Animal Science Faculty

  Xingen G. Lei   -   Professor

 

 

Email: xl20@cornell.edu

Current Research

The Lei Laboratory is located in Morrison Hall.

Selenium is considered an essential antioxidant micronutrient for animals and humans, with great potential in cancer and chronic disease prevention. Cellular glutathione peroxidase (GPX1) is the first identified and the most abundant selenium-dependent enzyme in mammals. Using GPX1 overexpressing and knockout mice, we have demonstrated that GPX1 protects mice against oxidative injuries mediated by reactive oxygen species (ROS)-generators such as paraquat or diquat. Strikingly, we have found that knockout of GPX1 renders mice or cells resistant to oxidative death and related signaling mediated by reactive nitrogen species (RNS) such as peroxynitrite. Thus, our current interest is to elucidate the biochemical mechanisms and signal pathways of the opposite role of GPX1 in coping with ROS and RNS under physiological conditions. We are using a variety of cutting-edge experimental approaches including single or double-gene knockout mouse lines, DNA chip, pathway-specific microarray, in situ immunostaining, and protein-protein interactions to tackle the problem. Because ROS and RNS are constantly produced in aerobic metabolism and are involved in many diseases, our research findings will have broad impact on nutrition and health.

Environmental pollution of excess phosphorus (P) in animal waste, especially from swine and poultry, is a serious problem that animal agriculture faces today. This mainly originates from the inefficiency of these simple-stomached animals to utilize phytate-P. Supplemental microbial phytases effectively improve phytate-P utilization by these animals, obviating the need for addition of inorganic phosphorus, a non-renewable nutrient, and reducing manure P excretion by 50%. However, the currently-available commercial phytases do not meet the practical needs due to their expense and stability constraints. To overcome these limitations, we are trying to develop catalytically effective, protease-resistant, and thermostable phytases by site-directed mutagenesis and DNA shuffling. We are also comparing the expression efficiency of different hosts, promoters, and signal peptides in producing phytases. Meanwhile, we are testing the effectiveness of our developed phytases in releasing phytate-P, calcium, iron and zinc from soy, corn, and wheat in vitro and in pigs. As phytate-induced zinc and iron deficiencies in humans are widespread problems throughout the world, our findings will contribute to improving not only animal nutrition and environmental protection, but also human health.