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          Front Page




UNM Researchers Contribute to Study Mapping the Genomes of Tiny Creatures

By John Fleck
Journal Staff Writer
    The little critter in Rob Miller's hands— Monodelphis domestica, the short-tailed opossum— has joined science's genomic revolution.
    "Opossum Genome Project" might not sound like it has the gravitas of its human counterpart. But to understand our own DNA, we need to compare it to the creatures around us, according to Miller, a University of New Mexico biology professor.
    In today's edition of the journal Nature, the short-tailed opossum becomes the latest addition to the menagerie of creatures that have had their genomes decoded.
    Miller and UNM colleagues Michelle Baker and Zuly Parra were part of an international team that did the work.
    Their goal, Miller said in an interview, is to untangle the complexities of mammals' immune systems, using differences between the opossum's and our own as a guide.
    A genome is an organism's genetic blueprint, written in DNA instructions.
    The work began four years ago when Miller and a group of colleagues persuaded the federal government to fund a study of the opossum's genome. As a marsupial, it is one of our most distant mammal relatives— close enough to have much in common with us, but distant enough for the differences to shed light on what makes us the way we are.
    With today's Nature publication, the short-tailed opossum joins humans, the dog, the chicken and the chimpanzee on a growing list of creatures whose genetic blueprint has been decoded.
    Native to the forests of Brazil, the short-tailed opossum gives birth early. In humans and other placental mammals, babies do more of their development in the womb. Marsupials give birth earlier, with the young clinging to their mother, often living in a pouch, a lifestyle made famous by the kangaroo.
    Short-tailed opossums have a simpler system— with no pouch, the babies latch onto the mother's teats for four weeks after birth. But, importantly, much of the development that in humans and other placental mammals happens in the womb takes place after birth in marsupials.
    One of the opossums from Miller's colony of 30 showed off a litter of 10, clinging to their mother and looking more like embryos than babies.
    That difference is important to Miller's work.
    Human babies are born with their immune systems largely developed, while opossums' immune systems develop largely after birth. Miller and his colleagues in the UNM-based Center for Evolutionary and Theoretical Immunology are trying to understand why.