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D Higuet

Publications and source records attributed to D Higuet.

10 recordsLinked to original sources
PubMed2001

corto genetically interacts with Pc-G and trx-G genes and maintains the anterior boundary of Ultrabithorax expression in Drosophila larvae.

In Drosophila melanogaster, segment identity is determined by specific expression of homeotic genes (Hox). The Hox expression pattern is first initiated by gap and pair-rule genes and then maintained by genes of the Polycomb-group (Pc-G) and the trithorax-group (trx-G). The corto gene is a putative regulator of the Hox genes since mutants exhibit homeotic transformations. We show here that, in addition to previously reported genetic interactions with the Pc-G genes Enhancer of zeste, Polycomb and polyhomeotic, mutations in corto enhance the extra-sex-comb phenotype of multi sex combs, Polycomb-like and Sex combs on midleg. corto also genetically interacts with a number of trx-G genes (ash1, kismet, kohtalo, moira, osa, Trithorax-like and Vha55). The interactions with genes of the trx-G lead to phenotypes displayed in the wing, in the postpronotum or in the thoracic mechanosensory bristles. In addition, we analyzed the regulation of the Hox gene Ultrabithorax (Ubx) in corto mutants. Our results provide evidence that corto maintains the anterior border of Ubx expression in third-instar larvae. We suggest that this regulation is accomplished through an interaction with the products of the Pc-G and trx-G genes.

Animals↗
PubMed2000

A scenario for the hobo transposable element invasion, deduced from the structure of natural populations of Drosophila melanogaster using tandem TPE repeats.

Temporal surveys of hobo transposable elements in natural populations reveal a historical pattern suggesting a recent world-wide invasion of D. melanogaster by these transposons, perhaps following a recent horizontal transfer. To clarify the dynamics of hobo elements in natural populations, and thus to provide further data for our understanding of the hobo invasion, TPE tandem repeats, observed in the polymorphic S region of the element, were used as molecular markers. The number of TPE repeats was studied in 101 current populations from around the world, and in 63 strains collected in the past. This revealed a geographical distribution which seems to have been stable since the beginning of the 1960s. This distribution is compatible with a number of hypotheses for the dynamics of hobo elements. We propose a scenario based on an invasion in two stages: first, a complete invasion by elements with three TPE repeats, followed by the beginning of a new invasion involving hobo elements with five or seven repeats.

Animals↗
PubMed1999

Characterization of permissivity for hobo-mediated gonadal dysgenesis in Drosophila melanogaster.

The hobo transposon is responsible for one of the three hybrid dysgenic systems that have been described in Drosophila melanogaster. Most studies on the hobo dysgenic system have been carried out using the PM system as a reference. However, these two systems differ significantly. In particular, several studies have failed to find any correlation between the molecular structures of hobo elements, the instability of the transposon and the incidence of gonadal dysgenic (GD) sterility. On the other hand, no study of the ability of females to permit hobo activity in their progeny when they are crossed with males harboring active hobo elements (permissivity) has yet been reported. In order to investigate the parameters involved in hobo permissivity, four E strains were studied with regard to the molecular nature of their hobo sequences and the GD sterility induced by a controlled source of hobo transposase. We show that hobo permissivity varies both within and between E strains. Moreover, permissivity decreases with age in E females. Our results are discussed with respect to similar phenomena that have been described in relation to the reactivity of the IR dysgenic system.

Aging↗
PubMed1997

Characterization of natural populations of Drosophila melanogaster with regard to the hobo system: a new hypothesis on the invasion.

Until now, with regard to the hobo system of hybrid dysgenesis, natural populations of Drosophila melanogaster have been investigated using only two criteria: at the molecular level, the presence or absence of XhoI fragments 2.6 kb long or smaller; and/or at the genetic level, the ability to induce gonadal dysgenesis sterility in crosses A (females of an E reference strain crossed with males under test) and A* (females under test crossed with males of an H reference strain). Recently, analyses of laboratory strains using these criteria as well as the mobilization of two reporter genes, the male recombination and the number of 'TPE' repeats in the S region, revealed a lack of correlation between the different dysgenic parameters themselves, and also between these parameters and the molecular characteristics of the strains. Thirteen current strains derived from world populations were therefore investigated with regard to all these dysgenic traits, to determine discriminating criteria providing a robust method of classifying natural populations and deducing the dynamics of hobo elements in these populations. We show, as in laboratory strains, a lack of correlation between the parameters studied. Therefore, the significance of each of them as well as the nature of hobo hybrid dysgenesis are discussed, to propose an analysis method of the hobo system applicable to natural populations. According to the geographical distribution of hobo activities in world populations and to the variable polymorphism of the number of 'TPE' repeats, we propose a new scenario for the invasion of D. melanogaster by hobo elements.

Animals↗
PubMed1997

Do the integrases of LTR-retrotransposons and class II element transposases have a common ancestor?

The integrases of retrotransposons (class I) and retroviruses and the transposases of bacterial type elements (class II) were compared. The DDE signature that is crucial for the integration of these elements is present in most of them, except for the non-LTR retrotransposons and members of the hAT and P super-families. Alignment of this region was used to infer the relationships between class II elements, retrotransposons, and retroviruses. The mariner-Tc1 and the Pogo-Fot1 super-families were found to be closely related and probably monophyletic, as were LTR retrotransposons and retroviruses. The IS elements of bacteria were clustered in several families, some of them being closely related to the transposase of the mariner-Tc1 super-family or to the LTR retrotransposon and retrovirus integrases. These results plus that of Xiong and Eickbush (1990) were used to develop an evolutionary history suggesting a common ancestral origin(s) for the integrases and transposases containing the DDE signature. The position of the telomeric elements (Het-A and TART) was assessed by comparing their gag and reverse transcriptase domains (when present) to those of group II introns and non-LTR retrotransposons. This preliminary analysis suggests that telomeric elements may be derived from non-LTR retrotransposons.

Amino Acid Sequence↗
PubMed1996

Relationships between transposable elements based upon the integrase-transposase domains: is there a common ancestor?

The integrase domain of RNA-mediated elements (class I) and the transposase domain of DNA-mediated transposable elements (class II) were compared. A number of elements contain the DDE signature, which plays an important role in their integration. The possible relationships between mariner-Tc1 and IS elements, retrotransposons, and retroviruses were analyzed from an alignment of this region. The mariner-Tc1 superfamily, and LTR retrotransposons and retroviruses were found to be monophyletic groups. However, the IS elements of bacteria were found in several groups. These results were used to propose an evolutionary history that suggests a common ancestor for some integrases and transposases.

Amino Acid Sequence↗
PubMed1996

Lack of correlation between dysgenic traits in the hobo system of hybrid dysgenesis in Drosophila melanogaster.

Currently in the hobo system of hybrid dysgenesis, strain classification is based on the presence/absence of the 2.6 kb Xho I restriction fragment. Using this criterion, strains are classified as: (1) H strains when full-size elements are detected by presence of a 2.6 kb Xho I restriction fragment; they can also contain internally deleted elements; (2) DH strains when only deleted elements are detected (Xho I restriction fragment less than 2.6 kb); (3) E strains, devoid of any restriction fragment equal to or less than 2.6 kb in length. In addition, the strains can be classified on their ability to generate gonadal atrophy (GD sterility) when males of a studied strain are crossed with females from an E strain (dysgenic cross). Here we try to define the nature of the dysgenic cross, which leads us to analyse the different components of the dysgenic syndrome and to look for eventual correlations between them. Molecular analysis, GD sterility tests, hobo mobilization with the haw strain and the vg(al) strain, and hereditary transmission of the instability at the vg locus have been assayed in different strains. We show that the occurrence of GD sterility depends on the tested H strains as expected, but also on the E strains used. On the other hand we do not find any correlation between the different dysgenic parameters. Our data reveal that molecular and GD sterility tests are not sufficient to classify strains in the hobo system, and that all the components of the dysgenic syndrome must be taken into account. Our results are discussed with regard to active and full-size elements in relation to the structure of the S region where an amino acid sequence (TPE) presents a repetition polymorphism.

Animals↗
PubMed1996

The relationship between structural variation and dysgenic properties of P elements in long-established P-transformed lines of Drosophila simulans.

Ten lines of Drosophila simulans were investigated with respect to P activity, P susceptibility and the number and structure of their P copies, eight years after transformation with the P element. All 10 were found to have reached a steady state. They exhibited varying levels of P activity (from 0 per cent to 96 per cent GD sterility) and, with the exception of one line, were not P-susceptible. In contrast with P element behaviour in D. melanogaster: (i) no relationship was found between the molecular pattern of P copies in a line and its ability to induce or to repress P expression in D. simulans; (ii) peculiar P element derivatives were observed in this species; (iii) the average number of P copies per genome was only half of that in D. melanogaster. This may result from transposon-host genome interactions, which lead to a low invading power of the P element in D. simulans.

Animals↗
PubMed1992

A particular P-element insertion is correlated to the P-induced hybrid dysgenesis repression in Drosophila melanogaster.

Transposable P elements in Drosophila melanogaster cause hybrid dysgenesis if their mobility is not repressed. The ability to regulate the dysgenic activity of the P elements depends on several mechanisms, one of which hypothesized that a particular deleted P element (the KP element) results in a non-susceptibility which is biparentally transmitted. In this study totally non-susceptible lines, and susceptible lines containing exclusively KP elements (IINS2 line and IIS2 line) were isolated from a M' strain. We show that non-susceptibility is correlated with a particular insertion of one KP element located at the cytological site 47D1. The repression ability of the GD sterility is determined by a recessive chromosomal factor, and cannot be due to the KP-element number. Here the repression of the P mobility is associated with reduction of the P transcripts and the inhibition of P promoter activity.

Animals↗