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

Antagonistic Behaviors of NMY-1 and NMY-2 Maintain Ring Channels in the C. elegans Gonad

Contractile rings play critical roles in a number of biological processes, including oogenesis, wound healing, and cytokinesis. In many cases, the activity of motor proteins such as nonmuscle myosins is required for appropriate constriction of these contractile rings. In the gonad of the nematode worm Caenorhabditis elegans, ring channels are a specialized form of contractile ring that are maintained at a constant diameter before oogenesis. We propose a model of ring channel maintenance that explicitly incorporates force generation by motor proteins that can act normally or tangentially to the ring channel opening. We find that both modes of force generation are needed to maintain the ring channels. We demonstrate experimentally that the type II myosins NMY-1 and NMY-2 antagonize each other in the ring channels by producing force in perpendicular directions: the experimental depletion of NMY-1/theoretical decrease in orthogonal force allows premature ring constriction and cellularization, whereas the experimental depletion of NMY-2/theoretical decrease in tangential force opens the ring channels and prevents cellularization. Together, our experimental and theoretical results show that both forces, mediated by NMY-1 and NMY-2, are crucial for maintaining the appropriate ring channel diameter and dynamics throughout the gonad.

Exploring transcriptional conservation between Ancylostoma caninum and Haemonchus contortus by oligonucleotide microarray and bioinformatic analyses

In this study, we identified, using an established oligonucleotide microarray platform for the parasitic nematode Haemonchus contortus, transcripts that are 'conserved' between serum-activated and non-activated L3s of Ancylostoma caninum (aL3 and L3, respectively) and H. contortus by cross-species hybridization (CSH) at high stringency and conducted extensive bioinformatic analyses of the cross-hybridizing expressed sequence tags (ESTs). The microarray analysis revealed significant differential hybridization between aL3 and L3 for 32 molecules from A. caninum, of which 29 were shown to have homologues/orthologues in the free-living nematode Caenorhabditis elegans and/or A. caninum and the other three molecules had no homologues in current gene databases. 'Non-wildtype' RNAi phenotypes were recorded for 13 of the C. elegans homologues. A subset of 16 C. elegans homologues/orthologues (i.e. genes abce-1, act-2, C08H9.2, C55F2.1, calu-1, col-181, cpr-6, elo-2, asp-1, K07E3.4, rpn-2, sel-9, T28C12.4, hsb-1, Y57G11C.15 and ZK593.1) were predicted to interact genetically with a total of 156 (range 1-88) other genes. Gene ontology (GO) analysis of the interacting genes revealed that the most common subcategories were signal transduction (7%), intracellular protein transport and glycolysis (6.2%) within 'biological process'; nuclear (25.7%) and intracellular (19.8%) within 'cellular component'; and ATP-binding (14.4%) and protein-binding (8.4%) within 'molecular function'. The potential roles of key molecules in the two blood-feeding parasitic nematodes are discussed in relation to the known roles of their homologues/orthologues in C. elegans. The CSH approach used may provide a tool for the screening of genes conserved across a range of different taxa of parasites for which DNA microarray platforms are not available.

Evaluation of follow-up of therapy with fenbendazole incorporated into stabilized liposomes and immunomodulator glucan in mice infected with Toxocara canis larvae

Anthelmintic activity of benzimidazole carbamate anthelmintics is low against dormant Toxocara canis larvae during late infections in paratenic hosts. The present study was conducted to examine the efficacy of pure fenbendazole, or drug incorporated into sterically stabilized liposomes (SL-FBZ) administered to T. canis-infected mice alone and after its co-administration with the immunomodulator (1-->3)-beta-D-glucan against larvae localized in muscles and brains. Therapy with either drug forms (in total 250 mg/kg in 10 doses) commenced on day 28 post-infection (p.i.) and the efficacy of treatment, examined on day 30 after the last dose of drug, was the highest in groups of mice treated with SL-FBZ in combination with glucan (89.5+/-5.8% in the muscles, 66.1+/-8.1% in brains). During 56 days of follow-up after termination of therapy, serum levels of anti-TES IgG antibodies, circulating IgG-TES immune complexes (CIC) as well as IgG antibodies to the most immunogenic part of recombinant myosin antigen of T. canis larvae were investigated. In contrast to anti-TES IgG antibodies, levels of CIC and anti-myosin antibodies were in the linear correlation with the efficacy of treatments beginning from day 38 post-therapy. We also showed that the serum levels of CIC as well as anti-myosin IgG antibodies seem to be the suitable serological markers for the monitoring of progress in larval destruction and TES resorption from the tissues.

Extending from PARs in Caenorhabditis elegans to homologues in Haemonchus contortus and other parasitic nematodes

Signal transduction molecules play key roles in the regulation of developmental processes, such as morphogenesis, organogenesis and cell differentiation in all organisms. They are organized into 'pathways' that represent a coordinated network of cell-surface receptors and intracellular molecules, being involved in sensing environmental stimuli and transducing signals to regulate or modulate cellular processes, such as gene expression and cytoskeletal dynamics. A particularly important group of molecules implicated in the regulation of the cytoskeleton for the establishment and maintenance of cell polarity is the PAR proteins (derived from partition defective in asymmetric cell division). The present article reviews salient aspects of PAR proteins involved in the early embryonic development and morphogenesis of the free-living nematode Caenorhabditis elegans and some other organisms, with an emphasis on the molecule PAR-1. Recent advances in the knowledge and understanding of PAR-1 homologues from the economically important parasitic nematode, Haemonchus contortus, of small ruminants is summarized and discussed in the context of exploring avenues for future research in this area for parasitic nematodes.