Neurogenetics of nictation, a dispersal strategy in nematodes

Abstract

Nictation is a behaviour in which a nematode stands on its tail and waves its head in three dimensions. This activity promotes dispersal of dauer larvae by allowing them to attach to other organisms and travel on them to a new niche. In this review, we describe our understanding of nictation, including its diversity in nematode species, how it is induced by environmental factors, and neurogenetic factors that regulate nictation. We also highlight the known cellular and signalling factors that affect nictation, for example, IL2 neurons, insulin/IGF-1 signalling, TGF-b signalling, FLP neuropeptides and piRNAs. Elucidation of the mechanism of nictation will contribute to increased understanding of the conserved dispersal strategies in animals.

A three-dimensional habitat for C. elegans environmental enrichment

“…In fact, although variable in number, we nearly always observed nictation on scaffold plates, but we never observed nictation on agar plates (Fig 2A). These results directly reinforce previous findings that the lack of nictation on agar is caused by physical limitations imposed by a smooth, two-dimensional substrate [12,14,22,28].…”

“…Nictation is an essential component of phoretic behavior for many wild nematodes [15]. We corroborate past observations that standard laboratory conditions are not permissive to the expression of this behavior (Fig 2A) [12,28]. On the other hand, dauer populations on our three-dimensional scaffold showed consistent and complex nictation behaviors (Fig 2).…”

“…In both situations, individually nictating animals had their tail anchored inside the scaffold. We were surprised to see jumping ("lashing") behavior in nictating C. elegans at the approach of an experimenter's pick, as this species of nematode has been previously reported to not have this behavior (Fig 2C and S4 Movie) [28]. Animals would sometimes adhere to both the pick and the scaffold at the same time.…”

“…C. elegans dauers cannot nictate on a flat agar surface, which creates difficulties for studying nictation [28]. They will however exhibit nictation if the agar is contaminated by fungus by climbing fungal hyphae [12].…”

Neuromodulators: an essential part of survival

“…The profound influence of neuromodulators on behavior, metabolism, and overall physiology is a common thread throughout this issue (Cheon, Hwang, & Kim, 2020;Honer et al, 2020;Kim & Flavell, 2020;Kim, Lee, Kim, & Lee, 2020;Liang, McKinnon, & Rankin, 2020;Liu & Zhang, 2020;Muirhead & Srinivasan, 2020;Prahlad, 2020;Srinivasan, 2020;Takeishi, Takagaki, & Kuhara, 2020;Yang, Lee, Yim, & Lee, 2020). In this perspective, we will focus on the roles of monoamines and neuropeptides in C. elegans survival.…”