González J M, Carlton B C
Plasmid. 1984 Jan;11(1):28-38. doi: 10.1016/0147-619x(84)90004-0.
Bacillus thuringiensis var. israelensis (BTI), serotype 14, which produces parasporal crystals toxic to certain dipteran larvae, was analyzed by agarose gel electrophoresis and found to contain a complex plasmid array. Eight plasmids were detected, with approximate sizes of 3.3, 4.2, 4.9, 10.6, 68, 75, 105, and 135 MDa, as well as a plasmidlike linear DNA element of approximately 10 MDa. Partially cured mutants of BTI implicated the 75-MDa plasmid in crystal production. Fifteen independently isolated acrystalliferous (Cry-) mutants were found to lack this plasmid. In plasmid transfer experiments, several of the BTI plasmids transferred into a plasmid-free, Cry- BTI recipient, but only transfer of the 75-MDa plasmid converted the recipient to crystal toxin production. The presence or absence of mosquito-toxic activity in all Cry+ and Cry- variants of BTI was confirmed by bioassay of sporulated cultures against larvae of Aedes aegypti. Southern blot analyses revealed that in one unusual Cry+ variant in which no 75-MDa plasmid band was detectable, plasmid sequences were still present, possibly integrated into the chromosome. The 75-MDa plasmid could also apparently recombine with the 68-MDa plasmid, to which it was partially homologous.
苏云金芽孢杆菌以色列变种（BTI），血清型14，可产生对某些双翅目幼虫有毒的伴孢晶体，通过琼脂糖凝胶电泳分析发现其含有一组复杂的质粒。检测到8个质粒，大小约为3.3、4.2、4.9、10.6、68、75、105和135兆道尔顿，以及一个大小约为10兆道尔顿的类质粒线性DNA元件。BTI的部分治愈突变体表明75兆道尔顿的质粒与晶体产生有关。发现15个独立分离的无晶体（Cry-）突变体缺乏该质粒。在质粒转移实验中，几个BTI质粒转移到了无质粒的Cry- BTI受体中，但只有75兆道尔顿质粒的转移使受体产生了晶体毒素。通过对产孢培养物针对埃及伊蚊幼虫的生物测定，证实了BTI所有Cry+和Cry-变体中是否存在蚊虫毒性活性。Southern印迹分析显示，在一个不寻常的Cry+变体中，未检测到75兆道尔顿的质粒条带，但质粒序列仍然存在，可能已整合到染色体中。75兆道尔顿的质粒显然也能与68兆道尔顿的质粒重组，二者部分同源。
