Project description:Two introgression strains (ZZY10307 and ZZY10330) of C. briggsae onto the X chromosome of C. nigoni results in male sterility. In order to determine the cause, we sequenced the mRNAs from young adult males from these two strains, and compared to fertile males of the two parent species (AF16 and JU1421). Two wild-type female samples were also included as platform QC.
Project description:Piwi proteins and Piwi-interacting RNAs (piRNAs) are best known for their roles in suppressing transposons and promoting fertility. Yet piRNA biogenesis and its mechanisms of action differ widely between distantly related species. To better understand the evolution of piRNAs, we characterized the piRNA pathway in C. briggsae, a sibling species of the model organism C. elegans. Our analyses define 25,883 piRNA producing-loci in C. briggsae. piRNA sequences in C. briggsae are extremely divergent from their counterparts in C. elegans, yet both species adopt similar genomic organization and transcription program that drive piRNA expression. By examining production of Piwi-dependent secondary small RNAs, we identified a set of protein-coding genes that are evolutionarily conserved piRNA targets. In contrast to C. elegans, small RNAs mapped to ribosomal RNAs or histone transcripts are not hyper-accumulated in C. briggsae. Instead, we found that fewer introns in transcripts are associated with hyper-accumulation of small RNAs. Together our work highlights evolutionary conservation and divergence of the nematode piRNA pathway and provides insights into its role in endogenous gene regulation.
Project description:To gain mechanistic insights into the molecular changes of Caenorhabditis briggsae between the two developmental stages: embryo and larvae
Project description:Different populations of the same species survive different environments through local adaptation. Temperature is one of the most important driving forces that could result in local adaptation. Here, we studied the influence of extreme low temperature on the survival of two genetically and geographically distinct populations of the free-living Caenorhabditis briggsae. We found that Caenorhabditis briggsae strains of temperate origin had a cold resistant phenotype, while those originating from a tropical climate had reduced survival after cold treatment. Using this phenotypic difference between geographically diverse populations as a model for how species adapt to their local environment, we then analyzed the transcriptional profiles of two Caenorhabditis briggsae strains of tropical and temperate origin to find genes that are involved in survival after extreme cold. In summary, the response to the extreme low temperature that clearly distinguishes the temperate and tropical Caenorhabditis briggsae strains could serve as an excellent example for studying local adaption of species that show genetic separation associated with their geographical distribution.
