Godeau F, Persson H, Gray H E, Pardee A B
EMBO J. 1986 Dec 20;5(13):3571-7. doi: 10.1002/j.1460-2075.1986.tb04684.x.
The combined use of a human c-myc probe and of an antibody raised against the human c-myc gene product demonstrated that the Xenopus cells contained a 2.5-kb c-myc transcript and synthesized a c-myc immunoreactive 65-kd polypeptide. In full-grown oocytes, p65c-myc was predominantly located in the nucleus. In non-dividing Xenopus oocytes c-myc mRNA was present at a steady-state level 10(4) times higher than that of growing somatic A6 cells. This very high level of c-myc transcript was reached early in oogenesis and remained constant thereafter. The rate of p65c-myc synthesis also reached high levels, but only in vitellogenic oocytes, suggesting a post-transcriptional control. Although the cell cycle is resumed at a very fast pace in developing embryos, no further increase in total embryonic content of c-myc RNA could be demonstrated up to the swimming tadpole stage. Furthermore, in embryos the rate of synthesis of p65c-myc decreased to a level markedly lower than that of cell cycle-arrested vitellogenic oocytes. This observation suggests that the function of the c-myc gene in the cell cycle may not be implicated directly in sustaining DNA synthesis or mitosis.
将人c-myc探针与针对人c-myc基因产物产生的抗体联合使用表明，非洲爪蟾细胞含有一个2.5 kb的c-myc转录本，并合成了一种c-myc免疫反应性65-kd多肽。在完全成熟的卵母细胞中，p65c-myc主要位于细胞核中。在未分裂的非洲爪蟾卵母细胞中，c-myc mRNA的稳态水平比正在生长的体细胞A6细胞高10^4倍。这种非常高的c-myc转录本水平在卵子发生早期就已达到，并在之后保持恒定。p65c-myc的合成速率也达到了高水平，但仅在卵黄生成的卵母细胞中，这表明存在转录后调控。尽管在发育中的胚胎中细胞周期以非常快的速度恢复，但直到蝌蚪游动阶段，c-myc RNA的总胚胎含量都没有进一步增加。此外，在胚胎中，p65c-myc的合成速率降至明显低于细胞周期停滞的卵黄生成卵母细胞的水平。这一观察结果表明，c-myc基因在细胞周期中的功能可能并不直接参与维持DNA合成或有丝分裂。
