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Small peptide–mediated self-recognition prevents cannibalism in predatory nematodes

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Science  05 Apr 2019:
Vol. 364, Issue 6435, pp. 86-89
DOI: 10.1126/science.aav9856

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Peptides let nematodes know family

To maximize fitness, organisms need to be able to recognize their own species, especially in the proximity of closely related individuals. Lightfoot et al. identified a hypervariable small peptide in the predatory nematode Pristionchus pacificus that is involved in species recognition to prevent predation of kin. They induced modifications in the carboxyl terminus of the peptide with a CRISPR-Cas9 system, which showed that this region is necessary for self-recognition. This molecular recognition system appears to prevent cannibalism and thus enables the worm to focus on appropriate prey species.

Science, this issue p. 86

Abstract

Self-recognition is observed abundantly throughout the natural world, regulating diverse biological processes. Although ubiquitous, often little is known of the associated molecular machinery, and so far, organismal self-recognition has never been described in nematodes. We investigated the predatory nematode Pristionchus pacificus and, through interactions with its prey, revealed a self-recognition mechanism acting on the nematode surface, capable of distinguishing self-progeny from closely related strains. We identified the small peptide SELF-1, which is composed of an invariant domain and a hypervariable C terminus, as a key component of self-recognition. Modifications to the hypervariable region, including single–amino acid substitutions, are sufficient to eliminate self-recognition. Thus, the P. pacificus self-recognition system enables this nematode to avoid cannibalism while promoting the killing of competing nematodes.

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