STUDIES OF PARASPORAL BODY FORMING BACILLI

苏云金芽孢杆菌的特征在于产生大量， 孢子形成过程中的胞内包涵体。 这些内含物中的每一个都是 包括一种或几种大的多肽（原毒素）， 对特定种类的昆虫幼虫有毒。 有一系列 这些毒素由B的亚种产生。苏云金杆菌每种都有一种独特的 对某些昆虫幼虫的毒性模式。 其中包括 许多对农作物和树木造成重大损害（鳞翅目）， 其他作为人类疾病的载体，如蚊子， 苍蝇 在某些亚种中，形成一个以上的内含物， 含有一种独特的毒素 这些多肽是在一部分 并包含大部分的蛋白质 在形成过程中的合成活动。 这些原毒素基因中有几个已从B中克隆出来。苏云 质粒导入B。枯草芽孢杆菌E.大肠杆菌穿梭载体，并充分表达 在这两种生物体中， 新生幼虫 毒素特异性的基础将通过以下方式确定： 比较亲本B的相对LC 50。苏云金菌株，克隆 原毒素基因（单独或组合）和B。转移蜡状体 包含B的选定阵列。苏云金杆菌质粒 B。苏云 亚种和克隆基因将被选择，以提供这些比较 具有重叠和非重叠特异性。 各地区 的克隆原毒素基因将被亚克隆，以检查毒性水平 以及特异性的改变。 在至少一个亚种中原毒素合成的调节是 这取决于两个隐蔽质粒的活性。 一个质粒影响 原毒素合成的温度，另一个是产生的量。 生物测定系统将采用克隆的原毒素基因， 克隆这些调控质粒的片段，以确定 每个质粒的一部分参与调控，是否有基因 产品，以及监管职能是否处于 转录或其他地方。

Bacillus thuringiensis is characterized by the production of a large, intracellular inclusion during sporulation. Each of these inclusions is comprised of one or a few classes of large polypeptides (protoxins) that are toxic for specific species of insect larvae. There is a spectrum of these toxins produced by subspecies of B. thuringiensis each with a unique pattern of toxicity for certain insect larvae. Included among these are many that cause major damage to crops and trees (Lepidoptera) as well as others that serve as carriers of human diseases, i.e. mosquitoes and flies. In some subspecies, more than one inclusion is formed and each contains a unique toxin. These polypeptides are produced during a portion of the sporulation process and comprise a substantial part of the protein synthetic activity during the period of formation. Several of these protoxin genes have been cloned from B. thuringiensis plasmids into B. subtilis E. coli shuttle vector and express sufficiently well in both organisms to permit determination of lethal doses for select neonate larvae. The basis for toxin specificity will be determined by comparing relative LC50's for parental B. thuringiensis strains, cloned protoxin genes (alone or in combination) and of B. cereus transcipients containing selected arrays of B. thuringiensis plasmids. B. thuringiensis subspecies and cloned genes will be chosen to provide a comparison of those with overlapping as well as non-overlapping specificities. Various regions of the cloned protoxin genes will be subcloned to examine toxicity levels as well as alterations in specificity. The regulation of protoxin synthesis in at least one subspecies is dependent on the activities of two cryptic plasmids. One plasmid affects the temperature of protoxin synthesis, the other the amount produced. Bioassay systems will be developed employing cloned protoxin genes plus cloned fragments of these regulatory plasmids in order to define the portion of each plasmid involved in regulation, whether there is a gene product and whether the regulatory function is at the level of transcription or elsewhere.