From Jim Cummins
Incompatibilities between paternal and maternal imprinted nuclear genes could
also explain developmental problems in cloned animals as well as the size
disparities found when different species of mice are crossed
(This Week, 12 December 1998, p 16).
However, we shouldn’t forget another possibility. Some of the proteins that
make up mitochondria, the powerhouses of cells, are coded for by DNA found in
the mitochondria, whereas others are coded for by DNA in the nucleus. Size
disparities may result from a lack of concordance between mitochondrial proteins
from these different sources. Optimal mitochondrial function is essential for
normal growth and function.
The strict requirements for harmony between the nucleus and mitochondria have
been demonstrated in cell systems as well as in whole animals. This should be
borne in mind when discussing cloning and the rather scary issue of human embryo
“rescue” by cytoplasmic transfer.
cummins@central.murdoch. edu.au
