Egg-laying and locomotory screens with C. elegans yield a nematode-selective small molecule stimulator of neurotransmitter release

Abstract

Nematode parasites of humans, livestock and crops dramatically impact human health and welfare. Alarmingly, parasitic nematodes of animals have rapidly evolved resistance to anthelmintic drugs, and traditional nematicides that protect crops are facing increasing restrictions because of poor phylogenetic selectivity. Here, we exploit multiple motor outputs of the model nematode C. elegans towards nematicide discovery. This work yielded multiple compounds that selectively kill and/or immobilize diverse nematode parasites. We focus on one compound that induces violent convulsions and paralysis that we call nementin. We find that nementin stimulates neuronal dense core vesicle release, which in turn enhances cholinergic signaling. Consequently, nementin synergistically enhances the potency of widely-used non-selective acetylcholinesterase (AChE) inhibitors, but in a nematode-selective manner. Nementin therefore has the potential to reduce the environmental impact of toxic AChE inhibitors that are used to control nematode infections and infestations.

CYP Gene Expression and In Vivo Biological Effects of Khat Ethanol Extract, Cathinone and Cathine in Caenorhabditis elegans

“…This may indicate that our treatment may reduce worm movement and feeding which may also reduce its egg-laying rate. The regulation of C. elegans egg-laying was claimed to rely on cholinergic, serotonergic, GABAergic, and peptidergic circuits which our data could not capture [70] . Cathinone was found to induce serotonin release and serotonin reuptake inhibition [71] which is a paradigm that khat and its active compounds may exert their effects via serotonergic pathways to alter egg-laying and feeding rates.…”

Nemacol is a small molecule inhibitor of C. elegans vesicular acetylcholine transporter with anthelmintic potential

“…Of the four original Nemacol hits, analogs 1 and 2 induced the strongest phenotypes in C. elegans . However, Nemacol-2 demonstrated adverse effects in our previous counter-screens 10 . We therefore focused on Nemacol-1 for much of the analyses presented below.…”

“…From our previous screen 10 , we identified four structurally similar molecules that stimulate C. elegans egg-laying (Egl) and elicit similar uncoordinated motor phenotypes (Fig. 1 ).…”

“…The dire need for new anthelmintics has been recognized by academic, industry and governmental experts for some time 1 , 8 , 9 . Towards identifying novel candidate anthelmintic scaffolds, our group has recently carried out small molecule screens for those that affect the motor activity of the free-living nematode Caenorhabditis elegans 10 . One scaffold that we focus on here inhibits cholinergic signalling.…”

Automated multimodal imaging ofCaenorhabditis elegansbehavior in multi-well plates

“…To address these limitations, researchers have developed systems for analyzing worm behaviors via video recording and software analysis (7,8). These include methods for imaging worms on standard agar plates (9)(10)(11)(12)(13)(14)(15), in microfluidic devices (16)(17)(18)(19)(20)(21), and in multiwell substrates (1,(22)(23)(24)(25)(26).…”