ABSTRACT: 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.
