Mechanism and gene expression of mesodermal inducing substances on the presumptive ectoderm of early amphibian development.

最近，研究了这些蛋白质的转化生长因子β（TGF-β）家族蛋白质、猪红细胞结合素A和激活素A（红细胞分化因子）的中胚层诱导作用。用激活素A处理外植体导致中胚层衍生物如间充质、脊索、血细胞和肌肉的分化，但白蛋白A的作用要小得多。激活素A以10-50 ng/ml的极低浓度作用于假定的外胚层。激活素A诱导的中胚层分化也通过使用针对肌肉肌球蛋白的多克隆抗体的分析来证实。通过间接免疫荧光分析，在激活素A处理的外植体中观察到肌肉块的分化，而在白蛋白A处理的外植体和对照外植体中没有观察到分化。这些发现证实了TGF-β家族的这种蛋白质具有中胚层诱导能力。为了寻找与激活素同源的基因。从非洲爪蟾自身克隆了三种c-DNA。有C4，B3和M4。为了进一步的实验，将需要检测这些mRNA是否在正常胚胎发育过程中表达。

Recently the mesoderm-inducing effects of the transforming growth factor beta(TGF-beta) family of proteins of these proteins, porcine inhibin A and activin A (erythroid differentiation factor) were examined. Treatment of explants with activin A led to differentiation of mesodermal derivatives such as mesenchyme, notochord, blood cells and muscle, but inhibin A had a much lesser effect. Activin A reacted on presumptive ectoderm with very low concentration at 10-50 ng/ml. The mesodermal differentiation induced by activin A was also confirmed by analyses using a polyclonal antibody against muscle myosin. By indirect immunofluorescence analysis, the differentiation of muscle blocks was observed in the activin-A-treated explants, whereas no differentiation was observed in inhibin-A-treated and control explants. These findings confirm that this protein of the TGF-beta family has mesoderm-inducing ability. To find out the activin-homology genes were tried. Three kinds of c-DNA were cloned from Xenopus itself. There are named C4, B3,and M4. For further experiments will be needed to detect whether these m-RNA are expressed during the normal embryonic development.