Immerglück K, Lawrence P A, Bienz M
Zoological Institute, University of Zurich, Switzerland.
Cell. 1990 Jul 27;62(2):261-8. doi: 10.1016/0092-8674(90)90364-k.
We report an induction process occurring between two germ layers in the Drosophila embryo that involves a cascade of five interacting genes. Two of these, Ultrabithorax and abdominal-A, encode nuclear homeobox proteins; each of them is expressed in one of two adjacent parasegments in the visceral mesoderm and directs expression in its parasegment of a separate target gene, decapentaplegic in parasegment 7 and wingless in parasegment 8. The activity of both target genes is required for normal expression of another homeotic gene, labial, in cells of the adhering midgut epithelium. Their products are putative extracellular proteins, which presumably act as signals between the two germ layers. Positional instruction of this kind may be needed since the endoderm, unlike the mesoderm, appears unsegmented at first as it originates from two primordia near the embryonic poles, outside the realm of segmentation genes.
我们报道了果蝇胚胎中两个胚层之间发生的一种诱导过程，该过程涉及五个相互作用基因的级联反应。其中两个基因，超双胸和腹部-A，编码核同源异型盒蛋白；它们各自在内脏中胚层的两个相邻副节之一中表达，并指导其副节中一个单独的靶基因的表达，在副节7中是脱壳蛋白，在副节8中是无翅蛋白。这两个靶基因的活性是另一个同源异型基因唇在粘附的中肠上皮细胞中正常表达所必需的。它们的产物是推测的细胞外蛋白，可能在两个胚层之间充当信号。由于内胚层与中胚层不同，最初似乎是不分节的，因为它起源于胚胎极附近的两个原基，处于分节基因的范围之外，所以可能需要这种位置指令。
