Advances in genomics technology have made sequence analysis of diverse organisms routine. Scientists armed with whole genome sequence data can now ask questions about genome structure and organization that impact gene expression.
Improved access to bioinformatics tools enables scientists to process, manage, and store raw data, annotate sequences to define genes, and quantitate RNA sequence data to get insight into gene expression patterns.
The progress being made by a number of companies and academic researchers enabling resolution of questions from genomic analysis was shared at the recent “Plant and Animal Conference” in San Diego.
Amy Radunz, a nutritionist from the department of animal sciences at the University of Wisconsin in River Falls, has partnered with molecular biologist Hasan Khatib, an associate professor at University of Wisconsin-Madison, to ask how differences in maternal diet during pregnancy induce gene expression and DNA methylation changes in fetal tissues in sheep.
The experiment called for the use of 15 ewes that were fed three different diets during gestation at the same energy intake. The control group was given haylage; this high fiber diet is the most common food source for sheep. The second group was given corn, which provides a high starch diet, and a third group was given distillers product, a byproduct of the ethanol industry, which provides a high protein, high fiber, and high fat diet. Each ewe was kept in a separate pen under standard temperature and exposure to light to control conditions including food intake and the influence of exercise on the transfer of nutrients to the growing fetus.
On day 130 of pregnancy, nonsurvival surgery was performed on the ewes to enable the measure of uterine blood flow to monitor nutrient supply to the fetus and to collect tissue samples from four fetal tissues. Unlike previous studies in cattle and sheep, the different treatments did not confer a noticeable difference in fetal weight.
The working hypothesis going into the experiment was that the primary impact on the fetal growth in previous studies was the result of the amount of glucose in the maternal diet. The high starch diet (corn) provides the greatest amount of glucose, whereas the distillers product provides both high protein and high fat, both of which stimulated greater maternal insulin production in the circulation but did not result in differences in maternal glucose circulation. The conclusion from this study where maternal nutrient supply was measured is that glucose supply to the fetus was not impacted by maternal glucose intake.
The current view is that the relative amount of different amino acids (arginine, methionine, and cysteine) may play a more significant role given that these amino acids contain methyl donor groups that can impact the activity of maternally and paternally imprinted genes.
The impact of maternally expressed genes was looked at for H19, IGF2R, GRB10, and MEG8. The study also looked at the impact of paternally expressed genes: IGF2, PEG1, PEG3, DLK1, and DIO3 for transcriptomic and epigenomic alterations of the imprinted genes in fetal tissues.