Cretekos C J, Rasweiler J J, Behringer R R
Department of Molecular Genetics, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Reprod Fertil Dev. 2001;13(7-8):691-5. doi: 10.1071/rd01115.
The basis of species-specific morphogenesis has been a topic of fascination and speculation for centuries. In 1828, Karl Ernst von Baer noted that at the pharyngula stage of development all vertebrate embryos are morphologically very similar. Most subsequent hypotheses have proposed that the vertebrate body plan develops by a conserved mechanism, and that divergent forms develop by differential elaboration on this basic plan. Gene cloning and expression studies have largely confirmed that the genetic pathways of embryonic patterning are highly conserved. The finding that the proteins encoded by paralogous and orthologous genes within and between species can functionally replace each another is no longer novel; in most cases this is the expected result. How, then, does divergent morphology arise between species? One hypothesis that fits well with comparative data is that divergent morphogenesis arises from genetic differences in the timing, level and pattern of orthologous gene expression during development. This idea is being tested using a functional genetic approach comparing limb morphogenesis between the mouse and bat.
几个世纪以来，物种特异性形态发生的基础一直是一个引人入胜且备受猜测的话题。1828年，卡尔·恩斯特·冯·贝尔指出，在发育的咽胚阶段，所有脊椎动物胚胎在形态上都非常相似。随后的大多数假说都提出，脊椎动物的身体结构是通过一种保守机制发育而来的，不同的形态是在这个基本结构的基础上通过差异细化而形成的。基因克隆和表达研究在很大程度上证实了胚胎模式形成的遗传途径是高度保守的。物种内部和物种之间的旁系同源基因和直系同源基因编码的蛋白质能够在功能上相互替代，这一发现已不再新奇；在大多数情况下，这是预期的结果。那么，物种之间的形态差异是如何产生的呢？一个与比较数据非常吻合的假说是，不同的形态发生源于发育过程中直系同源基因表达的时间、水平和模式上的遗传差异。目前正在使用一种功能遗传学方法来验证这一观点，该方法比较了小鼠和蝙蝠的肢体形态发生。
