Moscona M, Moscona A A
Differentiation. 1979;13(3):165-72. doi: 10.1111/j.1432-0436.1979.tb01579.x.
The hydrocortisone-mediated induction of glutamine synthetase (GS) in the neural retina of the chick embryo is a characteristic and unique feature of differentiation of this tissue. The induction involves genomic activity elicited by the inducer resulting in synthesis and accumulation of the enzyme. We describe correlations between the growth of embryonic retina tissue in vivo and in vitro and the development of its inducibility for GS, and demonstrate that this development proceeds through two phases: competence-acquisition phase (before the 7th day of development), and maturation phase. BrdU applied for 24 h to retinas of 5-day embryos irreversibly suppresses the development of induction-competence. However, BrdU does not affect the progressive maturation of inducibility when applied to retinas that already are fully induction-competent (8 days and older). The short treatment with BrdU of 5-day retinas also causes defective histogenesis resulting in drastic malformation of the tissue. The nature of the processes involved in competence-acquisition and in the maturation of inducibility for GS are examined. Possible mechanisms by which BrdU prevents the development of induction-competence for GS in the early embryonic retina and elicits defective histogenesis are discussed.
氢化可的松介导的鸡胚神经视网膜中谷氨酰胺合成酶（GS）的诱导是该组织分化的一个独特特征。这种诱导涉及诱导剂引发的基因组活性，从而导致该酶的合成和积累。我们描述了胚胎视网膜组织在体内和体外的生长与其对GS诱导能力的发展之间的相关性，并证明这种发展经历两个阶段：能力获得阶段（发育第7天之前）和成熟阶段。将5天龄胚胎的视网膜用BrdU处理24小时会不可逆地抑制诱导能力的发展。然而，当将BrdU应用于已经具有完全诱导能力的视网膜（8天及以上）时，它不会影响诱导能力的逐渐成熟。对5天龄视网膜进行短时间的BrdU处理也会导致组织发生缺陷，从而导致组织严重畸形。我们研究了参与能力获得和GS诱导能力成熟过程的性质。讨论了BrdU阻止早期胚胎视网膜中GS诱导能力发展并引发组织发生缺陷的可能机制。
