FATE OF PARENTAL MITOCHONDRIA IN EMBRYONIC STEM HYBRID CELLS
A. G. Menzorov,1 N. M. Matveeva,1 D. M. Larkin,1 D. V. Zaykin,2
O. L. Serov 1, *
1 Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, and 2 National Institute of Environmental Health Sciences,
Research Triangle Park, 27709 NC, Raleigh, USA;
* e-mail: serov@bionet.nsc.ru
When hybrid cells are created, not only nuclear genomes of parental cells unite but their cytoplasm as well. Mitochondrial DNA (mtDNA) is a convenient
marker of cytoplasm allowing one to gain insight into the organization of hybrid cell cytoplasm. We analyzed the parental mtDNAs in hybrid cells resulting from
fusion of Mus musculus embryonic stem (ES) cells with splenocytes and fetal fibroblasts of DD/c mice or with splenocytes of M. caroli. Identification
of the parental mtDNAs in hybrid cells was based on polymorphism among the parental mtDNAs for certain restrictases. We found that intra- and inter-specific ES
cell-splenocyte hybrid cells lost entirely or partially mtDNA derived from the somatic partner, whereas ES cell-fibroblast hybrids retained mtDNAs from both parents
in similar ratios with a slight bias. The lost of the "somatic" mitochondria by Es-splenocyte hybrids implies non-random segregation of the parental mitochondria as
supported by a computer simulation of genetic drift. In contrast, ES cell-fibroblast hybrids show bilateral random segregation of the parental mitochondria judging
from analysis of mtDNA in single cells. Preferential segregation of "somatic" mitochondria does not depend on the differences in sequences of the parental mtDNAs
but depends on replicative state of the parental cells.
Key words: embryonic hybrid cells, mitochondria, mitochondrial DNA, embryonic stem cells
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