Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
The Shoot apex is also known as the terminal bud of plants that grows from 0.1-1.0 mm and consists of the apical meristem, developing leaves and the immediate surrounding leaf primordial. The shoot apex is present in both dicot and monocot plants.
Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
The Shoot apex is also known as the terminal bud of plants that grows from 0.1-1.0 mm and consists of the apical meristem, developing leaves and the immediate surrounding leaf primordial. The shoot apex is present in both dicot and monocot plants.
Apomixis in flowering plants is defined as the asexual formation of a seed from the maternal tissues of the ovule, avoiding the processes of meiosis and fertilization, leading to embryo development.
Double fertilization is the process found in angiosperms in which out of the two male gametes released inside the embryo sac, one fuses with the egg cell (syngamy) and another fuse with secondary nucleus (triple fusion).
Pollen pistil interaction
Types of Incompatibility in plants
Methods to overcome Incompatibility
Prepared by
Dr. T. Annie Sheron
Assistant Professor of Botany
DEPARTMENT OF BOTANY
KAKATIYA GOVERNMENT COLLEGE, HANAMKONDA
intro-hostory and discovery-characteristics of phytochrome-chemical nature of phytochrome-mode of action-mechanism-phytochrome mediated physiological responses-phytochrome is a pigment system:some evidences-role of phytochrome
Apomixis in flowering plants is defined as the asexual formation of a seed from the maternal tissues of the ovule, avoiding the processes of meiosis and fertilization, leading to embryo development.
Double fertilization is the process found in angiosperms in which out of the two male gametes released inside the embryo sac, one fuses with the egg cell (syngamy) and another fuse with secondary nucleus (triple fusion).
Pollen pistil interaction
Types of Incompatibility in plants
Methods to overcome Incompatibility
Prepared by
Dr. T. Annie Sheron
Assistant Professor of Botany
DEPARTMENT OF BOTANY
KAKATIYA GOVERNMENT COLLEGE, HANAMKONDA
intro-hostory and discovery-characteristics of phytochrome-chemical nature of phytochrome-mode of action-mechanism-phytochrome mediated physiological responses-phytochrome is a pigment system:some evidences-role of phytochrome
The ovules is also known as megasporongia which are borne on a cushion-like tissue called placenta in the ovary. One or more than one ovules are present inside the ovary.
This upload includes description of structure of microsporangium, microsporogenesis, pollen grain and megasporogenesis.
It will be helpful to the students for their quick reference.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
This presentation intends to explore the communication of the cell within and others for sustainability along the regulation mechanisms by the cellular neural networks and others to sing the song of the life.
Bioenergetics is an important domain in biology. This presentation has explored ATP production and its optimum utilization in biological systems along with certain theories and experiments to give a bird's eye view of this important issue.
This presentation offers the bird's eye view of the cell as the basic structural and functional unit of life. It also addresses the origin of eukaryotic cells from the prokaryotic cell by the endosymbiotic theory.
This presentation has been intended to offer a bird's eye view about the phylogenetic classification of the plant kingdom in general and the Engler and Prantl system in particular with merits and demerits.
This PPT has been made to explore the plant classification in general and the classification as made by Bentham & Hooker for the classification of the flowering plants. It also offers the history of plant classification along with the merits and demerits of this aforesaid classification.
Energy and the biological systems are joined together and no biological world is almost impossible without ATP. This study material intends to explore the beauty of ATP to drive different biological processes.
This PPT offers a bird's eye view of ICBN and its different rules along with regulations for the naming of plants. It also highlights the history of IBC and its contribution to plant taxonomy.
This presentation intends to offer the basic features of plant metabolism along with the different types of mechanisms to regulate and control the metabolic pathways.
This presentation has been designed to give the foundation of taxonomy in general and Plant Taxonomy in particular as a matter of pleasure to explore the diversity of the plant world.
Sex and sexuality are very common words in biology but para-sexuality is a little bit uncommon, several organisms in general and fungi in particular have the pleasure of sexuality to bring variations by beside sex. This PPT explores the beauty of para-sexuality for the academic fraternity.
Sex life in fungi is not less fascinating than in other organisms. Heterosexuality is a matter of pleasure to explore the diversity of sex in fungi along with its cause and consequences. You can find a pleasure to go through the content.
This PowerPoint wants to explore the bird's eye view of the reproduction of bacteria in general and the genetic recombination of bacteria in particular.
This presentation gives the bird's eye view of bacterial nutrition along with some other issues required to understand bacterial diversity as far as nutrition is concerned.
This presentation explores the food value of mushrooms along with the long-term and short-term storage procedures. It also offers a detailed account of the nutrients that remain present in the edible mushrooms.
If you want to explore the role of Cyanobacteria in soil fertility in general & Azolla-Anabena association in particular, you can visit this PowerPoint Presentation.
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.
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.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
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 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.
1. REPRODUCTIVE BIOLOGY
Welcome to
Structure of Stigma & Style
By N.Sannigrahi, Associate Professor, Department of
Botany, Nistarini College, Purulia, 723101(W.B) India
3. POLLEN PISTIL INTERACTION
• Pollination→Pollen adhesion→ Pollen hydration→
Pollen germination→ Pollen tube entry into stigma→
Pollen tube growth to the style→ Pollen tube entry
into the ovule and embryo sac → Double fertilization.
• All the events leading from pollination to release of
gametes in the embryo sac form a part of pollen pistil
interaction is called Programic phase.
4. STRUCTURE OF PISTIL
• The female reproductive organ of the flower is called
Gynoecium and the individual member is called
pistil.Pistil is divisible into lower bulbous portion-
Ovary, the long filamentous structure -style and the
upper part of the style called stigma. All the three part
of the pistil enjoy a wide degree of diversity as far as
taxonomic point of view.But whatever may be the
diversity, it is adapted to receive the pollen, aid its
germination and subsequently entry of the pollen tube
into the ovary, ovule and finally into the embryo sac
for fertilization.The ultimate aim to acomplish the
biological actvities as designed for do that.
6. STRUCTURE OF STIGMA
• Stigma-the specialized part where pollen grains are trapped
during pollination.The features of the srtigma has wide
diversity as far as structural composition is cencerned.
• Stigma based on amount of secretion present during receptive
period, decoration of the reseptive surface with glandular cells
or papillae-Wet or Dry,
• The composition of secretion produced by the subepidermal
cells of the stigma highly heterogenous having lipids, proteins,
glycoproteins, amino acids, arbionogalactans, Ca++,Phenols.
• Stigma of four types-I, II, III, IV(J. Heslop-Harrison,
1976;Y.Heslop-Harrison & Shivanna, 1977).
• Enzymes are diverse types-non-specific esterases on the
receptive surface, Stigmatic epidermis is covered with cuticle
and some extracelluar protineaceous lipoidal layer called
Pellicle present.
• The layer capture pollen grains and hydration of pollen grains.
10. Structure of Dry Stigma
• In dry stigma, no exudates are released.
• The cuticle is discontinuous,
• Behind the Pellicle & cuticle, thin mucilagenous layer
opresent and the pectocellulosic layer id differentiated into
several layers that form parammural bodies associated with
secrtion of surface components, protein, Polysacchrides,
Constituents of pectocellulosic wall and intercellular matrix.
• In some cases, the pellicle shows ATPase and carbonic
anhydrase activity.
• The pellicle also binds to the lectins and contains
arbinogalactans, a group of carbohydrates with adhesive
properities ( Clarke et al, 1979).
11. FUNCTION OF STIGMA
• FUNCTION
• i.Pollen-Pistil interaction
• ii. Lipoidal components secreted by the stigma to prevent
evaporation and wetting by acting as liquid cuticle,
• iii.Pheolics & Protease inhibitors of stigma give protection
againest insects & pathogens,
• iv.Stigmatic exudates serve as a nutrient sources for
pollinating insects.
• v. Ther pellicle components originate from the epidermal cells
of the stigma or stigmatic papillae shows ATPase and carbonic
anahydrase activity,
• vi. The pellicle binds with lactins and arbinogalactans as
adhesive properities.
13. STRUCTURE OF STYLE
• Style is a tubular structure having the connections between
stima and ovary.
• Mainly of two types-Solid(closed) & Hollow(Open).
• The solid style has a central stand of transmitting tissues of
elongated cells interconnected by plasmodesmata.Intercellular
substances of protinaceous nature surrounded the cells of the
transmitting tissue. It also contains Proteins, glycoproteins and
lipid.A number of transmitting proline rich proteins have been
localized in intercellular matrix(Cheung et al, 1993)The cells
of the transmitting tissue exhibit normal ultrastructural profiles
with numerous mitochondria,active dictyosomes,
roughER,plastids and ribosomes.Pollen tube grow down the
style throgh the intercellular matrix of the transmitting tissue.
15. HOLLOW STYLE
• In the hollow style, the central core has one or more canals
which normally correspond to the number of carpels.The stylar
canal is bordered by one or few layers of glandular cells, canal
cells. A layer of cuticle lines the canal cells in the young bud
and the secretion product from the canal cells accumulate
below the cuticle.The canal cells aree glandular and may be
filled with secretion fluid.
• whatever may be, the pollen grains after getting attachment
with the stigma followed by the recognition of the pollen
grains as compatible for germination, either by the sol;id satyle
or the hollow style, a passage is made for the easy
transportation of the pollen grains after germination in the
form of pollen tube until the entire process of the biological
dramas of fertil;iozartuion cme to an end.
16. PATH OF POLLEN TUBE
• The pollen tube pathway depends on the nature of the
stigma.In the species with wet stigma and soild style differs
with that of wet stigma and hollow style.
• In wet stigma and solid style, the cuticle of the stgma or
papillae is disrupted during the secretion of exedutes, thus
there is no physical barrier for the pollen tube entry into the
intcellular spaces before the transmitting tissue of the stigma.
• In the wet stigma with hollow style, pollen tube grows on the
surface of the stigma and enter the stylar canal.
• In the species of the dry stigma and solid style, the cuticle
provides the physical barrier for the pollen tube entry.The
cuticle is eroded at the point of contact by the activity of the
cutineses released by the pollen.After the digestion of the
cuticle, the tube enters the pectocellulosic wall of the papillae
and finally grows throgh the intercellular substances of the
17. Pollen tube guidance
• of the stigma and the style.
• In most of the tissues, pollen tube makes their way to the
ovary though the intercellular matrix of the transmitting tissues
or throgh the mucilagenous matrix of ther hollow style.
Different types of glycoproteins, sugar, proteins plauyed an
important role in this regard.
• The pollen tube finally pushes throgh the ovule and reaches
the embryo sac.The guidance in the ovule is in terms of
essential signal originating from the male and female tissue.In
Arabidopsis, bel1 and sin1-the two genes activate in the
female gametophyte play a crucial role in the signalling
process that guides in the pollen tubes into the ovule.In fact,
pollen tube are always attracted to the ovules with a functional
embryo sac that confirms a female gametophyte control of
pollen tube guidance.