Organismal growth is one of the most fundamental biological processes, yet growth control varies tremendously between species. Growth in mammals appears to be controlled by a number of interacting genes subject to Genomic Imprinting. Genomic Imprinting is defined as genes that show unequal allelic transcription based on parental origin. The placenta is a key site of expression of these genes, and of growth control. The investigators have identified a system in which interactions among imprinted genes and perturbations of imprinting dramatically affect whole animal growth control. The proposed system utilizes reciprocal hybrids between two sister deer mouse species, Peromyscus maniculatans (BW) and Peromyscus polionotus (PO). Crosses between these two species yield undergrowth in one direction (BW female x PO male), and lethal overgrowth in the reciprocal cross (PO female x BW male). Placental tissues are particularly affected. It has been shown that these growth phenotypes are specifically correlated with loss of imprinting (LOI), and an apparent genetic interaction between one autosomal imprinted region, and one X-linked region (X linked loci are imprinted in the placenta). The proposed experiments will address the scale of the LOI, epigenetic changes associated with the LOI, and the scope of gene expression changes in the placenta.
The results of the proposed experiments will have important ramifications for understanding the genetics and evolution of growth control, and the role the placenta plays in these processes. In addition, these studies will bring together undergraduates, graduate students and postdoctoral researchers interested in speciation, genetics, development, chromatin biochemistry, sexual selection and molecular evolution. Therefore, this project will forge greater communication between people interested in these diverse areas of biology. There is also the possiblity that the researchers at UC-Irvine will initiate a graduate concentration in Evolutionary genetics, development and biochemistry.
