. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Matrix AddecH 468 Minutes 10 i: 03 0. TJ 0) I esO * " 2 30 40 50 60 70 80 NaOH Titrant, pMoles FIGURE 3. The effect of C-14 labeled matrix on CaCO3 crystallization in vitro measured using the pH-stat assay. In part A, the control curve represents crystallization in the absence of matrix. Curve a shows a 97% inhibition of crystal growth when /ug matrix/ml was added; curve b, 53% inhibition at ^g matrix/ml; curve c, 23% inhibition at ^g matrix/ml. In part B, the amount of C-14 labeled matrix
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Matrix AddecH 468 Minutes 10 i: 03 0. TJ 0) I esO * " 2 30 40 50 60 70 80 NaOH Titrant, pMoles FIGURE 3. The effect of C-14 labeled matrix on CaCO3 crystallization in vitro measured using the pH-stat assay. In part A, the control curve represents crystallization in the absence of matrix. Curve a shows a 97% inhibition of crystal growth when /ug matrix/ml was added; curve b, 53% inhibition at ^g matrix/ml; curve c, 23% inhibition at ^g matrix/ml. In part B, the amount of C-14 labeled matrix incorporated into the crystals grown during the experiments of part A is shown. DISCUSSION It is clear that the matrix from oyster shell, when added to the external medium, can reach the site of CaCOs crystallization during spicule formation by sea urchin embryos. This was evident from the experiments in which C-14 labeled matrix was detected in carefully isolated spicules from urchin embryos that had been grown in the presence of the labeled matrix (Table II). Spiculation was shown to be markedly suppressed in urchins treated with this amount of matrix (Fig. 1), indicating that the matrix did influence CaCO3 deposition. In addition, the residual radioactivity of the spicules that we attributed to the presence of matrix was entirely acid-stable which eliminated the possibility that the C-14 may have been in the form of Ca'4CO3, having become available as a source of inorganic carbon as respiratory CO2 (Sikes et al., 1981). These results also show that oyster shell matrix is relatively mobile in the sea urchin embryos despite the numerous intervening cellular and extracellular layers (Okazaki, 1975; Kingsley et al., 1984). To determine if the oyster matrix associated with spicules was sufficient to account for the observed inhibition of spiculation, the results in vivo can be compared to those of the pH-stat, in vitro experiments. This comparison seems reasonable because the. P
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
