Sechman A, Shimada K, Saito N, Ieda T, Ono T
Department of Animal Physiology, Faculty of Agriculture, Nagoya University, Japan.
J Exp Zool. 1994 Aug 1;269(5):450-7. doi: 10.1002/jez.1402690508.
The vitamin D3-dependent calcium binding protein, calbindin-D28K (CaBP-D28K), plays an important role in transepithelial calcium translocation. To evaluate its role in chick embryonic calcium metabolism, steady-state levels of CaBP-D28K mRNA in various tissues of the chick embryo were determined by Northern blot and slot blot analyses, and CaBP-D28K concentrations in the examined tissues and plasma were estimated by RIA. High levels of CaBP-D28K mRNA were found in the embryonic kidney (mesonephros) on embryonic day (E) 10 and E12 and thereafter gradually decreased until hatching. CaBP-D28K mRNA levels were low in the yolk sac until E16 but increased on E18 and reached a maximum on E20. A steady increase in CaBP-D28K mRNA levels was observed in the cerebellum during the development from E10 to post-hatching. CaBP-D28K mRNA levels in the intestine were very low during the incubation period but significantly increased on days 1 and 7 after hatching. By Northern blot analysis, CaBP-D28K mRNA was barely detectable in liver, heart, and chorioallantoic membrane of the embryonic chick. Changes in immunoreactive CaBP-D28K of each tissue paralleled observed changes in mRNA levels. In plasma, measurable levels of CaBP-D28K were found as early as E8 and were stable until E18, when 6.5-fold increase was observed compared to E16. The highest level of CaBP-D28K in plasma was found on E20 and decreased after hatching. These temporal profiles of CaBP-D28K suggest that it may play an important role in the regulation of chick embryonic calcium homeostasis.
维生素D3依赖性钙结合蛋白，即钙结合蛋白-D28K（CaBP-D28K），在跨上皮钙转运中起重要作用。为评估其在鸡胚钙代谢中的作用，通过Northern印迹和狭缝印迹分析测定了鸡胚各组织中CaBP-D28K mRNA的稳态水平，并通过放射免疫分析估计了所检测组织和血浆中CaBP-D28K的浓度。在胚胎第（E）10天和E12天的胚胎肾（中肾）中发现高水平的CaBP-D28K mRNA，此后逐渐下降直至孵化。直到E16，卵黄囊中CaBP-D28K mRNA水平较低，但在E18时升高，并在E20时达到最高。在从E10到孵化后发育过程中，小脑内CaBP-D28K mRNA水平持续升高。孵化期肠道中CaBP-D28K mRNA水平非常低，但在孵化后第1天和第7天显著升高。通过Northern印迹分析，在鸡胚的肝脏、心脏和绒毛尿囊膜中几乎检测不到CaBP-D28K mRNA。各组织中免疫反应性CaBP-D28K的变化与观察到的mRNA水平变化平行。在血浆中，早在E8时就发现了可测量水平的CaBP-D28K，并且直到E18时都保持稳定，此时与E16相比观察到增加了6.5倍。血浆中CaBP-D28K的最高水平出现在E20，孵化后下降。CaBP-D28K的这些时间分布表明它可能在鸡胚钙稳态调节中起重要作用。
