Kim K W, Roon R J
J Bacteriol. 1984 Mar;157(3):958-61. doi: 10.1128/jb.157.3.958-961.1984.
A positive selection method, D-aspartic acid beta-hydroxamate resistance, was used to isolate Saccharomyces cerevisiae strains lacking the ability to synthesize asparaginase II. Of 100 such mutant strains, 93 exhibited mutations which were allelic with asp3, a previously characterized mutation. The other seven strains carried a new mutation, asp6. The asp6 mutation segregated 2:2 in asp6 X wild-type crosses and assorted from the asp3 mutation in asp6 X asp3 crosses. All seven asp6 mutant isolates reverted at a relatively high frequency, whereas the asp3 mutant isolates did not revert under the same conditions. Various independent asp3 isolates were mated to give heteroallelic diploids, which when sporulated and spread on D-asparagine medium yielded no recombinant strains.
采用一种正向选择方法——D-天冬氨酸异羟肟酸抗性，来分离缺乏合成天冬酰胺酶II能力的酿酒酵母菌株。在100个这样的突变菌株中，93个表现出与asp3等位的突变，asp3是先前已鉴定的一个突变。另外7个菌株携带一个新的突变，asp6。在asp6×野生型杂交中，asp6突变以2:2分离，并且在asp6×asp3杂交中与asp3突变不连锁。所有7个asp6突变分离株都以相对较高的频率回复突变，而asp3突变分离株在相同条件下不发生回复突变。将各种独立的asp3分离株进行交配，得到异等位基因二倍体，这些二倍体在形成孢子并铺在D-天冬酰胺培养基上时，未产生重组菌株。
