Bar Arie
Institute of Animal Science, ARO, The Volcani Ctr., Bet Dagan 50250, Israel.
Comp Biochem Physiol A Mol Integr Physiol. 2008 Dec;151(4):477-90. doi: 10.1016/j.cbpa.2008.07.006. Epub 2008 Jul 11.
Egg laying and shell calcification impose severe extra demands on ionic calcium (Ca2+) homeostasis; especially in birds characterized by their long clutches (series of eggs laid sequentially before a "pause day"). These demands induce vitamin D metabolism and expression. The metabolism of vitamin D is also altered indirectly, by other processes associated with increased demands for calcium, such as growth, bone formation and egg production. A series of intestinal, renal or bone proteins are consequently expressed in the target organs via mechanisms involving a vitamin D receptor. Some of these proteins (carbonic anhydrase, calbindin and calcium-ATPase) are also found in the uterus (eggshell gland) or are believed to be involved in calcium transport in the intestine or kidney (calcium channels). The present review deals with vitamin D metabolism and the expression of the above-mentioned proteins in birds, with special attention to the strongly calcifying laying bird.
产卵和蛋壳钙化对离子钙（Ca2+）的体内平衡提出了严峻的额外需求；特别是对于那些具有长窝卵（在“休产期”前依次产下的一系列卵）特征的鸟类。这些需求会诱导维生素D的代谢和表达。维生素D的代谢也会因与钙需求增加相关的其他过程而间接改变，如生长、骨骼形成和产卵。因此，一系列肠道、肾脏或骨骼蛋白通过涉及维生素D受体的机制在靶器官中表达。其中一些蛋白质（碳酸酐酶、钙结合蛋白和钙ATP酶）也存在于子宫（蛋壳腺）中，或者被认为参与肠道或肾脏中的钙转运（钙通道）。本综述探讨了鸟类体内维生素D的代谢以及上述蛋白质的表达，特别关注强烈钙化的产卵鸟类。
