Meristematic tissue is made up of immature cells that have the ability to divide and differentiate into permanent tissues. There are three main types of meristematic tissue: apical meristem at the tips of roots and shoots, lateral meristem like vascular cambium, and intercalary meristem between permanent tissues. Meristematic tissue is classified based on origin, position, function, and plane of cell division. The quiescent center is a group of inactive cells in the root tip that acts as a reservoir and restores growth if the root is damaged.
Wall layers of anther have different functions most importantly they help in providing nutrition to developing pollens and also help in anther dehiscence.
The "Telome theory" of Walter Zimmermann (1930, 1952) is the most accepted theory that is based on fossil record and synthesizes the major steps in the evolution of vascular plants.
It describes how the primitive type of vascular plants developed from Rhynia like 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 "Telome theory" of Walter Zimmermann (1930, 1952) is the most accepted theory that is based on fossil record and synthesizes the major steps in the evolution of vascular plants.
It describes how the primitive type of vascular plants developed from Rhynia like plants.
Apical meristem, region of cells capable of division and growth in the root and shoot tips in plants. Apical meristems give rise to the primary plant body and are responsible for the extension of the roots and shoots. Unlike most animals, plants continue to grow throughout their entire life span because of the unlimited division of these and other meristems.
The genus Coleochaete is represented by about 10 species, out of which 3 species are found in India. They grow in fresh water either as epiphytes on different angiosperms. They show much variation in their heterotrichous nature. Due to well-developed prostrate system, it forms discoid thailus and looks like
pseudo- parenchyma of one cell in thickness.
This is a detailed presentation on Morphology, anatomy and reproduction of Marchantia spp. with high quality pics and eye capturing transitions and animations
Structure, Development & Function of PeridermFatima Ramay
A group of secondary tissues forming a protective layer which replaces the epidermis of many plant stems, roots, and other parts.
Although periderm may develop in leaves and fruits, its main function is to protects stems and roots.
The periderm consists of three different layers:
Phelloderm
Phellogen (cork cambium)
Phellem (cork)
Its main function is to protect the underlying tissues from:
Desiccation
Freezing
Heat injury
Mechanical destruction
Disease
Loss of epidermis.
Bounding tissue restricting the pathogen & insects.
Allowing gaseous exchange through lenticels.
Apical meristem, region of cells capable of division and growth in the root and shoot tips in plants. Apical meristems give rise to the primary plant body and are responsible for the extension of the roots and shoots. Unlike most animals, plants continue to grow throughout their entire life span because of the unlimited division of these and other meristems.
The genus Coleochaete is represented by about 10 species, out of which 3 species are found in India. They grow in fresh water either as epiphytes on different angiosperms. They show much variation in their heterotrichous nature. Due to well-developed prostrate system, it forms discoid thailus and looks like
pseudo- parenchyma of one cell in thickness.
This is a detailed presentation on Morphology, anatomy and reproduction of Marchantia spp. with high quality pics and eye capturing transitions and animations
Structure, Development & Function of PeridermFatima Ramay
A group of secondary tissues forming a protective layer which replaces the epidermis of many plant stems, roots, and other parts.
Although periderm may develop in leaves and fruits, its main function is to protects stems and roots.
The periderm consists of three different layers:
Phelloderm
Phellogen (cork cambium)
Phellem (cork)
Its main function is to protect the underlying tissues from:
Desiccation
Freezing
Heat injury
Mechanical destruction
Disease
Loss of epidermis.
Bounding tissue restricting the pathogen & insects.
Allowing gaseous exchange through lenticels.
It explains about what is plant tissue & both the types i.e meristem & permanent tissue. It also explains about the general characteristic, and how it has been classified based on origin, position, function and plane. It also furnish further information regarding the above
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
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.
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 .
2. TISSUE : Group of cells which are similar, having a common origin and performing
similar function.
A complex of cells of common origin.
-Fahn (1928)
Tissues are of three types :
TISSUE
MERISTEMATI
TISSUE
PERMANENT
TISSUE
SECRETORY
TISSUE
3. MERISTEMATIC TISSUE :
The term meristem was coined by Carl Wilhelm von Nägeli (1858).
Term meristem is derived from Greek word “Merismos” that means “divisible”.
Meristematic tissue is group of immature cells that has capacity of division and
redivision.
The term of meristem is applied to the region of more or less continuous cell division from
which new tissues and organs are produced .
Meristematic tissues are the products of meristem which do not develop into adult cells but
remain meristematic .
For example, the root and shoot apices and the cambium are meristems which produce
meristematic tissues that divide and differentiate into xylem ,phloem, parenchyma, etc.
4. CHARACTERSTICS OF MERISTEM
Ability to grow and divide, small immature cells, Isodiametric, rounded, oval or
polygonal, Absence of intercellular spaces.
Walls are thin, elastic and made up of cellulose, dense protoplasm with many small
vacuoles and large nuclei .
Pro-plastids are present instead of plastids.
Endoplasmic reticulum is poorly developed.
Mitochondria have simple structure, rate of respiration is very high.
These cell do not store reserve food materials or very low reserve food materials.
5. Functions of Meristematic Tissue:
Meristems are actively dividing tissues of the plant.
They are responsible for primary (elongation) and secondary (thickness) growth of the
plant.
All new organs and their growth occur by the division of meristematic tissue.
Secondary tissues such as wood, cork are also formed due to activity of meristematic
tissue.
6. Classification of meristem :
Meristematic
tissue
On the basis of
origin
Promeristem
Primary meristem
Secondary
meristem
On the basis of
position
Apical meristem
Lateral meristem
Intercalary
meristem
On the basis of
functions
Protoderm
Procambium
Ground meristem
On the basis of
plane of division
Rib meristem
Mass meristem
Plate meristem
7. Classification based on origin/development :
1. Promeristem or Primodial meristem -:
Origin: embryonic origin therefore called Primordial or Embryonic meristem.
It is earliest and youngest meristematic tissue.
It is present at the extreme tip of young and growing root and shoot consisting of only
few cells.
It give rises to primary meristem.
2. Primary meristem -:
Origin: From Promeristem
Cell are always active and dividing
Present below promeristem in the shoot and root tip, and also in intercalary position
It gives rise to secondary meristem and primary permanent tissue
8. 3.Secondary meristem -:
Origin: From primary meristem.
It is developed later in life.
It gives rise to secondary permanent tissue.
E.g. Vascular cambium and cork cambium.
9. Classification based on position in plant body :
Meristem
oApical meristem
oPresent at growing apices
of plant such as root tip and
shoot tip.
•It divides in different planes
and helps to increase the
length.
•Apical meristem has two
distinct zone:
•Promeristem zone: contains
group of dividing cell (apical
initials)
•Meristematic zone: contains
Lateral meristem
1.Located in between the
regions of permanent
tissues.
2.It divides periclinally .
3.It helps to increase
thickening or girth during
secondary growth.
4.Example: vascular
cambium (primary
meristem) and cork
cambium (secondary
meristem)
Intercalary meristem
These are the portions of apical
meristems which are separated
from the apex during the
growth of the axis and remain
intercalated between
permanent cells.
It helps in elongation of plant
body.
Commonly present in
monocots, grass and pines.
Two type of intercalary
meristem involved in
10.
11. Classification based on function -:
o Haberlandt (1914) classified meristem on the basis of function.
Meristem
Protoderm
Function: Protection
mechanical injury
•It gives rise to epidermis
layer.
•It is the outermost
meristematic tissue
Procambium
Function: Transport of
water and nutrition
•It gives rise to vascular
tissue (xylem and
phloem)
•It is the innermost
meristematic tissue
Ground meristem
Function: Various
functions
•It gives rise to cortex,
endodermis, pericycle
and pith in dicot and
hypodermis, ground
tissue in monocot.
14. Classification based on Plane of Division -:
On the basis of plane of division the meristem are grouped under the following
three types -
Rib meristem-The cells divide only in one plane (anticlinal)is called Rib meristem.
It’s important role is in the development of pith and cortex of young stem.
Mass meristem-Cells divide in three planes or all planes e.g. Early embryo.
It’s important role is in the early development of endosperm, sporangia, cortex and
pith.
Plate meristem -The cells divide chiefly in two planes giving a plate like increase is
called plate meristem.
It’s important role is in the development of leaves without increasing thickness.
15.
16. Quiescent Centre or Quiescent Zone:
o First time observed by Clowes(1956,58) in root tips of Zea mays.
o An inactive center in between root cap and meristematic region.
o It is a biconvex structure and made up of thousands of inactive cells.
o In this region the rate of cell division is very slow as compared to
surrounding cells.
o This region carries less amount of DNA, RNA, ER, mitochondria and
ribosomes.
o This zone is the site of auxin synthesis.
Functions:
It acts as reservoir of cells.
It is more resistant to injury and irradiation.
If root growth is stopped or root tip is damaged then this zone restores
growth.
