Tissue-Specific Transcriptome Comparisons in a Non-Model Insect, the Field Cricket Teleogryllus oceanicus
Background. ??Field crickets (family Gryllidae) are used in a wide range of research, including sexual selection, speciation, acoustic communication, neurophysiology, sperm competition and phylogeography studies. Despite their extensive use, crickets lack well-developed genomic and transcriptomic resources. Here we use the field cricket Teleogryllus oceanicus to address this shortcoming. Our aims were to generate transcriptome sequences from four T. oceanicus tissues, create a consensus transcriptome, identify and annotate differentially-represented transcripts, and evaluate functional differences between transcripts prevalent in the four tissues.??Results??We used Roche 454 pyrosequencing to sequence non-normalised cDNA libraries from head, testis, accessory gland, and whole body preparations. A master assembly from all four tissues yielded 43,426 isotigs (assemblages of contigs representing alternative splice variants). Reads from testes were most highly represented in the master assembly (ca. 74% mapping), although differentially-represented isotigs were identified from each tissue. Over 3,800 isotigs exhibited differential mapping among tissues after correction for isotig length, tissue-specific read number, and multiple comparisons. Functional classifications for isotigs were assigned using Gene Ontology (GO) terms. These differed significantly among tissues at the classification levels of biological process, cellular component, and molecular function, consistent with tissue-specific transcription and gene regulation.??Conclusions??This study yielded transcriptomic resources for T. oceanicus and other crickets. Several thousand differentially-represented isotigs were identified from a modest sample of transcriptomic data, demonstrating the utility of 454 pyrosequencing for identifying differentially represented mRNA transcripts. Overall, testis tissue and accessory gland tissue showed the greatest proportion of uniquely represented isotigs. Nevertheless, all tissues yielded isotigs that showed significantly different representation among tissues. Although gene ontology (GO) terms could be assigned to approximately 16 % of isotigs overall and compared among tissues, the modest availability of database information proved to be the limiting factor in the annotation of isotigs of interest.