Showing papers on "Uca pugilator published in 1976"

Effects of mercury, cadmium, and lead salts on regeneration and ecdysis in the fiddler crab, Uca pugilator

Abstract: Fiddler Crabs, Uca pugilator, were collected and brought into the laboratory. Autotomy of one chela and six walking legs was induced by pinching each merus with a hemostat. Immediately after autotomy, crabs were placed in solutions of Pb(NO/sub 3/)/sub 2/, HgCl/sub 2/ or anhydrous CdCl/sub 2/. The growth of limbs buds was measured twice weekly with a calibrated ocular micrometer and whole crabs were later analyzed for mercury, cadmium and lead using atomic absorption spectrophotometry. Reserve analysis revealed that the crabs exposed for 2 wk to 0.1 mg/liter of mercury had absorbed 0.026 +- 0.001 ppM, those exposed to 0.1 mg/liter of Cd had absorbed 0.50 +- 0.10 ppM and those exposed to 0.1 mg/liter of lead had absorbed 2.04 +- 0.55 ppM. Retardation of regeneration was a specific effect of Cd at both 0.1 and 1.0 mg/liter. At 0.1 mg/liter, Hg was not toxic and did not have an effect on the growth of limb buds. At 1.0 mg/liter Hg could almost total inhibition of limb growth, but also proved lethal to 60 percent of the crabs. Despite the high amounts absorbed, lead had no effect on regeneration rate. The effects on ecdysis varied according to the size of more » the crabs and the concentration of the solutions. (FMM) « less

Sodium extrusion by the sea-water-acclimated fiddler crab Uca pugilator: comparison with other marine crustacea and marine teleost fish.

Abstract: 1. Measurements of the blood Na concentration and transepithelial electrical potential (T.E.P.) across Uca pugilator acclimated to sea water indicate that Na is maintained out of electrochemical equilibrium with sea water. The resulting net Na influx as well as the sodium gain due to ingestion of the medium must be balanced by extrarenal Na extrusion. 2. The small T.E.P. (−0.7 mV) and the ‘transport numbers’ of Na and Cl indicate that the permeability to these ions is equivalent. 3. Removal of external K results in a significant stimulation of unidirectional Na efflux that is dependent upon external Na but is not inhibited by ouabain. 4. Transfer of Uca to K and Na-free sea water results in a 54% decline in unidirectional efflux, which is not due to T.E.P. changes. Readdition of 25mM-K stimulates Na efflux much more than can be accounted for by changes in the T.E.P. Readdition of 25mM-Na to potassium-free sea water does not change the Na efflux. 5. The results indicate that Na extrusion by Uca is via a Na/K exchange mechanism which partially inhibits Na/Na exchange. Cessation of Na/K exchange (in K-free sea water) removes this inhibition and allows rapid Na/Na exchange. It is not known whether Na/K and Na/Na exchange are via the same or parallel carrier systems.

Effects of time of year and limb removal on rates of ecdysis of eyed and eyestalkless fiddler crabs, Uca pugilator

Abstract: The incidence of ecdysis among monthly samples of female Uca pugilator, both intact and eyestalkless, was determined from May, 1974 through April, 1975. Among both the intact and eyestalkless crabs the percentages of the crabs that underwent ecdysis varied during the year. During the height of the breeding season in particular, ecdyses were rare among the eyestalkless crabs and absent among the intact ones. The effects of limb removal, either followed by or preceded by eyestalk removal, on the rate of ecdysis were also determined. Eyestalkless crabs from which 4 walking legs were removed either the day before or the day after their eyestalks had been removed underwent ecdysis at a slower rate than crabs lacking only eyestalks, but faster than crabs lacking only 4 walking legs. The high incidence of precocious ecdyses induced by removing large numbers of limbs from eyed crabs appears to be due to the number of limbs removed and not to the weight or volume of limb tissue removed.

A bacterial infection in the common shore crab Carcinus maenas and the fiddler crab Uca pugilator

Abstract: A bacterial infection in Carcinus maenas and in Uca pugilator is described. The percentage of infections recorded in the field was between 0 and 10%, depending on season. Infected crabs remain about 3 times longer in Intermolt Stages C3 and C4 than do healthy crabs. In infected specimens of both species, the glucose level in the hemolymph is increased and protein, copper and lipid concentrations in the hemolymph as well as the glycogen content of various tissues are diminished. The coagulation process is disturbed in infected crabs. The hemocytes aggregate, but the formation of fibrin-like fibers, which can be observed in healthy crabs, does not occur.

Comparison of the effects of illumination on the melanophores of intact and eyestalkless fiddler crabs, Uca pugilator, and inhibition of the primary response by cytochalasin B.

Abstract: Approximately 100 times more illumination is required to produce pigment dispersion in the melanophores of eyestalkless fiddler crabs (Uca pugilator) than in the melanophores of intact crabs The pigment in melanophores of isolated legs will normally disperse in response to irradiation, but this response is inhibited by cytochalasin B

Biosynthesis of amino acids from 3-(14C)-pyruvate in the fiddler crab Uca pugilator.

Abstract: 1. 1. The time course of in vivo incorporation of 3-[ 14 C]-pyruvate into free and protein-bound amino acids was studied in the fiddler crab, Uca pugilator , over a 72 hr period. 2. 2. Label was detected in alanine, glutamic acid, aspartic acid, glutamine, proline, and possibly serine, indicating that these are nonessential for this species. 3. 3. Peaks in total label content and specific activities of free amino acids (FAA) ∗ were observed within 4 hr after injection, with highest labeling in alanine and glutamic acid; however, significant amounts of 14 C were still present in the FAA after 72 hr. 4. 4. Of the three types of tissues analyzed, muscle showed the lowest pyruvate incorporation into FAA and almost none into protein, whereas hepatopancreas and “carcass” (all remaining tissues) exhibited more rapid turnover of both protein and FAA. 5. 5. Acid hydrolysis of FAA fractions from carcass and hepatopancreas released large amounts of some amino acids, especially glutamate and aspartate, from other TCA-soluble materials. However, only glutamate contained appreciable radiocarbon. 6. 6. The label distribution patterns found in Uca are consistent with those of most other crustaceans which have been studied.

Acoustic Interneurons of Fiddler and Ghost Crabs

Abstract: The properties of acoustic interneurons in fiddler (Uca pugilator and U. minax) and ghost (Ocypode quadrata) crabs are described, as revealed by tests with pure tones. Three types of interneurons were present in all species: tonic, which fired for the duration of the stimulus; phasic, which fired briefly at the onset of stimulation; and inhibited, in which ongoing spontaneous activity was suppressed during stimulation. Spectral sensitivities of the cells differed among the species and were "matched" to the energy composition of the sounds. The combined properties of the cells were suited to resolve the most likely temporal differences between the sounds of each species: pulse repetition rate, sound duration, and interval between successive sounds. None of the cells coded tone frequency. The responses of all cells were suppressed during locomotion (walking) by the preparations. Finally, all interneurons were "nonhabituating" and in this respect resembled their functional analogues in cricket and grasshoppe...