Grant: Operating Grant

Generation of a haploid female germ cell, the egg, is essential for animal and human reproduction. Aberrations in this process cause infertility, miscarriages, congenital birth defects (e.g. Down syndrome), as well as cancers (ovarian teratoma). This process, called meiosis, consists of two rounds of asymmetric cell division (meiosis I and meiosis II), yielding two diminutive and non-viable polar bodies and a large haploid egg. My lab has been at the forefront of studying animal egg meiosis, using the Xenopus frog model, discovering fundamental mechanisms that are important for egg meiosis in all vertebrates including mice and humans. For example, based on our earlier work on the metabolic enzyme ornithine decarboxylase (ODC) in frog oocytes (Zhou et al. 2009. Mol. Cell Biol. 29:1786-95), we have recently discovered that deficiency of the same enzyme, and its product putrescine, is a causal factor of aging-related infertility in mammals (Tao and Liu. 2013. Aging Cell 12:42-49; Liu and Tao. 2012. Aging 4:1-3). These studies may lead to a fertility treatment for older women (see a feature story in Science Update: http://www.scienceupdate.com/2012/12/egg/). We propose to continue our studies in the frog system to elucidate fundamental mechanisms important for animal egg meiosis. Unraveling these mechanisms will help understand animal and reproduction and reproductive abnormalities.