Blass D H, Hunt D M
Mol Gen Genet. 1980;178(2):437-42. doi: 10.1007/BF00270496.
The status of de novo pyrimidine synthesis in the dp mutant of Drosophila melanogaster was examined by measuring the activity of the rate-limiting orotate phosphribosyl transferase (OPRT) enzyme. Activity is significantly elevated in late third instar larvae of 5 different dp mutant strains. A more detailed analysis of a dpovc allele has shown that this elevation arises at about mid-larval life and persists until pupation. A low nucleotide diet causes a depression in OPRT activity in dpovc larvae which can be reversed by dietary supplementation of uracil. However, neither the low nucleotide diet nor uracil supplementation results in a change in the expressivity of the dp mutant phenotypes. Changes in expressivity are produced by 6-azauracil and by elevated temperature although, in those cases, the effect on OPRT activity is minimal. The significance of the observations is discussed in relation to the role of pyrimidine biosynthesis in dp expressivity and chitin synthesis.
通过测量限速酶乳清酸磷酸核糖基转移酶（OPRT）的活性，研究了黑腹果蝇dp突变体中从头嘧啶合成的状态。在5种不同dp突变体品系的三龄晚期幼虫中，该酶活性显著升高。对dpovc等位基因的更详细分析表明，这种升高大约在幼虫生命中期出现，并持续到化蛹。低核苷酸饮食会导致dpovc幼虫的OPRT活性降低，而通过在饮食中补充尿嘧啶可以使其恢复。然而，低核苷酸饮食和补充尿嘧啶均不会导致dp突变体表型的表达发生变化。6-氮尿嘧啶和高温会导致表达变化，不过在这些情况下，对OPRT活性的影响很小。结合嘧啶生物合成在dp表达和几丁质合成中的作用，对这些观察结果的意义进行了讨论。
