Spectral Tuning of Chemoreceptor Cells of the Third Maxilliped of the Lobster, Homarus americanus

Abstract

This is the first investigation of the spectral tuning properties of single chemoreceptor cells of the third maxillipeds (mouthparts) of the lobster Homarus americanus. These organs are used, among other functions, for chemical recognition of food. Based upon extracellular recordings of action potentials, we report on 53 cells identified with a 15-compound equimolar mixture of mostly amino acids in an artificial seawater background (applied mixture concentration 150 {mu}M). Subsequently, all cells were tested with each compound separately. Cells were generally narrowly tuned to a single compound. Twenty-five percent of the cells sampled responded best to L-glutamate, 17% to betaine, 11% to taurine, and 9% to ammonium chloride. There was no consistent second best stimulus for these four cell populations. Two other populations were more broadly tuned: one responded best to hydroxy-L-proline and the other to L-arginine. Some cells responded to both compounds. Arginine-sensitive cells (not necessarily "arginine-best" cells) tended to respond also to a lesser degree to leucine. Hydroxy-L-proline-sensitive cells tended to respond to a lesser degree to glycine. Among the lobster's chemoreceptive organs, the tuning of the maxillipeds is the broadest of all and resembles the tuning of the walking legs more than that of the antennules or antennae.

Tuning of chemoreceptor cells of the second antenna of the American lobster (Homarus americanus) with a comparison of four of its other chemoreceptor organs

“…Comparable results were obtained from Hyp-best cells of the lateral and medial antennule (Weinstein et al 1990;Tierhey et al 1988). In contrast, most Hyp-best cells of the legs and maxillipeds showed a less pronounced difference in response magnitudes to best and second best stimuli (Johnson et al 1984;Corotto et al 1992).…”

“…Mixture suppression is a common feature of Hyp sensitive cells of the lateral antennule of Homarus americanus (Atema et al 1989;Weinstein et al 1990 Weinstein et al 1990), medial antennule (n= 53; after , walking legs (n=66; after Johnson et al 1984) and maxillipeds (n=45; after Corotto et al 1992). Open scale bars on the left represent 25% maxillipeds were similar to legs with Glu (28%), Bet (15%), Hyp (13%) and Tau (13%) as major best cell populations.…”

“…Based on lesion experiments the lateral flagellum of the first antenna (lateral antennule) has been identified as a long-distance (olfactory) receptor organ while chelated walking legs (dactyls) and third maxillipeds serve more as gustatory organs (Atema 1977(Atema , 1980Ache 1982;Derby and Atema 1982;Corotto et al 1992). Although chemoreceptors of the medial flagellum of the first antenna (medial antennule) respond to amino acids it has been speculated that they play a role in social (mating) behavior (Fuzessery and Childress 1975); loss of the medial antennules does not impair orientation towards a food source (Devine and Atema 1982).…”

“…Few studies investigated the chemosensory properties of the medial antennule (Panulirus interruptus: Fuzessery and Childress 1975; Homarus americanus." , maxillipeds (Corotto et al 1992) or antenna (Tazaki 1977;Derby 1982). Amino acid detection plays an important role in crustacean feeding behavior.…”

Regulation of sex-specific feeding behavior in fiddler crabs: physiological properties of chemoreceptor neurons in claws and legs of males and females

“…Behavioral (Pearson and Olla 1977) and neural (Thompson and Ache 1980) sensitivity to picomolar concentrations have been reported. Maximal responses of neurons in other crustacean species are generally in the millimolar range, with saturation occurring at concentrations below 10 -2 M (Fuzessery et al 1978;Corotto et al 1992;Voigt and Atema 1992; but cf Borroni and Atema 1988). The differences in ambient stimulus levels of the environments occupied by semiterrestrial fiddler crabs and aquatic crustaceans may be similarly profound.…”