. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PHOSPHATE UPTAKE BY EMBRYOS 143. 60 TIME 120 180 MINUTES 240 FIGURE 7. Effect of 10 * M arsenate on P3!! uptake. The initial low level of activity represents the background count. Insemination was at zero time. Arrows indicate a change in the perfusion solution. surface-located ATPase was X 1O4 /mioles/10,000 eggs/hr. Both these figures are at the limits of the techniques, and indicate practically no change in the ATP in the sea water around the eggs. Therefore, the failure of ATP to relieve the DNP inhibition of P32 upt
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PHOSPHATE UPTAKE BY EMBRYOS 143. 60 TIME 120 180 MINUTES 240 FIGURE 7. Effect of 10 * M arsenate on P3!! uptake. The initial low level of activity represents the background count. Insemination was at zero time. Arrows indicate a change in the perfusion solution. surface-located ATPase was X 1O4 /mioles/10,000 eggs/hr. Both these figures are at the limits of the techniques, and indicate practically no change in the ATP in the sea water around the eggs. Therefore, the failure of ATP to relieve the DNP inhibition of P32 uptake during the lag phase may be due to insufficient penetration of the added ATP. Effect of arsenate on P3- uptake Arsenate, because of its structural similarity, is a competitive inhibitor of phosphate in a number of enzymatic reactions. As shown in Figure 7, a concentration of 10~4 M sodium arsenate markedly inhibits P32 uptake. Unlike DNP, this inhibition occurs whenever arsenate is applied from fertilization to 3l/2 hours after fertilization. The inhibition is com- pletely reversible upon removal (Fig. 7, Table II). A decrease in the rate of P32 accumulation sets in within 1 to 5 minutes after the arsenate has first entered the chamber, and recovery from this inhibition takes place within a comparable period of time upon removal of the inhibitor. When arsenate is applied at fertiliza- tion, a limited uptake commences after a lag period that is within the range of the normal lag period, for example, 26 minutes in one experiment. Therefore,. 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 (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 18
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