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Haemonchus contortus infections in small ruminants are of major economic importance worldwide. Heat shock proteins (HSPs) are a family of molecular chaperones that play important roles in the process of invasion and survival of nematodes. Although HSP70 has been identified in several parasitic nematodes, little is known of its distribution and function in Haemonchus contortus. The aims of this study were to characterize HSP70 from Haemonchus contortus (designed as Hc-hsp70), express Hc-hsp70 and analyse the promoter activity in Caenorhabditis elegans. Bioinformatic analysis revealed that the open reading frame of the Hc-hsp70 cDNA encodes a 646-amino acid peptide, which is highly conserved in comparison to HSP70 in other nematodes. Phylogenetic analysis indicated that H. contortus is closely related to Caenorhabditis. The 5'-flanking region promoted green fluorescence protein (GFP) expression in the intestine in all larval stages and adult with 2 expression patterns in C. elegans. Expression of Hc-hsp70 mRNA transcripts in C. elegans increased following 2, 4, 6 h of heat shock and peaked at 4 h. However, its expression induced down-regulation of hsp-1 of C. elegans. These results suggest that the H. contortus hsp70 might have a similar function to that of C. elegans hsp-1.

To construct the recombinant vector Pact-EGFP, the Act-1 core promoter region was amplified from the pUCm-T/Act-1 and subcloned into pEGFP-4.1 vector (derived from pEGFP-N1 with the removal of human cytomegalovirus immediate early promoter), by restriction enzymes Bgl II and Hind III. Transfection of Pact-EGFP vector into Vero cell by liposome indicated that Act-1 core promoter regulated the expression of EGFP gene in lower level in Vero cells. After Pact-EGFP microinjection into the gonad of Caenorhabditis elegans with pRF4 as a gene marker, green fluorescence was detected in the cortex, vice cortex and the pharyngeal of C. elegans. According to the locations, two different transgene lines were separated. The expression level of EGFP expressed in C. elegans was more than that in Vero cell. Some unique motifs might exist in Act-1 core promoter region of C. elegans, which was closely related to the expression level of EGFP. These results lay the foundation for the further research on gene function of parasitic nematodes using C. elegans.

Diapause induced in the early fourth stage of Haemonchus contortus is a strategy to adapt this nematode to hostile environmental conditions. In this study, we identified a new gene, Hc-fau , a homologue of human fau and Caenorhabditis elegans Ce-rps30 . Hc-fau encodes two proteins through alternative RNA splicing, Hc -FAUA and Hc -FAUB, consisting of 130 and 107 amino acids, respectively. Hc -FAU possesses a diverged ubiquitin-like (UBiL) protein domain and a conserved ribosome protein S30 domain. The protein is ubiquitously expressed, except in the gonad. However Hc-fau transcripts decrease significantly in diapausing L4s of H. contortus . In C. elegans , knockdown of Ce-rps30 confers an extended lifespan, increased lipid storage in the intestine and shortened body length. These morphological characteristics are comparable with dauer larvae of C. elegans , in which the gonad is condensed considerably. In contrast, a shortened lifespan is observed in C. elegans over-expressing Hc-faua , and especially Hc-faub , with hatching failure detected. The genes of insulin/IGF-1 signalling (IIS), TGF-β, cGMP, dafachronic acid (DA), apoptosis (AP) and fatty acids (FA) metabolism are all down-regulated in Ce-rps30 RNAi (RNA interference) worms, except for akt-1 and daf-16 . However, daf-16 up-regulation is inconsistent with its target gene down-regulation and the result from a heat stress assay in these worms. Daf-16 RNAi conducted in Ce-rps30 (tm6034/nt1) mutants failed to rescue the worms. The S30 domain stays in the nucleus, while UBiL accumulates in the cytoplasm. Compared with Hc -FAUA, results of UBiL domain and S30 domain over-expression indicate synergism between UBiL and S30 in regulating lifespan and reproduction. These results suggest the potential functions of Hc-fau in regulating larval diapause in H. contortus . [ABSTRACT FROM AUTHOR]