A study of the structure of the Bacillus subtilis 168 chromosome

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" A study of the structure of the Bacillus subtilis 168 chromosome "
M. Amjad P. J. Piggot

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112904
Doc. No	:	TLpq304083339
Main Entry	:	M. Amjad
	:	P. J. Piggot
Title & Author	:	A study of the structure of the Bacillus subtilis 168 chromosome\ M. AmjadP. J. Piggot
College	:	Temple University
Date	:	1993
student score	:	1993
Degree	:	Ph.D.
Page No	:	152
Abstract	:	An SfiI restriction map of the spore-forming bacterium Bacillus subtilis 168 was constructed. Twenty-three SfiI fragments were resolved by pulsed-field gel electrophoresis. These fragments ranged in size from 730 kb to 7 kb. The order of the fragments on the B. subtilis genome was deduced by a variety of methods. Extensive use was made of Southern blots using cloned, genetically mapped DNA fragments as probes. Integrative plasmids were used to distinguish fragments of similar size. Linking clones were used to determine the contiguity of 9 pairs of SfiI fragments. Partial SfiI digestion analysis was used to locate smaller fragments. Seventy cloned genetic markers were located on 19 SfiI fragments. Using these and other methods a complete SfiI restriction map was constructed. The size of the B. subtilis genome was estimated to be 4188 kb, 200 kb. The resulting physical map was used for mapping newly cloned DNA on the B. subtilis chromosome. Taking advantage of the physical map generated in this study, a general search was conducted in order to study chromosomal DNA rearrangements during sporulation. A study of SfiI restriction patterns of chromosomal DNA isolated from vegetative and sporulating bacteria confirmed the presence of about a 42 kb deletion in the region of spoIIIC; in fragment SF4. Using probes for cloned genes, representing 18 SfiI fragments, no other rearrangements were detected similar to the change in fragment SF4. A possible role of DNA gyrase (encoded by the gyrA, and gyrB genes) in nucleoid condensation during sporulation was investigated. In a series of experiments, no strong link was established between nucleoid condensation and transcription of either gyrA or gyrB.
Subject	:	Biological sciences
	:	Genetics
	:	Molecular biology
	:	Molecular biology
	:	nucleoid condensation
	:	sporulation