderms.
The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in the 1830s.
The ostracoderms resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them constitute a special group of jawless vertebrates, the Agnatha.
Characteristics: They use gills exclusively for respiration but not for feeding . Earlier chordates with gills used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. mostly small to medium-sized fishes, protected by a heavy, bony dermal (derived from skin) armor. bottom-dwellers; filter-feeders or grazers. no paired fins, but many with stabilizing paired flaps on either side of head.
(1) Ostracoderms were the first vertebrates.
(2) They were popularly called armoured fishes.
(4) They lived in freshwater.
(5) They were bottom dwellers.
(6) Their body was fish-like and did not exceed 30 cm in size.
(7) Paired fins were absent.
(8) Median and caudal fins were present.
(9) The caudal fin was of heterocercal type.
(10) The head and thorax were covered by heavy armour of bones. It protected ostracoderms from the giant scorpion like arthropods, eurypterids.
(11) Bony skull was well developed.
(12) Mouth was mostly present on the ventral side.
(13) They were having large number of gill slits.
(14) The nervous system had 10 pairs of cranial nerves.
(15) The head had a pair of lateral eyes, and a median pineal eye.
(16) They were filter feeders, feeding like a vacuum cleaner.
(17) The endoskeleton was either bony or cartilaginous.
ORIGIN OF CHORDATES
Animal kingdom is basically divided into two sub kingdoms:
Non-chordata- including animals without notochord.
Chordata- This comprising animals having notochord or chorda dorsalis.
Chordates were evolved sometime 500 million years ago during Cambrian period (invertebrates were also began to evolve in this period) .
Chamberlain (1900) pointed out that all modern chordates possess glomerular kidneys that are designed to remove excess water from body.
It is believed that Chordates have originated from invertebrates.
It is difficult to determine from which invertebrate group the chordates were developed.
Chordate ancestors were soft bodied animals. Hence they were not preserved as Fossils.
However, early fossils of chordates have all been recovered from marine sediments and even modern protochordates are all marine forms.
Also glomerular kidneys are also found in some marine forms such as myxinoids and sharks. That makes the marine origin of chordates more believable.
Chordates evolved from some deuterostome ancestor (echinoderms, hemichordates, pogonophorans etc.) as they have similarities in embryonic development, type of coelom and larval stages.
Many theories infers origin of chordates, hemichordates and echinoderms from a common ancestor.
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
INTRODUCTION
The jaw (Upper and lower) is any opposable articulated structure at the entrance of the mouth.
It is typically used for grasping and manipulating food.
Jaw suspension means the fusion of upper jaw and lower jaw or skull for efficient biting.
There are different ways in which these attachments are attained depending upon the modifications in visceral arches in vertebrates.
In most vertebrates, the jaws are bony or cartilaginous and oppose vertically.
The vertebrate jaw is derived from the most anterior two pharyngeal arches supporting the gills, and usually bears numerous teeth.
The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish which further diversified in the Devonian.
It is believed that the hyoid system suspends the jaw from the brain case of the skull, permitting great mobility of the jaws.
The original selective advantage offered by the jaw may not be related to feeding, but rather to increased respiration efficiency.
The jaws were used in the buccal pump (observable in modern fish and amphibians) that pumps water across the gills of fish or air into the lungs in the case of amphibians.
Over evolutionary time the more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified jaws for suction feeding and jaw protrusion, resulting in highly complex jaws with dozens of bones involved.
Jaw Suspension or Suspensoria:
The method by which the upper and lower jaws are suspended or attached from the chondrocranium is known as jaw suspension or suspensorium.
Amongst the visceral arches, the first (mandibular) arch consists of
= a dorsal palato pterygoquadrate bar forming the upper jaw,
= and ventral Meckel’s cartilage forms the lower jaw.
The second (hyoid) arch consists of = a dorsal hyomandibular supporting and suspending the jaws with the cranium, and a ventral hyoid.
The remaining visceral arches support the gills and are, hence, called branchial arches. Thus, splanchnocranium forms the jaws and suspends them with the chondrocranium.
Fishes, amphibians, reptiles, and birds have paired pharyngeal ultimobranchial glands that secrete the hypocalcemic hormone calcitonin. The corpuscles of Stannius, unique glandular islets found only in the kidneys of bony fishes, secrete a peptide called hypocalcin.
DENTITION IN MAMMALS
The study of arrangement structure and number of types of teeth collectively is called as dentition. Teeth are present in the foetal as well as in adults of mammals, based on the presence of teeth Mammals are two types.
Edentata : In some animals teeth are absent hence called as edentate. e.g., Echidna or spiny ant-eater (Tachyglossus) the teeth are absent in all stages of life.
Dentata : Teeth are present in all mammals though a secon¬dary toothless condition is found in some mammals. Modern turtles and birds lack teeth. The adult platypus (Ornithorhynchus) bears epidermal teeth but no true teeth are present. In platypus embryonic teeth are replaced by horny epidermal teeth in adult.
Classification According to the Shape and Size of the Teeth:
Homodont:
Homodont or Isodont type of teeth is a condition where the teeth are all alike in their shape and size in the toothed whales e.g., Pinnipedians. Fishes, amphibians, reptiles and in the extinct toothed birds.
Heterodont
Heterodont condition is the usual feature in mammals, i.e. the teeth are distinguished according to their shape, size and function. The function is also different at different parts of the tooth row.
According to the Mode of Attachment of Teeth:
Thecodont : The teeth are lodged in bony sockets or alveoli of the jaw bone and capillaries and nerves enter the pulp cavity through the open tips of the hollow roots e.g., mammals, crocodiles and in some fishes.
Acrodont: The teeth are fused to the surface of the underlying jawbone. They have no roots and are attached to the edge of the jawbone by fibrous membrane e.g., fishes, amphibians and some reptiles.
Pleurodont:
The teeth are attached to the inner-side of the jawbone. The tooth touches the bone only with the outer surface of its root. In acrodont and pleurodont types of dentition, there are no roots, and nerves and blood vessels do not enter the pulp cavity at the base, e.g., Necturus (Amphibia) and some reptiles.
According to the Succession or Replace¬ment of Teeth:
Introduction
Ostracoderms (shell-skinned) are of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates.
They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago. They were quite abundant during the upper Silurian and Devonian periods. Most of fossils of Ostracodermi were preserved in the bottom sediments of freshwater streams.
However, the opinion is sharply divided as to whether their habitat was freshwater or marine.
The first fossil fishes that were discovered were ostracoderms.
The Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland in the 1830s.
The ostracoderms resembled the present day cyclostomes (lampreys and hagfishes) in many respects and together with them constitute a special group of jawless vertebrates, the Agnatha.
Characteristics: They use gills exclusively for respiration but not for feeding . Earlier chordates with gills used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. mostly small to medium-sized fishes, protected by a heavy, bony dermal (derived from skin) armor. bottom-dwellers; filter-feeders or grazers. no paired fins, but many with stabilizing paired flaps on either side of head.
(1) Ostracoderms were the first vertebrates.
(2) They were popularly called armoured fishes.
(4) They lived in freshwater.
(5) They were bottom dwellers.
(6) Their body was fish-like and did not exceed 30 cm in size.
(7) Paired fins were absent.
(8) Median and caudal fins were present.
(9) The caudal fin was of heterocercal type.
(10) The head and thorax were covered by heavy armour of bones. It protected ostracoderms from the giant scorpion like arthropods, eurypterids.
(11) Bony skull was well developed.
(12) Mouth was mostly present on the ventral side.
(13) They were having large number of gill slits.
(14) The nervous system had 10 pairs of cranial nerves.
(15) The head had a pair of lateral eyes, and a median pineal eye.
(16) They were filter feeders, feeding like a vacuum cleaner.
(17) The endoskeleton was either bony or cartilaginous.
ORIGIN OF CHORDATES
Animal kingdom is basically divided into two sub kingdoms:
Non-chordata- including animals without notochord.
Chordata- This comprising animals having notochord or chorda dorsalis.
Chordates were evolved sometime 500 million years ago during Cambrian period (invertebrates were also began to evolve in this period) .
Chamberlain (1900) pointed out that all modern chordates possess glomerular kidneys that are designed to remove excess water from body.
It is believed that Chordates have originated from invertebrates.
It is difficult to determine from which invertebrate group the chordates were developed.
Chordate ancestors were soft bodied animals. Hence they were not preserved as Fossils.
However, early fossils of chordates have all been recovered from marine sediments and even modern protochordates are all marine forms.
Also glomerular kidneys are also found in some marine forms such as myxinoids and sharks. That makes the marine origin of chordates more believable.
Chordates evolved from some deuterostome ancestor (echinoderms, hemichordates, pogonophorans etc.) as they have similarities in embryonic development, type of coelom and larval stages.
Many theories infers origin of chordates, hemichordates and echinoderms from a common ancestor.
Origin of the Lateral Line System
Lateral line is a canal along the side of a fish containing pores that open into tubes supplied with sense organs sensitive to low vibrations.
Robert H. Denison explained the origin of the lateral line system. He explained that early vertebrates had a pore-canal system in the dermis which functioned as a primitive sensory system in detecting water movement.
Through the evidences from fossils, embryology and comparative anatomy, Denison (1966) established that the inner ear is closely related to the lateral line system. He found a distinct relationship between the pore canal system and the lateral line in Osteotraci.
The inner ear and the lateral line are developed from ectodermal thickenings, called dorso-lateral placodes. These have a number of similarities, including receptors with sensory hairs, and are both innervated by fibers in the acoustico-lateral area of the brain.
The pore canal system is present and developed in Osteostraci (ostracoderm).
It is also present in Heterostraci which is another group of ostracoderms and includes early vertebrates such as lungfishes and crossopterygians.
As its presence is extensive, it is reasonable to suggest that the pore canal system was a primitive character in early vertebrates .
In transverse sections also , it is very difficult to differentiate the pore canal system from a lateral line canal.
Structure of the Lateral Line System
Epidermal structures called neuromasts form the peripheral area of the lateral line.
Neuromasts consist of two types of cells, hair cells and supporting cells.
Hair cells have an epidermal origin and each hair cell has one high kynocyle (5-10 μm) and 30 to 150 short stereocilia (2-3 μm).
The number of hair cells in each neuromast depends on its size, and they can range from dozens to thousands.
Hair cells can be oriented in two opposite directions with each hair cell surrounded by supporting cells.
At the basal part of each hair cell, there are synaptic contacts with afferent and efferent nerve fibers. Afferent fibers, transmit signals to the neural centres of the lateral line and expand at the neuromast base. The regulation of hair cells is achieved by the action of efferent fibers.
Stereocilia and kinocilium of hair cells are immersed into a cupula and are located above the surface of the sensory epithelium.
The cupula is created by a gel-like media, which is secreted by non-receptor cells of the neuromast.
INTRODUCTION
The jaw (Upper and lower) is any opposable articulated structure at the entrance of the mouth.
It is typically used for grasping and manipulating food.
Jaw suspension means the fusion of upper jaw and lower jaw or skull for efficient biting.
There are different ways in which these attachments are attained depending upon the modifications in visceral arches in vertebrates.
In most vertebrates, the jaws are bony or cartilaginous and oppose vertically.
The vertebrate jaw is derived from the most anterior two pharyngeal arches supporting the gills, and usually bears numerous teeth.
The vertebrate jaw probably originally evolved in the Silurian period and appeared in the Placoderm fish which further diversified in the Devonian.
It is believed that the hyoid system suspends the jaw from the brain case of the skull, permitting great mobility of the jaws.
The original selective advantage offered by the jaw may not be related to feeding, but rather to increased respiration efficiency.
The jaws were used in the buccal pump (observable in modern fish and amphibians) that pumps water across the gills of fish or air into the lungs in the case of amphibians.
Over evolutionary time the more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified jaws for suction feeding and jaw protrusion, resulting in highly complex jaws with dozens of bones involved.
Jaw Suspension or Suspensoria:
The method by which the upper and lower jaws are suspended or attached from the chondrocranium is known as jaw suspension or suspensorium.
Amongst the visceral arches, the first (mandibular) arch consists of
= a dorsal palato pterygoquadrate bar forming the upper jaw,
= and ventral Meckel’s cartilage forms the lower jaw.
The second (hyoid) arch consists of = a dorsal hyomandibular supporting and suspending the jaws with the cranium, and a ventral hyoid.
The remaining visceral arches support the gills and are, hence, called branchial arches. Thus, splanchnocranium forms the jaws and suspends them with the chondrocranium.
Fishes, amphibians, reptiles, and birds have paired pharyngeal ultimobranchial glands that secrete the hypocalcemic hormone calcitonin. The corpuscles of Stannius, unique glandular islets found only in the kidneys of bony fishes, secrete a peptide called hypocalcin.
DENTITION IN MAMMALS
The study of arrangement structure and number of types of teeth collectively is called as dentition. Teeth are present in the foetal as well as in adults of mammals, based on the presence of teeth Mammals are two types.
Edentata : In some animals teeth are absent hence called as edentate. e.g., Echidna or spiny ant-eater (Tachyglossus) the teeth are absent in all stages of life.
Dentata : Teeth are present in all mammals though a secon¬dary toothless condition is found in some mammals. Modern turtles and birds lack teeth. The adult platypus (Ornithorhynchus) bears epidermal teeth but no true teeth are present. In platypus embryonic teeth are replaced by horny epidermal teeth in adult.
Classification According to the Shape and Size of the Teeth:
Homodont:
Homodont or Isodont type of teeth is a condition where the teeth are all alike in their shape and size in the toothed whales e.g., Pinnipedians. Fishes, amphibians, reptiles and in the extinct toothed birds.
Heterodont
Heterodont condition is the usual feature in mammals, i.e. the teeth are distinguished according to their shape, size and function. The function is also different at different parts of the tooth row.
According to the Mode of Attachment of Teeth:
Thecodont : The teeth are lodged in bony sockets or alveoli of the jaw bone and capillaries and nerves enter the pulp cavity through the open tips of the hollow roots e.g., mammals, crocodiles and in some fishes.
Acrodont: The teeth are fused to the surface of the underlying jawbone. They have no roots and are attached to the edge of the jawbone by fibrous membrane e.g., fishes, amphibians and some reptiles.
Pleurodont:
The teeth are attached to the inner-side of the jawbone. The tooth touches the bone only with the outer surface of its root. In acrodont and pleurodont types of dentition, there are no roots, and nerves and blood vessels do not enter the pulp cavity at the base, e.g., Necturus (Amphibia) and some reptiles.
According to the Succession or Replace¬ment of Teeth:
Phylum Mollusca-my report..
sorry for some overlapping of texts... i was not able to edit it..it is actually because of the animations that i put it..... i just uploaded it directly :)
This is a ppt on the Anamalia Kingdom. made by :-
Anushka Mukherjee
Riddhima Ghosh Roy
Sameeha Pathan
Shruti Ugalmugale
Akaanksha Kadam
from Vibgyor High School NIBM,Pune, Maharashtra, India
Water pollution is a threat to aquatic organisms, including fish, and is a global concern for aquatic biodiversity and ecosystem integrity. This study evaluates the effect of waterborne pollutants on Gangetic Mystus (Mystus cavasius) collected from Chambal River at Nagda, Ujjain. Mystus appeared to be a useful biomarker to assess the impact of toxicity of water pollution.
Zooplankton are the animal component of the plankton community. They are heterotrophic, meaning they can't make their own food and must eat other organisms. In particular, they eat phytoplankton, which are generally smaller than zooplankton.11 species of zooplankton were found in the Shivna River. The most abundant species were copepods Oithona similis, Paracalanus sp., and Calanus sinicus.The species composition of zooplankton varies by season. The highest number of species were found in winter, followed by autumn, summer, and spring. The highest abundance of zooplankton was found in summer, and the lowest in post-monsoon.
This presentation explores how climate change alters the pursuit of economic development: the transformation of poor economies and their people into prosperous ones.
This is hardly the first attempt to reconcile the climate agenda with that of economic development. The United Nations’ Sustainable Development Goals are significant for defining a dual agenda where development targets for people and planet sit alongside each other in a unifying framework.1 Much commentary focuses on the compatibility of the two agendas. A radical and specious view pits progress on climate change and economic development as strict substitutes and calls for no less than the unravelling of economic development to save the planet.2 Cooler heads point instead to their complementarity: the critical role of economic development in supporting adaptation and the recognition that investments in the green transition will propel economies rather than sacrifice living standards.3
In contrast, this essay takes as its starting point that the goals and salience of economic development are immutable. The question posed here is how the quest for economic development changes in a world gripped by a changing climate. The essay argues that climate change will force three major changes: a reappraisal of the causes of and prospects for development, the rebirth of the economics of transition, and a reformulation of the problem development is trying to solve. In a final section, it asks what these changes could mean for international security and for the community of national and global actors who set policy and strategy in this field.
Climate change refers to long-term shifts in temperatures and weather patterns. Such shifts can be natural, due to changes in the sun’s activity or large volcanic eruptions. But since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels like coal, oil and gas.
Burning fossil fuels generates greenhouse gas emissions that act like a blanket wrapped around the Earth, trapping the sun’s heat and raising temperatures.
The main greenhouse gases that are causing climate change include carbon dioxide and methane. These come from using gasoline for driving a car or coal for heating a building, for example. Clearing land and cutting down forests can also release carbon dioxide. Agriculture, oil and gas operations are major sources of methane emissions. Energy, industry, transport, buildings, agriculture and land use are among the main sectors causing greenhouse gases.
In India, bacteria that cause common infections, such as urinary tract and bloodstream infections, are becoming resistant to nearly all antibiotics. This resistance is due to a combination of factors: uncontrolled access to antibiotics, gaps in infection prevention and control (IPC) practices, and high rates of communicable diseases. Antibiotic resistance, or AR, is a serious problem throughout the country, and threatens to reduce the usefulness of antibiotics both in India and around the world.
Because of this emerging threat, India is committed to slowing the spread of AR. Two institutions within India’s Ministry of Health – the Indian Council of Medical Research and National Centre for Disease Control – each developed national networks of public and private hospitals to measure AR trends, prevent healthcare-associated infections (HAIs), and enhance appropriate use of antibiotics. The All India Institute of Medical Sciences is coordinating HAI measurement and prevention efforts in both networks. In addition, efforts in the state of Tamil Nadu focus on building district-level IPC capacity to prevent HAIs, focusing on maternal and neonatal patients.
The Indian Governamnet is is working closely with partners at the national and state level to:
Detect AR pathogens, including novel strains, by developing lab networks and lab expertise.
Use standardized surveillance to monitor and track AR infections in healthcare to learn how often these infections occur and to help develop strategies to prevent them.
Implement focused IPC activities and training.
Optimize use and reduce misuse of critical antibiotics through antibiotic stewardship programs.
Physiological and histopathological effects of Bisphenol A .Bisphenol A is less soluble in water. For that reason, dimethyl sulfoxide (DMSO) was used as a medium to obtain proper distribution in the test solution (Chen, J., et al, 2015). Working solution of commercial grade Bisphenol A (97% pure) was prepared by dilution of stock solution double distilled water immediately prior to experimental use. Serial dilutions of the stock solution were prepared using previously aerated, copper free and stored tap water. The water was continuously aerated. This was prepared by dissolving BPA (50mg) in 100ml of DMSO and the desired concentrations of BPA in tap water were prepared by adding appropriate volumes of this stock solution into test aquarium. A static non-renewable bioassay was conducted in triplicate for each concentration with four animals in each tub. No water exchange was done and the fishes were not fed during the period of the experiment. Percentage mortality was recorded at 12, 24, 48, 72 and 96 h interval. Control group was subjected to acetone at the maximum acetone volume used in the dilution of the dose concentrations. The range of LC50 for H.fossilis (mean wt. 36.78 g) under given conditions was determined to lie between 5 and 10 mg/L for BPA. Hence, for the definitive test, concentrations such as 2, 4, 6, 8, 10, 12, and 14 mg/L of BPA concentration were selected. The test was conducted in triplicate for each concentration with 10 fishes in each tank. At the end of 96 h, the fishes that had survived were anesthetized with clove oil at 100 mg/L, sampled for blood, and processed for hematological analysis. The data obtained from the experiment was processed by probit analysis using a Microsoft Excel computer program.
When pollutants are discharged from a specific location such as a drain pipe carrying industrial effluents discharged directly into a water body it represents point source pollution.
In contrast, non-point sources include discharge of pollutants from diffused sources or from a larger area such as runoff from agricultural fields, grazing lands, construction sites, abandoned mines and pits, etc.
Targets of Sustainable Development Goal 3
WHO Framework Convention on Tobacco Control; support research, development and universal access to affordable vaccines and medicines; increase health financing and support health workforce in developing countries
INTRODUCTION
Toxicology is the science of the poisons. It also studies the nature, effects, detection, assessment and treatment of their effects on biological material.
Toxicology is a multidisciplinary science. The ultimate objective of the combined research is to determine how an organism is affected by exposure to an agent.
This includes an understanding of:
How the agent moves and interact with living cells and tissues of the organism;
What parts of the organism are affected by its presence and health outcomes of this exposure.
Evaluation of the toxicity of substances whose biological effects may not have been well characterized.
The influence of chemical toxicity is mainly
determined by the dosage, duration of exposure,
route of exposure, species, age, sex, and environment.
The goal of toxicology is to contribute to the
general knowledge and harmful actions of
chemical substances.
2. to study their mechanisms of action,
3. and to estimate their possible risks to humans
HISTORY
Dioscorides, a Greek physician in the court of the Roman emperor Nero, made the first attempt to classify plants according to their toxic and therapeutic effect. Poisonous plants and animals were recognized and their extracts used for hunting or in warfare.
In 1500 BC people used hemlock, opium, arrow poisons, and certain metals to poison enemies or for state executions.
Theophrastus Phillipus Auroleus Bombastus von Hohenheim (1493–1541) (also referred to as Paracelsus, a Roman physician from the first century) is considered "the father" of toxicology.
He stated that "All things are poisonous and nothing is without poison; only the dose makes a thing not poisonous.“
Mathieu Orfila (1813) is considered the modern father of toxicology.
In 1850, Jean Stas became the first person to successfully isolate plant poisons from human tissue.
Hippolyte Visart de Bocarmé used nicotine to kill his brother-in-law. He extracted nicotine from tobacco leaves.
The 20th and 21st Centuries have marked by great advancements in the level of understanding of toxicology. DNA and various biochemicals that maintain body functions have been discovered. Our level of knowledge of toxic effects on organs and cells has expanded to the molecular level.
Central nervous system: The central nervous system consists of the brain and spinal cord. The brain plays a central role in the control of most bodily functions, including awareness, movements, sensations, thoughts, speech, and memory. Some reflex movements can occur via spinal cord pathways without the participation of brain structures. The spinal cord is connected to a section of the brain called the brainstem and runs through the spinal canal.
Peripheral Nervous System: Nerve fibers that exit the brainstem and spinal cord become part of the peripheral nervous system. Cranial nerves exit the brainstem and function as peripheral nervous system mediators of many functions, including eye movements, facial strength and sensation, hearing, and taste.
The autonomic nervous system: The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions, such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. This system is the primary mechanism in control of the fight-or-flight response.
The autonomic nervous system comprises two antagonistic sets of nerves, the sympathetic and parasympathetic nervous systems. The hypothalamus is the key brain site for central control of the autonomic nervous system, and the paraventricular nucleus is the key hypothalamic site for this control.
Divisions of Nervous System:
The vertebrate nervous system has three divisions:
(i) A central nervous system comprising the brain and spinal cord. Its function is to receive the stimulus from the receptors and transmit its response to the effectors. Thus, it coordinates all the functions of the body.
(ii) A peripheral nervous system consisting of cranial and spinal nerves arising from the brain and spinal cord respectively. It forms a connecting link between the receptors, central nervous system (CNS) and effectors.
(iii) An autonomic nervous system made of two ganglionated sympathetic nerves, ganglia in the head and viscera, and their connecting nerves. The autonomic nervous system is often regarded as a part of the peripheral nervous system because the two are connected. But all the three divisions of the nervous system are connected intimately both structurally and functionally.
The vertebrate brain
The vertebrate brain is the main part of the central nervous system. The brain and the spinal cord make up the central nervous system,
In most of the vertebrates the brain is at the front, in the head. It is protected by the skull and close to the main sense organs.
Brains are extremely complex and the part of human and animal body. The brain controls the other organs of the body, either by activating muscles or by causing secretion of chemicals such as hormones and neurotransmitters.
Muscular action allows rapid and coordinated responses to changes in the environment.
The brain of an adult human weights about 1300–1400 grams .
In vertebrates, the spinal cord by itself can cause reflex responses as well as simple movement such as swimming or walking. However, sophisticated control of behaviour requires a centralized brain.
The structure of all vertebrate brains is basically the same.
At the same time, during the course of evolution, the vertebrate brain has undergone changes, and become more effective.
In so-called 'lower' animals, most or all of the brain structure is inherited, and therefore their behaviour is mostly instinctive.
In mammals, and especially in man, the brain is developed further during life by learning. This has the benefit of helping them fit better into their environment. The capacity to learn is seen best in the cerebral cortex.
Three principles
The brain and nervous system is essentially a system which makes connections. It has input from sense organs and output to muscles. It is connected in several ways with the endocrine system, which makes hormones, and the digestive system and sex system. Hormones work slowly, so those changes are gradual.
The brain is a kind of department store. It has, all inter-connected, departments which do different things. They all help each other gather senses.
Much of what the body does is not conscious. Basically, much of the body runs on automatic (breathing, heart beat, hungry, hair growth) adjusted by the autonomic nervous system. The brain, too, does much of its work without a person noticing it. The unconscious mind refers to the brain activities which are hardly ever noticed.
Abstract: Soil contamination with heavy metals is a serious global concern due to their toxicity and bioaccumulation property. The present investigation was aimed to assess heavy metal contamination of agricultural soil around the polluted zone of the Chambal River at Nagda, Ujjain (M.P, India). Soil samples were collected at three sites S1, S2, and S3 alongside of Chambal River in December 2019 and analyzed for heavy metals like Cr, Ni, Cd, Pb, and Zn by atomic absorption spectrophotometer (AAS) methods. The Igeo results revealed that the study area has fallen in the category of uncontaminated and moderately contaminated with Cd and Pb in all study stations. Essential compositions were evaluated through the estimation of geochemical accumulation indices to find out the heavy metal contamination of soil. Significant enrichment of the soil with Cd, Zn, Cu, Ni, and Pb was observed in all study stations. The S1 station exhibited the highest concentrations of heavy metals in soil. The present outcome is useful for mitigating the impact of metallic pollution on environmental health and required strategies to prevent such effects.
Keywords: Chambal River, Geo-Accumulation Index, Heavy Metals, Industrial Pollution, Soil Quality.
The male and female reproductive systems develop initially embryonically "indifferent", it is the product of the Y chromosome SRY gene that makes the "difference".
♂ - Male ♀ - Female
The reproductive organs are developed from the intermediate mesoderm.
The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before the end of fetal life.
These embryonic structures are the mesonephric ducts (also known as Wolffian ducts) and the paramesonephric ducts, (also known as Müllerian ducts). The mesonephric duct remains as the duct in males which gives rise to seminal vesical, epididymes and vas deferens, and the paramesonephric duct as that of the female.
Importantly its sex chromosome dependence, late embryonic/fetal differential development, complex morphogenic changes, long time-course, hormonal sensitivity and hormonal influences make it a system prone to many different abnormalities.
Gonads:
Gonads Produce eggs and sperm cells, transport and sustain egg and sperm cells, nurture developing offspring, and produce hormones.
The gonads, ovary or testis, also develop in the intermediate mesoderm.
They originally form as swellings that lie just ventral to the anterior mesonephric kidney.
A mullarian duct also develops in the intermediate mesoderm near the mesonephric duct.
Due to fusion or failure of 1st ridge to differentiate, some vertebrates (agnathans, some female lizards & crocodilians, & most female birds) have a single testis or ovary.
Hormones cause differentiation of early gonads into either testes or ovaries.
As males develop the mesonephric duct makes connection with the testis as the primary sperm conducting duct, and the mullerian duct is lost.
Chemoreceptors
Chemoreceptors or organs of chemical sense consist of olfactory organs and organs of taste. Both these organs are stimulated only by chemical substances or odours in air (nostrils) and in solution (tongue).
The medium for dissolving substances for taste is water for aquatic animals and mucus for land animals.
The olfactory organs can respond to a low concentration of the dissolved substance, whereas organs of taste need a higher concentration of the dissolved substance for a response.
Olfactory Organs in Vertebrates:
Odours bind to and activate olfactory receptors located on the dendrites of sensory neurons in the nose. Olfactory organs (olfactory-receptors) are a pair of invaginations of the ectodermal cells of the skin forming olfactory sacs on the anterior end of head.
Their external openings are called nostrils or nares.
In most fishes the olfactory organs consist of a pair of pits lined with folds or ridges of sensory epithelium.
The cyclostomes have a single median olfactory organ. This is a blind pit in the lampreys, but in hagfishes it opens into the pharynx.
Dipnoans resemble higher vertebrates in possessing paired nasal passages that open by means of choanae into pharynx. The nasal passages, therefore, have both internal and external openings. The olfactory epithelium within canals appears in the form of folds.
Sensory systems consist of peripheral receptor cells and integrating neurons in the brain.
Impulses are transmitted from receptors by sensory fibres to the central nervous system where they are interpreted as sensations or messages, which are sent to effector organs through efferent or motor nerve fibres, for responding in an appropriate manner.
A vertebrate has receptors or sense organs for touch, smell, taste, sight, and hearing, which are stimulated by the environment. These sense organs are termed external receptors or exteroceptors.
There are other sense organs found in the body, which detect temperature, pain, hunger, thirst, fatigue, and muscle position. They are spoken of as internal receptors or interoceptors.
Besides these two, third is proprioceptors, which are stretch receptors found in the muscles, joints, tendons, connective tissue and skeletons. All receptors are closely associated with the nervous system and respond to external or internal stimuli.
List of Common Senses:
1. Touch.- It includes contact, pressure, heat and cold, etc.
2. Taste. -Receive stimulus by chemicals in solution.
3. Smell.- Receive volatile chemicals and gases in air.
4. Hearing.- Receive sound vibrations.
5. Sight. -Receive light waves.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
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1. General characteristics and organization
of early Gnathostomes
Dr. P.B.Reddy
M.Sc,M.Phil,Ph.D, FIMRF,FICER,FSLSc,FISZS,FISQEM
PG DEPARTMENT OF ZOOLOGY
GOVERTNAMENT PG COLLEGE, RATLAM.M.P
reddysirr@gmail.com
2.
3. Introduction
Gnathostomata are the jawed vertebrates. (gnathos= "jaw" + (stoma)="mouth".
It comprises roughly 60,000 species. (99% of all living vertebrates).
Living gnathostomes have teeth, and paired appendages.
A horizontal semicircular canal is present in the inner ear.
Myelin sheaths is present on the neurons.
Adaptive immune system uses V(D) J recombination ( it is the mechanism of somatic
recombination that occurs only in developing lymphocytes during the early stages of T and B cell
maturation. VDJ recombination is the process by which T cells and B cells randomly assemble
different gene segments – known as variable (V), diversity (D) and joining (J) genes – in order to
generate unique receptors (known as antigen receptors) that can collectively recognize many
different types of molecule. While Agnatha (petromyzon and hagfish) use genetic recombination
in the variable lymphocyte receptor gene.
It is now assumed that Gnathostomata evolved from ancestors that already possessed a pair
of both pectoral and pelvic fins.
In addition to this, some placoderms were shown to have a third pair of paired appendages,
that had been modified to claspers in males and basal plates in females—a pattern not seen in
any other vertebrate group.
It is believed that the jaws evolved from anterior gill support arches that had acquired a new
role, being modified to pump water over the gills by opening and closing the mouth more
effectively – the buccal pump mechanism.
4. • Presence of Calcified, bony skull and vertebra are the characteristic
features of Gnathostomata (fishes, amphibians, reptiles, birds and
mammals).
•Pelvic fins are situated just in front of the anus.
•Interventrals and basiventrals present in the backbone. These are the
elements of the backbone which lie under the notochord, and match
the basidorsals and interdorsals respectively.
•Gill arches which lie internally to the gills and branchial blood vessels,
contrary to the gill arches of all jawless craniates, which are external to
the gills and blood vessels.
•A horizontal semicircular canal in the inner ear.
• Paired nasal sacs which are independent from the hypophysial tube.
• There are numerous other characteristics of the soft anatomy and
physiology (e.g. myelinated nerve fibres, sperms passing through
urinary ducts, etc.), which are unique to the gnathostomes among
extant craniates, but cannot by observed in fossils.
5. Classification of Gnathostomata:
The classification of gnathostomes is a
major field of controversy among
authors. The present classificatory
scheme of Gnathostoma adopted here
is that of J.Z. Young (1981).
Fishes:
Living fishes with jaws mostly fall into
two well marked classes, the
cartilaginous fishes (Chondrichthyes)
and the bony fishes (Osteichthyes)
including the familiar ray- finned fishes
and the lung fishes.
These two groups arose in the late
Devonian period of geological time
scale. Before that time various other
types of fish dominated the waters.
6. Class — Placodermii: (plate-skinned)
All the fishes of this group are extinct.
Their epidermis were covered by heavy bony plates.
Instead of gill slits they possessed spiracles for respiration.
Were lived from the late Silurian to the end of the Devonian Period.
Their head and thorax were covered by articulated armoured plates and
the rest of the body was scaled or naked, depending on the species.
Placoderms were among the first jawed fish; their jaws likely evolved
from the first of their gill arches.
7. Class — Chondrichthyes: It includes jawed fishes having a cartilaginous skeleton. The class includes a diverse
group of fishes including sharks, rays, skates and chimaeras. They are mostly marine fishes.
1. Chondrichthyes characteristics
They are mostly marine fishes and cold blooded. They contain a pair of powerful jaws.
The mouth is present ventrally.
They contain cartilaginous endoskeleton, the deposits of calcium salts provide strength to it.
The notochord is present throughout life.
Most of them contain a heterocercal tail. Vertebrae extends into it.
The skin is covered by minute tooth-like structures called placoid scales.
Their teeth are modified placoid scales and are not attached to jawbones. They are embedded in the
tissue. Old teeth fall and are continuously replaced by the new teeth formed behind it.
They contain 5-7 pairs of gills. They lack air bladders so they swim actively to avoid sinking.
They are predatory fishes, they feed on other fishes, crustaceans and molluscs.
The heart is two-chambered, contains one auricle and one ventricle.
They contain a brain and a spinal cord, which is protected by vertebrae.
Sense organs are well developed. They have the ability to detect their prey electrically. Sharks contain
electroreceptors on their head, which helps them in navigation.
It also has sensory cells in the lateral line organ, which detect all the kinds of vibration, motion, water
pressure surrounding them.
Some of them possess electric organs or poison sting, which are used for defence as well as predation.
The digestive system comprises a mouth, pharynx, stomach, intestine (straight) and cloaca present on the
ventral side. Cloaca has a dual function in females and also acts as a reproductive organ apart from
excretion.
Male and females are separate and have internal fertilization.
Skates and some sharks are oviparous, most of the sharks are ovoviviparous and a few are viviparous.
Adult males bear claspers on their pelvic fins. These are used to transfer sperms to the cloaca of a female.
8. Elasmobranchii:
Swim bladders are absent. However elasmobranchs maintain buoyancy with large livers that
are full of oil. This stored oil may also function as a nutrient when food is scarce. Deep sea sharks
are usually targeted for their oil, because the livers of these species can weigh up to 20% of their
total weight.
Five to seven pairs of gill clefts opening individually to the exterior.
Skin is covered by plocoid scales.
The teeth are in several series.
The upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper.
Jaw suspensions are of amphistyly, orbitostyly, hyostyly, and euhyostyly.
The eyes have a tapetum lucidum (is a biologic reflector system that enhancing visual
sensitivity at low light levels) .
Claspers are present in the inner margin of each pelvic fin in the male fish.
These fish are widely distributed in tropical and temperate waters.
9. Subclass — Holocephali:
General characters:
1. The earliest fossils are of teeth and come from the Devonian period.
This group includes the rat fishes in the genus Chimaera, and the elephant fishes in the genus
Callorhinchus.
Pectoral fins are large.
The erectile spine in front of the dorsal fin is sometimes venomous.
Tail is long, thin and slender.
Live close to the seabed feeding on benthic invertebrates.
They lack a stomach, food moving directly into the intestine.
Small mouth aperture is guarded by jaws and lips.
Plate like teeth firmly attached with the jaws.
Holostylic upper jaw, i.e. rigidly attached to the skull.
Gill slit partially covered by operculum.
Cloaca absent, i.e., anus and urinogenital aperture separate.
Skin is naked in adults.
In addition to pelvic clasper males possess another clasper on the head.
Spiracle absent.
Examples:
Chimaera (Rat fish)(Fig. 1.27D), Callorhynchus, Harriotta.
10. Osteichthyes
Osteichthyes is a class of jawed fishes (Gnathostomata) having a bony
endoskeleton. It is the largest class of vertebrates and includes a diverse
group of marine and freshwater bony fishes.
The vast majority of fish are osteichthyes, which is an extremely diverse
and abundant group consisting of 45 orders, with over 435 families and
28,000 species.It is the largest class of vertebrates in existence today.
Osteichthyes is subdivided into three subclasses:
1. Acanthodii: (Acanthodii, or spiny sharks). They are a class of extinct
fishes, sharing features with both bony and cartilaginous fishes. They
resembled sharks, but their epidermis was covered with tiny rhomboid
platelets. They have a cartilaginous skeleton, but their fins had a wide,
bony base. Ex: Acanthodes bronni.
2. Actinopterygii- ray-finned fish: Their fins are webs of skin supported by
bony or horny spines ("rays"), hence called ray finned fish. Fin rays attach
directly to the proximal or basal skeletal elements of pelvic and pectoral
girdles. They are ubiquitous throughout freshwater and marine
environments from the deep sea. Ex: Sea horse.
3. Sarcopterygii (Crossopterygii)- lobed finned fish: Sarcopterygii sometimes
considered synonymous with Crossopterygii. Fins are fleshy and lobed. Fins
are borne on a fleshy, lobe like, scaly stalk extending from the body.
Pectoral and pelvic fins have articulations resembling those of tetrapod
limbs. Most species of lobe-finned fishes are extinct. The living non-
tetrapod sarcopterygians include two species of coelacanths and six
species of lungfish.
11. Dipnoi: Distribution, Morphology and Affinities
Structure of Dipnoi:
Dipnoi (Gr. di-two, pnoe-breathing) is a small order of fresh water bony fishes.
They respire by gills and lungs. Dipnoi evolved during Devonian period.
They are characterized by short jaws, crushing plate from teeth, internal nares, reduced exo-
and endo- skeleton, and diphycercal tail.
The air bladder i.e., so called ‘lungs’ are one or two. They are functional with related changes
in the circulatory system and in the heart.
Distribution of Dipnoi:
Fossil evidence support to the view that once dipnoans enjoyed cosmopolitan (worldwide)
distribution. Two fossil forms are Dipterus from Devonian period and Ceratodus from Triassic
period. But the modern lung fishes show discontinuous distribution.
The three surviving genera of lung fishes are Neoceratodus (=Epiceratodus) Protopterus and
Lepidosiren.
All they are inhabitants of river. But Protopterus lives in large lakes too. They all breath air.
Neoceratodus is found only in the Burnett and Mary rivers of Queens-land in Australia, so
commonly called as ‘Burnett Salmon’ or Australian lungfish.
Neoceratodus is the only living genus of the family Ceratodontidae, the other being extinct
Ceratodus.
Protopterus lives in large lakes and rivers of tropical Africa. It is commonly called as Nile
lungfish’ or African lung fish.
Lepidosiren is found in river Amazon and Paraguay basin in South America. It is commonly
called as ‘Amazon lungfish’ or South American lungfish.
12. Morphology of Dipnoi:
1. Neoceratodus forsteri:
The body of Dipnoi is elongated and compressed measuring about 90 to 150
cms.
The body surface including the head and paired fins is covered with thin, bony,
overlapping cycloid scales which are not regarded as denticles.
Paired fins are lobe like paddles, enabling the fish to crawl over the bottom. But
these are weak to support the fish outside water.
The fish has a diphycercal tail with symmetrical tail fin. Tail fin rays are un-
jointed and fibrous. External nostrils lie enclosed within the upper lip. Internal
nostrils (choanae) are present.
Branchial arches are four in number and bi-segmented.
The first four branchial arches carry holobranches. Gills are covered with bony
opercula.
A lateral line is present.
Lower jaw is with a small toothless dentary on each side. Dental plates are oval
crescentic or triangular terminating in a smooth or feebly denticulated biting
margins.
Neoceratodus is inactive and sluggish in habit, usually lying motionless on the
bottom. It is carnivorous and feeds on fresh water crustaceans, worms and
molluscs.
13. 2. Protopterus has four species.
The body is elongated, cylindrical and more or less eel-like.
It grows to a length of about 200 cms.
Body is covered over by over-lapping cycloid scales.
The pectoral and pelvic fins are represented as limbs.
They are long, thin and filamentous and help in walking along the bottom.
The caudal fin and its supporting fleshy lobe taper to a posterior point i.e. it is isocercal or
protocercal. The mouth is small.
The dorsal anal and tail fins are continuous and are supported by partially calcified fibre-
like rays called camptotricha. Inside the mouth margin internal nostrils are present.
The fleshy lips extend back on the sides of the head.
The eyes are small.
Six branchial arches and five gill slits are covered by operculum.
The opercular opening is limited to a slit just in front of the pectoral fin.
Gills are weakly developed.
The lateral line system is well developed.
The cloacal opening lies ventrally at the root of the tail and close to it are two abdominal
pores.
Protopterus is a carnivores and voracious feeder.
It feeds on worms, crustaceans, insects, frogs and many other small animals.
During un-favourable seasons it undergoes summer sleep or aestivation and burrow into
the soil to a depth of about 60 cms for atleast 6 months in waterproofed “cocoon” made of
clay and mucus.
14. 3. Lepidosiren paradoxa:
Body is elongated, cylindrical and more or less eel-like.
It grows to the length of about 125 cms.
The skin covering the body contains very small cycloid scales.
Gill slits are 5 pairs covered with operculum.
Gills are weakly developed, respiration is supplemented with two lungs
(Dipneumona).
Paired fins are thin and filamentous. Dorsal and caudal fins are united.
Pelvic fin have vascular filamentous in male during breeding season.
Eyes are moderate and well developed like Neoceratodus.
External (cutaneous) gills are absent in adult but present in larva.
Like Protopterus, they survive drought by secreting mucous cocoons in mud.
During aestivation the air bladder is used as lungs.
Lepidosiren is not exclusively carnivorous, food mainly comprises fresh snails
and mass of algae.
15. Affinities of Dipnoi:
Presence of the lungs in Dipnoi lead to the view that they are the ancestors of
amphibia. Other-words, they were considered as the connecting link between
Pisces and Amphibia. This view is no more supported. Present view is to treat them
as a specialized or degenerate descendants of the more primitive lobe-finned fishes
to which they closely resemble.
The affinities of Dipnoi can be studied under following heads:
1. Affinities with fishes:
Lung fishes are undoubtedly true fishes.
(a) Affinities with fishes in general:
1. Spindle-shaped, eel-like body.
2. Body covered with scales (Cycloid).
3. Presence of paired fins.
4. Diphycercal caudal fins.
5. Persistent notochord.
6. Skull with little ossification.
7. Paired gill-slits.
8. Branchial respiration.
9. Lateral line sense organs.
16. 2. Affinities and Dissimilarities with Amphibians:
(a) Affinities:
1. Semi aquatic habitat.
2. Internal nostrils
3. Vomerine teeth.
4. Autostylic jaw suspensorium.
5. Multicellular cutaneous glands.
6. Cutaneous gill in larva.
7. Pulmonary respiration.
8. Dermal scales as in Apoda.
9. Auricle and sinus venosus partially divided.
10. Ventral aorta short or absent
11. Presence of anterior abdominal vein, posterior vena cava, pulmonary artery and veins.
12. Thin walled pericardium.
13. Long and narrow cerebral hemispheres.
14. Similar structure of egg and development
(b) Dissimilarities:
1. Paired lobate-fins
2. Maxillae and premaxillae are absent.
3. Peculiar crushing tooth plates.
4. Few anterior vertebrae fused with skull.
5. Cartilagenous skull.
6. Lungs lie dorsal to gut.
7. Urinary bladder from dorsal wall of cloaca.
17. 3. Primitive Characters:
1. Unconstricted notochord.
2. Presence of cloaca.
3. Spiral valves in intestine.
4. Valves in the conus.
4. Specialized characters:
1. Premaxillae and maxillae absent
2. Anterior dorsal fin reduced or absent
3. Dental plate in jaws.
4. Cartilagenous cranium without ossification.
5. Reduction in number of dermal bones of skull.
6. Thin cycloid scales by modification of thick cosmoid scale.
7. Fusion of anterior vertebrae with skull.
8. Functional dorsally placed air bladder.
5. Conclusion:
The above affinities indicate that dipnoans are not most advanced Pisces from which
amphibians could evolve. They are degenerate descendants of Crossopterygii. According to
Jarvik (1968) dipnoans are more specialized than crossopterygian. According to latest view,
both dipnoans and amphibians have originated from some crossopterygian like ancestor.
There must have been a common ancestor for Dipnoi, Crossopterygii and Labyrinthodont
amphibia. So most probably, dipnoans are not the “fathers of the amphibia”, but “uncles of
the amphibian”.
18. Sarcopterygii or Crossopterygii (class Osteichthyes) : Sarcopterygii sometimes considered
synonymous with Crossopterygii. Subclass of bony fish comprising both fossil and living lobe-
finned or tassel-finned fish, including the Coelacanthiformes and Rhipidistia.
The Rhipidistia did become extinct, although not before they gave rise, in the Devonian, to the
amphibians.
The Crossopterygii are characterized by the fact that all fins (except the tail-fin) are based on
movable stalks or lobes. The tail fin is either heterocercal or diphycercal.
Early lobe-finned fishes are bony fish with fleshy, lobed, paired fins, which are joined to the
body by a single bone.
The fins of lobe-finned fishes differ from those of all other fish in that each is borne on a fleshy,
lobe like, scaly stalk extending from the body.
The morphology give indications of the transition from water to terrestrial life.
Pectoral and pelvic fins have articulations resembling those of tetrapod limbs.
The first tetrapod land vertebrates, basal amphibian organisms, possessed legs derived from
these fins. Sarcopterygians also possess two dorsal fins with separate bases.
The braincase of sarcopterygians primitively has a hinge line, but this is lost in tetrapods and
lungfish. Many early sarcopterygians have a symmetrical tail.
All sarcopterygians possess teeth covered with true enamel.
Most species of lobe-finned fishes are extinct. The largest known lobe-finned fish was
Rhizodus hibberti from the Carboniferous period of Scotland which may have exceeded 7 meters
in length. Among the two groups of extant (living) species, the coelacanths and the lungfishes,
the largest species is the West Indian Ocean coelacanth, reaching 2 m (6 ft 7 in) in length and
weighing up 110 kg (240 lb). The largest lungfish is the African lungfish which can reach 2 m
(6.6 ft) in length and weigh up to 50 kg (110 lb).