Irregular Replication of Substoichiometric Mt
DNA Copies
In contrast to the plastome, the hybrid
chondriomes could also show patterns, which deviate from the parental types
by a very high amplification of distinct mt genome regions. This was the
case for an additional atp6-homologous sequence. By hybridization
with the homologous probe containing atp6 the prominent additional
fragment becomes visible in 10% of the somatic hybrids but not in their
parents. Hybrids affected from this unregulated replication were found
in the combinations of population II [a
(+) g]
and population IV [a
(+) e]. An
example for this occurence is given in the upper autoradiography. The same
organisation was also found in the far related wild species S. polytrichon
and S. verrucosum. The duplication differed from the original
atp6 locus ("atp6_1") in the termination
region 211 bp downstream from the stop codon ("atp6_2").
Parents of fusion population IV (lanes
1, 2), and hybrids (lane 3, 4) cut with EcoRI, hybridised with probe
"atp6_1". In the deviating hybrid (lane 3) the blot makes visible a 3,4
kbp fragment, containing an additional atp6
gene with sequence deviation beginning 211 bp 3´ from stop codon.
The signals of the lower bands represent the normal
atp6/nad1 fragments.
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Loessl: Cytoplasm Genome Research
Andreas LÖSSL, 15.10.2010