. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Zinc Enzyme Synthesis (Carbonic Anhydrase). Activity Increasing FIGURE 6. Diagrammatic representation of the physiological and biochemical events occurring dur- ing the molt cycle of the blue crab. (A) the molt cycle of the blue crab with the duration of each portion indicating time. The designations of the molt stages are: C, —* C4, hard crab; D, —• D4; premolt; E, ecdysis; A,-A2, soft crab; B,-B2, papershell crab (Mangum, 1985). (B) The relative concentrations of copper and zinc on metallothionein are represented by the si
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Zinc Enzyme Synthesis (Carbonic Anhydrase). Activity Increasing FIGURE 6. Diagrammatic representation of the physiological and biochemical events occurring dur- ing the molt cycle of the blue crab. (A) the molt cycle of the blue crab with the duration of each portion indicating time. The designations of the molt stages are: C, —* C4, hard crab; D, —• D4; premolt; E, ecdysis; A,-A2, soft crab; B,-B2, papershell crab (Mangum, 1985). (B) The relative concentrations of copper and zinc on metallothionein are represented by the size of the copper, Cu and zinc, Zn symbols. (C) and (D) These two figures represent predicted hemocyanin and zinc enzyme synthesis activities generated from previously collected data (Engel, 1987). The degrees of shading are indications of the proposed activities of the biochemical pathways involved in hemocyanin synthesis and turnover, and zinc enzyme synthesis (carbonic anhydrase). components (Fig. 8). During the premolt period (D!-D3) when both zinc metallothio- nein and ecdysteroid are at their peaks, the new epidermis is being synthesized be- neath the existing exoskeleton. At molt both zinc metallothionein and ecdysteroid decrease, and between stages A, and A2 there is an abrupt increase in carbonic anhy- drase activity in the newly formed exoskeleton epidermis (Henry and Kormanik, 1985). This rapid increase, which occurs over a period of hours, suggests that the enzyme may be synthesized and present in the new epidermis as an apo-protein, and is not activated by zinc until after molt. Even though the decrease in zinc-metallothio- nein occurs in the digestive gland and the increase of carbonic anhydrase in the epi- dermis, these two events may be linked. Possibly some of the zinc bound to metallo- thionein at the time of molt could be mobilized via the hemolymph to activate the apo-carbonic anhydrase. This hypothesis is attractive since preliminary results from our l
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
