Fruitless RNAi knockdown in males interferes with copulation success in Schistocerca gregaria.
ABSTRACT In Drosophila melanogaster, the male-specific splice isoform of the fruitless gene (Fru(M)) codes for a set of transcription factors that are involved in the regulation of male courtship and copulation. Fru(M) is expressed in an interconnected neuronal circuit containing central and sensory neurons as well as motor neurons. A partial sequence from the Schistocerca gregaria fru-gene from an EST database allowed quantitative real time analysis of fru-expression in adult locusts, and revealed the highest expression in the testes, accessory glands as well as the brain (and optic lobes). Starting fru specific RNAi knockdown in the third and fourth nymphal stage resulted in a significantly lower cumulative copulation frequency of the RNAi-treated animals compared to controls after 3 h of observation. In addition, the testes of RNAi-treated males weigh less. Analysis of the egg pods resulting from a successful copulation event revealed that egg pods from females that mated with an RNAi-treated male were smaller and contained less fertilized eggs compared to egg pods from females who mated with control males. Starting injections in the fifth nymphal stage showed the complete opposite for the cumulative copulation frequency and testes weight. We conclude that already in the early nymphal phases of male desert locusts, fruitless starts to play an important role in the regulation of successful copulation in the adult. The RNAi treatment in the male has also its effects on fertility and fecundity. It remains unknown whether this effect is coming from aberrant courtship behaviour or from an altered composition of the sperm or seminal fluids.
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ABSTRACT: Little is known about the process of sex determination at the molecular level in species belonging to the subclass Acari, a taxon of arachnids that contains mites and ticks. The recent sequencing of the transcriptome and genome of the western orchard predatory mite Metaseiulus occidentalis allows investigation of molecular mechanisms underlying the biological processes of sex determination in this predator of phytophagous pest mites. We identified four doublesex-and-mab-3-related transcription factor (dmrt) genes, one transformer-2 gene, one intersex gene, and two fruitless-like genes in M. occidentalis. Phylogenetic analyses were conducted to infer the molecular relationships to sequences from species of arthropods, including insects, crustaceans, acarines, and a centipede, using available genomic data. Comparative analyses revealed high sequence identity within functional domains and confirmed that the architecture for certain sex-determination genes is conserved in arthropods. This study provides a framework for identifying potential target genes that could be implicated in the process of sex determination in M. occidentalis and provides insight into the conservation and change of the molecular components of sex determination in arthropods.Journal of biomolecular Structure & Dynamics 07/2014; · 2.98 Impact Factor
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ABSTRACT: There has been much debate concerning whether cis-regulatory or coding changes are more likely to produce evolutionary innovation or adaptation in gene function, but an additional complication is that some genes can dramatically diverge through alternative splicing, increasing the diversity of gene function within a locus. The fruitless gene is a major transcription factor with a wide range of pleiotropic functions, including a fundamental conserved role in sexual differentiation, species-specific morphology and an important influence on male sexual behaviour. Here, we examine the structure of fruitless in multiple species of Drosophila, and determine the patterns of selective constraint acting across the coding region. We found that the pattern of selection, estimated from the ratio of non-synonymous to synonymous substitutions, varied considerably across the gene, with most regions of the gene evolutionarily conserved but with several regions showing evidence of divergence as a result of positive selection. The regions that showed evidence of positive selection were found to be localised to relatively consistent regions across multiple speciation events, and are associated with alternative splicing. Alternative splicing may thus provide a route to gene diversification in key regulatory loci.Heredity advance online publication, 23 October 2013; doi:10.1038/hdy.2013.106.Heredity 10/2013; · 4.11 Impact Factor
Dataset: aedes fru 2013