Identification of chicken calbindin D28K pre-messenger RNA sequences by polymerase chain reaction.

A transcribed RNA sequence encompassing the junction between the first intron and the second exon of the chicken calbindin D28K gene was copied in a cDNA fragment and subsequently amplified by polymerase chain reaction. When intestinal RNA is used as template, the appearance of the 161 bp amplified fragment is strictly dependent on the vitamin D status of the animal. In fact no amplified fragment is obtained when the RNA is extracted from the intestine of vitamin D-deficient chickens, while it is easily detected when the RNA is extracted only 30 min after injection with 1,25-dihydroxycholecalciferol. Conversely, the amplified fragment is obtained, irrespectively of the vitamin D status of the animal, when the RNA template is extracted from the brain. The appearance of unspliced RNA sequences upon vitamin D induction is followed, after a 30 min lag, by the appearance of the corresponding mature mRNA sequences.