Tissue-specific biochemical responses during anoxia and recovery in the channeled whelk

Abstract

Anaerobic metabolism was monitored in five tissues of the channeled whelk Busycon canaliculatum (L.) over a time course of 24 h of experimental anoxia followed by 6 h of aerobic recovery. All tissues accumulated succinate and alanine as metabolic end products during anoxia and utilized glycogen and aspartate as substrates. Total end product accumulation was highest in ventricle ( succinate + alanine = 32.5 μmol · g − wet weight), lowest in hepatopancreas (1.4 μmol · g −), and intermediate in other tissues, suggesting differing rates of metabolism in individual tissues during anaerobiosis. Patterns of end product accumulation also varied between tissues. Gill and foot muscle depended upon the coupled conversion of glycogen to alanine and aspartate to succinate for ATP production throughout anoxia. Ventricle and radular retractor muscle, however, largely limited alanine accumulation and aspartate utilization to the first 8 h of anoxia; subsequently, the conversion of glycogen to succinate became the dominant ATP-producing pathway. Tissues also varied in their metabolic responses during recovery in aerated seawater. Ventricle and gill rapidly cleared accumulated end products and restored aspartate reserves within the 6-h recovery period. Foot and radular retractor, however, showed little or no change in metabolite levels over the recovery period. Imino acids (octopine, alanopine, strombine) were not accumulated in significant amounts in any tissue during anoxia but all three accumulated rapidly in the ventricle during the aerobic recovery period.