Chatwin, Heather M. (1994) Molecular genetic analysis of chemical-induced sporulation of Myxococcus xanthus. PhD thesis, University of Warwick.

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Abstract

Mutants resistant to glycerol-induction of sporulation were isolated from wild-type M. xanthus. The glycerol-resistant qlrA and alrB loci, previously mapped by Mx.8 transductions, were analysed by restriction mapping of clones and by complementation analysis. The location of the qlrA gene(s) was mapped to within a 2.2kb region, whilst the qlrB region proved very complex. The qlrA and qlrB gene products were reguired early in chemical-induced sporulation since two chemical-inducible lacZ fusions were not expressed in either qlrA or qlrB mutants during chemical-induction.
Only a minority of the glycerol-resistant mutants were unable to undergo fruiting body sporulation. Complementation studies of the qlrA and qlrB regions confirmed that mutations in chemical-induced and fruiting body sporulation were not linked. This suggests that the induction pathways of chemical-induced sporulation and fruiting body sporulation share few common genes.
Glycerol-resistant mutants were isolated from a non- motile strain, which is unable to form fruiting bodies. The majority of these mutants were able to form spores in the absence of fruiting bodies. Two mutants were unable to form spores. Isolating such mutants may provide a means of identifying truly sporulation-deficient mutants.
Expression from the chemical-inducible isqB>lacZ fusion, identified previously in a promoter probe vector, was blocked in 24 different glycerol-resistant mutants. Hence, the gene product was reguired late in the chemical-induced sporulation pathway. The complete transcription unit was cloned and disruption of the region by the insertion of a tetracycline cassette demonstrated that the gene is not essential for chemical- induced or starvation-induced sporulation.
Expression from a second chemical-inducible lacZ fusion, ÎÎDK4530, identified previously by random Tn£ lac insertion, was suppressed by amino acids in the growth media during chemical-induced sporulation and was blocked in both qlrA and qlrB mutants. Hence, expression of the gene product is dependent on both the qlrA+ and qlrB+ genes.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QR Microbiology
Library of Congress Subject Headings (LCSH):	Myxococcus xanthus| -- Genetics, Molecular biology, Cytology, Mutagenesis -- Genetics
Official Date:	March 1994
Dates:	Date Event March 1994 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Hodgson, D. A. (David A.)
Extent:	xix, 296 leaves : illustrations
Language:	eng

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