mitochondria, plastids and DNA inheritance

Jim Cummins cummins at
Tue Feb 22 02:29:21 EST 1994

In article <2kbt1n$ie8 at>
pw at (Paul Wakenight) writes:

> Also, wouldn't diploidy in plastids and the adaptive advantages of recombi-
> nation require mitotic machinery similar to that in the nucleus?  Also, what
> selective advantage could arise from dipl. - is it wrong to assume that      
> plastids have approached maximal effectiveness for their given function?

I can't answer your query on plastids, but the following references are
essential reading in the field of genome competition and the evolution
of sex.

Hurst LD. Intragenomic conflict as an evolutionary force. Proc Roy Soc
Lond B 1992; 248:135-140.
Hurst LD. A model for the mechanism of transmission ratio distortion
and for t-associated hybrid sterility. Proc Roy Soc Lond B 1993;
Hurst LD, Hamilton WD. Cytoplasmic fusion and the nature of sex. Proc
Roy Soc Lond B 1992; 247:189-194.
Margulis L, Sagan D. Origins of Sex. Yale University Press 1986.  This
has estensive discussion on the evolutionary origins of plastids.  A
quote may illuminate (p 66) "Mitochondria and plastid genetic
recombination can be demonstrated at a time when the cells in which
they reside reproduce by mitotic (nonsexual) division.  The implication
here-and it is only one of many clues giving similar hints - is that
these organelles were once free-living bacterial entities: their type
of sex, the recombination of DNA molecules, is a holdover from their
former independent lives"

Jim Cummins                   
School of Veterinary Studies
Murdoch University
Western Australia 6150  Tel +61-9-360 2668 Fax +61-9-310 4144
"An inordinate fondness for Beetles"

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