Transfer of mitochondrial DNA fragments into the nuclear genome in flies and cell line of <i>D.virilis</i>.

Transfer of mitochondrial DNA fragments into the nuclear genome in flies and cell line of D.virilis. Svetlana Y. Sorokina¹, Denis A. Romanov², Boris V. Andrianov², Ilya A. Zakharov². 1) Dept Genetics, Koltsov Inst Dev Biology, Moscow, Russian Federation; 2) Dept insect Genetics, Vavilov Inst Gen Genet, Moscow, Russian Federation.

We have developed a method of experimental detection of D.virilis Numt-sequences, based on site-specific insertion of Tv1-retrotransposon into mitochondrial microsatellite (AT)n, located at the spacer region between atp6 and cox3 mitochondrial genes. This approach allows us to detect the recent events of Numt-sequences insertions into nuclear genome. We show that D.virilis cell line, as well as D.virilis fly strains, have the fragments of atp6 mitochondrial gene of equal size (261 bps) in their nuclear genomes. In both cases atp6 fragments are associated with LTR of Tv1-retrotransposon. But comparative analysis of these sequences revealed different origins of atp6 Numt-sequences in flies and cell line. Atp6 Numt-sequences of all five studied D.virilis strains from different geographic localities have 18 point mutations in comparison to functional mitochondrial atp6 gene sequence of D.virilis. These mutations lead to seven aminoacid substitutions, but do not lead to stop-codon formation. Coincidence of atp6 Numt-sequences of all D.virilis strains studied allows us to suppose an ancestral status of D.virilis atp6 Numt-sequence from flies. In contrast, all atp6 Numt-sequences from D.virilis cell line found were completely identical to homological mt-sequence of D.virilis with one exception - C-8 clone that has only one synonymous substitution. However, Tv1 parts of all Numts revealed were different in length and nucleotide sequence. These facts suggest the recent origin of atp6 Numt-sequences in D.virilis cell line through a series of independent events. The study was supported by RFBR grant N 11-04-01630-a and the program of the Presidium of RAS Wildlife: Current status and problems of development.