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PubMed1988

[The use of ribonucleic acid as a marker for measuring microbial protein yield in the rumen. 1. Chemical determination of ribonucleic acid].

The determination of ribonucleic acid (RNA) in the duodenal digesta and the rumen microbes was carried out colorimetrically with orcinol after extraction with hot NaCl solution, precipitation with phosphotungstic acid and alkaline hydrolysis. 96 +/- 1% of the RNA supplemented to the digesta content was recovered (y +/- s, n = 5). The methodic error (repetition accuracy) was 1.1%. The relation of RNA-N:N (mg/g) in the bacteria mass amounted to 93.8 +/- 3.99 (y +/- s(-y), n = 48) and to 16.1 +/- 0.8 (y +/- s(-y), n = 51) mg RNA/g DM in the duodenal content.

Animals↗
PubMed1962

Actionmycin D inhibition of deoxyribonucleic acid-dependent synthesis of ribonucleic acid.

Minute amounts of actinomycin D inhibit the synthesis of ribonucleic acid by nuclear extracts of HeLa cells in a ribonucleic acid-synthesizing system that is dependent on deoxyribonucleic acid and requires the presence of all four ribonucleoside triphosphates. The inhibition can be reversed by adding deoxyribonucleic acid to the enzymatic reaction. These findings support the work of others on the mode of action of actinomycin D in vivo.

Antineoplastic Agents↗
PubMed1981

Chinese hamster polyadenylated messenger ribonucleic acid: relationship to non-polyadenylated sequences and relative conservation during messenger ribonucleic acid processing.

We have further analyzed the metabolism of specific messenger ribonucleic acid (mRNA) sequences within the cytoplasmic and nuclear RNA of Chinese hamster ovary (CHO) cells by using a set of previously constructed complementary deoxyribonucleic acid (DNA) clones (Harpold et al., Cell 17:1025-1035, 1979) as specific molecular probes in a variety of RNA:DNA hybridization experiments. The majority of the labeled mRNA complementary to each of the nine clones was found in the polyribosomes, with some variation between individual sequences. The great majority of each specific mRNA labeled for 3 h or less was in the polyadenylated [poly(A)+] fraction. However, the amount of each sequence increased in the non-poly(A)+ [poly(A)-] fraction after very long label times, suggesting the derivation of the poly(A)- RNA from the poly(A)+ RNA. Eight of the nine mRNA's have cytoplasmic half-lives ranging from 8 to 14 h, whereas one of the mRNA's, the scarcest in the group, has a somewhat shorter half-life of approximately 3 h. The proportion of each of the specific long-lived mRNA's within the total labeled mRNA increased as a function of labeling time, indicating that a large fraction, probably greater than 50%, of the initially labeled poly(A)+ mRNA in CHO cells has a half-life of less than 3 h. A quantitative analysis of the kinetics of labeling of specific nuclear and cytoplasmic sequences indicated that a significant fraction of the mRNA sequences transcribed from genes containing these nine CHO sequences were successfully processed into mRNA. However, two of the CHO mRNA sequences were only partially conserved during nuclear processing to yield mRNA. These studies demonstrated that events at two post-transcriptional levels, differential nuclear processing efficiency of different primary transcripts and cytoplasmic stability of different mRNA's, can be involved in the determination of the cytoplasmic concentrations of different mRNA's.

Animals↗
PubMed1976

The use of a dipolar ion-exchanger for the fractionation of transfer ribonucleic acid.

Transfer ribonucleic acid is well fractionated on columns of arginine-agarose, whose properties appear in general to be similar to those of DEAE-Sephadex. However, the amino acid acceptor species are separated into sharper peaks and in several instances, notably for methionine, glycine, serine, leucine and aspartate accepting tRNAs from Escherichia coli, isoaccepting species are well resolved. In the case of methionine accepting tRNA from E. coli the tRNA Met-m species is eluted before the tRNA Met-f species and since it is also eluted prior to the bulk of the tRNA it is obtained in a high degree of purity. By comparing the properties of columns of arginine-agarose and its methyl ester in which the carboxylate anion is blocked, it is seen that the carboxylate ion plays a role in the fractionation of the tRNA Met species.

Journal Article↗
PubMed1968

Inhibition of host protein synthesis during infection of Escherichia coli by bacteriophage T4. I. Continued synthesis of host ribonucleic acid.

The ribonucleic acid (RNA) synthesized at specified intervals during infection of Escherichia coli K-12 by bacteriophage T4 was hybridized to denatured E. coli or T4 deoxyribonucleic acids (DNA). The reactions were performed under conditions that maximized the yield and at RNA/DNA inputs such that excess DNA sites were available for all RNA species. Most of the RNA synthesized at any time during the first 3 min of infection was host-specific. The fraction declined rapidly as infection progressed; host RNA represented about half that made between 3 and 4 min. It is unlikely that this represented RNA synthesized by bacteria that had escaped infection, as judged by the kinetics of adsorption and killing as well as by the rapid inhibition of beta-galactosidase induction after infection. The nature of the host RNA was also examined. Part of the RNA synthesized during infection of cells rendered sensitive to actinomycin was stable in the presence of this inhibitor. This RNA was essentially all host-specific and it sedimented as ribosomal and transfer RNA; most of the ribosomal RNA was incorporated into 30S and 50S ribosomes. Hybridization analyses suggested that unstable E. coli messenger RNA was also synthesized for several minutes after infection; the proportion of unstable to stable host RNA synthesized appeared to be similar in infected and uninfected cells. Thus, it is concluded that significant amounts of E. coli RNA are synthesized during the first minutes of T4 infection. Host messenger RNA initiated after infection may not be translated into enzymes; alternatively, it is conceivable that continued bacterial messenger RNA synthesis only reflects the completion of transcription of operons whose reading was initiated prior to infection.

Bacterial Proteins↗
PubMed1968

Replication of Western equine encephalomyelitis virus. I. Some chemical and physical characteristics of viral ribonucleic acid.

The ribonucleic acid (RNA) from Western equine encephalomyelitis (WEE) virions sedimented through sucrose gradients with a sedimentation coefficient of 40S. Another viral RNA which was always associated with infected cells possessed a sedimentation coefficient of 26S. Both 40S and 26S RNA had identical base compositions and densities. The 40S RNA displayed a hyperchromic effect when heated with a T(m) of 57.5 C. When 40S RNA was heated at 90 C and cooled rapidly, it sedimented with a coefficient of 26S. Dialysis of 40S RNA against distilled water changed its sedimentation coefficient to 26S. The presence of 8 m urea or 50% dimethyl sulfoxide in the gradients also altered the sedimentation rate of 40S RNA to 26S. In the latter case, the 26S RNA retained 10% of the infectivity originally added as 40S RNA. Dialysis of 26S RNA against 0.5 m NaCl or 0.05 m acetate buffer at pH 4.0 altered it so that about 50% of the radioactivity sedimented with a coefficient of 40S. Chromatography on methylated albumin-kieselguhr columns failed to separate 40S RNA from 26S RNA. Viral RNA either exists in two conformations which sediment differently in sucrose or contains an extremely labile portion near the center and is easily broken into two equal pieces.

Arboviruses↗
PubMed1981

Ribonucleic acid splicing in Neurospora Mitochondria: secondary structure of the 35S ribosomal precursor ribonucleic acid investigated by digestion with ribonuclease III and by electron microscopy.

In Neurospora, the gene encoding the mitochondrial large (25S) ribosomal ribonucleic acid (rRNA) contains an intervening sequence of approximately 2.3 kilobases (kb). We have identified two temperature-sensitive mutants (289-67 and 299-9) which are defective in a factor encoded by a nuclear gene but required for the splicing of 25S RNA. When grown at the nonpermissive temperature (37 degrees C), the mutants accumulate a novel 35S RNA (5.2-5.6 kb) which is related to the natural precursor of 25S RNA and which has been shown to be a collinear transcript of the 25S RNA gene including the intervening sequence. In the present work, the secondary structure of 35S RNA was investigated by digestion with ribonuclease III and by electron microscopy of the RNA spread under partially denaturing conditions. Ribonuclease III cleaves 35S RNA predominantly at a central site or sites near the 5'-intron-exon boundary and produces fragments which correspond roughly to half-molecules (2.5-3 kb). Electron microscopy of 35S RNA shows a relatively large, central hairpin (180 +/- 45 nucleotides), which presumably corresponds to the central ribonuclease III site, and few other secondary structure features. Both experimental approaches indicate that the large hairpin is not present in 35S RNA. From this finding and from the location of the hairpin near the 5'-intron-exon boundary in 35S RNA, we infer that its formation requires intron sequences. 35S RNA from the mutants can be isolated as a ribonucleoprotein particle associated with almost the full complement of large subunit ribosomal proteins. The 35S RNA in such particles can be cleaved by ribonuclease III at the central site(s), consistent with the idea that the central hairpin is accessible to RNA-processing enzymes in vivo.

DNA Restriction Enzymes↗
PubMed1969

Ribonucleic acid synthesis in cells infected with herpes simplex virus. I. Patterns of ribonucleic acid synthesis in productively infected cells.

HEp-2 cells were pulse-labeled at different times after infection with herpes simplex virus, and nuclear ribonucleic acid (RNA) and cytoplasmic RNA were examined. The data showed the following: (i) Analysis by acrylamide gel electrophoresis of cytoplasmic RNA of cells infected at high multiplicities [80 to 200 plaque-forming units (PFU)/cell] revealed that ribosomal RNA (rRNA) synthesis falls to less than 10% of control (uninfected cell) values by 5 hr after infection. The synthesis of 4S RNA also declined but not as rapidly, and at its lowest level it was still 20% of control values. At lower multiplicities (20 PFU), the rate of inhibition was slower than at high multiplicities. However, at all multiplicities the rates of inhibition of 18S and 28S rRNA remained identical and higher than that of 4S RNA. (ii) Analysis of nuclear RNA of cells infected at high multiplicities by sucrose density gradient centrifugation showed that the synthesis and methylation of 45S rRNA precursor continued at a reduced but significant rate (ca. 30% of control values) at times after infection when no radioactive uridine was incorporated or could be chased into 28S and 18S rRNA. This indicates that the inhibition of rRNA synthesis after herpesvirus infection is a result of two processes: a decrease in the rate of synthesis of 45S RNA and a decrease in the rate of processing of that 45S RNA that is synthesized. (iii) Hybridization of nuclear and cytoplasmic RNA of infected cells with herpesvirus DNA revealed that a significant proportion of the total viral RNA in the nucleus has a sedimentation coefficient of 50S or greater. The sedimentation coefficient of virus-specific RNA associated with cytoplasmic polyribosomes is smaller with a maximum at 16S to 20S, but there is some rapidly sedimenting RNA (> 28S) here too. (iv) Finally, there was leakage of low-molecular weight (4S) RNA from infected cells, the leakage being approximately three-fold that of uninfected cells by approximately 5 hr after infection.

Carbon Isotopes↗
PubMed1969

Host-virus interaction in ribonucleic acid bacteriophage-infected Escherichia coli. I. Location of "late" MS2-specific ribonucleic acid synthesis.

When actinomycin-treated, MS2-infected Escherichia coli are labeled during a brief period later than 16 min after infection, the newly synthesized MS2 ribonucleic acid (RNA) appears first in the 30,000 x g sediment, probably bound to fragments of bacterial membranes, since the radioactivity can be released from the sediment with deoxycholate or urea. With longer labeling times, radioactivity also appears in the 30,000 x g supernatant fluid. While on the membrane, the RNA is organized into particles with sedimentation coefficients of 40, 32, and 27S in the presence of low Mg(2+). In the presence of high Mg(+), MS2-specific RNA is found in polyribosomes. These data are interpreted to mean that MS2-specific RNA is synthesized and organized into larger structures on membrane. More than 8 min of labeling is required before radioactivity is found in the 81S virion which appears in the supernatant fluid.

Bacteriophages↗