Word: humanities
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Dates: during 1980-1989
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Scientists remained uncertain about the exact number of human chromosomes until 1956, when improved photomicrographs of dividing cells clearly established that there were 46. This revelation led directly to identification of the cause of Down syndrome (a single extra copy of chromosome 21) and other ( disorders that result from distinctly visible errors in the number or shape of certain chromosomes...
...greater challenges lay ahead. How could a particular gene be assigned to any of the nonsex chromosomes? Scientists cleverly tackled that problem by fusing human cells with mouse cells, then growing hybrid mouse-human cells in the laboratory. As the hybrid cells divided again and again, they gradually shed their human chromosomes until only one -- or simply a fragment of one -- was left in the nucleus of each cell...
...identifying the kind of human protein each of these hybrid cells produced, the researchers could deduce that the gene responsible for that protein resided in the surviving chromosome. Using this method, they assigned hundreds of genes to specific chromosomes...
Even before the Human Genome Project was begun by the NIH, others were deeply involved in probing the genome. Building on a long-standing program of research on DNA damage caused by radiation, biologist Charles DeLisi in 1987 persuaded the Energy Department to launch its own genome program. In addition to the sequencer and computer-hardware engineering projects, Energy Department scientists are focusing their attention on mapping seven complete chromosomes...
...genes identified to date. Says McKusick: "That's an impressive figure, but we still have a long way to go." Several other libraries of genetic information are already functioning, among them GenBank at the Los Alamos National Laboratory and the Howard Hughes Medical Institute's Human Gene Mapping Library in New Haven, Conn...