Differences in transcription between free-living and CO2-activated third-stage larvae of Haemonchus contortus.

Background: The disease caused by Haemonchus contortus, a blood-feeding nematode of small ruminants, is of major economic importance worldwide. The infective third-stage larva (L3) of this gastric nematode is enclosed in a cuticle (sheath) and, once ingested with herbage by the host, undergoes an exsheathment process that marks the transition from the free-living (L3) to the parasitic (xL3) stage. This study explored changes in gene transcription associated with this transition and predicted, based on comparative analysis, functional roles for key transcripts in the metabolic pathways linked to larval development.

RNAi in Haemonchus contortus: a potential method for target validation.

RNA interference (RNAi) is a method for the functional analysis of specific genes, and is particularly well developed in the free-living nematode Caenorhabditis elegans. There have been several attempts to apply this method to parasitic nematodes. In a recent study undertaken in Haemonchus contortus, Geldhof and colleagues concluded that, although a mechanism for RNAi existed, the methods developed for RNAi in C.

Isolation and characterization of class II myosin genes from Haemonchus contortus.

In this study, cDNAs encoding myosin from the parasitic nematode Haemonchus contortus were isolated and characterized. Several exhibited a considerable degree of sequence variation at the nucleotide and limited divergence at the amino acid levels within the various functional domains. The results suggest that the cDNAs isolated represented a single myosin heavy chain, which, by comparison with a number of other myosins, is inferred to represent a homologue of a muscle myosin (CeMHCA) of the free-living nematode Caenorhabditis elegans.

Class II myosins in nematodes-- genetic relationships, fundamental and applied implications.

Myosins are represented by a wide range of different classes of molecule, of which the most extensively studied are the class II myosins which drive muscle contraction and cell organization; the functional unit of class II myosins comprises two myosin heavy chains (MHCs). This minireview gives an update on class II MHCs of nematodes and describes a comparative analysis of MHC genes from nematodes and other organismal groups. Genetic analyses of sequence data for the four functional domains of MHCs (i.

Haemonchus contortus: molecular cloning, sequencing, and expression analysis of the gene coding for the small subunit of ribonucleotide reductase.

Gastro-intestinal (GI) parasites are of great agricultural importance, annually costing the livestock industry vast amounts in resources to control parasitism. One such GI parasite, Haemonchus contortus, is principally pathogenic to sheep; with the parasite's blood-feeding behaviour causing effects ranging from mild anaemia to mortality in young animals. Current means of control, which are dependent on repeated treatment with anthelmintic chemicals, have led to increasing drug resistance.