Studies on contact sex pheromones of the caridean shrimp Palaemonetes pugio: II. The role of glucosamine in mate recognition

Abstract

The role of surface glycoproteins in mate recognition of the shrimp Palaemonetes pugio was studied using mating bioassays and fluorescence microscopy. Our data indicate that a glycoprotein associated with female shrimp functions in mate recognition in P. pugio. This glycoprotein is likely to be a glucosamine or an N-acetylglucosamine-containing glycoprotein complemented by a lectinlike receptor on males. Significantly fewer copulations occurred in seawater augmented with glucosamine as compared to seawater augmented with glucose. Thus, it is likely that glucosamine competitively inhibits mate recognition by binding male receptors and significantly reducing recognition of parturial females. The antennal lagellum of decapod crustaceans has long been considered to be chemotactile with bimodal, touch/taste receptors. The fluorescent dye, Lucifer Yellow, is incorporated into antennal setae from the surrounding seawater. Furthermore, the fluorescent dye, DiI, stained neural tissues at the base of the antennal setae. Taken together, these results are consistent with a bimodal, sensory function. When fluo-treated male antennal setae were exposed to the carapace of postmolt, parturial females, an immediate and significant increase in fluorescence intensity was observed, suggesting that Ca²⁺ likely acts as a second messenger for the receptor system. Fluo-labeled antennal setae of both males and females showed larger increases in intracellular Ca²⁺ levels when exposed to glucosamine as compared to glucose. The effects produced by glucosamine were sexually dimorphic, with male setae displaying a significantly greater mean overall change in fluorescence intensity than female setae. The dimorphic response observed suggests that glucosamine or a related compound serves as a female signal (i.e., contact sex pheromone) in mate recognition.

Key words:

• Crustacea
• Malacostraca
• glycoprotein
• glucosamine
• mate recognition
• pheromone