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WRONG NUMBER FILE NAME: DINODNA1.ZIP [From _The New York Times_, July 1, 1993] CELLS OF DINOSAUR APPARENTLY FOUND Scientists Believe Blood Cells in Tyrannosaurus Rex May Lead to Traces of DNA By MALCOLM W. BROWNE A Montana paleontologist and his colleagues believe they have found red blood cells in the fossilized leg bone of a Tyrannosaurus Rex and say they have high hopes of extracting DNA from the dinosaur's cells. The discovery of the putative dinosaur blood cells has not yet been submitted to a scientific journal or independently confirmed but was reported two weeks ago by the National Science Foundation, which has financed the exploratory project. Jack Horner, a paleontologist at Montana State University who directed the investigation, said in an interview yesterday that his group hoped to find matches between gene fragments left in the preserved blood cells with comparable DNA segments from modern crocodiles or birds. "If we're lucky enough to find matches," he said, "they could go a long way toward showing what the relationship between dinosaurs and birds might be. We're not there yet, but we think we're getting close." The femur, or leg bone, that Mr. Horner's group is studying is part of an unusually well-preserved tyrannosaur fossil, more than 65 million years old, which they found and excavated from the Hell Creek Formation in eastern Montana three years ago. The apparent blood cells were discovered by Mary Schweitzer, Mr. Horner's graduate student who was investigating the cell structure of fossilized bone and marrow tissue New Climate of Belief In the past, few paleontologists or molecular biologists believed that biological material could survive for millions of years without becoming mineralized, thus losing its organic molecular structure. The survival of any intact DNA, which ordinarily decays with time, seemed even less likely. But the recent discovery of organic material and even fragments of DNA in ancient plant and animal fossils has changed opinions. "Two years ago I would have called this baloney," said Dr. Raul J. Cano of California Polytechnic State University at San Luis Obispo, a molecular biologist who has himself extracted DNA fragments from fossilized insects and plants millions of years old. Told of Mr. Horner's belief that blood cells have survived in a tyrannosaur bone - and that they may contain dinosaur DNA fragments - Dr. Cano said: "It's certainly plausible. We have seen similar things ourselves, and there are reports from other investigators of the finding of surviving biological material inside fossil dinosaur bones, especially in the deep bone cortex, which seems to be somewhat protected from mineralization." Earlier this month, Dr. Cano and his associates reported in the British journal Nature that they had extracted DNA from a weevil that had been entombed in amber for 120 million to 135 million years. Doubter Grants Possibility A molecular biologist who has strongly questioned the premise that appreciable quantities of DNA could survive for very long periods is Dr. Russell Higuchi of Roche Molecular Systems in Alameda, Calif. But Dr. Higuchi said yesterday that it seemed possible that Mr. Horner's group,had actually seen dinosaur blood cells. Although Dr. Higuchi said he remained doubtful about the survival of dinosaur DNA, particularly in a fossil that was probably exposed to water, "we ourselves speculated 10 years ago that if dinosaur DNA survived at all, it might be found" deep inside a fossil bone. Mr. Horner said that microscopic examination of a thin slice through the dinosaur bone revealed that although its outer layers were mineralized the bone itself, brown in color, remained more or less intact in the interior of the marrow cavity. "Mary found spherical structures that appear to be nucleated red cells inside the blood vessels running through the bone, right where you'd expect to find blood, if it's there," he said. "Since then we've been trying everything we can think of to show that they're not blood cells, but they still seem to be the real thing." Fears of Contamination Part of the science foundation's grant to Mr. Horner's group went for laboratory equipment to conduct a polymerase chain reaction, a technique that can single out a lone molecular fragment of DNA and make enough copies so it can be analyzed using standard methods. "The biggest problem is contamination of the fossil by foreign DNA, "Mr, Horner said. "There's lots of it there, The real trick is in identifying some thing that is not a contaminant. This is why we are looking for matches with crocodile DNA, which is not a likely contaminant." Mr. Horner says he is certain that at least some original tissue remains in the fossil because his group has positively identified collagen in the bone. Collagen is a fibrous protein found in the connective tissue of animals, which ordinarily decays rapidly except under special circumstances. Cheryl Dybas, a spokeswoman for the National Science Foundation, acknowledged that her agency had intentionally released its report of Mr. Horner's progress to coincide with the opening of "Jurassic Park," a science fiction movie based on the premise that dinosaurs might one day be cloned from their surviving DNA. "We thought it would be a good opportunity to get the word out on 4 of the 10 dinosaur research projects the N.S.F. is funding this year, including that of Mr. Horner," Ms. Dybas said. WRONG NUMBER FILE NAME: DINODNA1.TXT


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