. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 502 C. S. SIKES AND A. P. WHEELER O) E <N 0 • Control, no matrix a 20 jjg matrix/ml & 100 jjg matrix/ml. 0 10 15 20 Minutes 25 30 FIGURE 4. The effect of matrix on oxygen consumption by embryos of the sea urchin, Arbacia punc- tulata. rates of crystal formation in vitro and in vivo can be similar. That is, based on the results of the radioisotopic incorporation (Fig. 1), urchins deposited ^moles of DIC-14 per ml (2800 embryos) per hour, or after correction for simultaneous in- corporation of carbona
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 502 C. S. SIKES AND A. P. WHEELER O) E <N 0 • Control, no matrix a 20 jjg matrix/ml & 100 jjg matrix/ml. 0 10 15 20 Minutes 25 30 FIGURE 4. The effect of matrix on oxygen consumption by embryos of the sea urchin, Arbacia punc- tulata. rates of crystal formation in vitro and in vivo can be similar. That is, based on the results of the radioisotopic incorporation (Fig. 1), urchins deposited ^moles of DIC-14 per ml (2800 embryos) per hour, or after correction for simultaneous in- corporation of carbonate that originates as respiratory CO2 (Table I), /umoles of CaCO3 deposition per 2800 embryos per hour. By computing a spherical volume for the embryos using 50 ^m as a typical radius based on microscopic examination using an ocular micrometer, each embryo would have a volume of X 10~7 cm3. Using this figure, we arrive at a value of /umoles of CaCO3 deposited per hour per cm3 of embryos. For comparison, the rate of deposition in the pH-stat in vitro assay can be read from Figure 2 as 48 yumoles of CaCO3 deposited per hour per cm3 of solution. Because of the similar rates of crystal formation, it seems reasonable to compare the concentrations of matrix required for inhibition in vitro to those that might occur in vivo. In the present study, the level of matrix incorporated into mineral that resulted in inhibition in vitro ( ^g per ^mole CaCO3) was somewhat higher than recorded in vivo ( ^g per ^irnole CaCO3) which was consistent with the somewhat higher rate of deposition measured in vitro as compared to that in vivo. Further, it is important to bear in mind that because of simultaneous secretion of unlabeled matrix by embryos, the value of matrix measured by C-14 incorporation into spicules may be an under- estimate of the total level of regulatory matrix to which growing crystals were exposed. Therefore, it can be tentatively concluded that the exo
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
