. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0 I ASP 10 15 0 10 15 mm FIGURE 2. Changes in levels of the amino acids alanine (ALA), glycine (GLY), and aspartate (ASP) as determined by HPLC of neutralized perchloric-acid extracts of electrically stimulated radula protractor muscles from Busvcon contrarium over time. Units are ^moles-g wet wt '. Points represent means ± 1 SD, n = 5. medium (Fig. 4). In fact, during the last 5 min, more D-lactate was released into the medium than accumulated in the muscle (Fig. 4). DISCUSSION The high activities of all four pyruv
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0 I ASP 10 15 0 10 15 mm FIGURE 2. Changes in levels of the amino acids alanine (ALA), glycine (GLY), and aspartate (ASP) as determined by HPLC of neutralized perchloric-acid extracts of electrically stimulated radula protractor muscles from Busvcon contrarium over time. Units are ^moles-g wet wt '. Points represent means ± 1 SD, n = 5. medium (Fig. 4). In fact, during the last 5 min, more D-lactate was released into the medium than accumulated in the muscle (Fig. 4). DISCUSSION The high activities of all four pyruvate reductases in the radula protractor muscle of B. contrarium are similar to those observed in the radula retractor muscles of this species (Ellington, 1982) and in other gastropod muscles (Baldwin and England, 1982; Livingstone et ai, 1983). The highest activity, exhibited by octopine dehy- drogenase, was comparable to activities observed in cephalopod molluscs (Baldwin and England, 1980). The simultaneous accumulation of D-lactate, alanopine, octo- pine, and to a lesser extent strombine, which occurs in the radula protractor system during muscular activity, indicates that all four of these reductases operate under functional anoxia. The accumulation of these end products is temporally correlated with changes in pyruvate levels. Pyruvate levels increased dramatically during the time course of muscle contraction. Pyruvate reductases are thought to be equilibrium enzymes (de Zwaan and Dando, 1984; Ga'de and Grieshaber, 1986) and are thus regulated by changes in the concentrations of substrates and products. Pyruvate is the common substrate for all four reductases. The observed elevations in pyruvate levels in B. contrarium radula. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory
Size: 1264px × 1977px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
