Team:Michigan

Abstract

The Latitudinal Defense Hypothesis predicts that levels of defense are highest near the equator and decrease toward the poles. This hypothesis is based mainly on insect herbivory that occurs during the summer. Mammilian herbivory in the winter is a more likely driver of plant defense levels in northern latitudes. Early successional trees such as birches are favored by fire and provide an important food source for mammals like snowshoe hares. In order to test the Latitudinal Defense Hypothesis, we collected birch seeds from eight locations in northwestern Canada and grew seedlings in a common garden. We assessed levels of defense by counting resin glands because resin glands are negatively correlated with snowshoe hare preference. This research will provide valuable information regarding the biogeography of defense and address the role of fire in plant-mammal interactions on a continental scale.

Each day 14,000 people become infected with HIV/AIDS, making the development of an effective vaccine one of the world’s top public health priorities. David Watkins’ laboratory is attempting to develop HIV vaccines that elicit cellular immune responses utilizing the simian immunodeficiency virus (SIV) – infected rhesus macaque animal model. A major component of the cell-mediated immune response are cytotoxic T-lymphocytes (CTL). It is thought that CTL play an important role in controlling HIV and SIV. Most standard immunological assays do not measure antiviral activity directly, limiting our understanding of CTL effectiveness. To address this, the Watkins laboratory developed a novel neutralization assay that quantifies the ability of virus-specific CTL populations to control viral growth. Evaluating the antiviral activity of CTL of different specificities will identify those CTL most effective against SIV. This information will likely impact the design of future HIV vaccines.