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M Monnerot

Publications and source records attributed to M Monnerot.

30 records · Page 2Linked to original sources
PubMed1994

Ancient DNA from Bronze Age bones of European rabbit (Oryctolagus cuniculus).

The European rabbit (Oryctolagus cuniculus) is now widely distributed throughout the world as a result of transportation by man. The original populations, however, were confined to southern France and Spain. In order to investigate the role of human intervention in determining the genetic diversity of rabbit populations, we are studying the origin of rabbits introduced onto a small Mediterranean island (Zembra) near Tunis over 1400 years ago, by examining ancient DNA extracted from rabbit bones found both on Zembra and on the European mainland. Ancient DNA was successfully extracted from rabbit bones found at two archaeological sites dated to at least the Early Bronze Age (more than 3500 years ago) in south-central France, and compared to that found in modern mainland and island populations using a small variable region of the cytochrome b gene. The results confirm that the Zembra Island population is descended from that present over 1400 years ago. The technical aspects of DNA extraction from bones and the implications of this type of research for determining the origin of introduced rabbit populations are discussed.

Animals↗
PubMed1994

Genetic analysis of systematic mitochondrial heteroplasmy in rabbits.

One unusual property of rabbit mitochondrial DNA (mtDNA) is the existence of repeated 153-bp motifs in the vicinity of the replication origin of its H strand. Furthermore, every individual is heteroplasmic: it carries mtDNA molecules with a variable number of repeats. A systematic study of 8 females and their progeny has been devised to analyze mtDNA transmission through generations. The results suggest that three mechanisms are acting simultaneously. (1) Genetic drift in the germ line is revealed by the evolution of heteroplasmy when two major molecular forms are present in a female. (2) A high mutation rate (around 10(-2) per animal generation) generating molecular diversity, by deletion and addition of repeated units, is required to explain the observation of heteroplasmy in every individual. Moreover, the rates of mutation from the most frequent type to the other types are unequal. The deletion of one unit is more frequent than a deletion of two units, which is in turn more frequent than a deletion of three. (3) Selection for shorter molecules in somatic cells is probable. The frequency distribution of mtDNA types depends on the organ analyzed (kidney-spleen and liver vs. gonads).

Animals↗
PubMed1994

Phylogeny of decapod cephalopods based on partial 16S rDNA nucleotide sequences.

Various systematic and phylogenetic relationships have been proposed for extent decapod Cephalopods, based mainly on morphology and on the rare paleontological remains. Nucleotide sequence data from the 3' end of 16S rDNA gene were used as an alternative approach to morphology; this gene portion having proved to be appropriate to test divergences in other groups of assumed equivalent age. The results from 27 Decapoda species allowed us to calculate phylogenetic trees by the neighbor joining and parsimony methods (Paup and Hennig86). The trees were submitted to bootstrapping. The order Sepioidea, including the sepiids, sepiolids and spirulids, is not supported by molecular evidence. Sepiolids are clearly excluded from the order, and the position of the Spirulidae needs further clarification. In oegopsids, the intrafamilial groupings obtained by the molecular approach is in agreement with morphological data. The unresolved phylogeny at the suprafamilial level might be the result of two different events: earlier divergence than the Cenozoic, or unequal evolutionary rates among taxa having appeared either by successive emergence or by fast radiation. The 3' end of 16S rDNA gene of cephalopods is a precious tool to analyze taxonomic relationships at the infrafamilial level. A gene with a lower evolutionary rate, is necessary to establish higher taxa phylogeny.

Animals↗
PubMed1993

Molecular characterization of mitochondrial DNA provides evidence for the recent introduction of Schistosoma mansoni into America.

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.

Africa↗
PubMed1990

Discrepancy in divergence of the mitochondrial and nuclear genomes of Drosophila teissieri and Drosophila yakuba.

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)

Africa↗
PubMed1989

The generation of transplasmic Drosophila simulans by cytoplasmic injection: effects of segregation and selection on the perpetuation of mitochondrial DNA heteroplasmy.

Experimental transplasmic Drosophila simulans were obtained through cytoplasm microinjection between eggs carrying different mitochondrial genomes. These genomes (siII and siIII) show a 1.5% difference in their sequences. They produced a large number of heteroplasmic flies in their F1 progeny and several flies were still heteroplasmic at the eighth generation. The distribution of frequencies of mitochondrial genotypes in the offspring of heteroplasmic females suggests that the stochastic processes involved in the evolution of experimental heteroplasmy of multiple nucleotide sites are very similar to those previously described for spontaneous length heteroplasmy. In addition, the siII genome has a noticeable advantage over the siIII genome in both directions of injection. This advantage is estimated at 58% per fly generation and 5% per cell generation.

Animals↗
PubMed1986

Mitochondrial DNA evolution in the melanogaster species subgroup of Drosophila.

Detailed restriction maps (40 cleavage sites on average) of mitochondrial DNAs (mtDNAs) from the eight species of the melanogaster species subgroup of Drosophila were established. Comparison of the cleavage sites allowed us to build a phylogenetic tree based on the matrix of nucleotide distances and to select the most parsimonious network. The two methods led to similar results, which were compared with those in the literature obtained from nuclear characters. The three chromosomally homosequential species D. simulans, D. mauritiana, and D. sechellia are mitochondrially very related, but exhibit complex phylogenetic relationships. D. melanogaster is their closest relative, and the four species form a monophyletic group (the D. melanogaster complex), which is confirmed by the shared unusual length of their mt genomes (18-19 kb). The other four species of the subgroup (D. yakuba, D. teissieri, D. erecta, and D. orena) are characterized by a much shorter mt genome (16-16.5 kb). The monophyletic character of the D. yakuba complex, however, is questionable. Two species of this complex, D. yakuba and D. teissieri, are mitochondrially indistinguishable (at the level of our investigation) in spite of their noticeable allozymic and chromosomal divergence. Finally, mtDNA distances were compared with the nuclear-DNA distances thus far established. These sequences seem to evolve at rather similar rates, the mtDNA rate being barely double that of nuclear DNA.

Animals↗
PubMed1984

Intra-individual length heterogeneity of Rana esculenta mitochondrial DNA.

Mitochondrial DNA extracted from Rana esculenta oocytes appears heterogeneous in size. The length of these molecules varies continuously from 18,700 bp to 19,700 bp. Each animal is heteroplasmic and can be characterized by the range of the variation (400-700 bp) and the extreme sizes of the various molecules it carries. The variable region of the genome has been localized between the coding region and the replication origin area.

Animals↗
PubMed1983

Mitochondrial DNA heteroplasmy in Drosophila mauritiana.

Mitochondrial DNA extracted from an isofemale strain of Drosophila mauritiana (subgroup melanogaster) appeared to be heterogeneous in size. A short genome [S; 18,500 base pairs (bp)] and a longer one (L; 19,000 bp) coexist in the preparation. The additional 500 bp have been located within the A+T-rich region. Hpa I digest patterns suggest that the S genome may carry a duplication of a 500-bp sequence including an Hpa I site and that the L genome may carry a triplication of the same sequence. At the 30th generation of the isofemale strain, 60 female genotypes were examined individually. Half of the files were pure either for the S or the L DNA. The remaining 50% exhibited various degrees of heteroplasmy for the two DNA types. Among metazoan animals, this D. mauritiana strain offers an exceptional situation with regard to the number of individuals heterogeneous for mtDNA and the relative stability of heteroplasmy through generations.

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