SGER: Parent-of-Origin Gene Expression in a Viviparous Arthropod?

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

Known definitively from only mammals and angiosperms, autosomal genomic imprinting is a form of non-Mendelian inheritance in which methylation and expression of an allele depend on whether it is inherited through sperm or egg. Imprinting disruption has been implicated in a growing list of embryonic abnormalities, unstable DNA diseases and cancers. Numerous hypotheses, ranging from chromosomal surveillance to maternal/paternal genome conflict over resource transfer from mother to embryo, have been proposed to explain imprinting, and virtually all invoke viviparity as crucial to its evolution. Unfortunately, evidence of imprinting in animals is currently restricted to mammals, thus limiting the scope for rigorous testing of alternative hypotheses. The aim of the proposed exploratory research is to establish whether genomic imprinting occurs in the pseudoscorpion, Cordylochernes scorpioides, as indirect evidence suggests. Allelic message display approach, a technique that utilizes RT-PCR to screen cDNA libraries for genomically imprinted genes will be used. To distinguish between maternal versus paternal allelic expression, polymorphic transcripts will be visualized in reciprocal hybrid and pooled backcross progenies from crosses between two C. scorpioides populations known to exhibit extensive DNA sequence divergence. Investigation will focus on the transcriptional activity of the embryonic pumping organ (a specialized mouth precursor responsible for sequestering nutritive fluid from the mother's reproductive tract) as the organ most likely to exhibit parent-of-origin gene effects. If imprinting is found to occur in C. scorpioides, this pseudoscorpion will provide a model viviparous arthropod system for investigating the importance of genomic imprinting in biological processes ranging from evolution to epigenetic-mediated disease.