Glutamate, GABA, and dense-core vesicle secretion regulate predatory feeding in the nematodePristionchus pacificus

Abstract

AbstractNematodes are one of the most diverse groups of organisms, found in various environments, and exhibit various feeding behaviours.Pristionchus pacificusdisplays two types of feeding behaviours: predatory and bacterial feeding. Previously, we showed that the neurotransmitter serotonin plays important roles in regulating predatory feeding inP. pacificus.However, the role of other neurotransmitters in predatory feeding remains unclear. Using the CRISPR/Cas9 system, we generated mutants of the dense-core vesicle (DCV)-based neuropeptide secretion system and genes related to seven neurotransmitters. Predatory assays revealed that the vesicular glutamate transporterPpa-EAT-4, glutamic acid decarboxylasePpa-UNC-25 which is involved in GABA synthesis, and the calcium-dependent activator protein for DCV secretionPpa-UNC-31, play roles in predatory feeding behaviour. We assessed the pharyngeal movement necessary for predation as well as locomotion rate in these mutants. While thePpa-eat-4andPpa-unc-31mutants decreased predation movement, thePpa-unc-25mutant showed a reduction only in bacterial events compared to wild type animals. Additionally,Ppa-unc-25andPpa-unc-31decreased in motor movement, potentially reducing predation efficiency. Together, these results suggest that glutamate, GABA and DCV secretion modulate feeding behaviours inP. pacificus. Our mutant collection of neurotransmitter-related genes will be useful for future analysis of neurobiology and behavioural evolution.