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K G Murti

Publications and source records attributed to K G Murti.

85 records · Page 5Linked to original sources
PubMed1979

Chromosome 1 contains the endogenous RAV-0 retrovirus sequences in chicken cells.

We have developed a structurally unique probe which can be used to determine the chromosomal location of nonreiterated genes in vertebrate organisms by the method of in situ hybridization. The probe consists of several specific RNA molecules attached by means of poly(A) . poly(BrdUrd) hybrids to 125I-labeled DNA of high molecular weight. The probe can be synthesized with a variety of RNA molecules, giving it versatility for detecting a variety of genes irrespective of gene size, copy frequency, and host genome complexity. Using this probe prepared with retrovirus genomic RNAs, we have physically mapped all three detectable endogenous genomes of Rous-associated virus type 0 (RAV-0) in Spafas gs- chf- (group-specific antigen negative, chicken helper factor negative) chicken fibroblasts to specific sites on chromosome 1. This finding suggests that these multiple nontranscribed RAV-0 genomes evolved through gene duplication of an original RAV-0 genome. The endogenous src gene coding for a 60,000-dalton protein also has been localized to one of the small macrochromosomes, 10, 11, or 12, in both chicken and Japanese quail cells. The results presented here are consistent with and greatly extend previously reported data obtained by using both chromosome fractionation and restriction endonuclease techniques and thus support the soundness of this hybridization approach.

Animals↗
PubMed1979

Assembly of vesicular stomatitis virus nucleocapsids in vivo: a kinetic analysis.

Pulse-chase labeling and cell fractionation were used to examine the pathways taken by the three nucleocapsid polypeptide species of vesicular stomatitis virus into nucleocapsids and then into virions. An improved method of polyacrylamide gel electrophoresis resolved nucleocapsid polypeptides N and NS from cellular actin, facilitating accurate quantitation of the viral polypeptides. Contrary to previous belief, the rate of NS synthesis was found to be a constant fraction of total virus protein synthesis throughout infection, indicating a consistent mechanism of virus protein synthesis regulation. In the kinetic studies, each polypeptide species displayed the following characteristic behavior. (i) Structural polypeptide N was the only species that entered a metabolically active soluble pool before assembly into nucleocapsids. The size of this pool increased with time after infection, causing an increasing delay in the appearance of pulse-labeled N molecules in nucleocapsids. (ii) Throughout infection, the entire complement of L molecules entered nucleocapsids immediately after their synthesis, without diversion through a soluble pool. (iii) Although 75% of newly synthesized molecules of the transcriptase-associated protein NS entered a soluble pool, they never emerged from the compartment. At all times after infection, about 25% of the NS molecules bypassed the soluble pool and entered nucleocapsids directly after their synthesis, as if in concert with L. These results indicate that VSV nucleocapsid assembly in vivo is a stepwise process, comprising an initial condensation of N with the viral RNA, followed by attachment of L and NS, analogous to the stepwise assembly of Sendai virus nucleocapsids. (D. W. Kingsbury, C.-H. Hsu, and K. G. Murti. Virology 91:86-94, 1978). About half of the intracellular nucleocapsids were recovered in a form that sedimented at anomalously low centrifugal forces, reflecting an association with large cellular organelles. This attachment was mediated mainly by electrostatic forces, since these "bound" nucleocapsids were released by elevated salt concentrations. The kinetic behavior of nucleocapsid polypeptides was the same in both fractions, providing no evidence for a division of nucleocapsid functions between cellular compartments.

Actins↗
PubMedDate not supplied

Sonometric evaluation of eustachian tube function using broadband stimuli.

New measurements of acoustical transmission through the eustachian tube (ET) have been obtained in a series of experiments directed toward the development of a clinical instrument to assess ET function behind an intact tympanic membrane (TM). Using a sound conduction method, a sound source was placed in one nostril, and the acoustical energy that was transmitted through the ET was measured by a microphone placed in the ear canal. The present study used a broadband noise as the acoustical stimulus, in contrast to the tonal stimuli employed in previous investigations. This stimulus was chosen because it is believed to reduce the variability in the data due to intersubject differences in the acoustics of the nasopharynx and ET, and to avoid any a priori assumptions concerning the specific frequencies that would be of greatest diagnostic significance. Averaged spectra of the sound transmitted to the ear canal were obtained for three experimental conditions: acoustical source present during subject swallowing, source present with no swallowing, and subject swallowing with source absent. A Bayesian classification scheme based on the statistics of these spectra was used in classifying subjects into one of two possible categories, normal and abnormal ET function. A comparison was made between sonometric classification and classification based on a tympanometric ET function test. Correlation between the two methods was 87.1%.

Acoustic Impedance Tests↗