Percentage Of RNA Research Articles

A mutant of alfalfa mosaic virus with an unusual structure

A spontaneous mutant of alfalfa mosaic virus (AMV) with an altered structure is described. By analysis of pseudorecombinants the mutation(s) responsible for the altered structure were assigned to RNA 3. By in vitro translation and serology it is shown that both proteins (35K protein and coat protein) encoded by RNA 3 are changed. The mutation(s) present in RNA 3 also have an effect on the ratio of the three genomic RNAs, both in virion as well as in double-stranded RNA preparations. Compared to wild-type particles mutant particles (1) have a lower electrophoretic mobility in polyacrylamide gels, (2) have a greater sedimentation velocity in sucrose density gradients, (3) do contain the same percentage of RNA, (4) are more prone to aggregation, (5) are somewhat less stable during storage, and (6) are less sensitive to uncoating by AMV-RNA. Electron micrographs show that the mutant preparations contain some very long bacilliform particles, however the majority of the particles is spheroidal and bear a strong resemblance to the particles of the ilarviruses. The structural properties of this mutant support the classification of AMV as an ilarvirus.

Inhibition of ciliary activity in organ cultures of ferret trachea in reference to genetic and biological characters of influenza virus strains

As reported previously, attenuated stable inhibitor-resistant influenza viruses can be screened by a 50% ciliary activity inhibition test in ferret tracheal organ cultures. This test was further applied to a 5 attenuated cold-adapted influenza strains and to 11 strains with known a percentage of RNA-RNA hybridization with the parental A/PR/8/34 (HON1) virus strain. Again, with one exception, attenuated strains could be clearly differentiated from virulent ones. It was concluded that virulence of influenza strains for man can be detected using this test regardless of the techniques used to prepare attenuated variants. A preliminary screening of attenuated candidates for live influenza vaccines can be achieved with confidence on ferret tracheal organ cultures.

Nuclear ribonucleoprotein particles from adenovirus infected Hela cells.

Heterogenous nuclear RNA-protein complexes (hnRNP) from adenovirus-2 (Ad-2) infected Hela cells contain most of the virus-specific RNA which is labeled in the nucleus during periods lasting from 45 seconds to 2 hours. Moreover, the percentage of RNA which is Ad-2 specific as monitored by filter hybridization increases progressively from early to late period where it accounts for as much as 50-60% of the labeled RNA. The Ad-2 sequences are found in heterogenous complexes sedimenting between 30 and 200 S the density of which in CsCl (rho approximately 1.39) as well as metrizamide (rho approximately 1.29) seems to be the same as that of the bulk particles. A more detailed analysis with restriction fragments shows that all regions of the Ad-2 genome are represented in these particles.

Biophysical and biochemical characterization of virus-like particles containing a high molecular weight ds-RNA from Helminthosporium maydis

Spherical virus-like particles (VLPs_ isolated from Helminthosporium maydis ATCC 32450 are 48 in diameter and have three serologically identical components which have the following properties: s 20,w = 152, 212, and 283; ϱ (in CsCl) = 1.298, 1.378, and 1.438 g cm −3; percentage of RNA = 0, 17, and 32; and molecular weight = 14, 17, and 21 × 10 6. The nucleic acid of the fastest sedimenting component is double-stranded and has the following properties: s 20,w = 20.69; T m = 79.6°; ϱ (in Cs 2SO 4) = 1.6062 g cm −3.; molecular weight = 6.3 ± 0.5 × 10 6.

Changes in biochemical components during the germination of spores of Penicillium roqueforti

AbstractGermination of spores of Penicillium roqueforti consisted of three stages, i.e. swelling, germ‐tube emergence and hyphal elongation which occurred at 4, 12 and 16 h respectively after initiation of incubation of resting spores in the germination medium. The swelling phase represents the period during which the germinating spore assembled required synthetic enzymes though there was only a small increase in dry weight (2 mg h−1 per 109 spores). Nuclear division occurred since DNA multiplied rapidly during spore swelling. The percentages of RNA and proteins reached their maxima at the end of this period. The unsaturated fatty acids, e.g. linoleic and linolenic acids, were synthesised. Germ‐tube emergence represented a transition phase during which growth was moderate (at a rate of 9 mg h−1 per 109 spores) as compared to hyphal elongation phase (34 mg h−1 per 109 spores). The percentage of RNA, proteins and carbohydrates decreased. The percentage of unsaturated fatty acids was highest at the middle of this period and then declined. The hyphal elongation phase represented a period of rapid growth. The relative contents of proteins and DNA remained constant while the percentage of carbohydrates and saturated fatty acids increased, reflecting the proliferation of cellular and membrane materials.

RNA contents of abnormally long particles of certain strains of alfalfa mosaic virus

A nucleoprotein particle longer than bottom component occurring in small amounts in preparations of the alfalfa mosaic virus (AMV) strain 15 64 has been partially purified by gradient centrifugation and characterized. The particle has the same shape, width, and RNA percentage as the major components of the virus. Its length and sedimentation coefficient are 87 nm and 113 S, respectively. It does not contain a single abnormally long RNA molecule, but two molecules of middle component RNA. Electrophoresis in polyacrylamide gel revealed that in addition to this type of particle other nucleoproteins containing different sets of RNA molecules occur in trace amounts in preparations of strain 15 64 . Particles with a length of up to about 400 nm of strain VRU have also been studied after they were freed from normal length particles by gradient centrifugation. In accordance with the results of others it has been found that the abnormally long particles did not contain any RNA molecules longer than bottom component RNA.

Untersuchungen am Chromatin der Wurzelspitze von Zea mays L.: I. Zur Zusammensetzung unterschiedlich dichter Chromatinfraktionen aus successiven Wurzelspitzenzonen zweier Maissorten

1. The ratio of DNA found in the diffuse chromatin in corn roots of two varieties, in relation to total DNA, is relatively high in the meristem (35 %), lower in the elongation zone, and high again in the differentiated tissue. The high value in the meristem is regarded in relation to the high level of DNA synthesis therein, and the high value in the differentiated tissue may be indicative, in our opinion, to a higher template activity in comparison with the elongation zone. 2. The RNA content of compact chromatin isolated from root tip zones is low. Diffuse chromatin contains more RNA, and the percentage of RNA therein increases from meristematic to differentiated tissue. From the comparison of the two corn varieties it is concluded that the RNA content changes in close correlation with the template activity and thus the results imply that the lowest template activity exists in the meristem. 3. The non-histone protein content and the RNA content show the same variations with one exception: Compact chromatin of the meristem contains an increased percentage of non-histone proteins in relation to RNA. It is suggested that these non-histone proteins playa role in the repression of RNA synthesis during mitosis. The comparison of the varieties indicates that in all other cases the non-histone protein content changes in close correlation with the level of RNA synthesis. 4. The histone content of chromatin shows opposite changes compared to the non-histone protein content. It is discussed wether the variations of histone content are an artefact of preparation caused by the insolubility of the histone + non-histone protein complexes in acid.

RNA metabolism during puff induction in Drosophila melanogaster.

RNA metabolism of the salivary glands of Drosophila melanogaster was studied for possible changes coinciding with the induction of new puffs by heat treatment.—The rate of 3H-uridine incorporation into RNA is identical at 37° C and at 24° C. It declines with time of incubation, possibly indicating the existence of a class of rapidly turning over RNA.—RNA extracted from glands pulselabelled at either 24° or at 37° C displays similar profiles if subjected to gel electrophoresis. Processing of the 38s ribosomal RNA precursor comes to a halt at 37° between 30 and 60 minutes of incubation, i.e., some time after puff induction is completed. At both temperatures newly synthesized pre-ribosomal RNA accumulates with time of incubation more rapidly than heterodisperse RNA, again suggesting that some heterodisperse RNA is of relatively short life span. After short pulses the portion of heterodisperse RNA is larger in glands kept at 37° C than in glands kept at 24° C. With increasing time this difference disappears.—Some of the pulse-labelled, high molecular weight heterodisperse RNA is rapidly degraded, if RNA synthesis is blocked by actinomycin D. If the chase is performed at 24° C, about 30% of the newly synthesized RNA is degraded within about 15 minutes. At 37° C the beginning of degradation appears delayed for about 30 minutes; subsequently the same percentage of RNA is degraded as at 24° C.—The possibility is considered that the local RNA accumulation visualized by the heat-induced puffs may have resulted from a change in RNA degradation rather than from a local stimulation of RNA synthesis.

DNA-membrane complex: macromolecular content and stimulation of enzymatic activity by polyadenylic acid.

A DNA-cell membrane complex has been isolated from cell suspensions of virulent pneumococci by sarcosyl lysis followed by centrifugation on a sucrose gradient. When polyadenylic acid plus the eight naturally occurring deoxyribonucleosides and deoxyribonucleotides are added to cell suspensions, the percentage of total DNA in the complex increases with incubation time. This increase is not observed in unsupplemented cell suspensions. However, the percentages of RNA, protein, and phospholipid do not increase with incubation time in either supplemented or control complexes. A variety of deoxyribonucleotide kinases and the DNA polymerase are also detected in the DNA-membrane complex, and their specific activities are greater in complexes extracted from supplemented cell suspensions than in those extracted from controls.

Ribonucleic acid synthesis in the rat uterus and its early response to estrogen

The synthesis of rapidly labeled RNA in the rat uterus, measured by in vivo cytidine-H 3 incorporation into RNA for a 20-minute period, was increased by approximately 88% within 1 hour after estrogen administration. Fractionation by sucrose density gradient centrifugation of RNA from the uterus synthesized in 20- and 60-minute time periods in vivo indicated that estrogen increased the synthesis of all RNA fractions. The percentage of RNA which would form hybrids with DNA was less than 5% and did not indicate that estrogen was having an effect on any specific DNA loci. It is concluded that methods having greater resolving power are necessary to determine whether the synthesis of specific RNA molecules in the rat uterus is involved in early estrogen action.