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Full text of this paper is not available in the ETD Center. Copies may be available for inter-library loan from University of Cincinnati or may be available for purchase from Proquest/UMI

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VISUALIZING GENOMIC INSTABILITY: IN SITU DETECTION AND QUANTIFICATION OF MUTATION IN MICE

Hersh, Megan N.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin991312483

Abstract Details

2001, PhD, University of Cincinnati, Medicine : Molecular Genetics, Biochemistry and Microbiology.
Multi-celled organisms are mosaic in nature because somatic mutations occur in individual cells of the body. Little is known about the frequency of mutation in most cell types of mammals. To make this phenomenon more amenable to study, transgenic mice carrying a histochemically detectable reporter gene were created, allowing for individual cells with a particular frameshift mutation to be detected. In order to enhance the chances of detecting spontaneous mutation events, the transgene was modified to contain a hypermutable region of 11 G:C basepairs. The mutation frequencies in mouse brain, heart, kidney and liver were quantified, yielding information about how often -1 frameshift mutations occur in the wildtype mouse genome. Although no particular tissue had consistently more mutation events than another from the same mouse, these frequencies tend to be, on average, 5- to 7-fold higher in brain and heart as compared to liver and kidney (i.e. ~20 events vs. ~2 events per million cells). This suggests that the tissues each have different methods for coping with mononucleotide runs. The DNA mismatch repair (MMR) system is responsible for recognizing and repairing DNA basepair mismatches that can result from recombination, chemical modification or DNA replication errors. The frameshift reporter transgene was crossed into mice lacking a functional Pms2 mismatch repair gene, the products of which are known to be involved in the repair of insertion/deletion events. Mutant frequency increased dramatically in this background, and was estimated to be at least 1000-fold greater than the respective wildtype tissues in brain, heart and kidney. However, frequency increased only 10-fold in liver. These data corroborate the evidence that Pms2 plays a significant role in the maintenance of genome stability at repetitive sequences, and suggest that Pms2 operates in a tissue-specific manner. To investigate this possibility, the effect of Mlh1-deficiency was also studied. Mlh1 is known to partner with Pms2 in mismatch repair, yet the respective knockout mice for each display slightly different phenotypes, with tissue-specific differences in tumor susceptibility. Interestingly, the Mlh1-deficient mice displayed a higher mutant frequency, but a similar tissue mutation spectrum to the Pms2-deficient mice.
James Stringer (Advisor)
DNA MUTATION; DNA REPAIR; MISMATCH REPAIR; MICE

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Citations

  • Hersh, M. N. (2001). VISUALIZING GENOMIC INSTABILITY: IN SITU DETECTION AND QUANTIFICATION OF MUTATION IN MICE [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin991312483

    APA Style (7th edition)

  • Hersh, Megan. VISUALIZING GENOMIC INSTABILITY: IN SITU DETECTION AND QUANTIFICATION OF MUTATION IN MICE. 2001. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin991312483.

    MLA Style (8th edition)

  • Hersh, Megan. "VISUALIZING GENOMIC INSTABILITY: IN SITU DETECTION AND QUANTIFICATION OF MUTATION IN MICE." Doctoral dissertation, University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin991312483

    Chicago Manual of Style (17th edition)

ucin991312483
© 2001, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.