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M Yun

Publications and source records attributed to M Yun.

41 records · Page 3Linked to original sources
PubMed1987

cis-acting regulatory elements within gag genes of avian retroviruses.

A cis-acting enhancer element has been detected within the gag gene of several avian retroviruses, including Rous sarcoma virus, Fujinami sarcoma virus, and the endogenous Rous-associated virus-0. A consensus enhancer core sequence, GTGGTTTG, is present in all of these viral genomes, approximately 900 bases downstream from the site of initiation of transcription. When an internal fragment derived from the gag gene of any of these viruses (spanning nucleotides 533 to approximately 1149) was inserted into a plasmid containing the chloramphenicol acetyltransferase (cat) gene under control of the simian virus 40 promoter, 9- or 21-fold enhancement of CAT expression was observed after transfection into mouse L cells and chicken embryo fibroblasts, respectively. This enhancement was not dependent on the position of insertion of the gag fragment into the plasmid. However, there was a strong dependence on orientation, with higher levels of CAT expression in constructs in which the 5' end of the gag fragment was nearest to the promoter, suggesting a possible negative regulatory element at the 3' end of this fragment. Deletion of the 3' end of the insert resulted in a gag fragment, containing nucleotides 533 to 1017, which enhanced expression equally in either orientation. When the gag fragment was inserted into a plasmid containing the cat gene under the control of an intact Rous sarcoma virus long terminal repeat, it induced a two- to threefold increase in CAT activity and CAT mRNA levels. Translation of the gag fragment did not appear to be necessary for the observed enhancement, since two insertional mutations resulting in frameshifts in the gag insert did not affect CAT expression. However, deletion of a 330-base internal fragment from the gag insert restored a basal level of CAT activity. These results suggest that retroviruses have regulatory elements within their genes distinct from those in the long terminal repeats that flank the genes.

Animals↗
PubMed1986

Human penicilliosis marneffei and its relation to the bamboo rat (Rhizomys pruinosus).

Fourteen cases of penicilliosis marneffei occurred in persons in the Guangxi region of the People's Republic of China; the first known case of that disease had been found in Vietnamese bamboo rats (Rhizomys sinensis). A survey of the wild rats in this region was initiated to determine if any of these animals were infected by Penicillium marneffei. Although R. sinensis rats live in the study area, they are relatively rare. The only rats captured were another species of bamboo rat (R. pruinosus). Of the 19 rats captured, 18 yielded cultures of P. marneffei from one or more of their internal organs. The implications of this finding in respect to the epidemiology of penicilliosis marneffei are discussed.

Animals↗
PubMedDate not supplied

Effects of synthetic kassinin on splanchnic circulation and exocrine pancreas in dogs.

Effects of intravenously administered synthetic kassinin on splanchnic circulation and exocrine pancreatic secretion were examined in six anesthetized dogs. Kassinin caused dose-related increases in the blood flow in superior mesenteric artery and portal vein, and produced an initial increase followed by a decrease in pancreatic blood flow, but did not affect the exocrine pancreatic secretion. This study demonstrates that kassinin affects splanchnic blood flow in dogs, and suggests that kassinin or a kassinin-like substance functions as a neuropeptide controlling the splanchnic circulation in mammalian species.

Animals↗