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Ascorbic acid and ancillary biochemical indices of pollutional stress in the blue crab, Callinectes sapidus, and the grass shrimp, Palaemonetes pugio
Investigation of the ascorbic acid (AsA) status of the blue crab, Callinectes sapidus, and the grass shrimp, Palaemonetes pugio, indicated that both organisms possess significant quantities of AsA and ascorbate 2-sulfate (AAS), but have only limited synthetic abilities. High concentrations of AsA were found in crab hepatopancreas and shrimp cephalothorax, whereas gill and muscle tissue had low quantities of AsA. AsA concentrations were influenced by molt-cycle seasonal, dietary, and ontogenetic variations. Both organisms were able to utilize AAS reserves to fulfill AsA requirements during dietary or pollutant stress. AsA concentrations were depleted by exposure to the water-soluble fraction (WSF) of a crude oil and pentachlorophenol (PCP) but were unaffected by cadmium and elevated by phenanthrene exposures. These data suggest that AsA fluctuations were pollutant-specific and dose-dependent. Induction of drug metabolizing systems by certain xenobiotics is speculated to play a role in this pollutant-specific AsA response. In Callinectes sapidus, rapid hyperglycemia occurred under both pollutant and physical duress whereas hypoglycemia occurred during chronic pollutant stress. Hepatopancreatic glycogen concentrations were correlated to glucose fluctuations. Hemolymph cholesterol and high density lipoprotein (HDL) cholesterol fluctuations occurred during exposure to PCP and after severe handling stress. Cholesterol fluctuations suggest a generalized stress response, similar to plasma cholesterol variations demonstrated in teleosts during physical and pollutant stress. Hemolymph osmolality was of little use as an index of handling or pollutional stress. The results of this investigation indicated that an integrated multi-parameter approach is necessary when utilizing biochemical alterations as indices of pollutional stress in crustaceans. There was no single parameter which could be considered as a viable index of stress under a spectrum of pollutional stressors. Consideration of AsA fluctuations in combination with glucose/glycogen variations appears to be a good system for evaluating acute exposure to specific pollutants. Although glucose fluctuations consistently reflected acute handling and pollutant stress as well as chronic pollutant exposure, concentrations are also influenced by dietary, seasonal, diurnal, and molt-stage variations. Such variations affect many biochemical systems in crustaceans and must be evaluated before laboratory findings can be extrapolated to field situations.
Includes bibliographical references (leaves 129-149).