Project description:Toxocariasis is an important, neglected zoonosis caused mainly by Toxocara canis. Although our knowledge of helminth molecular biology is improving through completed draft genome projects, there is limited detailed information on the molecular biology of Toxocara species. Here, transcriptomic sequencing of male and female adult T. canis and comparative analyses were conducted. For each sex, two-thirds (66-67%) of quality-filtered reads mapped to the gene set of T. canis, and at least five reads mapped to each of 16,196 (87.1%) of all 18,596 genes, and 321 genes were specifically transcribed in female and 1467 in male T. canis. Genes differentially transcribed between the two sexes were identified, enriched biological processes and pathways linked to these genes established, and molecules associated with reproduction and development predicted. In addition, small RNA pathways involved in reproduction were characterized, but there was no evidence for piwi RNA pathways in adult T. canis. The results of this transcriptomic study should provide a useful basis to support investigations of the reproductive biology of T. canis and related nematodes.
Project description:To encourage biological and biotechnological investigations on Toxocara canis, an important neglected tropical parasite, high-throughput sequencing was carried out to generate the sRNAs resource of adult Toxocara canis. In total, 11,632,676 and 10,723,433 sRNAs reads were yielded from male and female libraries, with similar proportion of small nucleolar RNA, micro RNA and small nuclear RNA. No PIWI-associated RNA was found in T. canis. 1,985 of male and 2,062 of female known miRNAs were respectively obtained, as well as 99 and 71 novel miRNAs in both genders. Comparative analysis was carried out on expression level which generated the lists of differential-expressed miRNAs, including 854 of male-specific expressed and 932 of female-specific expressed MiRNAs, and on sequence level which showed expression-sequence coordination. Based on Gene Ontology annotation and KEGG pathway analysis, the conservation and functional diversification of these differentially expressed miRNAs were investigated focusing on reproduction and larval development. 53 miRNA seed family, such as Tc-miR-1648/6090/7412/7931 and Tc-miR-698/1892/6795/6963/6980/7044/7078, were predicted to be involved in reproduction and development processes. Moreover, it was found that seed family with interspecies conservation, like ACCCGUA/ACCCUGU/CCCUGAG/GAAAGAC/GAGAUCA, have wide distribution in larvae, secretion and host serum, strongly suggesting the potential roles of these miRNAs in host and parasite interactions. This is the first exploration of sRNAs in T. canis, which would boost systematic biological investigations and encourage novel drugs vaccines and diagnostic tests.