Sex hormones play an important role in the sexual reproduction of fungi. Several types of sex hormones have been identified including sirenin, antheridiol, oogoniol, and trisporic acid. Sirenin is a pheromone produced by female Allomyces gametes that attracts male gametes. Antheridiol and oogoniol regulate sexual development in Achlya fungi. Trisporic acid stimulates zygophore development in Mucorales. Yeast also produces a sex hormone called alpha factor, a peptide pheromone that induces mating structure formation in yeast. These fungal sex hormones help control processes like gamete attraction, sex organ initiation and differentiation,
Heterothallic species have sexes that reside in different individuals. . The term is applied particularly to distinguish heterothallic fungi, which require two compatible partners to produce sexual spores, from homothallic ones, which are capable of sexual reproduction from a single organism.
Introduction,In some fungi ,true sexual cycle comprising of nuclear fusion and meiosis is absent.
These fungi derive the benefits of sexuality through a cycle know as parasexuaL cycle.
First Reported by- Gudio Pontecorvo and J.A.Roper(1952)
Parasexual cycle was reported in
Aspergillus nidulans,the imperfect stage of Emericella nidulans.
Since then parasexual cycle has been discovered not only in several members of Deutromycetes but also in fungi belonging to Ascomycetes and Basidiomycetes.
DEFINETION - Parasexuality is defined as a cycle in which Plasmogamy, Karyogamy and Meiosis [Haploidization] take place in sequence but not at a specified time or at specified points in the life cycle of an organism.
Generally parasexual cycle occurs in those fungi in which true sexual cycle does not take place.
Parasexualcycle also know as Somatic recombination. PASEXUALITY ALSO REPORTED IN SOME ORGANISMS- Aspergillus nigar, Penicillium crysogenum, STEPS OF PARASEXUAL CYCLE - 1) ESTABLISHMENT OF HETEROKARYOSIS, 2) Formation of Heterozygous DIPLOIDS, 3) occasional mitotic crossing-over during multiplication of diploid nuclei, 4)occasional haplodization through aneuploidy , COMPARISION BETWEEN SEXUAL AND PARASEXUAL CYCLE, IMPORTANCE OF PARASEXUALITY, C0NCLUSION
Heterothallic species have sexes that reside in different individuals. . The term is applied particularly to distinguish heterothallic fungi, which require two compatible partners to produce sexual spores, from homothallic ones, which are capable of sexual reproduction from a single organism.
Introduction,In some fungi ,true sexual cycle comprising of nuclear fusion and meiosis is absent.
These fungi derive the benefits of sexuality through a cycle know as parasexuaL cycle.
First Reported by- Gudio Pontecorvo and J.A.Roper(1952)
Parasexual cycle was reported in
Aspergillus nidulans,the imperfect stage of Emericella nidulans.
Since then parasexual cycle has been discovered not only in several members of Deutromycetes but also in fungi belonging to Ascomycetes and Basidiomycetes.
DEFINETION - Parasexuality is defined as a cycle in which Plasmogamy, Karyogamy and Meiosis [Haploidization] take place in sequence but not at a specified time or at specified points in the life cycle of an organism.
Generally parasexual cycle occurs in those fungi in which true sexual cycle does not take place.
Parasexualcycle also know as Somatic recombination. PASEXUALITY ALSO REPORTED IN SOME ORGANISMS- Aspergillus nigar, Penicillium crysogenum, STEPS OF PARASEXUAL CYCLE - 1) ESTABLISHMENT OF HETEROKARYOSIS, 2) Formation of Heterozygous DIPLOIDS, 3) occasional mitotic crossing-over during multiplication of diploid nuclei, 4)occasional haplodization through aneuploidy , COMPARISION BETWEEN SEXUAL AND PARASEXUAL CYCLE, IMPORTANCE OF PARASEXUALITY, C0NCLUSION
Chlamydomonas is unicellular, motile green algae. In this presentation the systematic position, occurrence, structure and different types of reproduction is being explained. palmella stage in vegetative reproduction is one of the outstanding character found among the other algae.
Detail about Basidiomycetes.In this detail about its Ecosystem Relationship,Symbiotic Relationships,General characters,Basidiospores,Life cycle and its Fruiting body.
Contact Email: mzeeshan_93@yahoo.com
Chlamydomonas is unicellular, motile green algae. In this presentation the systematic position, occurrence, structure and different types of reproduction is being explained. palmella stage in vegetative reproduction is one of the outstanding character found among the other algae.
Detail about Basidiomycetes.In this detail about its Ecosystem Relationship,Symbiotic Relationships,General characters,Basidiospores,Life cycle and its Fruiting body.
Contact Email: mzeeshan_93@yahoo.com
Introduction of Steroids
Nomenclature
Sex Hormones
Biosynthesis of sex hormones
Structure, synthesis of Testosterone, Oestriol, Oestradiol, Diethyl stilbestrol, Progesterone
Reference
HISTOCHEMICAL STUDIES OF ENZYMES INVOVED IN HORMONAL REGULATION IN GARDEN LI...paperpublications3
Abstract: Studies in situ changes in various enzyme activities viz. ∆5-3β-HSDH, Peroxidase, Acid and Alkaline phosphatases, Cytochrome oxidase &Lipids in the adrenal gland and ovary at different stages of reproductive cycle in Garden Lizard (Calotes versicolor). Peroxidase appears to be involved in the biosynthetic machinery controlling corticosteroidogenesis. Peroxidase and Cytochrome oxidase would also seem to transform adrenocortical cells and hypertrophied theca interna into highly oxidative compartments of the adrenal and ovary which attributes to the oxidation of pregnenolone to progesterone and corticosteroids towards maturation and ovulation of the oocyte from the ovary.
Keywords: Biosynthetic Machinery, Enzymes, Adrenal-Ovary Interrelation & Pregnenolone to Progesterone, Corticosteroidogenesis.
HISTOCHEMICAL STUDIES OF ENZYMES INVOVED IN HORMONAL REGULATION IN FISH (Cypr...paperpublications3
Abstract: In situ changes in the enzymes i.e.∆5 3β- Hydroxysteroid dehydrogenase, Peroxidase,Cytochrome oxidase, Acid and Alkaline phosphatases and lipids in the Interrenal Gland and Ovary at different stages of reproductive cycle in fish, Cyprinus carpio had been studied.Peroxidase appears to be involved in the biosynthetic machinery controlling corticosteroidogenesis. Peroxidase and Cytochrome oxidase would also seem to transform adrenocortical cells and hypertrophied theca interna into highly oxidative compartments of the adrenal and ovary which attributes to the oxidation of pregnenolone to progesterone and corticosteroids towards maturation and ovulation of the oocyte from the ovary.
HISTOCHEMICAL STUDIES OF ENZYMES INVOVED IN HORMONAL REGULATION IN FISH (Cypr...paperpublications3
Abstract: In situ changes in the enzymes i.e.∆5 3β- Hydroxysteroid dehydrogenase, Peroxidase,Cytochrome oxidase, Acid and Alkaline phosphatases and lipids in the Interrenal Gland and Ovary at different stages of reproductive cycle in fish, Cyprinus carpio had been studied.Peroxidase appears to be involved in the biosynthetic machinery controlling corticosteroidogenesis. Peroxidase and Cytochrome oxidase would also seem to transform adrenocortical cells and hypertrophied theca interna into highly oxidative compartments of the adrenal and ovary which attributes to the oxidation of pregnenolone to progesterone and corticosteroids towards maturation and ovulation of the oocyte from the ovary.
HISTOCHEMICAL STUDIES OF ENZYMES INVOVED IN HORMONAL REGULATION IN GARDEN LIZ...paperpublications3
Abstract: Studies in situ changes in various enzyme activities viz. ∆5-3β-HSDH, Peroxidase, Acid and Alkaline phosphatases, Cytochrome oxidase &Lipids in the adrenal gland and ovary at different stages of reproductive cycle in Garden Lizard (Calotes versicolor). Peroxidase appears to be involved in the biosynthetic machinery controlling corticosteroidogenesis. Peroxidase and Cytochrome oxidase would also seem to transform adrenocortical cells and hypertrophied theca interna into highly oxidative compartments of the adrenal and ovary which attributes to the oxidation of pregnenolone to progesterone and corticosteroids towards maturation and ovulation of the oocyte from the ovary.
fungi: heterothallism, heterokaryosis, parasexuality,fungi sex hormones, Mycorrhizae, Types of mycorrhizae, Defence mechanism in plants- structural and biochemical.
Histochemical Studies of Enzymes in the Adrenal Gland of Rat & Rabbit during ...paperpublications3
Abstract: Administration of ACTH stimulates adrenal secretion of progesterone as well as corticosterone (Resko, 19691; Feder et al., 1969; Feder et al., 1971; Piva et al., 1973). Progesterone is both an obligatory intra-adrenal substrate for corticosterone production and a steroid essential for maintenance of pregnancy. Thus, the regulation of adrenal steroidogenesis during pregnancy has two potentially important aspects: i.) Maintenance of optimal blood levels of corticosterone and ii.)Contributing significant amounts of progesterone to the total maternal pool. Since the extended luteotrophic function of ovary in rat & mice during pregnancy is related to the Peroxidase-Ascorbate system (Agrawal, P. & Laloraya, M.M. 1979). It appears likely that synthesis of progesterone under the action of ACTH during pregnancy may be controlled by a similar mechanism as reported for LH in the ovary, thus causing increased synthesis and secretion of the Progesterone and corticosteroids from the adrenal gland.
Histochemical Studies of Enzymes in the Adrenal Gland of Rat & Rabbit during ...paperpublications3
Abstract: Administration of ACTH stimulates adrenal secretion of progesterone as well as corticosterone (Resko, 19691; Feder et al., 1969; Feder et al., 1971; Piva et al., 1973). Progesterone is both an obligatory intra-adrenal substrate for corticosterone production and a steroid essential for maintenance of pregnancy. Thus, the regulation of adrenal steroidogenesis during pregnancy has two potentially important aspects: i.) Maintenance of optimal blood levels of corticosterone and ii.)Contributing significant amounts of progesterone to the total maternal pool. Since the extended luteotrophic function of ovary in rat & mice during pregnancy is related to the Peroxidase-Ascorbate system (Agrawal, P. & Laloraya, M.M. 1979). It appears likely that synthesis of progesterone under the action of ACTH during pregnancy may be controlled by a similar mechanism as reported for LH in the ovary, thus causing increased synthesis and secretion of the Progesterone and corticosteroids from the adrenal gland.
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans.
AAS is an analytical technique used to determine how much of certain elements are in a sample. It uses the principle that atoms (and ions) can absorb light at a specific, unique wavelength. When this specific wavelength of light is provided, the energy (light) is absorbed by the atom.
Strain improvement is one element of fermentation process management. It is the process of increasing the productivity of a microorganism by improving or selecting for a more productive phenotype.
Eukaryotic transcription is carried out in the nucleus of the cell and proceeds in three sequential stages: initiation, elongation, and termination. Eukaryotes require transcription factors to first bind to the promoter region and then help recruit the appropriate polymerase.
A mutation is a change in the DNA sequence of an organism. Mutations can result from errors in DNA replication during cell division, exposure to mutagens or a viral infection.2
A DNA vaccine is a type of vaccine that transfects a specific antigen-coding DNA sequence into the cells of an organism as a mechanism to induce an immune response.
DNA vaccines work by injecting genetically engineered plasmid containing the DNA sequence encoding the antigen(s) against which an immune response is sought, so the cells directly produce the antigen, thus causing a protective immunological response.
Bioremediation is a branch of biotechnology that employs the use of living organisms, like microbes and bacteria, in the removal of contaminants, pollutants, and toxins from soil, water, and other environments.
radioactivity is the act of emitting radiation spontaneously. This is done by an atomic nucleus that, for some reason, is unstable; it "wants" to give up some energy in order to shift to a more stable configuration.
Hypersensitivity reactions are exaggerated or inappropriate immunologic responses occurring in response to an antigen or allergen. Type I, II and III hypersensitivity reactions are known as immediate hypersensitivity reactions because they occur within 24 hours of exposure to the antigen or allergen.
Diphtheria is a serious infection caused by strains of bacteria called Corynebacterium diphtheriae that make toxin. It can lead to difficulty breathing, heart rhythm problems, and even death. CDC recommends vaccines for infants, children, teens, and adults to prevent diphtheria. Causes and How It Spreads.
Clostridium is a genus of anaerobic, Gram-positive bacteria. Species of Clostridium inhabit soils and the intestinal tract of animals, including humans. This genus includes several significant human pathogens, including the causative agents of botulism and tetanus.
transposon, class of genetic elements that can “jump” to different locations within a genome. Although these elements are frequently called “jumping genes,” they are always maintained in an integrated site in the genome. In addition, most transposons eventually become inactive and no longer move.1
Gene regulation is the process used to control the timing, location and amount in which genes are expressed. The process can be complicated and is carried out by a variety of mechanisms, including through regulatory proteins and chemical modification of DNA.
Genetic recombination (genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. The process occurs naturally and can also be carried out in the lab.
Mycotoxins are naturally occurring toxins produced by certain moulds (fungi) and can be found in food.
The moulds grow on a variety of different crops and foodstuffs including cereals, nuts, spices, dried fruits, apples and coffee beans, often under warm and humid conditions.
Mycotoxins can cause a variety of adverse health effects and pose a serious health threat to both humans and livestock.
Microbiology essentially began with the development of the microscope. Although others may have seen microbes before him, it was Antonie van Leeuwenhoek, a Dutch draper whose hobby was lens grinding and making microscopes, who was the first to provide proper documentation of his observations.
We can make various products like soup powder, papad, nuggets, chips, preserve, candy etc. using different mushrooms. products like pasta, noodles etc. by supplementing with fresh or dried mushroom powder.
The microbes are highly useful for making vaccines and antibiotics for making medicines. It is a well-known fact that harmful pathogens that cause different diseases by infecting our body. The antibiotics and medicines would help us in fighting these diseases and infections.
A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with the most common being an organism altered in a way that "does not occur naturally by mating and/or natural recombination". A wide variety of organisms have been genetically modified (GM), from animals to plants and microorganisms.
Biofertilizers are living microbes that enhance plant nutrition by either by mobilizing or increasing nutrient availability in soils. Various microbial taxa including beneficial bacteria and fungi are currently used as biofertilizers, as they successfully colonize the rhizosphere, rhizoplane or root interior.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
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 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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
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 .
The ASGCT Annual Meeting was packed with exciting progress in the field advan...
Sex hormones in fungi
1. Sex Hormones in Fungi
Dr. Rachana Choudhary
Department of Microbiology
Shri Shankaracharya Mahavidyalaya Junwani, Bhilai
2. INTRODUCTION
• De Bary (1881) first reported the presence of sex hormones in
dioecious species of Achlya.
• In 1908, Kaufmann supported the De Bary on the basis of his
observations on Saprolegnia hypogyna. According to him, the
development of antheridial hyphae is stimulated by certain
hormones.
• Couch (1924) & Bishop (1957) on Dictyuchus and Sapromyces
reinschii & Raper (1954) on Achlya have substantially confirmed
the role of hormones in sexual reproduction in fungi.
• Sex Hormones may be defined as a diffusible substance playing a
specific role in the sexual reproduction.
3. Machlis (1972) has classified the sex hormones into the following
three types:
(1) Erotactins: attracts motile cells (“sperm attractant”).
(2) Erotropins: includes chemotropic growth of sex organs.
(3) Erogens: controls the induction and differentiation of
sex organs.
There is evidence of existence of number of sex hormones in fungi, but
few are identified and chemically characterized such as Sirenin,
Antheridiol, Oogonial ,Trisporic acid & yeast D factor.
4. 1.Sirenin
• It is a sperm attracting hormone produced by water mould
Allomyces, A. macrogynous and A. arbuscula.
• It is the female gametes which release sirenin to attract the
male gametes.
• The synthesis of sirenin by female gametes and their
function to attract male gametes was demonstrated by
Machlis (1958). The empirical formula of sirenin is
C15 H 24O2 and the molecular weight is 236.
5. Structure of Sirenin
• Nutting Rapoport and Machlis
determined the structure of sirenin as
a bicyclic sesquiterpenediol and
suggested its stereochemistry by
analogy with the corresponding
hydrocorbon, sesquicarene, that had
just been described
• Plattner and Rapoport (1971)
synthesized d and l sirenin
separately and Machlis showed that
l- Sirenin attracted male gamete
6. 2. Antheridiol & Oogoniol:
• Raper (1939-1959), on the basis of his classical studies on
sex hormones in Achlya, demonstrated the presence of multi
hormonal regulatory system in A. ambisexualis and A.
bisexualis.
• He envisaged the presence of four hormones A, B, C and D
but now it has been conclusively proved that only two
hormones named as Antherldiol and oogoniol are involved.
Hormones A and C are antheridiols and hormones B and D
are oogoniols.
7. Structure of Antheridiol
Antheridiol is a crystalline compound having empirical
formula as C29 H42 O5 and molecular weight as 470. The
hormone was isolated by Mc Morris and Barksdali (1967) and
its structure was proposed by Arsenault et al (1969).
8. It is reported that Antheridiol stimulate four types of
reactions:
(a) initiation of antheridial hyphae on male plant,
(b) chemotropic stimulation of antheridial hyphae,
(c) stimulation of male hyphae for production of oogoniol and
(d) delimiation of antheridia.
9. Oogoniol
• The hormone is synthesized by male hyphae of Achlya
ambisexualis only in the presence of antheridiol.
• However, Barksdali et al. (1974) reported that Oogoniol is
synthesised by some hermaphrodite strains without the stimulus
of antheridiol.
• Two crystalline compounds, possessing hormone B activity have
been isolated from culture filtrates of Achlya heterosexualis by
Mc Morris and his coworkers (1975).
• These have been named Oogoniol-1 &Oogoniol-2.
10. Structure of Oogoniol
• Oogoniol is a crystalline steroid with molecular weight as 500.
The hormone stimulates the development of oogonium on
female hyphae.
11. 3.Trisporic acid
• Trisporic Acid is isolated from Blakeslea trispora and Mucor
mucedo. It has been found to play active role in sexual
reproduction of several members of the order Mucorales.
• Though the concept of sex hormone in mucorales was
developed in 1924 by Burgeff, it was only in 1956 that Burgeff
could isolate a sex hormone in cell free extract and this sex
hormone was named as Trisporic Acid.
• It is an unsaturated and oxygenated form of trimethyl cyclo-
hexane.
12. Structure of Trisporic Acid
• Three kinds of trisporic acid have been identified,
• trisporic acid A, B & C.
• Trisporic acid C plays the major role (80%)
• Trisporic acid B with 15% activity
& Trisporic acid A is least active with 1-2% activity
Empirical formula of
trisporic acid is
C18 H26 O4 & the
molecular weight is 306.
13. • The role of sex hormones in Mucor mucedo was studied by
Plempel et al. (1957-61). it is synthesized from B-carotene.
• In the heterothallic mycelia, trisporic acid B and C stimulate the
development of zygophores. This hormone is synthesized only
when the mycelia of (+) and (-) strains grow in a normal
continuous diffusable medium.
• The hormone trisporic acid synthesized in (-) strain induces the
development of progametangium in (-) strains and vice-versa.
• The zygophores of (+) and (-) strain are attracted towards each
other due to chemotropic response of a volatile substance which
also promotes the synthesis of trisporic acid in two opposite
mating types.
•
16. 4.Yeast α Factor:
• The presence and the involvement of some hormone in the
sexual reproduction of Saccharomyces cerevisiae was
suggested by Levi in 1950.
• the haploid cells are of two mating types a & α which
conjugate to form diploid cells.
• In 1956, Levi showed that the α haploid cells produce a
diffusible chemical which induces the formation of copulatory
process by compatible a cells.
17. • These a cells, due to influence of the chemical substance
produced by α cells, stop their growth and reproduction by
budding.
• Instead, these a cells swell in size and form giant cells of
various shapes. These giant cells are 30 or more times heavy in
dry weight in comparison to normal haploid cells. The α factor
acts only on a cells and has no effect on α cells.
• The α factor is reported to inhibit DNA replication in the a
cells. Duntze (1970 – 1973) isolated the α factor in pure form.
It is peptide complexed with copper ion and has molecular
weight of 1400.
