...And to muscle.. . . and to muscle A gene for a protein found in muscle of older embryos is activated in Xenopus development slightly later than the genes for keratin keratin (kĕr`ətĭn), any one of a class of fibrous protein molecules that serve as structural units for various living tissues. The keratins are the major protein components of hair, wool, nails, horn, hoofs, and the quills of feathers. . John B. Gurdon of Cambridge (England) University reports this gene is turned on only in the cells that eventually become muscle. The specification of this gene activity, like that of genes studied by Douglas Melton Douglas Melton is co-director of the Harvard Stem Cell Institute. His research into stem cell therapies is motivated in part by his children's affliction with Type 1 diabetes. He is known for pioneering work in developmental biology of the pancreas. (see above), appears to be spatially determined in the original egg. Gurdon and his colleagues have cut the fertilized fer·til·ize v. fer·til·ized, fer·til·iz·ing, fer·til·iz·es v.tr. 1. To cause the fertilization of (an ovum, for example). 2. egg into various zones. They find that the part of the egg necessary for musclegene activation lies just below the egg's equator. Studies of the embryo embryo (ĕm`brēō), name for the developing young of an animal or plant. In its widest definition, the embryo is the young from the moment of fertilization until it has become structurally complete and able to survive as a separate organism. at the 32-cell stage demonstrate that cells in an equatorial equatorial /equa·to·ri·al/ (e?kwah-tor´e-al) 1. pertaining to an equator. 2. occurring at the same distance from each extremity of an axis. band, which make up two out of four tiers of cells, normally can develop into muscle. But Gurdon reports that if the embryo is cut on the equator between the two muscle-making tiers (called tiers 2 and 3), only the lower of the two tiers can form muscle. The higher tier now forms skin and nerve. He concludes from additional experiments that a muscle-inducing substance is located in tier 3, and it diffuses into tier 2 when the cells are in contact. |
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