Effect of the Gene doublesex of Anastrepha on the Somatic Sexual Development of Drosophila

8 pages, 4 figures and 2 tables.[Background] The gene doublesex (dsx) is at the bottom of the sex determination genetic cascade and is transcribed in both sexes, but gives rise to two different proteins, DsxF and DsxM, which impose female and male sexual development respectively via the sex-specific regulation of the so-called sexual cyto-differentiation genes. The present manuscript addressed the question about the functional conservation of the tephritid Anastrepha DsxF and DsxM proteins to direct the sexual development in Drosophila (Drosophilidae).[Methodology] To express these proteins in Drosophila, the GAL4-UAS system was used. The effect of these proteins was monitored in the sexually dimorphic regions of the fly: the foreleg basitarsus, the 5th, 6th and 7th tergites, and the external terminalia. In addition, we analysed the effect of Anastrepha DsxF and DsxM proteins on the regulation of Drosophila yolk protein genes, which are expressed in the fat body of adult females under the control of dsx.Conclusions The Anastrepha DsxF and DsxM proteins transformed doublesex intersexual Drosophila flies into females and males respectively, though this transformation was incomplete and the extent of their influence varied in the different sexually dimorphic regions of the adult fly. The Anastrepha DsxF and DsxM proteins also behaved as activators and repressors, respectively, of the Drosophila yolk protein genes, as do the DsxF and DsxM proteins of Drosophila itself. Finally, the Anastrepha DsxF and DsxM proteins were found to counteract the functions of Drosophila DsxM and DsxF respectively, reflecting the normal behaviour of the latter proteins towards one another. Collectively, these results indicate that the Anastrepha DsxF and DsxM proteins show conserved female and male sex-determination function respectively in Drosophila, though it appears that they cannot fully substitute the latter's own Dsx proteins. This incomplete function might be partly due to a reduced capacity of the Anastrepha Dsx proteins to completely control the Drosophila sexual cyto-differentiation genes, a consequence of the accumulation of divergence between these species resulting in the formation of different co-adapted complexes between the Dsx proteins and their target genes.This work was financed by grant BFU2005-03000 awarded to L. Sa´nchez by the D.G.I.C.Y.T. (Spanish Government).Peer reviewe

Phylogeny and oscillating expression of period and cryptochrome in short and long photoperiods suggest a conserved function in Nasonia vitripennis

Photoperiodism, the ability to respond to seasonal varying day length with suitable life history changes, is a common trait in organisms that live in temperate regions. In most studied organisms, the circadian system appears to be the basis for photoperiodic time measurement. In insects this is still controversial: while some data indicate that the circadian system is causally involved in photoperiodism, others suggest that it may have a marginal or indirect role. Resonance experiments in the parasitic wasp Nasonia vitripennis have revealed a circadian component in photoperiodic time measurement compatible with a mechanism of internal coincidence where a two components oscillator system obtains information from dawn and dusk, respectively. The identity of this oscillator (or oscillators) is still unclear but possible candidates are the oscillating molecules of the auto-regulatory feedback loops in the heart of the circadian system. Here, we show for the first time the circadian oscillation of period and cryptochrome mRNAs in the heads of Nasonia females kept under short and long photoperiods. Period and cryptochrome mRNA levels display a synchronous oscillation in all conditions tested and persist, albeit with reduced amplitude, during the first day in constant light as well as constant darkness. More importantly, the signal for the period and cryptochrome oscillations is set by the light-on signal. These results, together with phylogenetic analyses, indicate that Nasonia’s period and cryptochrome display characteristics of homologous genes in other hymenopteran species

The Fruitless gene in Nasonia displays complex sex-specific splicing and contains new zinc finger domains

The transcription factor Fruitless exerts a broad range of functions during Drosophila development, the most apparent of which is the determination of sexual behavior in males. Although fruitless sequences are found in other insect orders, little is known about fruitless structure and function outside Diptera. We have performed a thorough analysis of fruitless transcripts in the haplo-diploid wasp Nasonia vitripennis and found both sex-specific and non-sex-specific transcripts similar to those found in Drosophila. In Nasonia, however, a novel, large fruitless transcript is present in females only. Putative binding sites for sex-specific splicing factors found in Nasonia fruitless and doublesex as well as Apis mellifera doublesex transcripts were sufficient to identify a corresponding female-specific fruitless exon in A. mellifera, suggesting that similar factors in both hymenopteran species could be responsible for sex-specific splicing of both genes. Furthermore, new C(2)H(2) zinc finger domains found in Nasonia fruitless transcripts were also identified in the fruitless locus of major holometabolous insect species but not in drosophilids. Conservation of important domains and sex-specific splicing in Diptera and Hymenoptera support the hypothesis that fruitless is an ancient gene and has conserved functions in insects. Considerable divergences in other parts of the gene are expected to underlie species-specific differences and may help to explain diversity observed in insect sexual behaviors

Functional and Evolutionary Insights from the Genomes of Three Parasitoid Nasonia Species

We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.

τ and ‘ratio-to-p’ values for all <i>Nasonia</i> strains in constant light (LL).

<p>Tau (τ, in hours), ratio-to-p, standard error (SEM), and number of wasps used are indicated for each strain. Species means are indicated in bold (except for column ‘Total wasps’, which indicates the total amount of wasps per each species). Tau means are weighted and, respectively, non-weighted (in brackets). For significant differences see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-g004" target="_blank">figures 4</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-g005" target="_blank">5</a>.</p

τ and CoG differences among <i>Nasonia</i> species.

<p>Data from distinct strains within one species were pooled in order to find differences among <i>Nasonia</i> species for τ and CoG. Significant differences are indicated with asterisks in the top panel: among strains (within one sex) on top, and between sexes (within each strain) at the bottom (* <i> = p</i><0.05; ** <i> = p</i><0.01; *** <i> = p</i><0.001).Circles in box plots represent outliers. Differences are based on a model that accounts for different amount of data per strain. Despite pooling, significant differences are found among species and between sexes. Differences between τ values in darkness and light are always significant.</p

CoG for all tested strains of four Nasonia species.

<p>CoG values are indicated for all strains used in <i>N. giraulti</i> (<b>A</b>), <i>N. longicornis</i> (<b>B</b>), and <i>N. vitripennis</i> (<b>C</b>). Significant differences are indicated in the top panel with asterisks: among strains (within each sex) on top, and between sexes (within each strain) at the bottom (* <i> = p</i><0.05; ** <i> = p</i><0.01; *** <i> = p</i><0.001).A summary of the data is given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-t003" target="_blank">table 3</a>.</p

Τ of standard <i>Nasonia</i> strains.

<p>Box-plots summarize τ values in constant darkness (DD) and constant light (LL) for the standard strain of each species. Significant differences are indicated with asterisks in the top panel: among strains (within one sex) on top, and between sexes (within each strain) at the bottom (* <i> = p</i><0.05; ** <i> = p</i><0.01; *** <i> = p</i><0.001). Circles in box plots represent outliers. Differences between τ values in darkness and light are always significant. A summary of the data is given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-t001" target="_blank">tables 1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-t002" target="_blank">2</a>.</p

Typical actograms for different <i>Nasonia</i> species.

<p>Representative actograms (double plotted) of male and female <i>Nasonia</i> are shown for standard strains in each species. Wasps were first entrained in LD 16∶8 (light phase from 8:00 to 24:00) for at least 4 days and then exposed to constant darkness (indicated with a gray background) for 8 days followed by constant light (white background). Y- and x-axes indicate time in days and hours, respectively.</p

CoG values for all <i>Nasonia</i> strains.

<p>CoG (hours:minutes; light phase is from 8:00 to 24:00), standard error (SEM), and number of wasps used are indicated for each strain. Species means are indicated in bold (except for columns ‘Total wasps’, which indicate the total amount of wasps per each species). CoG means are weighted and, respectively, non-weighted (in brackets). For significant differences see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-g003" target="_blank">figures 3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060167#pone-0060167-g006" target="_blank">6</a>.</p