REGULATION OF CALBINDIN MESSENGER-RNA AND CALBINDIN TURNOVER IN INTESTINE AND SHELL GLAND OF THE CHICKEN

A synthetic oligonucleotide was used as a probe for measurement of calbindin mRNA in the shell gland and intestine of chickens. The half time of calbidin mRNA in the duodenum and shell gland was estimated at 2 and 3.6 h and that of calbindin at 13.9 and 32.6 h, respectively. The formation rates of calbindin mRNA were 0.37 and 0.17 pmol.h-1.g-1 and the rate of calbindin formation was 0.099 and 0.031-mu-g.pmol mRNA-1.h-1 in the duodenum and shell gland, respectively. In the shell gland, calbindin mRNA and calbindin appeared at the time of sexual maturation during calcification of the first egg shell. Calbindin mRNA fluctuated markedly during the daily egg cycle, in close temporal association with egg shell calcification. When Ca2+ deposition was eliminated by expulsion of the ovum, the rise in calbindin mRNA was prevented. An indirect suppression of Ca2+ deposition by administration of the carbonic anhydrase inhibitor acetazolamide also resulted in a decrease in calbindin mRNA. The results are consistent with a possible role of Ca2+ flux in the regulation of calbindin mRNA appearance in the shell gland of chickens.