Much of the work in my laboratory focuses on the importance of individual variation and how this variation varies due to the environment and across different populations. That is, I am interested in whether the variation among individuals is affected by ecological or environmental setting and if it differs among populations. One of our speculations is that there are many patterns of gene expression that effect a similar physiology. That is, the variation in expression may alter the enzyme and biochemical pathways that effect a change in physiology, but the endpoint (e.g., higher metabolic rates, resistance to environmental assault) are the same. We are speculating that there are many ways “to skin a cat” and thus there is much standing genetic variation for gene expression within populations. There are many routes to address this speculation, and some of these are described below.
Two Ph.D student have recently finished their studies. One (Dr. Cinda Scott) examined the sources of technical, biological variation genetic variation in mRNA expression. Dr. Scott demonstrated that there is little technical variation or biological variation within an individuals (that is, when the same individual is sampled over 6 week period there is little added variation). Surprisingly, a variable environment does not increase variation in mRNA expression. However, the variation in mRNA expression is a function of genetic relatedness. These data and her soon to be published study on the heritability of mRNA expression, support the concept that the variation in mRNA expression is primarily due to genetic and not environmental variation.
The second student (Dr. Meredith Everett), examine the effect of hypoxia on gene expression. Dr. Everett compared the effect of hypoxia on whole animal metabolism defining a similar critical oxygen tension and that populations had significantly different metabolic rates at the lowest oxygen tension. Comparing the time and dose response, Dr. Everett, working with C. Antal (former undergraduate) discovered that liver response to hypoxia occurred in the first few hours, but cardiac tissue maximum response occurred at 96 hours. Surprisingly, in both tissue genes involved in aerobic respiration had an significant increase in expression. A comparison among six populations across the Gulf of Mexico suggest that populations with frequent exposure to hypoxia had more significant response.
Currently, Kat Loftus is examining the variation in Complex I (NADH dehydrogenase) the first enzyme in the oxidative-phosphorylation pathway. This enzyme is made up of 45 different protein subunits encode by nuclear (38 subunits) and mitochondrial genomes (7 subunits). Ms. Loftus research focuses on quantifying the variation in expression of these subunits and relating this to the variation in enzyme function and how these parameters vary among populations.
Future projects:
Mitochondrial Genomics: how does the expression of mRNA and protein affect metabolism and the variation within and among populations?
Individual variation: how does the variation is gene expression affect metabolism and how does environmental variation affect the variation in gene expression and metabolism?
The regulation of gene expression: how does the coordinate expression of genes vary environmentally and phylogentically? Are there shared transcriptional binding factors that co-regulate coordinate gene expression?
What is the evolutionary relationship between the variation in gene expression and variation in protein coding regions? Does adaptation affect both molecular mechanisms equally?
Cheers
dlc