Telomere Extension & Menopause Insights | Môn Biology Technology - Trường Đại học Quốc tế, Đại học Quốc gia Thành phố Hồ Chí Minh

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Telomere – How to prolong the telomere length?
Telomeres are natural ends, the tips of a whole linear chromosome.
- Function: protect the end of chromosome from deterioration and stabilize the chromosome end
- Without telomeres, the chromosome would lose the ends in time, which may lead
to lose necessary information they contain.
- Telomere Shortening DOES NOT Occur in Our Reproductive Cel s
-Telomere also participate in limiting cel division and it may play an important role in aging and cancer.
- Telomere can be shortening in cel division. Comparing to the adult stem cel
which telomere shorten in cel division, the embryonic stem cel has the telomere
enzyme, telomerase help telomere prolong.
-Somatic cells contain the gene for telomerase. The gene is shut OFF So, let’s turn it ON.
Menopause – How to prolong menopause?
Cessation of woman’s menstrual cycle
Midlife hypothalamic change may trigger onset of menopause
Hormones relating to the Ovarian cycle. Hormones:
Follicle stimulation hormone (FSH) lOMoAR cPSD| 59085392 luteinizing hormone (LH) Hormonal interactions –
During fol icular phase, rise in FSH signals ovarian fol icle to secrete more
estrogen – Rise in estrogen feeds back to inhibit FHS secretion which declines as follicular phase proceeds – LH rises in fol icular phase
• As it peaks in mid-cycle, it triggers ovulation
– Estrogen output decreases and mature fol icle is converted to a corpus luteum
– Corpus luteum secretes progesterone and estrogen during luteal phase
– Progesterone output inhibits release of FSH and LH
• Low LH – corpus luteum degenerates
• Progesterone levels decline
– FSH can start to rise again, initiating new cycle lOMoAR cPSD| 59085392
Gene Expression during preimplantation Formation the ICM: lOMoAR cPSD| 59085392
1. Oct4 is expressed first, and
blocks cells from taking on the trophoblastic fate
2. Nanog is expressed late and
prevents ICM cel s from becoming hypoblast cel s. 3. Stat3 (phosphorylation) is
stimulates self-renewal of ICM cel s The differences between male and female pronucleus
Male PN has a higher level of transcription than female PN.
Types of embryos and characteristics MALE (%) FEMALE (%) FULL TERM 1. Fertilized 50 50 60-70% lOMoAR cPSD| 59085392 2. Parthenogenetic diploid 0 100 0% embryo 3. Androgenetic diploid 100 0 0% embryo 4. SCNT embryo 50 50+ differentiated 2% genome 5. Haploidizated embryo 25 75 0% 6. Tetreploid fertilized 50 50 0% embryo
3 + 1 or 4  can develop ful term baby. 1+ 2  can be ful term. 2 + 6  prolong embryo.
2 + 4  can develop full term baby. lOMoAR cPSD| 59085392 lOMoAR cPSD| 59085392 lOMoAR cPSD| 59085392 Types of cells:
- Totipotent stem cel s: has the ability to develop into a human being (Zygote, embryonic cell at the
2-cell, 4-cell and early 8-cell embryos)
-Pluripotent stem cel s: has the ability to differentiate into all organs in the body(Embryonic stem
cells , Induced pluripotent stem (iPS) cells)
-Multipotent stem cel s: A multipotent stem cell can give rise to other types of cells but it is limited
in its ability to differentiate.
-Oligopotent stem cel s: differentiate into a few cel types - Unipotent cel s: lOMoAR cPSD| 59085392 TRAC NGHIEM: Fertilization
Oct-4 gene expresses in the first day, specifically 6 hours after fertilization, oct-4
genejust detected in nucleus only.
Oct-4 gene is in 1-cell, 2-cell, 4-cell and 8-cell embryo + Morula.
Cdx 2 gene become trophectoderm contributing placenta.
Oct-4 become ICM (Inner cel mass).
Preimplantation process: is the process by which zygote becomes blastocyst
MPF (maturation promoting factor) cause DESCONDENSE of sperm
E-cadherin -> Compaction
Trong Egg activation remember IP3 is the pathway to concrete egg membrane. & H+ go outside/ Na+ go inside
Na+ undergo ALKALINITY  egg activation lOMoAR cPSD| 59085392 lOMoAR cPSD| 59085392
Gastrulation: process epiblast differentiate into 3 endoderm: Ectoderm, endoderm, medoderm
CYTOCHALASIN B: use to stop cel dividion
Preimplantation development
2-cell embryo => 4-cell embryo => 8-cell embryo => Compact 8-cell => Morula
=> Blactocyst =>Hatching blastocyst
The morula consist of 2 cel group:
+ Trophoblast (trophectoderm) cell (TE) (OCT4)
+ Inner cel mass (ICM) cel s (CDX2
CÁC HISTON CÓ CHỨC NĂNG GÌ lOMoAR cPSD| 59085392
+ Histone H3 phosphorylation: Regulated chromosome condensation during pig oocytes maturation
+ Histone H3 acetylation: -Chromatin remodeling -Transcriptional activity
+ Histone H3 methylation: -Transcriptional repression -Epigenetic memory Meiosis & Mitosis Mitosis: Metaphase Chromosome condensation Nuclear membrane breakdown Chromosome segregation
Mitosis: Anaphase + telophase Chromosome de-condensation
Reformation of nuclear membrane
MPF is a heterodimer of cyclins and Cdks
MPF activity work wel in Meiosis II (metaphase arrest) lOMoAR cPSD| 59085392
M-Cdk (Cyclin act in Metaphase phase)  Trigger mitosis machinery
S-Cdk (Cyclin act in Synthesis phase)  Trigger DNA replication machinery
1. Phosphorylation: inhibits Cdk activity
2. Dephosphorylation: increases Cdk activity Telomeres and aging
A telomere is a region of repetitive DNA at the end of a chromosome, which
protects the end of the chromosome from deterioration. Telomeric repeat: TTAGGG
Telomere created in preimplantation lOMoAR cPSD| 59085392
Somatic cell turn to cancer cel  telomere work again
If you want to control gene expression, start at ZYGOTE
Knock out telomerase only effect on metastasis not growth inhibition of human cancer cel s lOMoAR cPSD| 59085392
The first mitotic division and our life
The process of compaction, the first morphological differentiation of embryo depend
on the time after ICSI but not the number of cel in embryo
The first differentiation occurs at the later start of 8-cell stage independent the
number of blastomeres but depend on the age of embryo.
Leading and lagging blastomere can differentiate into TE and ICM cel s.
Leading blastomere higher contribute into ECM cel s than lagging blastomere. lOMoAR cPSD| 59085392 ( Lead > lag) 1.
Leading and lagging blastomere distributed separate during the early division (until the morula stage). 2.
The first migration of leading and lagging blastomere toward opposite site
occurred at the early blastocyst stage, when the blastocoel is created. 3.
The starting of blastocoel at the early blastocyst stage is equivalent in both
leading and lagging blastomeres
WHY The female pronucleus was always located in the space side of the second
polar body? Because of micro-tubulin connection between 2nd polar and female pronucleus
How many types of stem cells are there?
+ Pluripotent stem cel s: blastocyst: TE and ICM
+ Totipotent stem cel s: from zygote to early blastocyst +
Multipotent stem cel s: aldult stem cel or somatic cell
What is difference between Chimeric animals + Transgenic animals?
- Chimeric animals are organisms composed of cel s from two or more genetically
distinct individuals, created through chimera formation, chimeras involve mixing cel s
from different individuals orembryos.
A transgenic animal is one that carries a foreign gene that has been deliberately inserted into its genome. lOMoAR cPSD| 59085392 lOMoAR cPSD| 59085392
- It is possible for an animal to be both chimeric and transgenic if it carries foreign
DNA and has cel s from different genetic backgrounds.
Mammalian Transgenesis by gene targeted ES cells & blastocyst injection
1. Diploid fertilized blastocyst injection
Injection of gene targeted ES cells in to normal fertilized embryo at the expanded blastocyst stage lOMoAR cPSD| 59085392
Injection of ES cell into blastocyst: The method to produce chimera
Diploid blastocyst injection to produce chiumera mouse lOMoAR cPSD| 59085392
Tetraploid blastocyst injection to produce chimera mouse