钙调蛋白及其调节酶PDE在鸡脑胚胎发育过程中的变化

钙调蛋白(CaM)参与脑中多种细胞过程的调节,推测它与大脑的分化发育有关。本实验研究了鸡脑从胚胎早期(原基)至大脑成熟各发育阶段可溶部分的CaM及其调节酶——环核苷酸磷酸二酯酶(PDE)的含量或活力变化。未经孵育的鸡胚中检测不出CaM,在孵育3—14天的胚脑中CaM含量逐渐增加:总CaM增加了3倍,活性CaM增加了4倍;而且在鸡脑细胞分裂分化最活跃的期间(皮质和髓质形成期间,即孵育8—14天),活性CaM的增加尤为显著(增加近3倍)。提示CaM与脑细胞的分裂分化有关。PDE的活力出现晚于CaM5天,随着胚龄增加,不断上升,提示它与脑细胞的分裂分化无直接关系,可能与大脑的功能活动有关。本实验还研究了鸡脑发育期中可逆性钙结合蛋白的变化。

CHANGES OF CALMODULIN LEVEL AND PHOSPHODIESTERASE ACTIVITY IN DEVELOPING CHICK BRAINS

The level of calmodulin(CaM) and the activity of CaM-dependent phospho-diesterase(PDE) in the soluble fractions of developing chick brains,have been determined The increase of CaM is well correlated with the morphological development of the brain.At 3 days after incubation of the egg,an appreciable amount of CaM was found in embryonic brain,corresponding to the morphological development stage,primordium.The CaM levels increased 3-fold (total CaM) to 4-fold (free CaM) between day 4 and 1 4 A marked elevation was observed between 8th and 14th days,a period corresponding to the formation of cortex and medulla of chick brain.The appearance of PDE was 5 days later than that of CaM.The enzyme activities increased progressively in the brains from 13 days before hatching through adulthood,whereas the CaM levels in the adult chick brains decreased by 30-50%,as compared with that in 14-day-embryonic samples.These results suggest a role for CaM in brain development,especially in the formation of cortex and medulla.The existence of Ca2 -binding proteins in developing chick brains was aslo reported.