Cell differentiation is the process by which a cell develops specialized structures and functions. It begins with totipotent cells that can differentiate into any cell type, and progresses to pluripotent and fully differentiated cells. Gene expression and transcription factors determine the cell type as environmental signals induce changes in protein production. The genetic material remains the same, but different genes are expressed depending on the cell's role. Differentiation results in diverse cell shapes, sizes, and specialized functions in tissues and organs.
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
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
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
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
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 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.
Here is a presentation of development biology. For further assistance contact at my email. It's a pleasure to me.if my work is helpful for anyone of you. Need your appreciation and criticism to improve my work. Thanks.
Cell division is a fundamental process by which living organisms grow, develop, and maintain their structure and function. It is a tightly regulated and highly coordinated mechanism that ensures the accurate distribution of genetic material and the formation of two genetically identical daughter cells from a single parent cell. Cell division plays a crucial role in various biological processes, including embryonic development, tissue repair, and the production of gametes for sexual reproduction.
Cell Division
Function
The function of cell division is essential for the growth, development, and maintenance of living organisms. It serves several crucial purposes, including:
Growth and Development: Cell division enables an organism to increase in size and complexity. During growth, cells divide to produce more cells, allowing tissues, organs, and the entire organism to expand. Additionally, during embryonic development, cell division plays a vital role in shaping and forming the various structures and organs of an organism.
Tissue Repair and Regeneration: In multicellular organisms, cell division is responsible for the repair and regeneration of damaged tissues. When an injury occurs, cells near the site of damage undergo division to replace the lost or injured cells. This process allows for the healing and restoration of injured tissues, enabling the organism to recover and maintain its normal function.
Asexual Reproduction: In some organisms, cell division is involved in asexual reproduction, where a single parent cell divides to produce genetically identical offspring. This type of reproduction occurs in many single-celled organisms and some multicellular organisms like plants, allowing them to quickly propagate and colonize new environments.
Gamete Production: In sexual reproduction, cell division is responsible for the production of specialized reproductive cells called gametes. These include sperm cells in males and egg cells in females. Through the process of meiosis, cell division reduces the number of chromosomes in the gametes to half the normal number, ensuring that when two gametes fuse during fertilization, the resulting offspring will have the correct chromosome count.
Genetic Diversity: Meiotic cell division also plays a crucial role in generating genetic diversity. By shuffling and recombining genetic material during meiosis, offspring inherit a unique combination of genes from their parents. This genetic diversity is essential for evolutionary processes, allowing for adaptation to changing environments and the survival
cell division & physiology of cell division, types, binary fission, meiosis, mitosis, regulation of cell cycle, cell cycle checkpoints, what is cyclin-dependent kinases and its importance
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.
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.
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.
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.
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.
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.
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. Cell Differentiation
“It is a biological process where in cells gain specialised roles and switch from one cell
type to another in an entity”
• All cells contain the same DNA so cells initially have the potential to become any type of cell.
• Cell Differentiation is irreversible.
• A cell that is able to differentiate into all cell types of the adult organism is known as pluripotent.
• A cell that is able to differentiate into a total organism with all cell types, including the placental
tissue, is known as totipotent.
• All cells in multicellular organism have the same number of chromosomes and DNA.
• Different parts of the genetic instructions are used in different types of cells.
• influenced by the cell's environment.
• Chemical signals may be released by one cell to influence the development and activity of another
cell.
Examples in Animals
Process of fertilization in animals produces zygote which is totipotent (Totipotent cells are those cells
that can be differentiated into any other cell type). All the complex tissues found in advanced animals
arise from the zygote. In entities, cell differentiation commences early on.
In mammals, totipotent cells, which can differentiate into any types of cells are present in the zygote and
blastomeres (cells after a few divisions). Slowly they start differentiating and giving rise to multicellular
organisms.
In higher plants, meristematic cells are pluripotent cells, they can differentiate into many types of cells,
e.g. root and shoot apical meristem.
In animals, stem cells are pluripotent cells.
3. What is the purpose of cell differentiation?
All cells of multicellular organisms derive from a single cell. By the process of cell
differentiation, cells gain their specific phenotype and functionality at maturity. Cell
differentiation leads to various different types of cells, which perform vital functions.
4. Cellular Differentiation :
• It is the process by which a cell acquires or develops certain properties and functions or
capabilities and becomes a more specialized cell type.
• Differentiation occurs when a simple zygote turns in to a complex system of tissues and
cell types.
• Adult stem cells divide and create fully differentiated daughter cells during tissue repair
and during normal cell turnover.
• Size, shape, membrane potential, metabolic activity, and responsiveness to signals of a
cell change drastically during differentiation .
• These changes are mostly because of highly controlled gene expression .
• With a few exceptions, cellular differentiation almost never involves a change in the
DNA sequence itself.
• Thus, different cells can have very different physical characteristics despite having the
same genome.
5. Specialized Cells-
• Nerve Cells communicate information either by using electric signals
(within a cell) or chemical signals (between cells).
• Muscle cells contain protein filaments that side past one another,
producing a contraction that changes both the length and the shape of
the cell.
• Blood cells are the most common type of blood cell and the vertebrate
organism's principal means of delivering oxygen to the body tissues.
• The process of development involves the division of the fertilization egg into many
cells which assume different size, shape, structure and function.
• The various cells constitute tissues and organs that together form the complete
animal .
• This whole process is called The process of differentiation is irreversible because the
differentiated or specialized cells cannot revert back to undifferentiated stem cells.
• Differentiation is divided into intracellular differentiation and intercellular
differentiation. intracellular differentiation is found in protozoa, in spermatogenesis
and in oogenesis. intercellular differentiation is met in multicellular animals and
plants.
6. Type of differentiation :
Differentiating cells show unique characters in the form of shape, structure, chemical
nature and behaviour. The process of differentiation can be divided into four kinds on the
basis of these differences:
1. Morphological differentiation : The differences acquired in shape and size of cells
during the course of development is called morphological differentiation.
2. Physiological differentiation : This includes the difference in the functional activities
of the cells.
3. Behavioural differentiation: The difference in the behavioural pattern of certain cells
like the nerve cells to be able to transmit impulses and secretion of bile by hepatic cells.
4. Biochemical differentiation : This is the most important kind of differentiation. During
the whole process of cleavage and gastrulation the different areas of the original egg
become biochemically from each other. This biochemical difference results in the
formation of different cells, tissues, etc.
7. Cell Differentiation – Mechanism
Transcription factors are key to the cell differentiation process. The chemicals and
hormones involved determine the course of action revolving around the DNA,
deciding the transcription. The body and cells in the proximity decide the factors
found in cells right from the fetal developmental stage to death. Both the DNA
constituted in a cell and the location of expression of DNA is pivotal.
The cell differentiation process has a range of the transcription factor has a direct
influence on the proteins transcribing the DNA transforming it gradually to operating
proteins and other cells. But, cells signal each other when they start to compress
together indicating the action can no longer proceed.
8. Process involved in differentiation :
1. Totipotency of Nucleus –Thus, countless cells making up the embryo or adult body contain
the same genetic information as possessed by the original zygote. This had been proved by a
member of experiments .
(A) Hans Spemann (1928) Contricted the newt, triturus egg lengthwise with a loop of fine
hair .The construction was not carried out completely, so that the two halves still had a
narrow of cytoplasm connection. The nucleated out of the zygote cleavage, the non-
nucleated half did not after 16 cell stage, a nucleus happened to pass through the cytoplasmic
bridge into non nucleated half .Hence forth, this half also showed cleavage and further
development. Spemann tightened the noose, cutting the two halves of the egg. Each half now
developed into a full fledged larva except that the half with delayed nucleus was delayed in it
development, Spemann concluded that the nuclei remained totipotent.
9. This process takes place in several steps:
i. Fertilization: Fusion of sperm and egg.
ii. Cleavage: Development of zygote to form blastula (group of undifferentiated cells).
iii. Gastrulation:Differentiation and movement of cells to form specialised cell layers.
iv. Differentiation: Development of specialised cells into tissues, organs and growth of the
embryo.
v. Growth, Maintenance and Regeneration of some cells.
These are used as a model in the developmental genetics for the following
reasons:
i. Short life cycle (3 days).
ii. Ease of maintenance like E. coli.
iii. Can reproduce by self or by cross- fertilization.
iv. Hermaphrodite (XX)—contains 5 pairs of autosomes and 1 pair of X chromosomes.
v. The male (XO) contains 5 pairs of autosomes and a single X chromosome.
vi. Haploid genome is about 8 x 107 bp.
vii. More than 600 genes have been identified.
viii. Easy to obtain homozygous populations, as self-fertilization is possible.
ix. In-breeding is automatic in hermaphrodite population.
x. DNA transformation through microinjection at the selected stage of development is
possible in this animal.
10. Level of differentiation:
Rutter, Wesself and other (1976), shows that the both exocrine and endocrine cells
recognize four levels of differentiation. They are :
(i) The undifferentiated state,
(ii) The prodifferentiated state,
(iii) Differentiated state,
(iv) Modulation
For example- cancer cells can be
graded differently depending on their
level of differentiation as poorly
differentiated, moderately
differentiated and well differentiated.
11. Factors causing differentiation:
1. Induction
2. Competence
3. Determination
Control of Differentiation:
1. Genetic amplification
2. Gene regulation by histones
3. Gene expression
Gene expression regulates differentiation :
• Gene expression is regulated by factors both extrinsic and intrinsic to the cell.
• Cell-extrinsic factors include environmental causes, such as small molecules, secreted
proteins, temperature and oxygen.
• Intrinsic factors include growth factors, morphogens, cytokines or signaling molecules.
• Signaling causes changes in transcription or expression of genes that may include turning
off or on of some genes. This can influence the cell fate and cell functions.
• In addition, gene expression changes can lead to changes in an entire organism, such as
molting in insects.
12. Gene expression is said to be the reason. Gene set in all entities is identical as the
genetic code is replicated from the actual egg cell that is fertilized by the sperm cell. To
undertake a specific role, a cell from its genetic code only uses a few of the genes,
ignoring the remaining.
Cell differentiation is primarily influenced by:
Structure of the gene – it is the prime factor for cell differentiation. Every viable gene
possesses crucial instructions which decide the cell type and physical traits of the host.
Any mistake here will influence the cell differentiation process and host-development.
Environmental determinants – temperature-change, oxygen supply and many other
environmental factors have an impact on the working of hormones because of the
different proteins dedicated to transforming information and stimulation of hormones.
Any impact on these molecules will cause the cell differentiation and development
process to get affected.
There are few instances leading to cell differentiation:
• Regular turnover of cells (blood cells in mature entities)
• Immature entity growing into an adult
• Damaged tissues undergoing repair when special cells are to be substituted
• Influence of cytoplasm
• Interaction between cells
• Hormones
