Calcium homeostasis and vitamin D metabolism and expression in strongly calcifying laying birds.
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.
Bar
Arie
A
Institute of Animal Science, ARO, The Volcani Ctr., Bet Dagan 50250, Israel. ariebar@agri.gov.il
D000818:Animals; D001717:Birds / Q000235:genetics / Q000378:metabolism*; D001842:Bone and Bones / Q000378:metabolism; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism; D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism; D004528:Egg Shell / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D006706:Homeostasis; D017136:Ion Transport; D008954:Models, Biological; D010058:Oviposition / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism; D014807:Vitamin D / Q000378:metabolism*
D064026:Calbindins; D012739:Gonadal Steroid Hormones; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D064030:S100 Calcium Binding Protein G; D050916:TRPV Cation Channels; D014807:Vitamin D; D002256:Carbonic Anhydrases; D000252:Calcium-Transporting ATPases; D002118:Calcium