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Biomedical subjects

G Périquet

Publications and source records attributed to G Périquet.

10 recordsLinked to original sources
PubMed2004

Maintenance of a large pericentric inversion generated by the hobo transposable element in a transgenic line of Drosophila melanogaster.

The impact of the hobo transposable element in the global reorganization of the Drosophila melanogaster genome has been investigated in transgenic lines generated by the injection of hobo elements into the Hikone strain, which lacked them previously. Extensive surveys of transgenic lines followed for 250 generations have identified 13 inversions with hobo inserts at most breakpoints. One of these inversions is pericentric on chromosome 2. It has been maintained in the line where it was discovered and in several sublines at frequencies from 0.19 to 0.45, generating stable chromosomal polymorphisms, similar to cosmopolitan paracentric inversions in natural populations. Individuals homozygous for this inversion were viable and fertile, allowing the creation of a new homozygous strain.

Animals↗
PubMed1998

Hobo transposons causing chromosomal breakpoints.

Several laboratory surveys have shown that transposable elements (TEs) can cause chromosomal breaks and lead to inversions, as in dysgenic crosses involving P-elements. However, it is not presently clear what causes inversions in natural populations of Drosophila. The only direct molecular studies must be taken as evidence against the involvement of mobile elements. Here, in Drosophila lines transformed with the hobo transposable element, and followed for 100 generations, we show the appearance of five different inversions with hobo inserts at breakpoints. Almost all breakpoints occurred in hobo insertion sites detected in previous generations. Therefore, it can be assumed that such elements are responsible for restructuring genomes in natural populations.

Animals↗
PubMed1992

The 28S ribosomal RNA-encoding gene of Hymenoptera: inserted sequences in the retrotransposon-rich regions.

The genomes of two parasitoid wasps, Diadromus pulchellus and Eupelmus vuilleti, and the honey bee, Apis mellifera, contain few interspersed repeated sequences corresponding to transposons (Tn). This suggests that the genomic organisation of Hymenoptera could be due to the elimination of deleterious Tn in haploid males. We have used restriction-fragment length polymorphism analysis to show that nondeleterious Tn are present in the DNA (rDNA) encoding ribosomal RNA of twelve species of Hymenoptera. Sequence analysis of the 28S rDNA type-I and type-II insertion-rich regions of 80 species showed that this region is very highly conserved (95.8%). A consensus sequence and restriction map of the rDNA region were established. These sequence data were used to develop a strategy for detecting inserted elements in the rDNA fragments containing type-I or type-II insertion sites, and this strategy was used to screen twelve hymenopteran species and four non-Hymenoptera control species. The rDNA fragments from the Hymenoptera and control species contained inserted sequences in the area where type-I and type-II elements are inserted in the 28S rDNA retrotransposon-rich region of Diptera and Lepidoptera. The hymenopteran genomes therefore appear to contain repeated elements, the mobility and nature of which remain to be determined.

Animals↗
PubMed1985

Hybridization on squashed flies: a method to detect gene sequences in individual Drosophila.

Specific gene sequences can be detected by DNA hybridization to individual Drosophila squashed on cellulose or nylon filters. This "squash-blot" method permits the rapid survey of DNA polymorphism in large Drosophila population samples. It could also be useful for studying chromosome aberrations, departure from diploidy, and detection of pathogenic agents in vector insects.

Animals↗
PubMed1985

P-element distribution in Eurasian populations of Drosophila melanogaster: A genetic and molecular analysis.

Genetic and molecular investigations were carried out with Eurasian Drosophila melanogaster populations on the P-M system of hybrid dysgenesis. In 27 strains sampled from France to Middle Asia, a clear gradient exists between Western Europe, in which most modern strains are of the Q type, and eastern areas, in which M-cytotype strains predominate. Molecular analysis on individual flies was performed with two complementary probes of the cloned 2.9-kilobase P element. The results provide evidence for a gradually decreasing frequency of P elements from west to east, but the presence of P-homologous sequences has been ascertained in all of the wild M-cytotype populations analyzed. Moreover, some active P elements with GD sterility potential were revealed in the majority of M-cytotype populations when tested with a highly sensitive reference line. The gradual change in distribution of the polymorphic P family in Eurasia is discussed in relation to the structure of the elements together with the theories of P-M evolution and is interpreted as the present invasion of Eurasian populations by these elements.

Journal Article↗
PubMed1984

Hybrid dysgenesis in Drosophila melanogaster: influence of temperature on cytotype determination in the P-M system.

In Drosophila melanogaster, the P-M system of hybrid dysgenesis is a syndrome of germ line abnormalities, including temperature dependent gonadal dysgenesis (GD sterility), high rates of mutation and male recombination, which occurs in some interstrain hybrids but only from one of the two crosses. In the P-M system, hybrid dysgenesis results from interaction between chromosomally transposable elements of the P element family and a particular extrachromosomal state referred to as the M cytotype. Cytotype (M or P) is known to be determined by the absence or presence of chromosomal factors, but principally with limited cytoplasmic transmission. In a series of experiments in which F1 hybrid females from various P and M strains were submitted to different preadult and ageing temperature treatments, it was found that the cytotype switch is strongly temperature-dependent in the F1 females from M female X P male but not in the reciprocal cross. In the F1 females from the former cross, a strong M cytotype occurs at a low developmental temperature (18 degrees C) and a weak M cytotype occurs at a high developmental temperature (26.5 degrees C). On the other hand, a high ageing temperature applied after a low developmental temperature switches the cytotype from M to P and reciprocally, a low ageing temperature applied after a high developmental temperature switches the cytotype from P to M.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1982

Cytotype polymorphism of the P-M system in two wild populations of Drosophila melanogaster.

In Drosophila melanogaster the interactions of the P-M system generate germ-line aberrations (e.g., sterility, mutations) found in certain interstrain hybrids. Two wild populations, from France and Tunisia, were examined in order to determine the distribution of the chromosomal P factor and the extrachromosomal cytotypes. No P factors active for potential GD sterility were found in these populations. But search for the M cytotype, which causes susceptibility to the P factors, and for the P cytotype, which causes resistance to the P factors, showed that both populations are polymorphic for the cytotypes. Such a polymorphism seems to be stable in the wild, at least over a 2-year period. Mutator activity (measured by generated mutations at the sn and ras loci) was found to be present. Some possible interactions between cytotype polymorphism, mutator activity, and the structure of Drosophila populations are discussed.

Animals↗
PubMed1975

[The discovery, in Drosophila, of viruses belonging to three new groups].

Viruses belonging to three new groups have been discovered by the technique used to detect the Picornaviruses. Virus F was found in two French laboratory stocks of D. melanogaster. Virus G and virus RS came from wild flies: a sample of D. melanogaster from Guiana (virus G) and a mixture of different Drosophila species from Singapore (virus G and virus RS).

Animals↗