Word: dna
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Dates: during 1990-1999
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Scientists have been talking about producing better foods through genetic engineering ever since the technology first became available, more than 20 years ago. By mixing and matching bits of DNA -- cutting a gene from one kind of organism and pasting it into another -- they hoped to make new, improved plants and animals. Over the years they've put corn genes in rice, trout genes in catfish, chicken genes in potatoes, even firefly genes in tobacco (yielding a plant that actually glowed in the dark). A few years ago, Department of Agriculture researchers tried to produce leaner pork by splicing...
Kinks in proteins that form the nuclear matrix -- a dynamic scaffold to which DNA is attached -- may be particularly diabolical. The reason cancer cells typically have a swollen and misshapen nucleus, believes Johns Hopkins molecular biologist Donald Coffey, is that the proteins that form the nuclear matrix are misaligned in some fashion. Inside the matrix, notes Coffey, 50,000 to 100,000 loops of DNA are coiled like a Slinky, but the length of the loops, and where they begin and end, varies from tissue to tissue. The genes closest to the matrix are those that a particular cell intends...
...tumor-suppressor gene p53 is often described as "the guardian of the genome" because it keeps watch over DNA during cell division. When damage occurs, p53 commands other genes to bring cell division to a halt. If repairs are made, then p53 allows the cell cycle to continue. But in some cases, if the damage is too serious to be patched, p53 activates other genes that cause the cell to self-destruct. Mutations in p53, which have been detected in more than 50% of all human cancers, are thus extremely dangerous. In laboratory cultures, some cancer cells that possess mutant...
Healthy cells apparently have a precise system for ensuring their mortality; short strips of DNA known as telomeres seem to provide a molecular clock. When a cell is young, it has more than a thousand telomeres strung along the ends of chromosomes like beads in a necklace. Each time a cell divides, 10 to 20 telomeres are lost, and the necklace grows shorter. Eventually, after many cell divisions, the necklace becomes so short that the cell fails an internal health check designed to keep old, possibly damaged cells from reproducing. Result: cell division stops, the cell begins to age rapidly...
Researchers looking for mutant strands of DNA in skin-cancer cells have discovered a gene that may be at the root of many -- if not most -- cancers, including such major types as lung, breast, brain, bone, bladder, kidney, ovary and lymphocyte. In healthy tissue, the gene acts as a brake on runaway cell division. Scientists hope that by replacing damaged genes with healthy ones, they may someday be able to prevent many types of cancer...