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Toxocara canis is an intestinal nematode of canids with a worldwide distribution, causing an important but neglected parasitic zoonosis in humans. Aquaporins (AQP) are a family of water channel proteins, which function as membrane channels to regulate water homeostasis. In this study, the coding sequence of aquaporin-1 gene of T. canis ( Tc-aqp-1) was cloned and characterized. The obtained Tc-aqp-1 coding sequence was 933 bp in length, which predicted to encode 311 amino acids. Two conserved asparagine-proline-alanine (NPA) motifs were identified in the multiple sequence alignments. Phylogenetic analysis revealed the closest relationship between T. canis and Opisthorchis viverrini based on aquaporin-1 amino acid sequence. A structure was predicted with ligand binding sites predicted at H93, N95, N226, L94, I79, and I210 and with active sites predicted at I256 and G207. Gene Ontology (GO) annotations predicted its cellular component term of integral component of plasma membrane (GO: 0005887), molecular function term of channel activity (GO: 0015250), and biological process term of water transport (GO: 0006833). Tissue expression analysis revealed that the Tc-aqp-1 was highly expressed in the intestine of adult male. The findings of the present study provide the basis for further functional studies of T. canis aquaporin-1. [ABSTRACT FROM AUTHOR]

Toxocara canis is an common intestinal nematode of canids and the principal causative agent of human toxocariasis. Vitellogenin (Vg), a source of amino acids and lipids in the eggs, are considered to play an important role in embryo development of a wide range of organisms. In the present study, the transcriptional levels of Tc-vit-6 gene in male and female adult T. canis were determined by quantitative real-time PCR, which indicated high transcription of Tc-vit-6 in the intestine, reproductive tract and body wall of male and female adult T. canis . The fragment of Tc-vit-6 encoding a vWD domain, was cloned and expressed to produce a rabbit anti- Tc vWD polyclonal antibody. Tissue distribution of Tc Vg6 was detected by immunohistochemical assays, which showed predominant distribution of Tc Vg6 in the tissues of intestine, as well as reproductive tract (including some of the germ cells) and musculature of male and female adult worms. Collectively, these results indicated multiple biological roles of Tc Vg6 apart from that in the reproduction of T. canis . [ABSTRACT FROM AUTHOR]

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. 2 2 Note: Transcriptomic data can be accessed in the NCBI Gene Expression Omnibus ( http://www.ncbi.nlm.gov/geo ) under accession no. GSE75536. [ABSTRACT FROM AUTHOR]