Mass Spectrometry-Driven Discovery of Neuropeptides Mediating Nictation Behavior of Nematodes.

Neuropeptides regulate animal physiology and behavior, making them widely studied targets of functional genetics research. While the field often relies on differential -omics approaches to build hypotheses, no such method exists for neuropeptidomics. It would nonetheless be valuable for studying behaviors suspected to be regulated by neuropeptides, especially when little information is otherwise available. This includes nictation, a phoretic strategy of Caenorhabditis elegans dauers that parallels host-finding strategies of infective juveniles of many pathogenic nematodes. We here developed a targeted peptidomics method for the model organism C. elegans and show that 161 quantified neuropeptides are more abundant in its dauer stage compared with L3 juveniles. Many of these have orthologs in the commercially relevant pathogenic nematode Steinernema carpocapsae, in whose infective juveniles, we identified 126 neuropeptides in total. Through further behavioral genetics experiments, we identify flp-7 and flp-11 as novel regulators of nictation. Our work advances knowledge on the genetics of nictation behavior and adds comparative neuropeptidomics as a tool to functional genetics workflows.

Exploring neuropeptide signalling through proteomics and peptidomics.

INTRODUCTION: Neuropeptides are neuro-endocrine signaling molecules capable of signaling as neurotransmitters, neuromodulators or neurohormones. Studying how neuropeptide signaling is integrated in endocrine pathways and how neuropeptides regulate endogenous processes is crucial to understanding how multicellular organisms respond to environmental and internal cues. Areas covered: This review will cover proteomics and peptidomics approaches used in researching peptide signaling systems and breakthroughs that were achieved in this field. Both differential mass spectrometry and reverse genetic approaches are commonly used to study neuropeptidergic signaling. The field of proteomics quickly developed in the past decades and expanded from gel-based approaches to include advanced liquid chromatography and mass spectrometry. We explore how proteomics is used to reveal neuropeptide maturation and identify downstream targets of neuropeptide signaling pathways. We show how peptidomics differs from standard proteomics approaches and how it is used to study both neuropeptide processing and signal pathway identification. Expert commentary: Thanks to recent advancements in isolation techniques and increased sensitivity of equipment, proteomics and peptidomics studies of neuropeptide signaling are contributing increasingly to elucidating functional implications of endocrine signaling. Further technical progress should allow for full peptidomic profiling of single neurons, eventually providing us with a complete comprehension of endocrine signaling.

Dry-freezing Steinernema carpocapsae infective juveniles for robust preservation of stocks.

Cryopreservation allows strains to be stored, eliminating genetic drift and maintenance costs. Existing cryopreservation methods for the economically-important entomopathogenic nematode Steinernema carpocapsae involve multiple incubation and filtration steps to precondition the animals. The standard protocol for freezing the model organism Caenorhabditis elegans in buffer is simpler, and a recent C. elegans dry-freezing protocol allows stocks to survive multiple freeze-thaws, a possibility during a power failure. Here we report the efficacy of C. elegans cryopreservation protocols adapted for S. carpocapsae . We show that dry freezing with disaccharides, but not glycerol-based or trehalose-DMSO-based freezing buffer, allows reliable recovery of infective juveniles.