M.S. - Physiology

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    Water sparing in chronic ethanol exposure is associated with elevated renal estrogen receptor beta and vasopressin V2 receptor mRNA in the female rat
    ( 2007) Huckstep, Odaro J.
    Fluid handling is known to differ between males and females. Interactions between sex steroids such as estrogen with fluid regulating hormones like vasopressin (VP) are likely key to establishing these differences. Research has identified estrogen receptor (ER) α and β in renal tissue which may affect renal fluid handling. Thus, this study hypothesized that chronic ethanol exposure would elicit different alterations to water load excretion between male and female Sprague Dawley (SD) rats due to changes in renal VP V2 receptor (V2R) or ER mRNA expression. Therefore, in this study we compared 120 minute excretion of a 2% Body Weight (BW) water load between male control (n=6) and ethanol-fed (n=14) rats, and female control (n=26) and ethanol-fed (n=26) rats. Additionally renal papilla mRNA expression of V2R, ERα, and ERβ was compared between male control (n=5) and ethanol-fed (n=15) rats, and female control (n=12) and ethanol-fed (n=17) rats. Female ethanol fed rats showed a 16% reduction in water load excretion (p<0.05) compared to controls. RT-PCR analysis revealed that the decreased water excretion in ethanol-fed females was accompanied by a 40% increase in V2R mRNA (p<0.05) and a 146% increase in ERβ mRNA (p<0.05) in renal papilla tissue compared to controls. In contrast, ethanol treatment in male rats resulted in no difference in water excretion, and yielded no change to V2R or ERβ mRNA expression in the renal papilla. ERα expression was not different between males and females, nor affected by ethanol treatment. Overall, these results suggest that females can better compensate for the dehydrating effects of ethanol exposure by increasing renal responsiveness to VP via upregulating renal V2R. Also, ethanol specifically upregulates the ERβ subtype in the female kidney which may modulate renaI sensitivity to VP.
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    Linkage analysis of the tuft mutation
    ( 2008) Drumhiller, Wallace C.
    A spontaneous mouse mutant, tuft, exhibits a large intracranial lipoma, the development of which is consistent with a neural tube defect. The purpose of this study was to identify the tuft locus, appraise possible candidate genes, and evaluate two different methods of DNA electrophoresis, one of which was used in previous work. Linkage analysis mapped the tuft mutation to two candidate regions on chromosome 10 within 16Mb distal and proximal to D10MIT115, at 60Mb and 80Mb respectively. Primers designed by the author for microsatellites in these regions were non informative. A literature survey showed the tuft mutation shares a similar phenotype with only one known mutation on chromosome 10 affecting the Apafl gene. A primer designed by the author, WD5, for a micro satellite 2kb from the Apafl gene showed a recombination percentage of 35%. A microsatellite marker within 1cM of the gene containing the tuft mutation would be expected to show a near zero recombination percentage. PCR products for two primers designed by the author for microsatellites on chromosome 10 were analyzed using the 4% metaphor gel method, which was previously used, and a Beckman/Coulter CEQ 8000 capillary based method. All samples which showed a result in both methods showed the same result, with a single exception which is likely due to the greater sensitivity of the CEQ. These data suggest that tuft maps to chromosome 10 within 16Mb of the microsatellite marker D10MIT115, that the tuft mutation is not likely located within the Apafl gene, and that the genotypic methods used are reliable.