WASHINGTON - For the first time, genes of a weak virus in serted in chickens by researchers are being passed from generation to generation, scientists at the U.S. Department of Agriculture report. TCiis brings closer the day when geneticists can custom-design chickens to resist disease, lay bigger eggs, or have other traits valued by producers, said Lyman B. Crittenden, a geneticist with the Agricultural Research Service’s AUTO TURN CARTS *500.00 B’. 9- •575.00 10’ *625.00 12’ *675.00 Little Britain Welding Shop 455 Nottingham Road, Nottingham, Pa. 19362 or Coll 717-284-4745 before 8 AM imperial PAINTED STEEL ROOFING & SIDING • High tensile galvanized steel panels • Five major nbsf 3 /*” height) • 36" coverage • Anti-siphon feature • Warranted Ceramic Siliconized Polyester Paint System • 12 colors in galvalume, plain or painted Imperial Rib is custom-cut to the inch to fill your needs in lengths up to 45 feet, reducing or eliminating end laps. 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So far, said Salter, the genes have been inherited by three generations of descendants from that first pairing. “With more research,” said Crittenden, “turning the avian leukosis virus against itsdf may be one of the first practical achievements of exploiting its need to use a cell’s own genes to reproduce.” Consumers and chicken producers will benefit, he said, when scientists find how to r\ COLORS \ \ AVAILABLE \ \ Red, Tan, \ Harvest Gold, l \ Sherwood NOTE [5.95 13.12 25.11 20.95 14’ 12’ 6.15 4.99 SALES use genes of the vims not only to make it self-destruct but also to transport other useful genes into chickens. Changing file genetic inheritance of animals is not new, but it’s always been done through breeding, by mating animals that have desirable traits. Today many scientists are trying new genetic techniques to make breeding more efficient Within five to 10 years, Crittenden said, the research should provide harmless vims genes into which other inheritable genes can be spliced for research uses. The two scientists used tbe avian leukosis vims because it’s a retrovirus, which invades a cell's own genes to “trick” the cell into prodiring more virus particles. “Once inside the cell, a retrovirus unlike other viruses releases an enzyme that con verts the virus’ RNA to DNA,” Crittenden said. “This DNA seeks out the cell’s genes and merges into them. The cell then produces a new virus particle.” The poultry industry is closely following the work of the two scientists and their collaborators, scientists at the Frederick (Md.) Cancer Research Facility and a Veterans Administration facility in Salt Lake CSty, Utah. 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Then we repeated that step Car a second generation of chicks and found that the viral genes had became a stable part of the duck’s genetic library.” To turn the virus against itself, Salter said, “we would have to inoert defective virus genes. These could not produce virus partides but could block similar disease causing viruses Cram entering a cdL” ra«rif#nK and other animals could someday have custom inserted genes to control growth and other functions. But this could occur only after much more is learned about which genes or gene groups regulate these functions, said Crittenden, who in 1985 was namad one of the research agency’s outstanding scientists for his work with poultry viruses. Retroviruses could provide a much more efficient way to in tegrate new genes in other farm animals, said Robert J. Wall, member of a research team doing this work at the agency’s Agricultural Research Center in RettsviDe,Md. lON
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