Evidence of a mate-finding cue in the hermaphrodite nematode Caenorhabditis elegans

Abstract

When males of the roundworm Caenorhabditis elegans come into association with their hermaphroditic counterparts they cease foraging behavior and begin to mate. Here we detail several assays used to demonstrate that a diffusible cue is correlated with this process. This cue is sexually dimorphic, given off only by the hermaphrodite and eliciting a response only in the male. Males are attracted to, reverse direction of movement frequently, and remain in regions of agar conditioned with hermaphrodites. From our studies we suggest a form of kinesis that works by attracting males to their mating partners from a distance and functions, once males arrive, in holding attracted males in close proximity. The hermaphrodite vulva is not required for the cue. Males from general sensory mutants osm-5 and osm-6 fail to respond to the cue, whereas male-specific mutants lov-1 and pkd-2 respond. Finally, that males from multiple isolates of C. elegans also respond similarly to this cue indicates that this cue is robust and has been maintained during recent evolution.sensory behavior ͉ mating behavior ͉ kinesis M ate-location behavior depends on the ability of the nervous system to integrate incoming mate-specific cues and translate this information into appropriate responses in muscles and other effectors. Odorant cues have been studied extensively in fruit flies (1), other insects (2), fish (3, 4), and rodents (5), and less in reptiles (6, 7), birds (8), various mammals (9, 10), and primates including humans (11-13). Although mate-finding cues are common throughout Nematoda (14, 15) and have been found in the hermaphroditic trematodes (flukes; refs. 16-18), it remains odd that no chemical communication has been demonstrated in bringing together Caenorhabditis elegans mating partners.Although it has been suggested that some nontactile cue may work as a catalyst to a series of stereotyped steps by males resulting in successful reproduction (J. Sulston and E. Jorgensen, personal communication; see also ref. 19), no assays to address such a mate-finding cue have come into common practice (E. Jorgensen and R. Horvitz, personal communications; C. Song, K. Liu, and P.W.S., unpublished results). Moreover, other than for the fruit fly (20)(21)(22), simple, straightforward model systems in which to study the role of sensory organs and the underpinning genetic and neurologic machinery for processing of such sexrelated olfactory cues remain poorly described. Here we describe the design and results of several assays that provide evidence for a mate-finding cue in C. elegans. We also tested vulvaless hermaphrodites for their ability to condition agar and as well both general and specific male sensory mutants for their ability to respond. Last, we report cue-detection results from males of several C. elegans isolates from diverse locations. Materials and MethodsStrains. Unless indicated otherwise, all males come from the him-5(e1490) mutant, which segregates XO male progeny by X chromosome nondisjunction during meiosis (23). To construct cue ...

FMRFamide-Like Neuropeptides and Mechanosensory Touch Receptor Neurons Regulate Male Sexual Turning Behavior inCaenorhabditis elegans

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Generation and modulation of chemosensory behaviors in C. elegans

“…Similarly, although a major regulator of worm behavior and development is levels of the constitutively produced dauer pheromone [8][9][10][107][108][109], the neurons that respond to pheromone are also not yet defined. Presumably, males and hermaphrodites also produce signals to attract or repel each other, but these cues and the relevant sensory neurons are unknown [3,4]. As "...behavior is messy" (with apologies to [110]), the development of technologies for imaging neuronal activity in single neuron types in vivo in response to an applied stimulus [111][112][113][114][115] may allow for more precise functional mapping of chemicals to sensory neuron types.…”

“…For the sake of brevity, I will concentrate solely on these behaviors in the hermaphrodite. I refer the reader to several excellent publications and references therein addressing C. elegans male chemosensory behaviors [1][2][3][4][5][6].…”

Fitness effects of thermal stress differ between outcrossing and selfing populations inCaenorhabditis elegans

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