CHANGES IN CONCENTRATIONS OF GLYCOLYSIS AND KREBS CYCLE METABOLITES IN MOSQUITOFISH, GAMBUSIA-HOLBROOKI, INDUCED BY MERCURIC-CHLORIDE AND STARVATION

Concentrations of glycolysis and Krebs cycle metabolites in the tail tissues of mosquitofish, Gambusia holbrooki, were measured in response to starvation and to exposure to 0.62 mg Hg l-1 (as HgCl2) for 48 h. In control fish, starvation caused decreased concentrations of glucose-6-phosphate (G6P, -58%) and fructose-6-phosphate (F6P, -79%). Mercury exposure resulted in decreased concentrations of G6P (-56%) and F6P (-79%), and to increased concentrations of pyruvate (+75%), alpha-ketoglutarate (+41%), succinate (+39%), and malate (+47%). Krebs cycle activity increased in response to mercury exposure, perhaps in response to greater energy needs associated with maintaining homeostasis under stressful conditions. We conclude that glycolytic activity is reduced in fish exposed to mercury and that this response is similar to that caused by a cessation of feeding.