Localization of FMRF amide‐like peptides in Caenorhabditis elegans

Abstract

The neuropeptide FMRFamide (Phe-Met-Arg-Phe-NH2) is a member of a large family of related peptides that have been found throughout the animal kingdom. By using an antiserum specific for the Arg-Phe-NH2 moiety, we have found that about 10% of the neurons in the nematode Caenorhabditis elegans are immunoreactive. Most of these neurons, which include sensory, motor, and interneurons, were identified on the basis of their number, position, and projection pattern and by analysis of characterized mutants. Neurons that were immunoreactive in hermaphrodite animals were generally also found in males, but each sex had, in addition, sex-specific immunoreactive cells. Staining of hermaphrodite animals from different larval stages suggests that the onset of FMRFamide-like expression is differentially regulated among the cells. We have found a possible neuromodulatory role for the related peptide FLRFamide (Phe-Leu-Arg-Phe-NH2). In an egg-laying assay, FLRFamide by itself was not active but could potentiate a serotonin effect. The FMRFamide-like immunoreactivity was also used as a marker to examine the differentiation of cells that normally undergo programmed cell death. Cells that are destined to die in the Pn.a lineages appear to differentiate and adopt the fate of lineally equivalent cells before cell death.

SER-7, aCaenorhabditis elegans5-HT7-like Receptor, Is Essential for the 5-HT Stimulation of Pharyngeal Pumping and Egg Laying

“…The ser-7(tm1325), ser-7(tm1728) and ser-1(ok345) animals failed to exhibit any obvious Egl phenotype (Table 3), suggesting that serotonergic signaling may be at least partially redundant in the regulation of egg laying, as was observed above for pharyngeal pumping, and that other pathways, perhaps mediated by one of the many neuropeptide receptors in the C. elegans genome, can also stimulate egg laying (Schinkmann and Li, 1992;Waggoner et al 2000). In contrast, ser-7(tm1325) ser-1(ok345) double mutants exhibited a modest, but statistically significant, Egl phenotype, suggesting that both 5-HT receptors may couple to at least some common downstream target(s) (Table 3).…”

“…However, no role for SER-7 or for any Ga s -coupled receptor in the regulation of egg laying has been described. Both the VCs and HSNs secrete multiple neurotransmitters, including acetylcholine, 5-HT, and at least one, but probably several, related peptides (Schinkmann and Li 1992;Rand and Nonet 1997). Acetylcholine can either stimulate egg laying, as demonstrated by the addition of the nicotinic agonist levamisole or inhibit egg laying, by the activation of Ga i/o -coupled muscarinic receptors (GAR-2?)…”

“…Presumably, 5-HT signaling in vulval muscle is at least partially redundant, as hypothesized above for pharyngeal pumping. For example, the egg-laying neurons secrete a number of different FARPs and their role in the regulation of egg laying has been predicted (Schinkmann and Li 1992). However, ser-7 ser-1 double mutants do exhibit an Egl phenotype, suggesting that at least some of the downstream effectors of the SER-1 and SER-7 mediated pathways may overlap.…”

Comparative immunohistochemistry of the cerebral ganglion in Gastrotricha: an analysis of FMRFamide-like immunoreactivity in Neodasys cirritus (Chaetonotida), Xenodasys riedli and Turbanella cf. hyalina (Macrodasyida)

“…Unfortunately, the distribution of equivalent FMRFamidergic perikarya in most other cycloneuralians, with the exception of Caenorhabditis elegans (Nematoda), is unknown. Immunolocalization of FaRPs in C. elegans reveals IR in the neuropil and associated cells (Schinkmann and Li 1992), but no dumbbell shape is evident, and so the results are diYcult to compare with those observed in gastrotrichs. Additional data on other nematodes, and other cyloneuralians, will help clarify whether patterns of FMRFamide-like IR in the cerebral ganglion can be used as a phylogenetic character in support of these hypotheses.…”

Patterning of sexually dimorphic neurogenesis in the Caenorhabditis elegans ventral cord by Hox and TALE homeodomain transcription factors

“…1A) (Sulston and Horvitz, 1977). In hermaphrodites, six Pn.aap cells (P3.aap-P8.aap) differentiate into VC neurons (VC1-VC6), which are cholinergic and peptidergic and innervate vulval muscles to modulate egg laying (White et al, 1986;Schinkmann and Li, 1992;Bany et al, 2003;Duerr et al, 2008). In males, nine Pn.aap cells (P3.aap-P11.aap) divide to produce pairs of CA and CP neurons (CA1-CA9 and CP1-CP9).…”