Biomedical subjects

N Chaminade

Publications and source records attributed to N Chaminade.

5 recordsLinked to original sources

PubMed2001

Dynamics of the hobo transposable element in transgenic lines of Drosophila melanogaster.

The impact of the hobo transposable element in global reorganization of the Drosophila melanogaster genome has been investigated in transgenic lines generated by injection of hobo elements into the Hikone strain, which lacked them. In the present extensive survey, the chromosomal distribution of hobo insertion sites in the line 28 was found to be homogeneous and similar for all chromosomal arms, except 3L, when compared with other transgenic lines. However, some original features were observed in this line at the genetic and chromosomal levels. Several hotspots of insertion sites were observed on the X, second and third chromosomes. Five sites with a high frequency of hobo insertions were present on the 3L arm in most individuals tested, suggesting the action of selection for hobo element in some sites. The presence of doublets or triplet was also observed, implying that hobo inserts can show local jumps or insertions in preferred regions. This local transposition occurred independently in 11 specific genomic regions in many individuals and generations. The dynamics of this phenomenon were analysed across generations. These results support the use of the hobo system as an important tool in fundamental and applied Drosophila genetics.

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↗

PubMed1998

Transmission pattern of hobo transposable element in transgenic lines of Drosophila melanogaster.

This study is an attempt to trace the fate of hobo elements in the genomes of E strains of Drosophila melanogaster that have been transfected with pHFL1, a plasmid containing an autonomous hobo. Such long-term population studies (over 105 generations) could be very useful for better understanding the population and genomic dynamics of transposable elements and their pattern of insertions. Molecular analyses of hobo elements in the transfected lines were performed using Southern blots of XhoI-digested genomic DNAs. The complete element was observed in all six injected lines. In two lines we observed, at generation 100, two deleted elements, which did not correspond to Th1 and Th2. The results obtained by the in situ method show that the number of hybridization sites increases in each line and prove that the hobo element may be amplified in an RM genome. The hobo activity does not seem to be systematically correlated with the number of hobo elements. After generation 85, the evolution of the hobo element's insertion site number depends on the injected line. In all lines, the total number of insertions remains quite small, between 0 and 11. Hobo elements are located on each of the chromosomal arms. We describe 'hotspots'-insertion sites present in all lines and in all generations. On the 3R arm, a short inversion appeared once at generation 85.

Animals↗

PubMed1995

Chromosomal distribution and population dynamics of the 412 retrotransposon in a natural population of Drosophila melanogaster.

The localization of the insertion sites of the 412 retrotransposable element was analysed by in situ hybridization to the polytene chromosomes of the genomes of males from a natural population of Drosophila melanogaster. Non-parametric statistical tests do not reveal any particular distribution of the insertion sites over the chromosomes, suggesting an apparently random distribution of the 412 element. Aggregation and dispersion tests were highly significant with data of copy number (when all genomes are pooled, many copies may be at a given site), suggesting the existence of sites with high insertion frequency. Comparison with other data from the literature confirms the tendency for a low proportion of insertions on the X chromosome in comparison with the autosomes, a result in agreement with selection acting against the detrimental effect of the 412 element insertions.

Animals↗

PubMed1990

The effects of lindane poisoning on N-acetyldopamine and N-acetyl 5-hydroxytryptamine concentrations in the brain of Locusta migratoria L.

High-performance liquid chromatography with electrochemical detection was used to measure N-acetyldopamine and N-acetyl 5-hydroxytryptamine in the cerebral ganglia of the African migratory locust, Locusta migratoria (fifth instar) exposed to lindane, a chlorinated insecticide. Locusts were poisoned by this insecticide in order to assess the effects of this neuroactive compound on these acetylated metabolites levels. Relatively low concentrations of N-acetyldopamine were observed in the cerebral ganglia. Incubation of ganglia resulted in increased concentrations of N-acetyldopamine and N-acetyl 5-hydroxytryptamine. Lindane significantly reduces N-acetyldopamine and N-acetyl 5-hydroxytryptamine levels in the cerebral ganglia. These results can be correlated with a decrease in N-acetyltransferase activity.

Administration, Topical↗