Freethought & Rationalism Archive

Blinn · 08-22-2002, 01:08 PM

<a href="http://www.msnbc.com/news/797315.asp?0bl=-0" target="_blank"> Mitocondria traced to father alters belief on inheritance</a>

simian · 08-22-2002, 01:22 PM

OK, assuming this is confirmed, and that it has an impact on where the mitochondria in women's reproductive cells come from:

What will this do to the age of the last common "mother" of the human race? Will she be older or younger than the previous estimates? I don't know the math behind the estimates, so can't really figure that one out.

Thanks,

Simian

pz · 08-22-2002, 01:27 PM

Quote:

Originally posted by Zetek:
<a href="http://www.msnbc.com/news/797315.asp?0bl=-0" target="_blank"> Mitocondria traced to father alters belief on inheritance</a>

This has been known for a long, long time, since I was an undergraduate. It's obvious, actually: sperm contain mitochondria to fuel motility, and they fuse completely with the ovum. It's just that the volume of a sperm cell is minute and essentially negligible relative to the size of the egg.

Principia · 08-22-2002, 01:32 PM

<a href="http://www.sciencemag.org/cgi/content/full/286/5449/2436a" target="_blank">older Science article on transmission of paternal mtDNA</a>

<a href="http://www.sciencemag.org/cgi/content/full/286/5449/2524" target="_blank">another one</a>

and an abstract, same group:

Quote:

Does human mtDNA recombine?
Eyre-Walker A, Awadalla P
JOURNAL OF MOLECULAR EVOLUTION
53 (4-5): 430-435 OCT-NOV 2001

Abstract:
In this article we review the evidence for and against recombination in human mtDNA. If recombination occurs, there needs to be a route by which genetic material can incorporate itself into the mitochondrial genome, and hence between mitochondrial lineages. We review the evidence for possible routes and then review the current state of the population genetic evidence for recombination. We conclude that there is no firmly established route by which recombination can occur, and that while some of the population genetic evidence is suggestive of recombination, it is far from conclusive.

[ August 22, 2002: Message edited by: Scientiae ]

Blinn · 08-22-2002, 04:39 PM

Quote:

Originally posted by pz:


This has been known for a long, long time, since I was an undergraduate. It's obvious, actually: sperm contain mitochondria to fuel motility, and they fuse completely with the ovum. It's just that the volume of a sperm cell is minute and essentially negligible relative to the size of the egg.

When I read this article, I thought that I recalled something about a few of the mitochondria from the sperm's neck being transferred to the ovum, but I didn't recall the details about what happened to them after that (assuming that's known; seems it isn't). Any ideas on how, in this case, the paternal mitochondria end up segregated into muscular tissue?

Nic Tamzek · 08-22-2002, 05:27 PM

Quote:

Both the sperm and the egg that come together to make an embryo carry mitochondria. However, the sperm packs only about 100 copies, while the egg has 100,000.

...which gives some idea of the relative influence.

However, perhaps there is some kind of selfish DNA thing going on here, where the egg cell most of the time actively kills off foreign mitochondria?

nic

Doubting Didymus · 08-22-2002, 05:47 PM

Quote:

However, perhaps there is some kind of selfish DNA thing going on here, where the egg cell most of the time actively kills off foreign mitochondria?

I doubt it, as foreign mitochondria would not be a detriment to the egg cell.

HRG · 08-22-2002, 11:21 PM

[QUOTE]Originally posted by Doubting Didymus:

I doubt it, as foreign mitochondria would not be a detriment to the egg cell.[/QB]

But it would be a detriment to the particular mtDNA because it decreases its chance to get into the next generation. To a selfish gene, the mere presence of a different allele is "detriment".

Imagine a new allele in a diploid organism which decreases the fertility of the organism by 10%, but makes it 100% sure that it will be "chosen" at meiosis. It will have a big advantage: instead of having a 50% chance at 100%, it has a 100% chance at 90%.

Mark Ridley has written an excellent introduction into those topics ("Mendel's Demon").

Regards,
HRG.

MortalWombat · 08-23-2002, 09:43 AM

Quote:

Originally posted by Nic Tamzek:
However, perhaps there is some kind of selfish DNA thing going on here, where the egg cell most of the time actively kills off foreign mitochondria?

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=110415 17&dopt=Abstract" target="_blank">Here</a>

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=938210 9&dopt=Abstract" target="_blank">here</a>

and

<a href="http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v402/n6760/abs/402371a0_fs.html&dynoptions=doi1030124662" target="_blank">here</a>

are some articles dealing with the elimination of sperm mitochondria by the fertilized ovum.

Nic Tamzek · 08-23-2002, 10:23 AM

Heh. I suspected as much. I should be an ev. bio....

nic

08-22-2002, 01:08 PM	#1
Blinn Veteran Member Join Date: Aug 2001 Location: Ohio, USA Posts: 1,162	Mitochondria traced to father <a href="http://www.msnbc.com/news/797315.asp?0bl=-0" target="_blank"> Mitocondria traced to father alters belief on inheritance</a>

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

08-22-2002, 01:22 PM	#2
simian Veteran Member Join Date: Sep 2001 Location: St. Louis, MO area Posts: 1,924	OK, assuming this is confirmed, and that it has an impact on where the mitochondria in women's reproductive cells come from: What will this do to the age of the last common "mother" of the human race? Will she be older or younger than the previous estimates? I don't know the math behind the estimates, so can't really figure that one out. Thanks, Simian

08-22-2002, 11:21 PM	#8
HRG Veteran Member Join Date: May 2001 Location: Vienna, Austria Posts: 2,406	[QUOTE]Originally posted by Doubting Didymus: I doubt it, as foreign mitochondria would not be a detriment to the egg cell.[/QB] But it would be a detriment to the particular mtDNA because it decreases its chance to get into the next generation. To a selfish gene, the mere presence of a different allele is "detriment". Imagine a new allele in a diploid organism which decreases the fertility of the organism by 10%, but makes it 100% sure that it will be "chosen" at meiosis. It will have a big advantage: instead of having a 50% chance at 100%, it has a 100% chance at 90%. Mark Ridley has written an excellent introduction into those topics ("Mendel's Demon"). Regards, HRG.

08-23-2002, 10:23 AM	#10
Nic Tamzek Senior Member Join Date: Jan 2002 Location: California Posts: 646	Heh. I suspected as much. I should be an ev. bio.... nic

Freethought & Rationalism Archive

The archives are read only.