STREPTOMYCIN RESISTANCE: A GENETICALLY RECESSIVE MUTATION
STREPTOMYCIN RESISTANCE: A GENETICALLY RECESSIVE MUTATION
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链霉素耐药性：遗传隐性突变
DOI：
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发表时间：
1951
影响因子：
3.2
通讯作者：
J. Lederberg
中科院分区：
文献类型：
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作者：
J. Lederberg
细菌从链霉素敏感性（S8）的正常状态自发突变为耐药性（Sr），这在该化疗药物的临床应用（米勒和Bohnhoff，1950）以及细菌变异的实验研究中具有相当重要的意义。迄今缺乏的一个重要数据是Ss和Sr的显性关系;即，Ss和Sr在同一细胞中一起存在是否导致敏感性或抗性。这个问题已经研究的帮助下，独特的杂合二倍体培养的大肠杆菌。这些培养物是从菌株K-12的多营养缺陷型突变体的杂交中分离出来的。关于分离技术和遗传行为的详细描述，导致这些培养物被鉴定为杂合二倍体，已经发表（Lederberg，1949; Zelle和Lederberg，1951）。同样的考虑将本材料鉴定为携带来自每个亲本的S8和Sr因子的二倍体。用于获得SI/Sr杂合二倍体培养物的亲本原种为W-67和W-1177。W-67是生物素和甲硫氨酸的营养缺陷型（双突变体原种58-161; Tatum，1945），还携带乳糖阴性突变Lac 4-，但为野生型或对链霉素敏感。W-1177（677 sr; Lederberg，1950）是苏氨酸、亮氨酸和硫胺素营养缺陷型;乳糖和麦芽糖阴性;和Sr。两个亲本可分别表示为BMT+ L+ B1+ Lac，+Lac 4 SI和B+ M+ TLB 1 Lac 1 Lac 4 + Sr。将它们在合成的EMB乳糖琼脂培养基上杂交，分离出罕见的乳糖阳性原养型，以验证它们是二倍体杂合子（Lac，+Lac 4-/Lac 1 Lac 4+）还是重组原养型（Lac，+Lac 4+）。(See Lederberg，1949年，第183页。）从这样的杂交中，分离出两种对于Sr/SI为杂合的二倍体培养物。通过在合成EMB乳糖琼脂平板上重复单菌落分离来纯化这些细胞。二倍体培养物的悬浮液在含乳糖的充气合成液体培养基中生长。这种培养物中90%至95%的细胞仍然是二倍体。其余的由单倍体分离体组成，这些分离体不断被二倍体细胞抛弃，但由于它们从原始亲本遗传的营养缺陷型和乳糖阴性突变，它们不能在合成培养基中持续生长。以下关于二倍体悬浮液平板接种的报告针对最初存在的分离子进行了校正。
The spontaneous mutation of bacteria from their normal status of streptomycin sensitivity (S8) to resistance (Sr) is of considerable importance in the clinical application of this chemotherapeutic agent (Miller and Bohnhoff, 1950) as well as in experimental studies of bacterial variation. An important datum hitherto lacking is the dominance relationship of Ss and Sr; that is, whether the presence of Ss and Sr together in the same cell results in sensitivity or in resistance. This question has been studied with the help of unique heterozygous diploid cultures of Escherichia coli. These cultures have been isolated from crosses of polyauxotrophic mutants of strain K-12. A detailed account of the isolation techniques and of the genetic behavior that led to the characterization of these cultures as heterozygous diploids has been published (Lederberg, 1949; Zelle and Lederberg, 1951). The same considerations identify the present material as diploids carrying an S8 and Sr factor from each parent. The parent stocks used to obtain diploid cultures heterozygous for SI/Sr were W-67 and W-1177. W-67 is auxotrophic for biotin and methionine (double mutant stock 58-161; Tatum, 1945) and also carries a lactose-negative mutation, Lac4-, but is the wild type or is sensitive to streptomycin. W-1177 (677 sr; Lederberg, 1950) is auxotrophic for threonine, leucine, and thiamine; lactoseand maltose-negative; and Sr. The two parents can be symbolized as BMT+ L+ B1+ Lac,+ Lac4SI and B+ M+ TLB1Lac1Lac4+ Sr, respectively. They were crossed on a synthetic EMB lactose agar medium, and the rare lactose-positive prototrophs were isolated to verify whether they were diploid heterozygotes (Lac,+ Lac4-/Lac1Lac4+) or recombinant prototrophs (Lac,+ Lac4+). (See Lederberg, 1949, p. 183.) From such crosses, two diploid cultures were isolated that were heterozygous for Sr/SI. These were purified by repeated single colony isolations on synthetic EMB lactose agar plates. Suspensions of the diploid cultures were grown in aerated synthetic liquid medium containing lactose. From 90 to 95 per cent of the cells from such cultures were still diploid. The remainder consists of haploid segregants which are continually thrown off by the diploid cells but which are incapable of sustained growth in the synthetic medium owing to the auxotrophic and lactose-negative mutations that they have inherited from the original parents. The following report of the platings of the diploid suspensions is corrected for the segregants initially present.