Halling S M, Zehr E S
U.S. Department of Agriculture, National Animal Disease Center, Ames, Iowa 50010.
J Bacteriol. 1990 Dec;172(12):6637-40. doi: 10.1128/jb.172.12.6637-6640.1990.
The species of Brucella are very closely related, but Brucella ovis does not express detectable amounts of a protein, designated BCSP31, that is common to the other species. We studied the lack of expression of BCSP31 by Southern analysis. DNAs from the B. ovis culture collection strains and field isolates were probed with a 1.3-kb HindIII fragment encoding BCSP31 of Brucella abortus. The probe hybridized to a 1.6-kb HindIII fragment of all B. ovis strains tested, showing that the gene is present in B. ovis but occurs on a larger restriction fragment. DNA linkage studies and restriction mapping of the cloned polymorphic region of B. ovis showed that the polymorphism was due to a DNA insertion of approximately 0.9 kb at a site downstream of the BCSP31-coding region. When the 1.6-kb polymorphic B. ovis fragment was used to probe a HindIII Southern blot of cellular DNA of strains of B. ovis and of B. abortus, at least 24 fragments of B. ovis and 6 fragments of B. abortus hybridized to the inserted DNA. Specimens of B. ovis collected over a 30-year period on two continents had similar hybridization patterns. The large difference between B. ovis and B. abortus in the number of copies of the repeated DNA is interesting in the context of the closeness of the Brucella species.
布鲁氏菌属的各个物种之间亲缘关系非常密切，但绵羊布鲁氏菌不表达一种名为BCSP31的蛋白质，而该蛋白质在其他物种中是可以检测到的。我们通过Southern分析研究了BCSP31的不表达情况。用编码流产布鲁氏菌BCSP31的1.3 kb HindIII片段对绵羊布鲁氏菌培养物保藏菌株和野外分离株的DNA进行探针杂交。该探针与所有测试的绵羊布鲁氏菌菌株的1.6 kb HindIII片段杂交，表明该基因存在于绵羊布鲁氏菌中，但位于一个更大的限制性片段上。绵羊布鲁氏菌克隆多态性区域的DNA连锁研究和限制性图谱分析表明，这种多态性是由于在BCSP31编码区下游的一个位点插入了约0.9 kb的DNA。当用1.6 kb的绵羊布鲁氏菌多态性片段对绵羊布鲁氏菌和流产布鲁氏菌菌株的细胞DNA的HindIII Southern印迹进行探针杂交时，至少24个绵羊布鲁氏菌片段和6个流产布鲁氏菌片段与插入的DNA杂交。在两大洲30年期间收集的绵羊布鲁氏菌标本具有相似的杂交模式。在布鲁氏菌属物种亲缘关系密切的背景下，绵羊布鲁氏菌和流产布鲁氏菌在重复DNA拷贝数上的巨大差异很有意思。
