Download ECOL 330

02/11/2016
Evolution of Animal Form & Function Dr Alex Badyaev
ECOL 330
Creating pluripotent cells out of specialized ones.
Lecture 8
Does oocyte (egg) care if it is reprogramming
spermatozoa or say a skin cell?
2016
Dynamics of DNA demethylation
Using oocytes to reprogram
your own cells and replace your body
parts?
S Noggle et al. Nature 478, 70-75 (2011)
Somatic cell genome transfer with retention of the oocyte genome.
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Nature, 1 hour before
ECOL330 (in 2014)
Chimaeric mouse generation from STAP cells.
Low-pH-induced pluripotent cells.
H Obokata et al. Nature 505, 641-647 (2014) doi:10.1038/nature12968
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Germ cell formation and migration in birds
Germ cell formation and migration in birds
1) 16 hours: Germ cells are induced from epiblast cells
3) 24 hrs: Germ cells are carried to the forming intestine
and migrate to the edge of area pellucida to form extra‐embryonic Germinal Crescent
2) 18‐20 hours: Germ cells multiply within germinal crescent
When blood vessels form in the crescent area, germ cells enter those vessels
and are carried by circulation towards intestine
4) 3 hrs later: Germ cells leave blood vessels and crawl towards the gonads
Squeeze between the cells of blood vessels and tissues. Chemotaxis towards gonads??
“Parental
effects” in birds nd day of incubation
House finch embryo, 2
Path
I – the most direct link to inheritance
Periodic acid‐Schiff staining (PAS)
Continuity of phenotype
Germ cells
Gametogenesis steps:
1) The formation of the germ cells and
their migration into developing gonads
Meiosis:
Once in the gonad, the germ cells continue to divide mitotically producing millions of potential gamete precursors. But they are diploid…
(germ cells: deaf and mute passengers on the somatic bus)
2) Meiosis and formation of sperm cells
3) Formation of gonads
4) Spermatogenesis
5) Spermiogenesis
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Meiosis:
Meiosis:
Complex evolved machinery that assures that only one gene copy and only one chromosome
is transmitted. Why worry about this?
Ho:
‐each gene within genome – has its own line of descent and its own competitive dynamics among its alleles (states of the gene). ‐each allele – its own functional role within genome. Strong competition among alleles of the same genes, BUT strong cooperation with other genes…
Formation of testis
Why keep bi-potentiality window open for so long?
2 months in humans!
First exam | ECOL 330
‐ Paired regions of mesoderm adjacent to the developing kidneys ‐ Can differentiate either into testis or ovary, the path
determines the sexual development (up to 7 wks – bipotential!)
Formation of testis
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