Uca pugilator

About: Uca pugilator is a research topic. Over the lifetime, 376 publications have been published within this topic receiving 12303 citations.

Cadmium and naphthalene-induced hyperglycemia in the fiddler crab, Uca pugilator: differential modes of action on the neuroendocrine system.

Abstract: Hyperglycemia is a typical response of aquatic organisms to heavy metals. In crustaceans, the medulla terminalis X-organ-sinus gland neuroendocrine complex in the eyestalk is the source of the crustacean hyperglycemic hormone (CHH). The role of CHH in pollutant-induced b1ood glucose changes has only recently begun to be studied. Reddy provided evidence that CHH mediates cadmium-induced hyperglycemia in the red swamp crayfish, Procambarus clarkii. In a study of another hormonally-regulated function, color changes, cadmium exposure resulted in pigment in the melanophores of the fiddler crab, Uca pugilator, becoming less dispersed than in unexposed crabs. Earlier studies showed that, like cadmium, both a PCB, Aroclor 1242, and naphthalene induced black pigment aggregation in Uca poor. In general, when crabs are exposed to a pollutant, hydrocarbon or cadmium, they aggregate the pigment in their melanophores, but apparently by different mechanisms. Hydrocarbons appear to inhibit release of black pigment-dispersing hormone (BDPH), whereas cadmium appears to inhibit its synthesis. These apparent different modes of action of cadmium and naphthalene on the color change mechanism led us to compare the impact of these pollutants on the hormonal regulation of blood glucose in Uca pugilator. The present study was performed to determine (1) whether cadmium and naphthalenemore » induce hyperglycemia in Uca pugilator, (2) whether CH has a role, if naphthalene and cadmium do induce hyperglycemia, and (3) the effects, if any, of cadmium and naphthalene on CHH activity in the eyestalk neuroendocrine complex.« less

Synergistic effects of environmental variables on larvae of Uca pugilator

Abstract: The effects of sublethal concentrations of mercury in combination with stressful temperature-salinity regimes were considered for larval development of the fiddler crab Uca pugilator (Bosc.). Control organisms were compared to those treated with 1.8 ppb Hg for the following suboptimal regimes: 30°C, 30 ‰ S; 30°C, 20 ‰ S; 20°C, 30 ‰ S, and 20°C, 20 ‰ S. As physiological indicators of larval response, the survival rate, the O2 consumption rate, and phototactic response were measured, following either acute 24 h doses of Hg, or chronic rearing in Hg. All response parameters were modified in larvae maintained under the suboptimal conditions; mercury compounded the effects.

Regulatory effects of environmental chemical signals on search behavior and foraging success

Abstract: To appreciate the mechanisms governing olfactory-mediated behavior, pro- cesses of chemical signal production and transmission in fluid media (air or water) must be understood. With new tools becoming available in analytical chemistry and fluid dy- namics, investigators can now quantitatively address the processes governing chemical signals in field habitats. This study identifies the role of amino acids as signal molecules regulating search behavior and foraging success by estuarine mud snails (Ilyanassa ob- soleta). For the first time, methods are described for measuring chemical signal production, release, and transport in field habitats, over temporal and spatial scales consistent with olfactory information processing. Rates of advection and turbulent mixing were determined, and shear velocities and roughness Reynolds numbers were estimated to characterize bottom boundary layer flows. Nearly instantaneous chemical measurements were made using a computerized microprobe system and conservative tracer to establish the environmental distributions of signal molecules at rates similar to those sampled by olfactory receptor neurons. In addition, we determined the dissolved free amino acid (DFAA) compositions (up to 18 amino acids), concentrations, and effluent release rates for live intact and injured fiddler crabs (Uca pugilator) and hard clams (Mercenaria mercenaria), which are common prey from mud snail habitats. The field site populated by mud snails was found to be more conducive at broadcasting stronger chemical signals over longer distances than most other estuarine and ocean habitats. Live fiddler crabs released amino acids at very low fluxes (0.1 nmol-min-'-g (wet tissue aiass)-V), while live intact clams took up amino acids from seawater. Once injured, hard clams and fiddler crabs released DFAAs at 88 and 6804 nmol-min-1-g-1, respectively. Mud snails were significantly attracted to injured clams and crabs, but not to intact prey, as compared with controls. Synthetic mixtures of amino acids, simulating fluids leaking from injured prey, were also highly attractive. When we tested for effects of amino acid composition, concentration, mean volume flow rate (of chemical input), and flux, in separate experiments, only flux directly correlated with the number of mud snails attracted. The attraction of mud snails is thus more tightly coupled to the physical transport of chemical stimuli than to the molecular properties of specific amino acids.