1) The anterior-posterior polarity of the Drosophila embryo is established by maternal mRNA gradients that are deposited in the egg during oogenesis.
2) Key maternal mRNAs - bicoid, hunchback, nanos, and caudal - establish protein gradients in the early embryo that determine its anterior-posterior axis. Bicoid mRNA is localized to the anterior pole and translates into a Bicoid protein gradient, while nanos mRNA is localized to the posterior pole and translates into a Nanos protein gradient.
3) These opposing Bicoid and Nanos gradients regulate the translation of hunchback and caudal mRNA, producing complementary Hunchback and Caudal protein gradients along the anterior-
Introduction
About Drosophila
Genome of Drosophila
Life cycle
Differentiation
Development of Drosophila
* Embryonic development
* Dorsal -ventral and
* Anterior posterior development
* Body segmentation
* Homeotic gene
Conclusion
Reference
Polyspermy describes an egg that has been fertilized by more than one sperm. Diploid organisms normally contain two copies of each chromosome, one from each parent. The cell resulting from polyspermy
The first issue that an egg and a sperm of any organism type face in successfully producing an embryo is the possibility of polyspermy. Polyspermy is the fertilization of an egg by multiple sperm, and the results of such unions are lethal.
If multiple sperm fertilize an egg, the embryo inherits multiple paternal centrioles. This causes competition for extra chromosomes and results in the disruption of the creation of the cleavage furrow, thus causing the zygote to die. As an important model organism in the study of fertilization and embryonic development, polyspermy in sea urchins has been studied in detail. The sea urchin’s methods of polyspermy prevention have been broken down into two main pathways. These two primary pathways are known as the fast block and the slow block to polyspermy
After the sperm’s receptors come into contact with the egg’s jelly layer and the acrosomal enzymes are released and break down the jelly layer, the sperm head comes into contact with the vitelline and plasma membranes of the egg. When the two plasma membranes contact one another, signals in the egg are initiated.
First, Na+ channels in the egg open, allowing Na+ to flood into the egg. This causes a depolarization of the egg from it’s normal resting potential of -70 mV.
While depolarization is occurring, the remainder of the jelly layer is dissolving. With the dissolution of the jelly layer and the depolarization of the plasma membrane, the first block to preventing fertilization by multiple sperm is put into place.
These two simple changes are part of the first block to polyspermy, known as the fast block. Within 1/10th of a second of contact, the fast block t
Slides about Cell Fate, Cell Potency, Differentiation, Specification, Modes of Specification, Role of Cytoplasm. Cell Interactions, Regulation in Development
Introduction
About Drosophila
Genome of Drosophila
Life cycle
Differentiation
Development of Drosophila
* Embryonic development
* Dorsal -ventral and
* Anterior posterior development
* Body segmentation
* Homeotic gene
Conclusion
Reference
Polyspermy describes an egg that has been fertilized by more than one sperm. Diploid organisms normally contain two copies of each chromosome, one from each parent. The cell resulting from polyspermy
The first issue that an egg and a sperm of any organism type face in successfully producing an embryo is the possibility of polyspermy. Polyspermy is the fertilization of an egg by multiple sperm, and the results of such unions are lethal.
If multiple sperm fertilize an egg, the embryo inherits multiple paternal centrioles. This causes competition for extra chromosomes and results in the disruption of the creation of the cleavage furrow, thus causing the zygote to die. As an important model organism in the study of fertilization and embryonic development, polyspermy in sea urchins has been studied in detail. The sea urchin’s methods of polyspermy prevention have been broken down into two main pathways. These two primary pathways are known as the fast block and the slow block to polyspermy
After the sperm’s receptors come into contact with the egg’s jelly layer and the acrosomal enzymes are released and break down the jelly layer, the sperm head comes into contact with the vitelline and plasma membranes of the egg. When the two plasma membranes contact one another, signals in the egg are initiated.
First, Na+ channels in the egg open, allowing Na+ to flood into the egg. This causes a depolarization of the egg from it’s normal resting potential of -70 mV.
While depolarization is occurring, the remainder of the jelly layer is dissolving. With the dissolution of the jelly layer and the depolarization of the plasma membrane, the first block to preventing fertilization by multiple sperm is put into place.
These two simple changes are part of the first block to polyspermy, known as the fast block. Within 1/10th of a second of contact, the fast block t
Slides about Cell Fate, Cell Potency, Differentiation, Specification, Modes of Specification, Role of Cytoplasm. Cell Interactions, Regulation in Development
cell commitment and differentiation, stem cell,types of differentiationshallu kotwal
The commitment of cells to specific cell fates and their capacity to differentiate into particular kinds of cells.
Cellular differentiation is the process in which a cell changes from one cell type to another. Usually, the cell changes to a more specialized type. Differentiation occurs numerous times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover.
cell lineage , cell fate - diverse class of cell fate, cell fate in plant meristem, mammalian development cell fate, nutritional effects on epigenetics, epigenetics of plants,
control of cell fate.
INTRODUCTION
DEFINATION
GAMETES
STRUCTURE OF GAMETES
SPERM
OVUM
RECOGNITION OF EGG AND SPERM
CAPACITATION
ACROSOME REACTION
SPECIES-SPECIFIC RECOGNITION
GAMETE BINDING AND RECOGNITION
GAMETE FUSION
PREVENTION OF POLYSPERMY
ACTIVATION OF GAMETE METABOLISM
FUSION OF THE GENETIC MATERIAL
SIGNIFICANCE OF FERTILIZATION
CONCLUSIONS
REFERENCES
How does the Drosophila embryo get its pair-rule stripes How is the .pdfdeepakarora871
How does the Drosophila embryo get its pair-rule stripes? How is the evenskipped enhancer
build to ensure transcription of even-skipped in stripes? Use the even-skipped stripe 2 enhancer
as an example. Describe in general terms the inputs of transcription factors, and how the
embryonic expression domains of these factors are generated in the Drosophila embryo.
Solution
Initially,12 nuclear divisions take place which result in a multinucleate syncitium which is an
early drosophilla embryo; formation of pole cells take place followed by cellularization and
gastrulation. During gastrulation, extension of germ band takes place driving the posterior trunk
regions around the posterior end and the dorsal side, here the first signs of segmentation are seen.
At the syncitial blastoderm stage anterior-posterior and dorso-ventral axes get fully established.
Maternal factors in the form of mRNAs and proteins specify the anterior-posterior axis of the
embryo and the dorso-ventral aspect is governed by the localization of maternal proteins within
the envelope of egg vitelline and the positional information.
Even skipped acts as a transcriptional repressor of numerous genes.There is a combination of
maternal factors, transcription activators, and repressors, which defines each stripe of eve already
patterned in the egg either prior to fertilization or prior to cellularization.There are regional
specific enhancers which governs the stripe pattern of eve transcription.A stripe-specific
enhancer regulate each stripe. As seen in the case of eve stripe 2,in the range of -1.5 and -1.0 kb
upstream from the eve start site a minimal stripe 2 enhancer has been identified which assures
eve transcription in the second pair rule stripe.
Reference
1. Wolpert,L., Tickle, C., & Arias, A,M. (2015).Principles of development. Oxford: Oxford
university press.
2. Jiang, P., Ludwig, M. Z., Kreitman, M. and Reinitz, J. (2015). Natural variation of the
expression pattern of the segmentation gene even-skipped in melanogaster. Dev Biol [Epub
ahead of print]. PubMed ID: 26129990.
cell commitment and differentiation, stem cell,types of differentiationshallu kotwal
The commitment of cells to specific cell fates and their capacity to differentiate into particular kinds of cells.
Cellular differentiation is the process in which a cell changes from one cell type to another. Usually, the cell changes to a more specialized type. Differentiation occurs numerous times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover.
cell lineage , cell fate - diverse class of cell fate, cell fate in plant meristem, mammalian development cell fate, nutritional effects on epigenetics, epigenetics of plants,
control of cell fate.
INTRODUCTION
DEFINATION
GAMETES
STRUCTURE OF GAMETES
SPERM
OVUM
RECOGNITION OF EGG AND SPERM
CAPACITATION
ACROSOME REACTION
SPECIES-SPECIFIC RECOGNITION
GAMETE BINDING AND RECOGNITION
GAMETE FUSION
PREVENTION OF POLYSPERMY
ACTIVATION OF GAMETE METABOLISM
FUSION OF THE GENETIC MATERIAL
SIGNIFICANCE OF FERTILIZATION
CONCLUSIONS
REFERENCES
How does the Drosophila embryo get its pair-rule stripes How is the .pdfdeepakarora871
How does the Drosophila embryo get its pair-rule stripes? How is the evenskipped enhancer
build to ensure transcription of even-skipped in stripes? Use the even-skipped stripe 2 enhancer
as an example. Describe in general terms the inputs of transcription factors, and how the
embryonic expression domains of these factors are generated in the Drosophila embryo.
Solution
Initially,12 nuclear divisions take place which result in a multinucleate syncitium which is an
early drosophilla embryo; formation of pole cells take place followed by cellularization and
gastrulation. During gastrulation, extension of germ band takes place driving the posterior trunk
regions around the posterior end and the dorsal side, here the first signs of segmentation are seen.
At the syncitial blastoderm stage anterior-posterior and dorso-ventral axes get fully established.
Maternal factors in the form of mRNAs and proteins specify the anterior-posterior axis of the
embryo and the dorso-ventral aspect is governed by the localization of maternal proteins within
the envelope of egg vitelline and the positional information.
Even skipped acts as a transcriptional repressor of numerous genes.There is a combination of
maternal factors, transcription activators, and repressors, which defines each stripe of eve already
patterned in the egg either prior to fertilization or prior to cellularization.There are regional
specific enhancers which governs the stripe pattern of eve transcription.A stripe-specific
enhancer regulate each stripe. As seen in the case of eve stripe 2,in the range of -1.5 and -1.0 kb
upstream from the eve start site a minimal stripe 2 enhancer has been identified which assures
eve transcription in the second pair rule stripe.
Reference
1. Wolpert,L., Tickle, C., & Arias, A,M. (2015).Principles of development. Oxford: Oxford
university press.
2. Jiang, P., Ludwig, M. Z., Kreitman, M. and Reinitz, J. (2015). Natural variation of the
expression pattern of the segmentation gene even-skipped in melanogaster. Dev Biol [Epub
ahead of print]. PubMed ID: 26129990.
Pathogen-Driven Proteomic Changes in Haemolymph of NPV-Infected Silkworm Bomb...Mr. Suresh R. Jambagi
It will explain the structural proteins of baculoviruse, hemolymph proteins of silkworm, Host-pathogen interaction between BmNPV and silkworm and proteomic countermeasures to BmNPV infection by silkworm has been explained with few case studies
A Review on Genetic Dominant Disorder-Polydactylyijtsrd
Polydactyly is genetic disorder in which there is mutation of gene that is located on short arm of chromosome 7. One gene that can cause polydactyly is GLI3 and it is one among number of genes that are known to be involved in the patterning of tissues and organs during development of the embryo. Mutations of GLI3 gene during development will cause two types of polydactyly. Those are postaxial ulnar and preaxial radial polydactyly. The treatment plan is based on the outcome of analysis of patients medical history, social history, motivation, social and psychological disturbance. Akshata. B. Kichadi | Dr. Uma B Gopal | Santhosh Singarapu | Chaitra. S | Manukrishnan. K | Jeevankumar. Giri "A Review on Genetic Dominant Disorder-Polydactyly" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-2 , February 2019, URL: https://www.ijtsrd.com/papers/ijtsrd20232.pdf
Paper URL: https://www.ijtsrd.com/medicine/anatomy/20232/a-review-on-genetic-dominant-disorder-polydactyly/akshata-b-kichadi
Evolutionary Biology: Based on CBCS (2019 Credit Pattern); Savitribai Phule P...Shoeb Ahmad
The Presentation contains following chapters with adequate contents based on CBCS (2019 Credit Pattern); Savitribai Phule Pune University Syllabus-
1.1 Concept of Evolution.
1.2 Origin of life.
1.3 Origin of eukaryotic cell (Origin of mitochondria, plastids & symbionts).
Evidences of Evolution:
2.1 Analogy and Homology.
2.2 Embryological Evidences of Evolution.
2.3 Evolutionary & Paleontological Evidences.
Historical Review of Evolutionary Concept:
3.1 Theories of Evolution. 3.2 Lamarckism.
3.3 Darwinism and Neo Darwinism.
3.4 Mutation Theory.
3.5 Modern Synthetic theory.
4. Sources of Variations:
4.1 Variation and Mutations.
5. Isolation
6. Speciation:
6.1 Types of speciation (Allopatric & Sympatric).
6.2 Mechanism of speciation.
6.3 Patterns of speciation.
6.4 Factors influencing speciation.
7 Population Genetics:
7.1 Hardy-Weinberg Law & Genetic Drift.
7.2 Types of Natural Selection.
Origin of Man:
8.1 Evolution of Man (Evolution of anthropoids including man) - Kenyapithecus to Homo sapiens.
9. Zoogeographical Realms With reference to fauna
10. Extinctions:
10.1 Extinction - An Overview.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Han’s Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insider’s LMA Course, this piece examines the course’s effects via a variety of Tim Han LMA course reviews and Success Insider comments.
1. Dr. Shoeb Ahmad (Assistant Professor), Department of Zoology, AKI’s Poona College of Arts, Science and Commerce,
Camp, Pune-01, Maharashtra Page 1
Pattern Formation in Drosophila
The anterior-posterior polarity of the embryo, larva, and adult has its origin in the
anterior-posterior polarity of the egg. The maternal effect genes expressed in the
mother's ovaries produce messenger RNAs that are placed in different regions of
the egg. These messages encode transcriptional and translational regulatory
proteins that diffuse through the syncytial blastoderm and activate or repress the
expression of certain zygotic genes. Two of these
proteins, Bicoid and Hunchback, regulate the production of anterior structures,
while another pair of maternally specified proteins, Nanos and Caudal, regulates
the formation of the posterior parts of the embryo. Next, the zygotic genes
regulated by these maternal factors are expressed in certain broad (about three
segments wide), partially overlapping domains. These genes are called gap
genes (because mutations in them cause gaps in the segmentation pattern), and
they are among the first genes transcribed in the embryo. Differing concentrations
of the gap gene proteins cause the transcription of pair-rule genes, which divide
the embryo into periodic units. The transcription of the different pair-rule genes
results in a striped pattern of seven vertical bands perpendicular to the anterior-
posterior axis. The pair-rule gene proteins activate the transcription of the segment
polarity genes, whose mRNA and protein products divide the embryo into 14
segment-wide units, establishing the periodicity of the embryo. At the same time,
the protein products of the gap, pair-rule, and segment polarity genes interact to
regulate another class of genes, the homeotic selector genes, whose transcription
determines the developmental fate of each segment.
Embryological evidence of polarity regulation by oocyte cytoplasm
There are at least two “organizing centers” in the insect egg, one in the anterior of
the egg and one in the posterior. For instance, Klaus Sander (1975) found that if he
ligated the egg early in development, separating the anterior from the posterior
region, one half developed into an anterior embryo and one half developed into a
2. Dr. Shoeb Ahmad (Assistant Professor), Department of Zoology, AKI’s Poona College of Arts, Science and Commerce,
Camp, Pune-01, Maharashtra Page 2
posterior embryo, but neither half contained the middle segments of the embryo.
The later in development the ligature was made, the fewer middle segments were
missing. Thus, it appeared that there were indeed gradients emanating from the two
poles during cleavage, and that these gradients interacted to produce the positional
information determining the identity of each segment. Moreover, when the RNA of
the anterior of insect eggs was destroyed by ultraviolet light, the resulting embryos
lacked a head and thorax. Instead, these embryos developed two abdomens and
telsons (tails) with mirror-image symmetry: telson-abdomen-abdomen-telson.
Thus, Sander's laboratory postulated the existence of a gradient at both ends of the
egg, and hypothesized that the egg sequesters an RNA that generates a gradient of
anterior-forming material.
The anterior-posterior axis of the Drosophila embryo appears to be patterned
before the nuclei even begin to function. The nurse cells of the ovary deposit
mRNAs in the developing oocyte, and these mRNAs are apportioned to different
regions of the cell. In particular, four maternal messenger RNAs are critical to the
formation of the anterior-posterior axis:
bicoid and hunchback mRNAs, whose protein products are critical for head
and thorax formation
nanos and caudal mRNAs, whose protein products are critical for the
formation of the abdominal segments
The bicoid mRNAs are located in the anterior portion of the unfertilized egg, and
are tethered to the anterior microtubules. The nanos messages are bound to the
cytoskeleton in the posterior region of the unfertilized egg.
The hunchback and caudal mRNAs are distributed throughout the oocyte. Upon
fertilization, these mRNAs can be translated into proteins. At the anterior pole,
the bicoid RNA is translated into Bicoid protein, which forms a gradient highest at
the anterior. At the posterior pole, the nanos message is translated into Nanos
protein, which forms a gradient highest at the posterior. Bicoid protein inhibits the
3. Dr. Shoeb Ahmad (Assistant Professor), Department of Zoology, AKI’s Poona College of Arts, Science and Commerce,
Camp, Pune-01, Maharashtra Page 3
translation of the caudal RNA, allowing Caudal protein to be synthesized only in
the posterior of the cell. Conversely, Nanos protein, in conjunction with Pumilio
protein, binds to hunchback RNA, preventing its translation in the posterior portion
of the embryo. Bicoid also elevates the level of Hunchback protein in the anterior
of the embryo by binding to the enhancers of the hunchback gene and stimulating
its transcription. The result of these interactions is the creation of four protein
gradients in the early embryo (Figure-1)
Figure-1 A model of anterior-posterior pattern generation by the Drosophila maternal effect
genes. (A) The bicoid, nanos, hunchback, and caudal messenger RNAs are placed in the
oocyte by the ovarian nurse cells. The bicoid message is sequestered anteriorly.
The nanos message is sent to the posterior pole. (B) Upon translation, the Bicoid protein
gradient extends from anterior to posterior, and the Nanos protein gradient extends from
posterior to anterior. Nanos inhibits the translation of the hunchback message (in the
posterior), while Bicoid prevents the translation of the caudal message (in the anterior). This
inhibition results in opposing Caudal and Hunchback gradients. The Hunchback gradient is
secondarily strengthened by the transcription of the hunchback gene in the anterior nuclei
(since Bicoid acts as a transcription factor to activate hunchback transcription). (C) Parallel
interactions whereby translational gene regulation establishes the anterior-posterior patterning
of the Drosophila embryo.
4. Dr. Shoeb Ahmad (Assistant Professor), Department of Zoology, AKI’s Poona College of Arts, Science and Commerce,
Camp, Pune-01, Maharashtra Page 4
An anterior-to-posterior gradient of Bicoid protein
An anterior-to-posterior gradient of Hunchback protein
A posterior-to-anterior gradient of Nanos protein
A posterior-to-anterior gradient of Caudal protein
The Bicoid, Hunchback, and Caudal proteins are transcription factors whose relative
concentrations can activate or repress particular zygotic genes. The stage is now set for
the activation of zygotic genes in those nuclei that were busily dividing while this
gradient was being established.
Evidence that the bicoid gradient constitutes the anterior organizing center:
In Drosophila, the phenotype of the bicoid mutant provides valuable information about the
function of gradients. Instead of having anterior structures (acron, head, and thorax) followed
by abdominal structures and a telson, the structure of the bicoid mutant is telson-abdomen-
abdomen-telson. It would appear that these embryos lack whatever substances are needed for
the formation of anterior structures. Moreover, one could hypothesize that the substance that
these mutants lack is the one postulated by Sander and Kalthoff to turn on genes for the
anterior structures and turn off genes for the telson structures.
Further studies have strengthened the view that the product of the wild-type bicoid gene is the
morphogen that controls anterior development. First, bicoid is a maternal effect gene.
Messenger RNA from the mother's bicoid genes is placed in the embryo by the mother's
ovarian cells (Figure-2). The bicoid RNA is strictly localized in the anterior portion of the
oocyte, where the anterior cytoskeleton anchors it through the message's 3´ untranslated
region. This mRNA is dormant until fertilization, at which time it receives a longer
polyadenylate tail and can be translated. Driever and Nüsslein-Volhard (1988) have shown
that when Bicoid protein is translated from this RNA during early cleavage, it forms a
gradient, with the highest concentration in the anterior of the egg and the lowest in the
posterior third of the egg. Moreover, this protein soon becomes concentrated in the
embryonic nuclei in the anterior portion of the embryo (Figure 2 C-D).
5. Dr. Shoeb Ahmad (Assistant Professor), Department of Zoology, AKI’s Poona College of Arts, Science and Commerce,
Camp, Pune-01, Maharashtra Page 5
Figure-2 Gradient of Bicoid protein in the early Drosophila embryo.
(A) bicoid mRNA passing into the oocyte from the nurse cells during oogenesis.
(B) Localization of bicoid mRNA to the anterior tip of the embryo. (C) Gradient of
Bicoid protein shortly after fertilization. Note that the concentration is greatest
anteriorly and trails off posteriorly. Notice also that Bicoid protein is concentrated
in the nuclei of the embryo. (D) Densitometric scan of the Bicoid protein gradient.
The upper curve represents the gradient of Bicoid protein in wild-type embryos.
The lower curve represents Bicoid protein in embryos of bicoid mutant mothers