Department of Cell Biology, Biozentrum, Basel University, Klingelbergstr. 70, CH-4056 Basel, Switzerland.
EMBO J. 1984 Sep;3(9):2087-94. doi: 10.1002/j.1460-2075.1984.tb02095.x.
We have isolated several cDNA clones of the white locus which are derived from embryonic and pupal transcripts of Drosophila melanogaster. The cDNA sequences map within 7.5 kb (coordinates -3.0 to +4.6) of the genomic DNA and correspond mainly to sequences within the distal region of the gene (coordinates -0.2 to -3.0). A major RNA species of 2.6 kb was detected on Northerns of poly(A) RNA isolated from all developmental stages. The total accumulation of this transcript peaks in the mature third instar larva to a level of 0.003% which is about ten times higher than that observed in embryos. The spatial distribution of white locus transcripts was determined by in situ hybridization to tissue sections. In embryos, hybridization signals are restricted to the cells of the developing Malpighian tubules and the signal strength corresponds with 50 transcripts per cell. Before the termination of the third instar stage, hybridization signals are also detected at a comparable level in the eye antennal disks. At the same stage, a third site of labeling is observed over a small cluster of cells which seems to be associated with the larval photoreceptor organs. Thus, white locus expression is largely restricted to tissues which are known to be involved in the biosynthesis of eye pigments and these different cell types act in a temporally autonomous manner with respect to the induction of the white gene during development.
我们已经分离了几个来自黑腹果蝇胚胎和蛹期转录本的白区位点 cDNA 克隆。cDNA 序列在基因组 DNA 的 7.5kb 范围内（坐标 -3.0 到 +4.6），主要对应于基因远端区域的序列（坐标 -0.2 到 -3.0）。在从所有发育阶段分离的 poly(A)RNA 的 Northern 印迹上检测到 2.6kb 的主要 RNA 种类。这种转录本的总积累在成熟的三龄幼虫中达到 0.003%的峰值，大约是胚胎中观察到的水平的十倍。通过原位杂交对组织切片确定白区位点转录本的空间分布。在胚胎中，杂交信号仅限于发育中的马氏管细胞，信号强度与每个细胞的 50 个转录本相对应。在三龄期结束之前，眼触角盘也以类似的水平检测到杂交信号。在同一阶段，在似乎与幼虫光感受器器官相关的一小簇细胞上观察到第三个标记位点。因此，白区位点的表达主要局限于已知参与眼色素生物合成的组织，这些不同的细胞类型在发育过程中对白基因的诱导表现出时间上自主的方式。
