. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PUROMYCIN EFFECT ON KCHIXOID EGGS 299 450 to 'O X 350 UJ §250 Q. O 0 150- 6 3 0 .. B o A o x CD fe o I 7 HOURS FIGURE 2. (a) Unfertilized eggs of Strongylocentrotus were exposed to 1 //c/ml "C amino acids for three hours, washed, and placed in sea water ( « ) or sea water containing M ethionine (O). Both groups incorporated labeled amino acids from their endogenous pools into acid insoluble material (lower curves). The level of uptake (upper curves) remained essen- tially constant for controls, , the labeled am
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PUROMYCIN EFFECT ON KCHIXOID EGGS 299 450 to 'O X 350 UJ §250 Q. O 0 150- 6 3 0 .. B o A o x CD fe o I 7 HOURS FIGURE 2. (a) Unfertilized eggs of Strongylocentrotus were exposed to 1 //c/ml "C amino acids for three hours, washed, and placed in sea water ( « ) or sea water containing M ethionine (O). Both groups incorporated labeled amino acids from their endogenous pools into acid insoluble material (lower curves). The level of uptake (upper curves) remained essen- tially constant for controls, , the labeled amino acids accumulated during the three hour exposure do not wash off or leak out. Eggs exposed to ethionine lost a substantial portion of their endogenous label during this time. Note that ethionine does not significantly affect the rate of incorporation from the endogenous pool into protein until after four hours of treatment, (b) Eggs were maintained in sea water (•) or sea water containing unlabeled amino acids (methionine HI, ethionine O, or leucine A) at M for five hours, washed, and given one hour pulse labels with 14C amino acids at intervals thereafter. The eggs which were exposed to unlabeled amino acids incorporate at a rate times higher than controls (overall average). The overall loss of amino acids from pools caused by the amino acid pretreatment, as judged from Figure 2a, is a factor of Thus the effect of the amino acid pretreatment seems to be the exchange of the internal pools of many amino acids for the single amino acid present in the medium, lowering the size of pools of all amino acids except that supplied by approximately a factor of three and thereby inflating subsequent incorporation rates by a factor of three. That the value of cpm in the homogenate (uptake) accurately reflects these changes is evidence for its validity as a measure of radioactivity in endogenous amino acid pools. in the usual way ; these were counted with a low backgro
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
