General survey of hAT transposon superfamily with highlight on hobo element in Drosophila.

The hAT transposons, very abundant in all kingdoms, have a common evolutionary origin probably predating the plant-fungi-animal divergence. In this paper we present their general characteristics. Members of this superfamily belong to Class II transposable elements.

Mapping candidate genes for Drosophila melanogaster resistance to the parasitoid wasp Leptopilina boulardi.

Drosophila melanogaster resistance against the parasitoid wasp Leptopilina boulardi is under the control of a single gene (Rlb), with two alleles, the resistant one being dominant. Using strains bearing deletions, we previously demonstrated that the 55E2-E6; 55F3 region on chromosome 2R is involved in the resistance phenomenon. In this paper, we first restricted the Rlb containing region by mapping at the molecular level the breakpoints of the Df(2R)Pc66, Df(2R)P34 and Df(2R)Pc4 deficiencies, using both chromosomal in situ hybridization and Southern analyses.

Evolution of the chromosomal location of rDNA genes in two Drosophila species subgroups: ananassae and melanogaster.

The evolution of the chromosomal location of ribosomal RNA gene clusters and the organization of heterochromatin in the Drosophila melanogaster group were investigated using fluorescence in situ hybridization and DAPI staining to mitotic chromosomes. The investigation of 18 species (11 of which were being examined for the first time) belonging to the melanogaster and ananassae subgroups suggests that the ancestral configuration consists of one nucleolus organizer (NOR) on each sex chromosome. This pattern, which is conserved throughout the melanogaster subgroup, except in D.

Mitotic and polytene chromosomes: comparisons between Drosophila melanogaster and Drosophila simulans.

This review deals with the differences between Drosophila melanogaster and Drosophila simulans in their mitotic and polytene chromosomes. The description of the mitotic karyotypes of D. melanogaster and D.

Detection of transposable elements in Drosophila salivary gland polytene chromosomes by in situ hybridization.

In situ hybridization is particularly appropriate for mapping specific DNA sequences on polytene chromosomes of Drosophila and other dipterans. This technique is based on the recognition and binding of one labeled sequence (the probe) to homologous sequences on chromosomes fixed on a microscope slide. The probes are labeled with biotin or other nonradioactive products, and the probe signal can be detected as a thin line on the chromosomes, following the shape of the classical Giemsa-stained chromosome bands, thus allowing the detection of TE insertions within the range of 50 to 200 kb.

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.

Identification and characterization of Moca-cyp. A Drosophila melanogaster nuclear cyclophilin.

Cyclophilins are enzymes catalyzing the cis-trans isomerization of peptidyl-prolyl bonds and belong to the enzyme class of peptidyl-prolyl cis-trans isomerases (PPIases), which includes two more families (FK506 binding proteins and parvulins). We report the characterization of a novel cyclophilin (Moca-cyp) isolated from Drosophila melanogaster. The single-copy Moca-cyp gene, which is localized on chromosome 3R, was cloned and sequenced.

Visualization of polydnavirus sequences in a parasitoid wasp chromosome.

Polydnaviruses, obligatorily associated with endoparasitoid wasps, are unique in that their segmented genome is composed of multiple double-stranded DNA circles. We present here the first cytological evidence that virus segments are integrated in the wasp genome, obtained by using in situ hybridization of virus probes with viral sequences in the chromosomes of a wasp from the braconid family of hymenopterans.

Chromosomal inversion polymorphism in Afrotropical populations of Drosophila melanogaster.

When 41 populations from Africa (south of the Sahara) and Indian Ocean islands were analysed for their chromosomal inversion polymorphism, 34 rearrangements were found, including the four common cosmopolitans (In(2L)t, In(2R)NS, In(3L)P and In(3R)P), four rare cosmopolitans (In(2L)NS, In(3R)C, In(3R)Mo and In(3R)K) and six African polymorphic ('recurrent') endemics. Mean inversion frequencies per major autosome arm were positively and, generally, highly correlated to each other. There was no altitudinal nor latitudinal cline of inversion frequency, except for one African polymorphic endemic.

Advantages of a P-element construct containing MtnA sequences for the identification of patterning and cell determination genes in Drosophila melanogaster.

The P[MTW] transposon carries a functional MtnA (metallothionein) gene and a miniwhite reporter gene. When P[MTW] was transformed into Drosophila, many lines were found to show position-dependent expression patterns of the miniwhite or the MtnA transgene. Identification of several of the target genes indicated that this construct behaves as an enhancer or silencer trap.

Genetic and molecular features of Su(P), a gene that interacts with ref(2)P in male fertility of Drosophila melanogaster.

The ref(2)P gene is involved in the control of sigma rhabdovirus multiplication in Drosophila melanogaster. ref(2)P activity is also necessary for male fertility. However, in one-third of laboratory strains tested, males that lacked ref(2)P activity were fertile.

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.

Chromosome fission associated with growth of ribosomal DNA in Neodiprion abietis (Hymenoptera: Diprionidae).

The haploid complement consists of seven metacentric chromosomes in most diprionid species but has evolved to n = 8 by fission in Neodiprion abietis. This fission generated a small telocentric chromosome and a large pseudoacrocentric chromosome with a short arm carrying a satellite. In situ hybridization indicated that the location of the rRNA gene cluster corresponds to the whole short arm.

Evolutionary novelties in islands: Drosophila santomea, a new melanogaster sister species from São Tomé.

The finding of new melanogaster sister species may help us in understanding more about how the emergence of genetic novelties, particularly in insular habitats, can result in speciation. Here we report on the discovery of Drosophila santomea, which is the first melanogaster sibling found off West-equatorial Africa, on São Tomé, one of the Gulf of Guinea islands. Although the eight other melanogaster sister species are remarkably conservative in their morphology except for their terminalia, the new find has a morphological trait distinguishing it from all of these: a pure yellow body coloration of both sexes without the normal black abdominal banding.

Drosophila resistance genes to parasitoids: chromosomal location and linkage analysis.

Insect hosts can survive infection by parasitoids using the encapsulation phenomenon. In Drosophila melanogaster the abilities to encapsulate the wasp species Leptopilina boulardi and Asobara tabida each involve one major gene. Both resistance genes have been precisely localized on the second chromosome, 35 centimorgans apart.

Genetic localization of a Drosophila melanogaster resistance gene to a parasitoid wasp and physical mapping of the region.

Drosophila melanogaster larvae usually react against eggs of the parasitoid wasp Leptopilina boulardi by surrounding them with a multicellular melanotic capsule. The genetic determinism of this response has been studied previously using susceptible (non-capsule-forming) and resistant (capsule-forming) strains. The results suggest that differences in their encapsulation response involve a single gene, resistance to Leptopilina boulardi (Rlb), with two alleles, the resistant one being dominant.

The chromosomes of Diprion pini and D. similis (Hymenoptera: Diprionidae): implications for karyotype evolution.

Earlier cytological investigations characterize the family Diprionidae with a modal chromosome number of seven. This study shows that Diprion pini and D. similis have 14 acrocentric chromosomes (n = 14 for haploid males and 2n = 28 for diploid females).

Distribution of the retrotransposable element 412 in Drosophila species.

Copy numbers of sequences homologous to the Drosophila melanogaster retrotransposable element 412, their distribution between the chromosome arms and the chromocenter, and whether they contain full-size copies were analyzed for 55 species of the Drosophila genus. Element 412 insertion sites were detected on the chromosome arms of D. melanogaster, Drosophila simulans, and a few species of the obscura group, but the chromocenter was labeled in almost all species.

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.

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.

Amyrel, a paralogous gene of the amylase gene family in Drosophila melanogaster and the Sophophora subgenus.

We describe a gene from Drosophila melanogaster related to the alpha-amylase gene Amy. This gene, which exists as a single copy, was named Amyrel. It is strikingly divergent from Amy because the amino acid divergence is 40%.

Spread of the autonomous transposable element hobo in the genome of Drosophila melanogaster.

The transposable element hobo has been introduced into the previously empty Drosophila melanogaster strain Hikone so that its dynamics can be followed and it can be compared with the P element. Five transformed lines were followed over 58 generations. The results were highly dependent on the culture temperature, the spread of hobo element being more efficient at 25 degrees C.

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.

IR hybrid dysgenesis increases the frequency of recombination in Drosophila melanogaster.

The I factor is a LINE-like transposable element responsible for the I-R system of hybrid dysgenesis in Drosophila melanogaster. Inducer strains of this species contain several I factors whereas reactive strains do not. I factors are stable in inducer strains, but transpose at high frequency in the germ-line of females, known as SF females, produced by crossing reactive females and inducer males.