I–R system of hybrid dysgenesis in Drosophila melanogaster: analysis of the mitochondrial DNA in reactive strains exhibiting different potentials for I factor transposition

Abstract

In the I±R hybrid dysgenesis system, Drosophila melanogaster strains fall into two categories denoted inducer (I) and reactive (R). Among the reactive strains we can distinguish strains with weak, medium or strong reactivity levels. These levels are inherited in a complex way involving both chromosomal and nonchromosomal determinants, the nonchromosomal determinant being mainly maternally inherited. We were interested in determining the molecular basis of this maternal transmission. In this article we analyse the possible implication of the mitochondrial DNA in the determination of the reactivity levels. The mtDNA was analysed in lines with very dierent reactivity levels with the aim of correlating sequence dierences with reactivity levels. The mtDNA was analysed by sequencing and restriction fragment length. No correlation was established between reactivity level and mtDNA sequence. This may favour the hypothesis that epigenetic changes would be responsible for the dierent reactivity levels and their transgenerational transmission.

Coevolution of Drosophila melanogaster mtDNA and Wolbachia Genotypes

“…Previous studies [12], [23], [29], [39] (“b, d, e” datasets) have focused on M -clade genomes. Seven complete or nearly complete mtDNA genomes presented in GenBank belong to the M- clade (AJ400907, AF200829, FJ190106–10) and only two sequences belong to the S- clade (AF200828 and FJ190105) (Table 1) [25], [39], [40]. The genetic distance ranges from 0.0002 to 0.0019 within the M- clade and it is 0.0001 within the S -clade; while between these two clades it ranges from 0.0037 to 0.0042.…”

“…Shown are 1) the position of our lines and those of [25], [39], [40] in the tree and their associations with Wolbachia genotypes; 2) the correspondence between clades identified in Richardson et al [12] and our datasets; clade VII*, identified here by us, is associated with wMelCS2 genotype; 3) the biogeography data of mitotypes; Southeast Asia** according to [10] where genotype wMel2 was found; 4) 28 samples from Rand et al [23] (“d” dataset) belonging to the tree that is based on the analysis of relevant region of 1515 bp alignment (Supporting Information S1). Clade-branch I-II-III-IV is not clearly resolved in this case (Figure S2); 5) the correspondence of the tree to M and S clades.…”

“…Notes:*the 2757-bp sequence in JF736852 is identical to the 12508-bp sequence in FJ190105 [25];**Oregon-R (“b” dataset) is uninfected [7], we used only information on the mitochondrial genome [39];***Z53 (“b” dataset) is infected [38], AF200829 [39];****no data on infection (all “b” dataset), sequences presented [25], [40];LS (laboratory stock), origin unknown; repeated GenBank accession numbers JF730694 and JF730696 designate the TC and CC haplotypes; the sequence fragments of TC haplotype samples (JF730695– not indicated) were extended.…”

“… Archive of the 1515 bp alignment extracted from [ 12 ], [23], [25], [39], [ 40 ] (“b, d, e” datasets) in Fasta format. …”

On the Roles of Repetitive DNA Elements in the Context of a Unified Genomic‐Epigenetic System

“…There do exist infectious elements that transpose or generate copies for retrotransposition when placed in a “permissive” nuclear/cellular environment. The P 17,35,87 transposon and I 88–94 long interspersed nuclear elements (LINEs) of Drosophila melanogaster serve as prime examples of infectious sequences. P elements appear to be recent additions to the D. melanogaster gene pool as laboratory strains were found to lack the sequences, while the elements were detected to be abundantly distributed in wild flies.…”