Showing papers on "Uca pugilator published in 2002"

The Crustacean Neuropeptides of the CHH/MIH/GIH Family: Structures and Biological Activities

Abstract: Abramowitz et al. (1944) were the first to demonstrate that injection of an extract from eyestalks of Uca pugilator into the blue crab, Callinectus sapidus, caused a rather drastic increase of the blood sugar level. They found this “diabetogenic factor” to be heat-stable, very potent (0.001 eyestalk equivalents gave a significant effect), and mainly confined to Hanstrom’s sinus gland, a neurohemal organ associated with the eyestalk ganglia. This suggested the existence of a hyperglycemic neurohormone. This finding was confirmed by subsequent studies and, when micromethods for peptide analysis had become widely established, this diabetogenic factor, now called crustacean hyperglycemic hormone (CHH), was isolated and fully characterized from sinus glands of the shore crab, Carcinus maenas (Kegel et al. 1989). Isolation and identification from other crustacean species followed, which led to the recognition of a family of closely related peptides. Another line of research, which originated in the early observation that eyestalk ablation accelerated molting in decapods, focused on a molt-inhibiting hormone (MIH) in the eyestalk. The first peptide which fulfilled criteria for an MIH by the demonstration that it suppressed ecdysteroid synthesis in molting glands (Y-organs) was isolated and sequenced from sinus glands of Carcinus maenas (Webster 1991). Surprisingly, this MIH turned out to be similar to CHH (see third section).

Intrageneric predation by fiddler crabs in south carolina

Abstract: In South Carolina, two species of fiddler crab, Uca pugilator and U. pugnax, often feed in droves on the sand flats of smooth cordgrass salt marshes. Another fiddler crab, U. minax, does not drove, but large males of this species occasionally move onto sand flats and prey on members of the other smaller species. Successful predatory attacks entail a pounce, entrapment of prey in ambulatory appendages, reorientation of the predator to the supine position, maneuvering of the prey between the dactyl and propodus of the major cheliped, killing the prey by piercing or crushing its carapace with the major cheliped, and consumption. Females are successfully attacked with higher frequency than males. The frequency of predatory attacks declines exponentially as the composition of droves becomes biased towards larger males. This may indicate that predators face injury when attacking large males because only males possess potentially defensive claws and claw length increases with the square of body width. Uca pugilator individuals form pods in response to the approach of a predator. Pods are tight clumps of fleeing individuals that may function as mini-selfish herds. Pod composition is biased towards individuals most susceptible to U. minax predation, females and males of small body size, suggesting that pod formation is a selectively advantageous behavior.

Effects of melatonin on hemolymph glucose and lactate concentrations in the fiddler crab, uca pugilator

Abstract: Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone produced by the pineal gland that works to regulate sleep/wake cycles and activity rhythms. The effects of melatonin in metabolism are far from understood. Melatonin was injected into the fiddler crab, Uea pugilator, to investigate the effects of melatonin on hemolymph glucose and lactate levels. Following injection at t=O, hemolymph samples were collected at t=O.5, 1.0, 1.5 and 5.0 hours. Melatonin caused a decrease in the stress response to injection and also caused delayed hyperglycemia. Melatonin-injected crabs also retained the glucose and lactate rhythymicity when compared to saline-injected crabs. Glucose and lactate rhythms followed the same pattern indicating Lhat the cycles are coupled. Also, melatonin was synthesized using tbe Fischer Indole synthesis and characterized using HINMR. The synthetic melatonin demonstrated biological activity when injected into the crabs as when compared to pure melatonin on the effects on glucose and lactate concentrations. Overall. melatonin influences both glucose metabolism and the production of lactate.