Most newborn animals are highly vulnerable to assault from pathogens and infectious diseases. In response to these threats mechanisms have evolved to provide the newborn with maternal factors for protection. This is particularly true for marsupial mammals, such as opossums and kangaroos, whose young are born less mature than that of humans or other placental mammals. In contrast to placental mammals that are born with a fairly developed immune system, marsupials do not develop their immune system until after they are born. The goal of this project is to investigate whether novel mechanisms in the marsupial immune system have evolved to protect the newborn. The project focuses on a population of cells called B lymphocytes, or B cells, which are the cells that make antibodies, and utilizes a model marsupial species, the gray short-tailed opossum, which recently had its complete genome sequenced, the first for a marsupial. In contrast to humans where antibodies from the mother cross the placenta, opossum newborns are born lacking maternal antibodies and do not develop mature B cells until they are nine days old. The goals of the project are to use cellular and molecular techniques to investigate the diversity of antibodies provided by the mother via the milk and the timing, location and diversity of antibody producing B cell development in the newborn. This project will provide a better understanding of strategies used in early immune protection in mammals. This project will also increase the available knowledge of the immune system of a marsupial species that can be used to model fetal and early newborn development and is also used as a model of cancer and infectious disease. This project will involve both graduate and undergraduate students and provide the opportunity for a postdoctoral fellow to gain experience mentoring undergraduate students. In addition to direct research experience, students at all levels, including undergraduate, will participate in publications, presentations at national and international meetings, and the collaborations with domestic and international colleagues, the latter primarily in Australia. The work outlined in this project will be integrated with ongoing comparative genomic analyses with marsupials and, in that way, will contribute to the larger comparative genomic efforts and has significance for the NSF Tree of Life Initiative.
