Biomedical subjects
Publications and source records attributed to K C McElfresh.
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This report examines the effect of anaerobic stress on the expression of sucrose synthase in maize (Zea mays L.). Following 24 hours of anaerobic treatment, alcohol dehydrogenase displayed the classical characteristics of induction: increased mRNA and protein levels. However, there was no detectable increase in sucrose synthase specific proteins by either native or denaturing Western blot analysis nor was there an increase in sucrose synthase activity. Anaerobic treatment did induce significantly higher steady state levels of sucrose synthase mRNA. Even though previous work has implicated sucrose synthase as an anaerobically induced protein, the data in this report suggest that sucrose synthase is not inducible at the protein level by anaerobic treatment.
The gene products of the two major alleles of alcohol dehydrogenase (ADH-F and ADH-S) have been subjected to kinetic and biochemical analyses over a range of temperatures. Although temperature was found to have a significant effect on both kinetic and biochemical properties of Drosophila ADH, no significant differential effect was observed between the major ADH allozymes. The results are discussed within the context of the selective maintenance of Adh polymorphism in natural populations.
Previous studies carried out in mammalian systems indicated that an organism's NAD+/NADH balance is carefully regulated but can be destabilized by dietary stresses. Since Drosophila alcohol dehydrogenase (ADH) uses NAD+ to remove a hydrogen from ethanol in the first step of alcohol catabolism, it is possible that under alcohol stress conditions the in vivo NAD+ levels in Drosophila may decrease. In this study genetically homozygous flies were stressed with maximally sublethal concentrations of ethanol (10%) for periods of up to 24 hr. The results indicate that NAD+ levels do in fact drop by at least 20% in response to ethanol stress. Evidence is presented that suggests that this decrease is the direct result of ADH-mediated catabolism.