RESUMEN
Parasitic nematodes transition between dramatically different free-living and parasitic stages, with correctly timed development and migration crucial to successful completion of their lifecycle. However little is known of the mechanisms controlling these transitions. microRNAs (miRNAs) negatively regulate gene expression post-transcriptionally and regulate development of diverse organisms. Here we used microarrays to determine the expression profile of miRNAs through development and in gut tissue of the pathogenic nematode Haemonchus contortus. Two miRNAs, mir-228 and mir-235, were enriched in infective L3 larvae, an arrested stage analogous to Caenorhabditis elegans dauer larvae. We hypothesized that these miRNAs may suppress development and maintain arrest. Consistent with this, inhibitors of these miRNAs promoted H. contortus development from L3 to L4 stage, while genetic deletion of C. elegans homologous miRNAs reduced dauer arrest. Epistasis studies with C. elegans daf-2 mutants showed that mir-228 and mir-235 synergise with FOXO transcription factor DAF-16 in the insulin signaling pathway. Target prediction suggests that these miRNAs suppress metabolic and transcription factor activity required for development. Our results provide novel insight into the expression and functions of specific miRNAs in regulating nematode development and identify miRNAs and their target genes as potential therapeutic targets to limit parasite survival within the host.
Asunto(s)
Haemonchus/genética , MicroARNs/biosíntesis , ARN de Helminto/biosíntesis , Animales , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Colestenos/farmacología , Femenino , Eliminación de Gen , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Ontología de Genes , Haemonchus/efectos de los fármacos , Haemonchus/crecimiento & desarrollo , Larva , Masculino , MicroARNs/genética , ARN de Helminto/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptor de Insulina/genética , Especificidad de la EspecieRESUMEN
Among-individual variation in antibody-associated immunity to gastrointestinal nematode parasites (GIN) is known be associated with life-history traits and vital rates in wild vertebrate systems. To date, measurement of levels of antibodies against GIN antigens in natural populations has exclusively been based on invasive blood sampling techniques. Previous work in laboratory rodents and ruminant livestock suggests that antibody measures from feces may provide a viable noninvasive approach. We measured total and anti-GIN antibodies of different isotypes (immunoglobulin (Ig) G, IgA and IgE) from paired samples of plasma and feces from free-living Soay sheep of different ages and sexes. We tested the correlations among these measures as well as their associations with body mass and Strongyle nematode fecal egg counts (FEC). Significant positive correlations were present among plasma and fecal anti-GIN antibody levels for IgG and IgA. Generally, correlations between total antibody levels in plasma and feces were weaker and not significant. No significant relationships were found between any antibody measures and body mass; however, fecal anti-GIN antibody levels were significantly negatively correlated with FEC. Our data clearly demonstrate the feasibility of measuring anti-GIN antibodies from fecal samples collected in natural populations. Although associations of fecal antibody levels with their plasma counterparts and FEC were relatively weak, the presence of significant correlations in the predicted direction in a relatively small and heterogeneous sample suggests fecal antibody measures could be a useful, noninvasive addition to current eco-immunological studies.