A STUDY OF HEMOLYMPH PROTEINS AND HINDGUT EPITHELIUM ATPASE ACTIVITY DURING THE MOLTING CYCLE OF THE TERRESTRIAL ISOPOD, ARMADILLIDIUM VULGARE
The hindgut of the terrestrial isopod, Armadillidium vulgare, is a straight tube lined throughout its length by cuticle continuous with that of the exoskeleton. The isopod is unique among crustacea in that it molts biphasically, the posterior and anterior halves of the exoskeleton being molted about twenty-four hours apart. The cuticle lining the digestive tube is molted out of synchrony with that of the exoskeleton in a posterior to anterior direction. The molted hindgut cuticle passes out attached to the posterior exuviae and the foregut cuticle with that of the anterior exuviae. The presence of apical and basal plasma membrane infoldings in the anterior and posterior hindgut epithelium changes with the stage of the molt cycle. The infoldings are most prominent during intermolt, receding during premolt and intramolt and reappearing during postmolt. Extensive apical and basal infoldings are found in the rectum. The basal infoldings have a strong association with large elongated mitochondria. The morphology of these rectal infoldings was not observed to change during the molting cycle. Ca('++)-ATPase activity is localized in the basolateral plasma membranes of the anterior and posterior hindgut cells during intermolt, intramolt, and postmolt. Mg('++)-ATPase activity is localized in the basolateral plasma membranes of the anterior and posterior hindguts and rectum throughout the molt cycle with the lowest levels of activity found in the anterior hindgut and the highest in the postmolt rectum. The presence of this ATPase activity supports the contention that the hindgut is an organ of osmoregulation. The hemolymph protein concentration decreases during premolt and intramolt. A 198,000 D and a 102,000 D protein band disappears completely during intramolt while the other proteins are diluted by an increase in hemolymph fluid volume. Hemocyanin has been identified as two polypeptide chains of 72,000 D and 75,000 D. The concentration of hemocyanin decreases during premolt and intramolt possibly reflecting its use as an energy source. Hemocyanin can be found in the intermolt hemolymph of A. vulgare as a 2-hexamer, 23S, a hexamer, 16S, and a monomer, 5S. About 80% is present in the hemolymph as the hexamer. The molecular weight of the hexamer is approximately 450,000 D.
ZUNG, JAIME L, "A STUDY OF HEMOLYMPH PROTEINS AND HINDGUT EPITHELIUM ATPASE ACTIVITY DURING THE MOLTING CYCLE OF THE TERRESTRIAL ISOPOD, ARMADILLIDIUM VULGARE" (1986). ETD Collection for Fordham University. AAI8628545.