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This paper investigates interspecies relationships within the genus Acomys (spiny mice) by analyzing entire mitochondrial cytochrome b gene (1141 bp). This gene provides strong phylogenetic signal, as shown by high support of the topology obtained (bootstrap value and RNA support number). The phylogeny is congruent with inferences from allozymes for the species considered. Controversial taxonomy of Acomys cahirinus, dimidiatus, airensis, and ignitus is clarified, with their specific ranks confirmed on the basis of tree topology and nucleotide distances. Phylogenetic relationship between the undescribed species Acomys sp. from west Africa and A. airensis argue in favor of two distinct colonization events in this zone., (Copyright 1998 Academic Press.)

Mitochondrial DNA was analyzed from 6 strains of Schistosoma mansoni with 12 restriction enzymes, corresponding to 40 restriction sites or about 1.5% of the coding region. An extensive length polymorphism among strains of S. mansoni was found, with size ranging from 16,500 bp to 24,900 bp. Five restriction sites among 40 were polymorphic; phylogenetic analysis using parsimony criteria supports the idea that American strains were introduced very recently from Africa. Two large fragments (2800 and 5400 bp), representing half of the coding region were cloned. The location of some genes was determined using heterospecific multigenes probes and suggests that this platyhelminth genome differs from all other known mtDNA gene organization.

Restriction sites were compared in the mitochondrial DNA (mtDNA) molecules from representatives of two closely related species of fruit flies: nine strains of Drosophila teissieri and eight strains of Drosophila yakuba. Nucleotide diversities among D. teissieri strains and among D. yakuba strains were 0.07% and 0.03%, respectively, and the nucleotide distance between the species was 0.22%. Also determined was the nucleotide sequence of a 2305-nucleotide pair (ntp) segment of the mtDNA molecule of D. teissieri that contains the noncoding adenine + thymine (A + T)-rich region (1091 ntp) as well as the genes for the mitochondrial small-subunit rRNA, tRNA(f-met), tRNA(gln), and tRNA(ile), and portions of the ND2 and tRNA(Val) genes. This sequence differs from the corresponding segment of the D. yakuba mtDNA by base substitutions at 0.1% and 0.8% of the positions in the coding and noncoding regions, respectively. The higher divergence due to base substitutions in the A + T-rich region is accompanied by a greater number of insertions/deletions than in the coding regions. From alignment of the D. teissieri A + T-rich sequence with those of D. yakuba and Drosophila virilis, it appears that the 40% of this sequence that lies adjacent to the tRNA(ile) gene has been highly conserved. Divergence between the entire D. teissieri and D. yakuba mtDNA molecules, estimated from the sequences, was 0.3%; this value is close to the value (0.22%) obtained from the restriction analysis, but 10 times lower than the value estimated from published DNA hybridization results.(ABSTRACT TRUNCATED AT 250 WORDS)