Veterinary Biosciences - Research Publications

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    First Evidence of Function for Schistosoma japonicum riok-1 and RIOK-1
    Mughal, MN ; Ye, Q ; Zhao, L ; Grevelding, CG ; Li, Y ; Di, W ; He, X ; Li, X ; Gasser, RB ; Hu, M (MDPI, 2021-07)
    Protein kinases are known as key molecules that regulate many biological processes in animals. The right open reading frame protein kinase (riok) genes are known to be essential regulators in model organisms such as the free-living nematode Caenorhabditis elegans. However, very little is known about their function in parasitic trematodes (flukes). In the present study, we characterized the riok-1 gene (Sj-riok-1) and the inferred protein (Sj-RIOK-1) in the parasitic blood fluke, Schistosoma japonicum. We gained a first insight into function of this gene/protein through double-stranded RNA interference (RNAi) and chemical inhibition. RNAi significantly reduced Sj-riok-1 transcription in both female and male worms compared with untreated control worms, and subtle morphological alterations were detected in the ovaries of female worms. Chemical knockdown of Sj-RIOK-1 with toyocamycin (a specific RIOK-1 inhibitor/probe) caused a substantial reduction in worm viability and a major accumulation of mature oocytes in the seminal receptacle (female worms), and of spermatozoa in the sperm vesicle (male worms). These phenotypic alterations indicate that the function of Sj-riok-1 is linked to developmental and/or reproductive processes in S. japonicum.
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    Cryptosporidium of birds in pet markets in Wuhan city, Hubei, China
    Liao, C ; Wang, T ; Koehler, AV ; Hu, M ; Gasser, RB (ELSEVIER, 2021)
    Cryptosporidium is a group of protistan parasites of a range of vertebrates including mammals and birds. Stimulated by previous work that revealed "zoonotic" Cryptosporidium meleagridis subtypes (i.e. IIIbA26G1R1b and IIIbA22G1R1c) in diarrhoeic children and domestic chickens in Wuhan city and environs in Hubei Province, China, here we explored whether zoonotic C. meleagridis subtypes might also occur in pet birds in Wuhan city. From 11 bird markets in this city, we collected 322 faecal samples from 48 species of birds (representing six taxonomic orders), isolated genomic DNA and then conducted PCR-based sequencing of genetic markers in the small subunit (SSU) of the nuclear ribosomal RNA and the 60 kDa glycoprotein (gp60) genes of Cryptosporidium. Using SSU, Cryptosporidium was detected in 55 (17%) of the 322 samples. Cryptosporidium avium, C. baileyi, C. meleagridis, C. muris and C. proventriculi were characterised in 18%, 47%, 11%, 2% and 20% of the 55 samples, respectively, and a novel Cryptosporidium galli-like taxon in one sample. Using gp60, only one subtype (IIIeA17G2R1) of C. meleagridis was identified, which had not been detected in a previous study of diarrhoeic children in Wuhan. However, IIIe subtypes have been found in both humans and birds around the world. The relatively high prevalence and genetic diversity of Cryptosporidium recorded here in pet birds raise awareness about possible reservoirs of zoonotic variants of Cryptosporidium in birds in Wuhan, and potentially, other provinces in China.
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    Identification and characterization of an R-Smad homologue (Hco-DAF-8) from Haemonchus contortus
    Li, F-F ; Gasser, RB ; Liu, F ; Shan, J-N ; Di, W-D ; He, L ; Zhou, C-X ; Wang, C-Q ; Fang, R ; Hu, M (BMC, 2020-04-03)
    BACKGROUND: Smad proteins are essential cellular mediators within the transforming growth factor-β (TGF-β) superfamily. They directly transmit incoming signals from the cell surface receptors to the nucleus. In spite of their functional importance, almost nothing is known about Smad proteins in parasitic nematodes including Haemonchus contortus, an important blood-sucking nematode of small ruminants. METHODS: Based on genomic and transcriptome data for H. contortus and using bioinformatics methods, a Smad homologue (called Hco-daf-8) was inferred from H. contortus and the structural characteristics of this gene and its encoded protein Hco-DAF-8 established. Using real-time PCR and immunofluorescence assays, temporal transcriptional and spatial expression profiles of Hco-daf-8 were studied. Gene rescue in Caenorhabditis elegans was then applied to assess the function of Hco-daf-8 and a specific inhibitor of human Smad3 (called SIS3) was employed to evaluate the roles of Hco-DAF-8 in H. contortus development. RESULTS: The features of Hco-DAF-8 (502 amino acids), including conserved R-Smad domains and residues of the L3-loop that determine pathway specificity, are consistent with a TGF-β type I receptor-activated R-Smad. The Hco-daf-8 gene was transcribed in all developmental stages of H. contortus studied, with a higher level of transcription in the fourth-stage larval (L4) females and the highest level in adult males. Hco-DAF-8 was expressed in the platymyarian muscular cells, intestine and reproductive system of adult stages. Gene rescue experiments showed that Hco-daf-8 was able to partially rescue gene function in a daf-8 deficient mutant strain of C. elegans, leading to a resumption of normal development. In H. contortus, SIS3 was shown to affect H. contortus development from the exsheathed third-stage larvae (L3s) to L4s in vitro. CONCLUSIONS: These findings suggest that Hco-DAF-8, encoded by the gene Hco-daf-8, is an important cellular mediator of H. contortus development via the TGF-β signalling pathway. They provide a basis for future explorations of Hco-DAF-8 and associated pathways in H. contortus and other important parasitic nematodes.