Differential gene expression in day 12 and day 15 equine conceptuses.

This research examines the different levels of gene expression in horse embryos on day 12 and day 15 of gestation, focusing on the significant changes necessary for successful pregnancy. The study identifies several genes with increased expression on day 15, confirming increased expression levels of specific proteins linked to pregnancy.

Methodology

• The researchers made use of a technique known as suppression subtractive hybridization. This method allows for comparing two DNA samples and identifying genes that are expressed more in one sample than another. In this case, the method was employed to discover the genes that are more highly expressed on the 15th day of gestation as compared to the 12th day in horse embryos.
• Alongside this, they also examined two specific genes – glyceraldehyde-3-phosphate dehydrogenase and alpha-fetoprotein (AFP) – in the subtracted (those more expressed on day 15) and unsubtracted samples to evaluate the efficacy of the subtraction process.

Findings

• The researchers were able to isolate a total of 50 clones, which they partially sequenced, and then compared these sequences with known sequences to discern their identities.
• Among the genes identified were pregnancy-associated glycoprotein (PAG), fumarylacetoacetase, cytokeratins 8 and 18, and isocitrate and succinate dehydrogenases. These were identified as having higher expression on day 15 of gestation.
• Further analysis conducted on PAG and AFP verified the differential gene expression between days 12 and 15. The results showed that the expression of PAG increased approximately 30 times and that of AFP increased by at least 1000 times between these two days.

Significance

• The results are significant as they offer valuable insights into the mechanisms of gene expression that have to occur for a successful pregnancy in horses.
• The emphasis on the genes PAG and AFP, in particular, highlights their role in crucial stages of fetal development like the maternal recognition of pregnancy and the onset of gastrulation, the process that forms the three layers of the embryo.