RIZKI T M, RIZKI R M
J Cell Biol. 1963 Apr;17(1):87-92. doi: 10.1083/jcb.17.1.87.
An adaptive increase in tryptophan pyrrolase activity was obtained in the cell-free extracts of Drosophila melanogaster larvae which were given a dietary supplement of L-tryptophan. This activity was detectable in the extracts prepared from larval fatbodies when these were isolated from the remaining body tissues, but the present methods did not reveal any activity in extracts from the latter. These experiments confirm previous observations on the cellular distribution of kynurenine after feeding experiments with tryptophan. The autofluorescence characteristic of kynurenine in the larval fatbody is limited to the cells of the anterior region under normal feeding conditions, but, when larvae are fed tryptophan, autofluorescent kynurenine globules are found in a larger number of fat cells. In vitro incubation of isolated posterior fat cells with tryptophan has shown that these cells are capable of producing kynurenine. It is this same region of the fatbody in the suppressor of vermilion mutant that develops kynurenine autofluorescence, thus indicating that the absence of kynurenine in these cells in the normal strain is the result of an inhibition of their genetic potential to produce kynurenine. It has been concluded that the differentiation of "kynurenine cells" in the fatbody is controlled by a genetic mechanism which operates through the inducible tryptophan pyrrolase system.
给黑腹果蝇幼虫的饮食中补充L-色氨酸后，其无细胞提取物中获得了色氨酸吡咯酶活性的适应性增加。当从幼虫脂肪体中分离出这些脂肪体并与其余身体组织分开时，在从幼虫脂肪体制备的提取物中可检测到这种活性，但目前的方法未在后者的提取物中发现任何活性。这些实验证实了先前在用色氨酸进行喂养实验后关于犬尿氨酸细胞分布的观察结果。在正常喂养条件下，幼虫脂肪体中犬尿氨酸的自发荧光特性仅限于前部区域的细胞，但是，当给幼虫喂食色氨酸时，在大量脂肪细胞中发现了自发荧光的犬尿氨酸小球。用色氨酸对分离出的后部脂肪细胞进行体外培养表明，这些细胞能够产生犬尿氨酸。在朱红色突变体的抑制子中，正是脂肪体的这个相同区域产生了犬尿氨酸自发荧光，因此表明正常品系中这些细胞中犬尿氨酸的缺失是其产生犬尿氨酸的遗传潜力受到抑制的结果。已经得出结论，脂肪体中“犬尿氨酸细胞”的分化受一种遗传机制控制，该机制通过可诱导的色氨酸吡咯酶系统起作用。
