Tiong S Y, Nash D
Department of Genetics, University of Alberta, Edmonton, Canada.
Genetics. 1990 Apr;124(4):889-97. doi: 10.1093/genetics/124.4.889.
The Gart gene of Drosophila melanogaster is known, from molecular biological evidence, to encode a polypeptide that serves three enzymatic functions in purine biosynthesis. It is located in polytene chromosome region 27D. One mutation in the gene (ade3(1)) has been described previously. We report here forty new ethyl methanesulfonate-induced mutations selected aga!nst a synthetic deficiency of the region from 27C2-9 to ++28B3-4. The mutations were characterized cytogenetically and by complementation analysis. The analysis apparently identifies 12 simple complementation groups. In addition, two segments of the chromosome exhibit complex complementation behavior. The first, the 28A region, gave three recessive lethals and also contains three known visible mutants, spade (spd), Sternopleural (Sp) and wingless (wg); a complex pattern of genetic interaction in the region incorporates both the new and the previously known mutants. The second region is at 27D, where seven extreme semilethal mutations give a complex complementation pattern that also incorporates ade3(1). Since ade3(1) is defective in one of the enzymatic functions encoded in the Gart gene, we assume the other seven also affect the gene. The complexity of the complementation pattern presumably reflects the functional complexity of the gene product. The phenotypic effects of the mutants at 27D are very similar to those described for ade2 mutations, which also interrupt purine biosynthesis.
从分子生物学证据可知，黑腹果蝇的Gart基因编码一种在嘌呤生物合成中具有三种酶促功能的多肽。它位于多线染色体区域27D。该基因的一个突变（ade3(1)）先前已有描述。我们在此报告另外四十个由甲磺酸乙酯诱导产生的突变，这些突变是针对从27C2 - 9到28B3 - 4区域的合成缺陷筛选出来的。通过细胞遗传学和互补分析对这些突变进行了表征。分析结果明显鉴定出12个简单互补群。此外，染色体的两个区段表现出复杂的互补行为。第一个区段是28A区域，产生了三个隐性致死突变，并且还包含三个已知的可见突变体，即铲形眼（spd）、胸侧板（Sp）和无翅（wg）；该区域复杂的遗传相互作用模式涵盖了新的和先前已知的突变体。第二个区域在27D，七个极端半致死突变在该区域呈现出复杂的互补模式，其中也包含ade3(1)。由于ade3(1)在Gart基因编码的一种酶促功能中存在缺陷，我们推测其他七个突变也影响该基因。互补模式的复杂性大概反映了基因产物的功能复杂性。27D处突变体的表型效应与ade2突变所描述的非常相似，ade2突变也会中断嘌呤生物合成。
