The Caenorhabditis elegans DEG-3/DES-2 Channel Is a Betaine-Gated Receptor Insensitive to Monepantel

Natural plant compounds, such as betaine, are described to have nematocidal properties. Betaine also acts as a neurotransmitter in the free-living model nematode Caenorhabditis elegans, where it is required for normal motility. Worm motility is mediated by nicotinic acetylcholine receptors (nAChRs), including subunits from the nematode-specific DEG-3 group. Not all types of nAChRs in this group are associated with motility, and one of these is the DEG-3/DES-2 channel from C. elegans, which is involved in nociception and possibly chemotaxis. Interestingly, the activity of DEG-3/DES-2 channel from the parasitic nematode of ruminants, Haemonchus contortus, is modulated by monepantel and its sulfone metabolite, which belong to the amino-acetonitrile derivative anthelmintic drug class. Here, our aim was to advance the pharmacological knowledge of the DEG-3/DES-2 channel from C. elegans by functionally expressing the DEG-3/DES-2 channel in Xenopus laevis oocytes and using two-electrode voltage-clamp electrophysiology. We found that the DEG-3/DES-2 channel was more sensitive to betaine than ACh and choline, but insensitive to monepantel and monepantel sulfone when used as direct agonists and as allosteric modulators in co-application with betaine. These findings provide important insight into the pharmacology of DEG-3/DES-2 from C. elegans and highlight the pharmacological differences between non-parasitic and parasitic nematode species.

Mapping of Plant-Parasitic Nematode Using GIS Technology in Tainal Watershed, Sulaimaniyah Province, Iraq

The present experiment was conducted to evaluate soil samples which had been taken from depths ranging from 0-30 cm in greenhouses planted with different vegetables such as cucumbers, tomatoes, peppers and eggplants in 24 agricultural sites in 19 villages. GIS application was used to make maps showing the results of a field survey that was conducted. The experiment was conducted for an area of 12 km2 in the Tainal Plain, west of Sulaimaniyah Province. Nearly 30% of the soil of the greenhouses were heavily infected. Plant analysis showed that the characteristics of ash, fat and moisture were significantly affected as a result of infection with nematodes. The spread of root-knot nematode juveniles in the villages of Al-Mahmoudia, Kani Pengsharma and Kani Shaya was 706, 695 and 622 per 250 g of soil. In tissues of the studied plants, the highest nitrogen content was 68.2 mg in Ziyeka, 60.4 mg in Gawani and 59.7 mg in Ali Bzaw. Phosphorus concentrations were highest in Kani Shaya, Shwankara and Ziyeka (25.5, 25.3 and 23.1 mg, respectively). Warmizyar had 91.8 mg of potassium, Kani Shaya had 78.6 mg and Kani Big had 71.6 mg. The calcium concentrations in Ziyeka, Gawani and Mewk were 54.5, 48.4 and 47.7 mg, respectively.

PARASITIC NEMATODE INFECTIONS OF ANURANS FROM A DERIVED SAVANNA BIOTOPE IN EDO STATE, NIGERIA

As part of a broader study to increase the information of parasite infections of anurans from the savanna biotope, an investigation of the nematode parasites of anurans in Agbede, a location in the derived savanna of Edo State, Nigeria was undertaken from August 2007 to July 2008. Anurans were collected at night using the visual acoustic encounter survey (VAES) sampling method, dissected and examined for nematode infections. A total of 329 anurans belonging to sixteen taxa, were examined, of which 235 were infected with an overall prevalence of 71.43%. Seasonal prevalences were 85.63% for wet season and 52.48% for the dry season (p<0.05). Ten nematode species, namely: Amplicaecum africanum, Cosmocerca ornata, Oswaldocruzia hoeplii, Physaloptera sp., Rhabdias africanus, Rhabdias sp., Camallanus dimitrovi, an unidentified oxyurid nematode, Ophidascaris larva, and an unidentified nematode were recovered from the hosts examined. The most common nematode species was Amplicaecum africanum (31.31%), whereas the least common was an unidentified oxyurid nematode (0.30%).Physaloptera sp. is a new record for the anurans of the derived savanna.

Dysidenin from the Marine Sponge Citronia sp. Affects the Motility and Morphology of Haemonchus contortus Larvae In Vitro

High-throughput screening of the NatureBank marine extract library (n = 7616) using a phenotypic assay for the parasitic nematode Haemonchus contortus identified an active extract derived from the Australian marine sponge Citronia sp. Bioassay-guided fractionation of the CH2Cl2/MeOH extract from Citronia sp. resulted in the purification of two known hexachlorinated peptides, dysidenin (1) and dysideathiazole (2). Compound 1 inhibited the growth/development of H. contortus larvae and induced multiple phenotypic changes, including a lethal evisceration (Evi) phenotype and/or somatic cell and tissue destruction. This is the first report of anthelmintic activity for these rare and unique polychlorinated peptides.

Sertraline as a new potential anthelmintic against Haemonchus contortus: toxicity, efficacy, and biotransformation

Haemonchus contortus is a parasitic nematode of ruminants which causes significant losses to many farmers worldwide. Since the drugs currently in use for the treatment of haemonchosis are losing their effectiveness due to the drug-resistance of this nematode, a new or repurposed drug is highly needed. As the antipsychotic drug sertraline (SRT) has been shown to be effective against the parasitic nematodes Trichuris muris, Ancylostoma caninum and Schistosoma mansoni, the aim of the present study was to evaluate the possible effect of SRT on H. contortus. The potential hepatotoxicity of SRT was tested in sheep, a common H. contortus host. In addition, the main metabolic pathways of SRT in H. contortus and the ovine liver were identified. While no effect of SRT on H. contortus egg hatching was observed, SRT was found to significantly decrease the viability of H. contortus adults in drug-sensitive and resistant strains, with its effect comparable to the commonly used anthelmintics levamisole and monepantel. Moreover, SRT in anthelmintically active concentrations showed no toxicity to the ovine liver. Biotransformation of SRT in H. contortus was weak, with most of the drug remaining unmetabolized. Production of the main metabolite hydroxy-SRT did not differ significantly between strains. Other minor metabolites such as SRT-O-glucoside, dihydroxy-SRT, and SRT-ketone were also identified in H. contorts adults. Compared to H. contortus, the ovine liver metabolized SRT more extensively, mainly via desmethylation and glucuronidation. In conclusion, the potency of SRT against H. contortus was proven, and it should be tested further toward possible repurposing.

Genome-Wide Identification of CircRNAs of Infective Larvae and Adult Worms of Parasitic Nematode, Haemonchus contortus

CircRNAs, a novel class of ncRNA family, are endogenous transcriptional products involved in various biological and physiological processes in plants and animals. However, almost no information is available for circRNAs of parasitic helminths. In the present study, the circRNAs repertoire was comprehensively explored in Haemonchus contortus, a blood-sucking parasitic nematode of ruminants. In total, 20073 circRNAs were identified and annotated from three key developmental stages/genders of H. contortus including the free-living infective third-stage larvae (L3, 18883), parasitic adult female (Af, 3491), and male worms (Am, 2550) via deep-sequencing technology and bioinformatic analysis. Among these identified circRNAs, 71% were derived from exonic regions of protein-coding genes. The number of circRNAs transcribed from the X chromosome (4704) was higher than that from Chromosome I-V (3143, 3273, 3041, 3030, 2882). The amount of highly expressed circRNAs in third-stage larvae was significantly more abundant than that in adult stage. 15948 and 16847 circRNAs were differentially expressed between Af and L3s and between Am and L3, respectively. Among them, 13409 circRNAs existed in both comparisons. Furthermore, 1119 circRNAs were differentially expressed between Af_and_Am. GO enrichment analysis indicated that source genes of circRNAs differentially expressed between Am and L3 as well as between Af and L3 were significantly enriched in many biological processes, primarily including signaling, signal transduction and cell communication terms. KEGG analysis revealed that parental genes of differentially expressed circRNAs were mainly related to metabolism (pyruvate metabolism, glycerophospholipid metabolism, and carbon metabolism), MAPK signaling pathway, and phosphatidylinositol signaling system. Moreover, many circRNAs contained one or more miRNA potential binding sites, suggesting that they could regulate gene expression at the post-transcriptional level. Furthermore, the correctness of head-to-tail back splicing site and alternative circularization events were verified by Sanger sequencing using both divergent and convergent primers. Finally, the reliability of RNA-Seq data and the resistance of circRNAs to RNase R digestion were confirmed by quantitative RT-PCR. Taken together, our findings provide a foundation for elucidating the regulatory mechanisms of circRNAs in H. contortus, which will advance the understanding of circRNAs in parasitic nematodes.

Genomic landscape of drug response reveals novel mediators of anthelmintic resistance

Understanding the genetic basis of anthelmintic drug resistance in parasitic nematodes is key to tracking and combatting their spread. Here, we use a genetic cross in a natural host-parasite system to simultaneously map resistance loci for the three major classes of anthelmintics. This approach identifies novel alleles for resistance to benzimidazoles and levamisole and implicates the transcription factor, cky-1, in ivermectin resistance. This gene is within a locus under selection in ivermectin resistant populations worldwide; functional validation using knockout and gene expression experiments supports a role for cky-1 overexpression in ivermectin resistance. Our work demonstrates the feasibility of high-resolution forward genetics in a parasitic nematode, and identifies variants for the development of molecular diagnostics to combat drug resistance in the field.