CAA: Genetic Exchange Between Bacillus Species

物种的性质，以及密切相关的物种在多大程度上被遗传交流的障碍所划分，对于细菌来说，可能比对任何其他主要的有机体群体来说都不那么清楚。凯瑟琳·邓肯博士正在对关系密切的土壤细菌枯草芽孢杆菌和地衣芽孢杆菌之间的遗传交换进行研究，以检验关于反对细菌之间自由基因交换的可能机制的假说。了解自然界中可能阻止土壤细菌之间基因自由交换的机制将极大地帮助做出关于释放基因工程微生物的决定。研究将集中在：(1)在灭菌土壤中萌发的孢子之间的自发、自然的交换；(2)原生质融合；(3)用纯化的DNA转化感受态枯草杆菌。将对产生的杂交进行分析，以确定DNA转移的程度，方法包括测序、限制性内切酶消化、等位酶电泳和选择性培养基上的生长试验，以确定特定基因的来源。杂交菌株的适合度将在土壤中生长期间进行评估，以估计在自然界中成功的可能性。%分子遗传学的新方法使监测土壤细菌之间的基因交换成为可能，这一现象对于人们对基因工程生物的担忧至关重要。凯瑟琳·邓肯博士使用复杂的DNA分析来评估芽孢杆菌土壤细菌之间基因转移的程度和命运，包括携带来自密切相关物种的DNA块的杂交菌株所起的作用。

The nature of species, and to what degree closely related species are demarcated by barriers to genetics exchange, are perhaps less clear for bacteria than for any other major group of organisms. Studies of genetic exchange between the closely related soil bacteria Bacillus subtilis and Bacillus licheniformis are being conducted by Dr. Kathleen Duncan in order to test hypotheses about possible mechanisms opposing free gene exchange among bacteria. Knowledge of mechanisms operating in nature that might prevent the free interchange of genes among soil bacteria would greatly aid in making decisions about the release of genetically engineered microorganisms. Investigations will focus on: (1) spontaneous, natural exchange between spores germinated in sterilized soil; (2) protoplast fusion; and (3) transformation of competent B. subtilis with purified DNA. The hybrids produced will be analyzed to determine the extent of DNA transfer using methods of sequencing, restriction-enzyme digests, allozyme electrophoresis, and growth tests on selective media to identify the origin of specific genes. The fitness of hybrid strains will be evaluated during growth in soil in order to estimate the likelihood of success in nature. %%% New methods in molecular genetics make possible the monitoring of gene exchange among soil bacteria, a phenomenon critical to concerns about genetically engineered organisms. Dr. Kathleen Duncan employs sophisticated DNA analyses to evaluate the extent and fate of gene transfer among Bacillus soil bacteria, including the role of hybrid strains carrying blocks of DNA from closely related species.