Degree Type

Dissertation

Date of Award

1992

Degree Name

Doctor of Philosophy

Department

Biochemistry, Biophysics and Molecular Biology

First Advisor

Donald C. Beitz

Second Advisor

Jerry W. Young

Abstract

Changes in expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene, which codes for a key regulatory enzyme of gluconeogenesis, were studied in bovine liver tissue. Induction of ketosis was attempted in cows by a protocol of restricting feed intake (FR) and supplementing with 1,3-butanediol (BD), a ketogenic precursor, beginning at 15 d postpartum (FRBD protocol). Twenty Holstein cows were distributed in equal numbers among four treatments: normal control, obese control, normal cows given FRBD, and obese cows given FRBD. Liver biopsies were obtained at nine different times during early lactation: 10 d prepartum, 5 and 14 d postpartum (just before FRBD begins), 21, 28, and 36 d postpartum (about the time when ketosis should begin), and 49 and 63 d postpartum. Not all FRBD cows developed clinical ketosis; some only had subclinical ketosis;Relative concentrations of mRNA for phosphoenolpyruvate carboxykinase (PEPCK) in the lactating cows increased up to about d 35 postpartum, then a dramatic decrease occurred around d 42 postpartum, the time when clinical signs of ketosis became evident. The control groups did not exhibit as dramatic a decrease (P 0.05) with PEPCK mRNA (-0.20) and with concentrations of protein (-0.18), suggesting that both PEPCK mRNA and PEPCK protein decreased as the triacylglycerol to glycogen ratio increased;To amplify the cytosolic PEPCK gene in bovine liver, primers were synthesized from selected homologous sequences of the rat PEPCK gene for amplification by the polymerase chain reaction (PCR). A 200-base pair (bp) fragment was amplified from bovine genomic DNA, whereas a 960-bp fragment was amplified from bovine cDNA. The amplified bovine PEPCK cDNA was found to be 80% homologous to the rat PEPCK cDNA.

DOI

https://doi.org/10.31274/rtd-180813-11709

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Sowmya Moorthi

Language

en

Proquest ID

AAI9223949

File Format

application/pdf

File Size

213 pages

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