Showing papers on "Uca pugilator published in 1975"

The mechanism of tanning in the fiddler crab, Uca pugilator--I. Tanning agents and protein carriers in the blood during ecdysis.

Abstract: 1. 1. Labeled N-acetyldopamine, N-acetylnoradrenalin and their beta-glucoside forms were identified by paper chromatography as metabolites of 2-14C-dopamine in the blood of the fiddler crab, Uca pugilator, undergoing ecdysis. 2. 2. The blood appears to be the main site of synthesis of the glucoside forms. 3. 3. The label became tightly incorporated into the cuticle at ecdysis, suggesting that the glucoside forms are involved in the tanning process. 4. 4. The attachment of the labeled glucosides to two proteins (∼ 150,000 and >400,000 daltons) and the subsequent incorporation of these glucosides into the cuticle matrix suggests that these proteins act as carriers in the transport of tanning agents into the cuticle.

The mechanism of tanning in the fiddler crab, Uca pugilator--II. The cyclic appearance of tanning agents and attached carrier proteins in the blood during the molting cycle.

Abstract: 1. 1. Fluctuations in the levels of tanning agents and carrier proteins in the blood, epidermis, midgut gland, and cuticle were determined by paper chromatography after injection of 2- 14 C-dopamine into fiddler crabs at all the major periods of the molting cycle. 2. 2. During the intermolt period, when cuticle incorporation is almost nonexistent, the tanning agents are abundant in the blood, but virtually no carrier proteins are labeled. 3. 3. During proecdysis, carrier proteins become labeled, but cuticle incorporation remains negligible. 4. 4. Label is rapidly incorporated into the cuticle only early in postecdysis. A tanning hormone in the fiddler crab is postulated.

Relative Effectiveness of Ultraviolet and Visible Light in Eliciting Pigment Dispersion in Melanophores of the Fiddler Crab, Uca pugilator, through the Secondary Response

Abstract: Adaptive color changes in animals have been the subject of a large number of investigations. One genus that has been extensively studied is the fiddler crab, Uca (Fingerman 1968). The effects of light, temperature, and hormones on the chromatophores of this animal have been successfully described and analyzed. However, incident radiation can elicit chromatophore responses in Uca in two ways (Brown and Sandeen 1948). One is the direct action of light on the chromatophores (primary response). The other effect (secondary response) is an indirect one caused by light entering the eyes of the animal and ultimately resulting in secretion of neurohormones that affect the crab's chromatophores. Background responses of Uca are typical secondary responses (Brown and Hines 1952). In a previous publication (Coohill, Bartell, and Fingerman 1970), it was shown that wavelengths in the nearultraviolet (300-400 nm) region of the spectrum could elicit a primary (melanin-dispersing) response in Uca pugilator. This light region is, in fact, 200 times more efficient in eliciting melanin dispersion in this crab than is visible light. It was possible in this case to obtain accurate measurements of the incident dose of near ultraviolet required to elicit a certain response level in the melanophores. We calculated that there was enough near-ultraviolet l ght in the solar spectrum to produce the same response in the natural setting as observed under laboratory conditions. The adaptive value of this response was discussed. This result differe from those obtained with the amphibian, Xenopus laevis, where visible light was more effective than near ultraviolet for the melanophore primary response (Van der Lek 1967). The results of Yoshida (1956, 1957) on the primary response of the sea urchin, Diadema setosum, are ambiguous in that a peak of sensitivity was found in the blue region of the spectrum, but no attempt was made to expose these chromatophores to near-ultraviolet light. The only investigation dealing with the direct spectral response of crustacean chromatophores, other than that of Coohill et al. (1970), is that of Pau sch (1953), who, using the shrimp, Crangon crangon, obtained maximum pigment dispersion when the illumination was in the region of 300-450 nm. The objective of the present investigation was to compare the relative efficiences of ultraviolet and visible light in inducing melanin dispersion in the fiddler crab, Uca pugilator, by means

Evidence for acclimation to hydrostatic pressure in Uca pugilator (Crustacea: Decapoda: Ocypodidae)

Abstract: Groups of male Uca pugilator (Bosc) (Crustacea, Decapoda, Ocypodidae), acclimated to sublethal pressure (34 atm) subaqueously for 5 and 10 days, were observed subsequently at pressures up to 272 atm. Behavioral indicators of pressure resistance (“first response” and tetany) were employed to measure degrees of pressure acclimation in comparison with simultaneously and non-simultaneously conducted control experiments. No firm conclusions can be made on the basis of “first response” results, but the pressures required to induce tetany were significantly higher (P≤0.02, one-tailed comparison) in acclimated groups than in non-acclimated groups. These data and earlier studies by other investigators support the assertion that some shallow marine species are capable of at least limited short-term pressure acclimation.