Download Fertilization, cell proliferation and differentiation

Fertilization, cell proliferation and
differentiation
www.sciencepicturecompany.com Molecular Cell Gene-cs 416451 Mingkwan Nipitwa6anaphon folliculogenesis
= a maturation of the ovarian follicle
Overian follicle is a densely packed shell of somatic cells that contains an immature
oocyte.
Order of changes in ovary.
1 - Menstruation
2 - Developing follicle
3 - Mature follicle
4 - Ovulation
5 - Corpus luteum
6 - Deterioration of corpus luteum
h6ps://en.wikipedia.org/wiki/Folliculogenesis folliculogenesis
h6ps://en.wikipedia.org/wiki/Folliculogenesis spermatogenesis
Production of Spermatozoa from primodial germ cells
- Used both mitosis and meiosis
h6ps://en.wikipedia.org/wiki/Spermatogenesis Spermatidogenesis
•  Creation of spermatid from secondary
spermatocytes
Spermiogenesis
•  Maturation of spermatid into mature spermatozoa
Spermiation
•  Releasing of mature spermatozoa from Sertoli cells
to the lumen of seminiferous tubules
Spermiogenesis
•  Maturation of spermatid into mature spermatozoa
•  4 stages
–  Golgi phase
•  change from radially symmetrical shape to become more polarity shape
•  head formation at one end and Golgi apparatus create acrosome, the
other end mitochondrial gather and distal centriole form axoneme
•  DNA is densely packed --> transcriptionally inactive
–  Cap phase / acrosome phase
•  Golgi apparatus becoming acrosomal caps
–  Formation of tail
–  Maturation stage
•  Access cytoplasm is phagocytosed by Sertori cells in the testes
Spermiogenesis
h6ps://en.wikipedia.org/wiki/Spermiogenesis Maturation stage
Access cytoplasm is phagocytosed by Sertori cells in the testes
h6ps://en.wikipedia.org/wiki/Spermatogenesis fertilization
•  Fusion of 2 haploid gametes to become diploid
zygote
–  Internal fertilization
–  External fertilization
•  Involved in many signaling processes and cell
division
•  In animals, there must be mechanisms to prevent
polyspermy
–  in mammals, the "cortical reaction" modifies the
extracellular coat of the egg (the zona pellucida), and
additional mechanisms modify the egg's plasma
membrane
fertilization
•  When the sperm bind to the egg before
fertilization, the egg become metabolically
active
–  Lots of transcription, translation and protein
synthesis
•  The fusion of the sperm to the egg continues
the meiotic process resulting in the releasing
of polar nuclei
fertilization
•  Fertilization is completed when there is a formation of
pronuclei
•  Also called a "zygote", "1 cell embryo" or "2 pronuclei
embryo"
h6p://www.advancedfer-lity.com/fer-liza-on.htm fertilization
en.wikipedia.org fertilization
Click to see
fertilization video link
h6p://bit.ly/1F7gaxd h6p://humanphysiology2011.wikispaces.com/ fertilization
Proliferation
•  Cleavage - Rapid cell division
•  Gastrulation - Cell movements and 3 layers form
–  Ectoderm –  Mesoderm
–  Endoderm •  Organogenesis
–  Pattern formation
–  Cell differentiation
•  Endoderm -> digestive tract •  Mesoderm -> support tissues, e.g. skeleton, muscle, connective tissues,
blood, urogential system
•  Ectoderm - > epidermis, nervous system
www.stemcure.com Differentiation
•  A process by which individual cells
become specialized and distinct from other
groups of cells
•  Change in cell’s size, shape, membrane
potential, metabolic activity,
responsiveness to signals
•  Differentiation occurs at various stage of
development but mostly after fertilization
Different ways of differentiation
Determination & differentiation
•  Determination = the process of establishing
which genes will be expressed and which
will not.
•  Cells progressively lose their genetic
capacity (genes, or chromosomes) during
the development à cells become
determined?
•  In fact, determination is regulated by gene
expression
h6p://biology.kenyon.edu/courses/biol114/Chap11/Chapter_11.html Asymmetric segregation determines the cell type
Asymmetric segregation of cellular
determinants is based on the asymmetric
localization of cytoplasmic molecules
(usually proteins or mRNAs) within a cell
before it divides. During cell division, one
daughter cell receives most or all of the
localized molecules, while the other
daughter cell receives less (or none) of
these molecules. This results in two
different daughter cells, which then take on
different cell fates based on differences in
gene expression. The localized cytoplasmic
determinants are often mRNAs encoding
transcription factors, or the transcription
factors themselves.
h6p://biology.kenyon.edu/courses/biol114/Chap11/Chapter_11.html Control of gene activity
•  RNA level
–  Transcription regulation - epigenetics
–  RNA processing
–  RNA transport
–  Selection of mRNA for translation
–  mRNA degradation
•  Protein level
–  Translational control
–  Protein modification –  Protein degradation
mRNA processing
apbio-­‐werle.wikispaces.com mRNA degradation
Specialized cells in different tissues
have large amount of certain mRNAs
Fraction
No. Of different
mRNAs
Copies per cell
% of total mRNAs
Oviduct
I
1
100,000
50
II
8
3,750
15
III
14,000
5
35
I
1
32,800
16
II
106
750
40
III
11,600
7
44
Liver
Fraction I = highly abundant
Fraction II = moderately abundant
Fraction III = rare
Ex. Despite Cell A and B have iden-cal gene-c materials, there are some genes that expressed only in Cell type A or Cell type B, but many of them can s-ll share the same expression pa6erns. Thus, different types of cells expressed genes differently. Cell A 17 Cell B 179 25 Housekeeping gene products "luxury gene products", presen-ng specific developmental program h6p://biology.kenyon.edu/courses/biol114/Chap11/Chapter_11.html Cell potency
•  Developmental potency = ability of cell to
develop into different cell types
–  Unipotency
–  pluripotency
–  totipotency
h6p://163.16.28.248/bio/ac-velearner/16/ch16c4.html Pluripotency: stem cells can differentiate into many blood
cell types
h6ps://en.wikipedia.org/wiki/File:Hematopoiesis_(human)_diagram.png Types of blood cells
•  White blood cells (leucocytes)
–  Neutrophils – most abundant, 40-75% of WBC
•  Innate (non-specific) immune system
•  polymorphonuclear cells (PMNs), contain various
cytotoxic substance
•  phagocytic
–  Basophils – least common, 0.01-0.3% of WBC
•  e.g. mast cells – store histamine
•  Parasitic infection and allergy function
–  Eosinophils – 1-6% of WBC
•  combating multicellular parasites
•  associated with allergy and asthma (หอบหืด)
Types of blood cells
•  White blood cells (leucocytes)
–  Monocytes – largest types of leucocyte,
2-10% of WBC
•  Unilobal nuclear, like amoeba
•  eplenishing resident macrophages
•  response to inflammation signals from sites of
infection in the tissues
•  differentiation into macrophages or dendritic cells
to effect an immune response
–  Lymphocytes
Types of blood cells
•  White blood cells (leucocytes)
–  Lymphocytes
•  Thymus (T)-cell
–  T helper cell – release cytokines and growth factors that
regulate other immune cells
–  T cytotoxic cell – lysis of virally infected cells, tumour
cells and allografts
•  Bone marrow (B)-cell – secrete antibody
•  Natural killer (NK) cell – lysis of virally infected
cells and tumour cells
Regeneration
•  A process of renewal, restora-on, and growth to repair the damage or maintain physiological and morphological stages •  Regulated by a sexual cellular process snowbio.wikispaces.com psi.wikia.com www.tutorvista.com Pattern formation
•  Cells need to know what they are and
what they do
•  A local group of cells organize into a
pattern of different cell types
–  Need communication between cells by chemical
signal
–  The signal can vary in concentrations (gradient)
resulting in different fate of cells
morphogen
•  A special type of chemical signal that specifies
development of particular pattern
•  There is a threshold of the morphogen
–  Reach the threshold -> cell become determined -> differentiate
Threshold 1 à cell differen-ates into type 1 Threshold 2 à cell differen-ates into type 2 Threshold 3 à cell differen-ates into type 3 h6p://biology.kenyon.edu/courses/biol114/Chap11/Chapter_11.html Pattern formation
In Drosophila embryo development Bicoid = a transcription factor
that acts as a morphogen
gradient
Bicoid is enriched in the
anterior part of the embryo
resulting in differential
levels of other
transcriptional factors, e.g.
hunchback, tailess, empty
spiracles, Kupppel
h6p://biology.kenyon.edu/courses/biol114/Chap11/Chapter_11.html Pattern formation
Pattern
formation
h6p://plantdev.bio.wzw.tum.de/index.php?id=58 Mutation of the homeobox (transcriptional factor) result in
developmental abnormality: antenapedia (fly that have legs
where the antena should be
Eyeless is a transcription factor
eyeless mutant has no eye while overexpression of this gene results in
developing eyes at the legs
www.gehring.biozentrum.unibas.ch www.scienceforums.net Dedifferentiation
•  A cellular process that differentiated cells reverts to the earlier
developmental stage
–  Ex. worms and amphibians in which a partially or terminally differentiated cell
reverts to an earlier developmental stage, usually as part of
a regenerative process. Dedifferentiation also occurs in plants.
•  Cells in cell culture can lose properties they originally had, such as protein
expression, or change shape. This process is also termed
dedifferentiation.
•  Dedifferentiation can be an aberration of the normal development cycle
that results in cancer
•  A small molecule dubbed reversine, a purine analog, has been discovered
that has proven to induce dedifferentiation in myotubes. These
dedifferentiated cells could then redifferentiate into osteoblasts and
adipocytes.
levels of differentiations in
cancer cells
•  Grade 1: well differentiated cancer cells,
look a lot like normal cells, slow growing.
•  Grade 2: moderately differentiated, do not
look like normal cells, growing faster than
normal cells.
•  Grade 3: poorly differentiated, do not look
like normal cells, fast-growing or
“aggressive.”
h6p://gcmaf.-msmithmd.com/book/chapter/60/ Terminal differentiation
•  Cells specilized
•  Post mitotic (stop dividing) -> die
•  Sometimes cell dead is a part of
differentiation, e.g. Progressive
keratinization of skin cell, progressive
lignification of xylogenic cells
Click to see keratnization
video link
h6p://bit.ly/1Dkf4cN