From: Joel.M Dimech (firstname.lastname@example.org)
Date: Fri 07 Oct 2005 - 02:50:28 GMT
>>> Derek : How can you possibly say that nuclear genes are not relevant to the physical development of the embryo? It's been _totally_ proven that they are.
>> Joel : Not quite. What has been totally proven is the leading role of extra-nuclear genes, and the crucial importance of the ovum's kinetic moment.
> Derek : No, I'm sorry, I have to insist that it has been absolutely and completely proven that nuclear genes are vital in embryogenesis. They are orders of magnitude more important than any slight extranuclear or kinetic effects.
Joel : You are probably right, why should we care for "slight" kinetic effects? Ova that have lost their total kinetic moment are just prompting the method of ooplasm donation (cytoplasmic transfer). I assume that you will not bother at a few reminders :
- Healthy mitochondria (their genes) are essential for accurate chromatid segregation at the time of fertilization and subsequent mitotic divisions.
- Mitochondria are responsible for respiratory process and ATP production. In addition to their energetic nature, mitochondria are involved in the control of apoptosis.
- The embryo's development is regulated by a balance of pro- and anti-apoptotic genes, since oogenesis throughout the pre-implantation period.
- Organs are being shaped by means of apoptosis.
- Zygote survival almost exclusively depends on maternal mRNAs and proteins that accumulate during oocyte growth and maturation. The transition from maternally controlled zygote to activated embryonic genome depends on maternal transcripts. Assisted fertilization exists for three decades, and there is a huge amount of data on extra-nuclear genes. If you wish so, I'll send a list of references. Right now, things related with mRNA polyadenylation come to mind : Dickson et al. 2001, Hodgman et al. 2001 - About specific changes in polyadenylation that contribute to gene expression in embryos, and their direct relation with developmental competence : El Mouatassim et al. 1999, Brevini et al. 2002. Joel
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