Word: mammalian
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Dates: during 2000-2009
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...bone marrow, and now two groups of scientists from Boston report that they have identified a similar mother stem cell from which most heart cells arise. Working with mice, one group at Massachusetts General Hospital isolated a cardiac stem cell that generates the three major cell types of the mammalian heart, while another group at the hospital found a stem cell that gives rise to the contracting and smooth muscle cells found in heart vessel walls...
...still surprised that cloning works," says Ian Wilmut, the embryologist who led the team that created Dolly. Ten years and 15 mammalian species later, the efficiency of the process is no better than it was at Dolly's birth: only 2% to 5% of the eggs that start out as clones end up as live animals. For each clone born, hundreds of others never make it past their first days and weeks, the victims of defects in development too severe to allow them to survive...
...hard to appreciate why. Mammalian cloning is an intricate process involving at least three animals, hundreds of eggs, hundreds of more mature cells and not a single sperm. The key challenge is to undo the development of an adult cell--which, like all cells, contains in its DNA the genetic blueprint of the entire organism--that has been programmed or "differentiated" to be one kind of cell (skin or bone or nerve) and no other kind. Somehow, scientists must trick this mature, fully developed cell into resetting its genetic clock so that it can begin life anew as an embryo...
...mammalian body is surprisingly forgiving and can often compensate for minor programming errors. That's why some genetic changes in clones may not have any measurable functional effects on the animals...
...eyes set low on a round face; low, small ears; and other signifiers of infancy. The drive to nurture what only remotely resembles a human baby is so strong that,according to The New York Times, researchers have recorded positive responses to "the young of virtually every mammalian species, fuzzy-headed birds like Japanese cranes, woolly bear caterpillars, a bobbing balloon, a big round rock stacked on a smaller rock, a colon, a hyphen and a close parenthesis typed in succession." : - ) There. Doesn't it just make you want to go "awwwwww...