Neave B, Holder N, Patient R
Division of Biomedical Sciences, King's College, London, UK.
Mech Dev. 1997 Mar;62(2):183-95. doi: 10.1016/s0925-4773(97)00659-x.
The effects of signal perturbation on expression domains of molecular markers for the mesoderm and ectoderm have been analysed across the dorso-ventral axis in zebrafish embryos. Injection of RNA encoding bone morphogenetic protein-4 (BMP-4) ventralised the embryo, expanding the intermediate mesoderm and non-neural ectoderm at the expense of the dorso-anterior mesoderm and neural plate. A dose-dependent response was observed both morphologically and in expression of gta3, MyoD and pax2. Conversely, increases in dorso-anterior mesoderm and neurectoderm were generated by injection of RNA encoding either a dominant-negative BMP receptor (delta BMPR) or noggin, as demonstrated by goosecoid and pax2 expression. Ventral BMP-4 expression was also inhibited. Thus, patterning of both the mesoderm and the ectoderm during gastrulation appears to depend, directly or indirectly, on the level of BMP activity. Consistent with their locations prior to formation of the neural tube, elevated BMP-4 increased the number of dorsal spinal cord neurons whilst sonic hedgehog and islet1 expression in the ventral spinal cord were reduced. However, the ectopic neurons were not positioned more ventrally, implicating a prepattern in the dorsal neural tube that is independent of the ventral central nervous system.
在斑马鱼胚胎中，已沿背腹轴分析了信号扰动对中胚层和外胚层分子标记表达域的影响。注射编码骨形态发生蛋白-4（BMP-4）的RNA使胚胎腹侧化，以牺牲背侧前中胚层和神经板为代价，扩大了中间中胚层和非神经外胚层。在形态学以及gta3、肌分化因子（MyoD）和配对盒基因2（pax2）的表达方面均观察到剂量依赖性反应。相反，如通过 goosecoid 和 pax2 表达所证明的，注射编码显性负性BMP受体（δBMPR）或头蛋白（noggin）的RNA可使背侧前中胚层和神经外胚层增加。腹侧BMP-4的表达也受到抑制。因此，原肠胚形成过程中中胚层和外胚层的模式形成似乎直接或间接地依赖于BMP活性水平。与它们在神经管形成之前的位置一致，BMP-4水平升高增加了背侧脊髓神经元的数量，而腹侧脊髓中音猬因子和胰岛1（islet1）的表达减少。然而，异位神经元并未更靠近腹侧定位，这意味着背侧神经管中存在一种独立于腹侧中枢神经系统的前模式。
