When an essential nutrient is depleted from the medium, cultures of wildtype
E. coli cells enter a period called stationary phase. The transition into
stationary phase is marked by distinct changes in cell physiology, gene
expression, and morphology. Pr???? and Matsumura (18) found a mutant strain of
E. coli that was able to continue growing exponentially at a time when wild-type
cells had stopped growing and entered stationary phase. They concluded that
FlhD, a transcriptional activator of flagellar genes, was responsible for this
growth phenotype and that it is a regulator of cell division (17, 18). Contrary to
the findings of Pr???? and Matsumura, research in our lab has shown that the
mutant growth phenotype observed in the strain used by Matsumura and Pr???? is
flhD independent. This study sought to identify the second mutation, which we
call cdr (cell division regulator) in the strain used by Matsumura and Pr????. We
used Hfr mapping and P1 transduction to localize the mutation to a specific
region of the chromosome. We also sought to determine if this growth
phenotype was due to loss of function or gain of function and whether the
mutation in the cdr gene was sufficient to cause the observed growth phenotype
in other strain backgrounds. In addition the growth phenotype of these two
strains was compared to that of other wild-type and standard laboratory E. coli
strains. Our results indicate that the cdr mutation is located in the 88.5. region of
the chromosome and is due to loss of Cdr function. We also discovered that the
growth phenotype assigned to the mutant strain more closely reflects that of
other wild-type laboratory strains as did the morphology of cells in stationary
phase. This evidence suggests that the actual mutant strain might be the one
that was designated as the wild-type strain by Matsumura and Pr???? and both
strains may contain mutations that actually cause a decrease in cell number
instead of an increase as previously reported.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/2356 |
| Date | 29 August 2005 |
| Creators | Bain, Sherrie Valarie |
| Contributors | Siegele, Deborah A. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Electronic Thesis, text |
| Format | 364241 bytes, electronic, application/pdf, born digital |
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