Developmental-timing differences between species are linked to protein turnover “Fugit irreparabile tempus,” wrote Virgil, a reminder that our lives are defined by the irreversible flow of time. As soon as the egg is fertilized, embryonic cells follow a developmental program strictly organized in time. The sequence typically is conserved throughout evolution, but individual events can occur over species-specific time scales. Such differences can have marked effects. For instance, it takes 3 months to generate cerebral cortex neurons in a human but only 1 week in a mouse. This prolonged neurogenesis likely contributes to evolutionary expansion of the human brain (1). But the mechanisms underlying developmental time scales remain largely unknown. On pages 1449 and 1450 of this issue, Rayon et al. (2) and Matsuda et al. (3), respectively, report an association between species-specific developmental time scales and the speed of biochemical reactions that support protein turnover.

中文翻译：

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Tempus fugit：开发过程中时间是如何过的

Virgil 写道，物种之间的发育时间差异与蛋白质周转有关“Fugit 无法修复的时间”，这提醒我们我们的生活是由不可逆转的时间流逝决定的。一旦卵子受精，胚胎细胞就会按照严格及时组织的发育程序进行。该序列通常在整个进化过程中是保守的，但个别事件可能发生在物种特定的时间尺度上。这种差异会产生显着的影响。例如，人类产生大脑皮层神经元需要 3 个月，而小鼠只需要 1 周。这种延长的神经发生可能有助于人类大脑的进化扩张 (1)。但是发育时间尺度的潜在机制在很大程度上仍然未知。在本期第 1449 和 1450 页上，Rayon 等人。(2) 和松田等人。(3) 分别，