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Circular forms of Uukuniemi virion RNA: an electron microscopic study

Hewlett, Martinez J. and Pettersson, Ralf F. and Baltimore, David (1977) Circular forms of Uukuniemi virion RNA: an electron microscopic study. Journal of Virology, 21 (3). pp. 1085-1093. ISSN 0022-538X.

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Because the ribonucleoprotein forms of the segments of the Uukuniemi virus genome have previously been characterized as circular, we examined the isolated RNAs by electron microscopy under conditions of increasing denaturation. After spreading under moderately denaturing conditions (50 or 60% formamide), 50 to 70% of the molecules were circular. Increasing the formamide concentration to 70 and 85% decreased the number of circular forms, and only linear forms were observed after incubation of the RNA at 60 degrees C for 15 min in 99% formamide. When spread from 4 M urea-80% formamide--another condition known to denature RNA--only 5 to 30% circular molecules were observed. Pretreatment of the RNA with 0.5 M glyoxal at 37 degrees C for 15 min prior to spreading from 50% formamide gave less than 5% cirucular forms. Length measurement of the molecules showed that they were not significantly degraded by any of the methods employed. The circular molecules were destroyed by treatment with pancreatic RNase, but were unaffected by DNase or proteinase K treatment. After complete denaturation of the RNA, the circles could be reformed under reannealing conditions. We conclude that the three size classes of RNA that comprise the Uukuniemi virus genome are circular molecules probably maintained in that form by base pairing between inverted complementary sequences at the 3' and 5' ends of linear molecules.

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Baltimore, David0000-0001-8723-8190
Additional Information:Copyright © 1977 by the American Society for Microbiology. Received for publication 28 September 1976 We thank Claire Moore for excellent technical assistance in the electron microscopy work. This work was supported by Public Health Service grant AI-08388 from the National Institute of Allergy and Infectious Diseases and Public Health Service grants CA-14051 and CA-12174 from the National Cancer Institute. M. H. was a postdoctoral fellow of the American Cancer Society. R. P. was a recipient of Public Health Service international fellowship F05 TW-2245 from the Fogarty International Center. D. B. is an American Cancer Society research professor.
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ID Code:2265
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Deposited On:20 Mar 2006
Last Modified:02 Oct 2019 22:51

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