Isolation of low molecular weight nuclear RNA from small numbers of nuclei with cetyltrimethylammonium bromide

A method is presented for the isolation of low molecular weight nuclear (LMN) RNAs from small numbers of nuclei. Cetyltrimethylammonium bromide (CTAB) is used to precipitate small quantities of whole nuclear RNA from dilute aqueous solution following phenol-SDS extraction of purified nuclei. No carrier RNA is necessary during the precipitation step. LMN RNAs are separated from whole nuclear RNA by electrophoresis on polyacrylamide gels. No further purification of the RNA is necessary prior to electrophoresis. Both radioactivity and absorbance profiles of the LMN RNAs on the gels can be obtained. Thus, specific activities of labeled LMN RNA species can be estimated.     

Process of infection with bacteriophage phiX174. XXXVII. RNA metabolism in phiX174-infected cells.

The RNA produced in vivo from bacteriophage phiX174 DNA has been analyzed by polyacrylamide-agarose gel electrophoresis and sedimentation in dimethyl sulfoxide gradients, and the results of Hayashi and Hayashi (1970) have been confirmed and extended. An efficient procedure for recovery of RNA from gels, followed by a hybridization assay, has indicated the presence in infected cells of 18 distinct RNA species with sizes up to and greater than the unit (viral) length. The sizes of phiX mRNA's were similar irrespective of whether material was analyzed on gels or in dimethyl sulfoxide gradients. When virus-induced RNA was detected by a double-label method, seven additional low-molecular weight species were observed on gels and the resolution of dimethyl sulfoxide gradients was enhanced. The present results lend support to aspects of the model of Hayashi and Hayashi (1970) for the generation of these discrete mRNA species; an alternative model is also discussed.     

GelStar nucleic acid gel stain: high sensitivity detection in gels.

GelStar nucleic acid gel stain can be used for sensitive fluorescent detection of both double-stranded (ds) and single-stranded (ss) DNAs, oligonucleotides and RNA in gels. The stain can be added to agarose gels at casting for immediate imaging after electrophoresis or can be used after electrophoresis with both agarose and acrylamide gels. GelStar stain is highly fluorescent only when bound to nucleic acids thus giving superior signal-to-noise ratios and obviating the need to destain the gel. The detection limits of GelStar strain are 20 pg for dsDNA, 25 pg for ssDNA and 10 ng for native or glyoxal-treated RNA.     

Comparative electrophoresis of the 18-22S RNAs of Newcastle disease virus.

Between 80 and 90% of the 18-22S Newcastle disease virus intracellular RNA molecules contain poly(A) sequences. Electrophoresis of the 18S RNA in formamide-polyacrylamide gels resolves five species resolved by electrophoresis in aqueous gels. Thus, these five RNA species are probably unique size classes of RNA and not different conformations of the same RNAs. They are of sufficient size to code for the five smaller Newcastle disease virus proteins, and their combined molecular weights represent 60% of the viral genome-a value identical to that obtained by annealing 18-22S RNA with genome RNA. Formamide or heat treatment of the 22S RNA converts most of it into species with migration rates similar to those of the 18S species. Thus, the 22S RNA may not contain unique RNA species.     

Electrophoretic Analysis of Ribosomal and Viral Ribonucleic Acids with a Simple Technique for Slicing Low-Concentration Polyacrylamide Gels

The electrophoretic mobilities of ribosomal ribonucleic acids (RNA) from cultured mammalian (HeLa, Vero, MDBK), avian (chick embryo), and bacterial (Escherichia coli) cells, and RNA species extracted from selected viruses (Sindbis, polio, tobacco mosaic, Sendai) were compared, employing a simple, inexpensive technique for slicing low-concentration polyacrylamide gels. The procedure provides for rapid fractionation of gels used for characterization of RNA, incorporating extrusion and serial sectioning of frozen gels. Among 28S ribosomal RNA species, Vero and MDBK were indistinguishable, whereas HeLA RNA had a slightly lower mobility (higher apparent molecular weight) and chick RNA had a higher mobility (lower apparent molecular weight). The 18S ribosomal RNA species of the three mammalian sources were indistinguishable, but chick 18S RNA had a slightly lower apparent molecular weight. The inverse relation between mobility and log-molecular weight among the ribosomal and viral RNA species, though not highly precise, demonstrates the applicability of the technique to the study of molecular weights of viral RNA species.     

An apparatus for the simultaneous casting of large numbers of uniform cylindrical polyacrylamide gels

An apparatus for the simultaneous casting of a large number of cylindrical polyacrylamide gels is described. Gels can be cast that are uniform with respect to length, loading-surface flatness, and internal polymerization properties. The basis of the method is casting the gels as an inverted single block which totally excludes oxygen from gel-loading surfaces during polymerization.     

Identification of bacteria by low molecular weight RNA profiles: a new chemotaxonomic approach

A new chemotaxonomic method is presented for the identification of eubacteria. This method is based on one-dimensinal gel electrophoresis of total RNA extracts from eubacteria. Only low molecular weight (<150 nucleotides) RNA, comprising 5S ribosomal and transfer RNA, was used for the identification. The high resolution of the electrophoresis, better than half a nucleotide, allowed construction of low molecular weight (LMW) RNA profiles that contained 10 to 20 bands per strain. LMW RNA profiles of a set of eubacterial reference strains showed on variation in dependence on culture conditions or physiological state of the cells. Computer-assisted data evaluation, including six molecular weight markers, enabled the calculation of relative nucleotide units (RNU) for every band. The resulting normalized band pattern allowed the identification of identical strains on different gels. The relative position of the single bands from the different groups of RNAs made an identification of bacterial strains to genus and often species level possible.Especially valuable for the identification were the large, class 2 tRNAs that showed certain variation among species of the same genus and varied considerably among different genera. RNA profiles can provide a rapid and inexpensive screening technique for the taxonomic classification of single bacterial strains. Potential fields of application for this technique might be bacterial taxonomy, biotechnology and ecology.     

Genotyping of Heterotrophic Bacteria from the Central Baltic Sea by Use of Low-Molecular-Weight RNA Profiles

The Gotland Deep, an anoxic basin, was investigated for its heterotrophic microflora as a station representative of the central Baltic Sea and as an example of a brackish water environment. One hundred twenty-three bacterial strains were isolated along the water column by use of four different cultivation procedures. High-resolution electrophoresis of the low-molecular-weight (LMW) RNA (5S rRNA and tRNA) was used for analysis of the taxonomic position of the strains. The banding pattern of the LMW RNA generated by the electrophoresis allowed a taxonomic grouping at the species level of the 123 strains into 24 different genotypes. This grouping was confirmed by use of long-range gels with a substantially better resolution than that of standard gels; i.e., about 60% more tRNA bands were obtained on the long-range gels, and the distance between the bands was increased by about two-thirds. The majority of the strains (76%) could be identified to the species level by comparison with LMW RNA profiles from reference strains stored in an electronic database. Eighty-seven percent of the strains could be assigned to the families Vibrionaceae, Enterobacteriaceae, and Pseudomonadaceae (rRNA group I). The most abundant species among the isolates were Shewanella putrefaciens (48%) and a new Pseudomonas species (24%). The remaining fraction of 28% of the isolates was split into 22 other genotypes. Thirteen of these genotypes were represented by single isolates. This study demonstrates the utility of LMW RNA profiling for a rapid assessment of genotypic diversity of heterotrophic isolates from natural environments.     

Separation and quantitation of intracellular forms of poliovirus RNA by agarose gel electrophoresis.

Intracellular poliovirus-specific RNA species can be measured directly by electrophoresis of total cytoplasmic nucleic acids through 1% agarose gels, resulting in the separation of single- and double-stranded forms of poliovirus RNA from each other and from HeLa cell 28S ribosomal RNA. Single-stranded RNA molecules differing by only 15% in length are resolved in this gel system. RNA species can be visualized as fluorescen bands appearing after staining of the gels with ethidium bromide and observation under ultraviolet illumination. The total amount of RNA can be determined by densitometric quantitation of the fluorescent response. In this way, the amount of poliovirus-specific RNA within the cytoplasm of HeLa cells infected for various times has been estimated. At 170-min postinfection, there are 0.67 X 10(5) molecules of single-stranded poliovirus RNA per cell and at 230 min, the amount has increased to 3.7 X 10(5) molecules/cell. Poliovirus double-strnaded RNA reaches a maximum of 0.7 X 10(5) molecules/cell at 330 min after infection.     

Analytical and preparative electrophoresis of RNA in agarose-urea.

Agarose-6 m urea gels at neutral pH stained with ethidium bromide give high resolution of complex mixtures of RNA molecules. These RNA species can be readily distinguished from contaminating DNA, which does not have to be purified away from the RNA, and electrophoresis can be carried out using phenol-saturated deproteinated cellular extracts without loss of resolution. Individual RNA species can be extracted from the gels by freezing, thawing, and centrifugation; the RNA may then be purified by phenol extraction and ethanol precipitation. Such purified RNA is an excellent substrate for RNA-DNA hybridization and cell-free translation. In addition, the RNA can be easily transferred with high resolution from the agarose-6 m urea gels to diazobenzyloxymethyl paper for subsequent hybridization to labeled DNA.     

A rapid electrophoretic procedure for the detection of SDS-released oncorna-viral RNA using polyacrylamide-agarose gels

A rapid method for analyzing SDS-released viral RNA on acrylamideagarose gels is described. Studies carried out on Rauscher leukemia virus and Mason-Pfizer monkey virus utilizing this method show that the distribution and recovery of the RNA components are similar for phenol-extracted or SDS-released viral RNA. The method is approximately 20 times more sensitive than sucrose gradient analysis and can be utilized in cases where virus concentration (EM particle count or radioactivity) is low.Data presented illustrate the versatility of this method.     

Denaturing RNA electrophoresis in TAE agarose gels

Current methods of analytical RNA electrophoresis are based on the utilization of either complicated laboratory instrumentation or toxic, carcinogenic, or expensive chemicals. We suggest here the use of classical Tris-acetate-ethylenediamine tetraacetic acid (TAE) agarose gels combined with prior denaturation of RNA samples in hot formamide for the electrophoretic separation of RNA species. We present a brief comparison of the proposed TAE/formamide method with the most common 3-(N-morpholino)propanesulfonic acid/formaldehyde agarose gel protocol and show that both methods produce comparable results for size determination of RNA molecules and subsequent Northern blotting of gels. In addition to purified RNA samples, the robustness of the TAE/formamide protocol is demonstrated by its suitability for the analysis of RNA quality in crude yeast cell lysates containing large amounts of proteins, DNA, and other contaminating molecules. We therefore propose the TAE/formamide agarose electrophoresis as a rapid, simple, and cheaper alternative to current methods of RNA electrophoresis. Additionally, another benefit is the reduced exposure of laboratory personnel to hazardous chemicals.     

Preparation of GDP-D-mannose specifically labeled with tritium in the D-mannosyl moiety

A method, called “bidirectional transfer”, has been described for the transfer of DNA and RNA from agarose or polyacrylamide gels onto diazobenzyloxymethyl (DBM)-paper or nitrocellulose filters. The gels were sandwiched between either two nitrocellulose filters or two diazobenzyloxymethyl-papers. Next, the nucleic acids were allowed to diffuse out of the gels onto the filters. In this way, duplicate blots were obtained from a single gel. The bidirectional transfer of DNA or RNA from 0.5 to 1% agarose gels was complete and nearly quantitative after 1 h of transfer. DNA fragments from 5% polyacrylamide gels were efficiently blotted after 36 h onto nitrocellulose filters using bidirectional transfer. The fragments were transferred with good resolution and were shown to be efficient substrates for homologous [³²P]DNA probes.     

Plant Nucleases: III. Polyacrylamide Gel Electrophoresis of Corn Ribonuclease Isoenzymes

Isoenzymes of RNase were detected in plant extracts after polyacrylamide gel electrophoresis with a new buffer system. The gels were incubated in an RNA solution, then dipped for 30 seconds into 0.2% toluidine blue. The method is rapid and is sensitive to very small amounts of RNase. The effects of buffers and ethylenediaminetetraacetate on the different enzymes are illustrated by photographs and scans of the gels.     

A method for the recovery of nucleic acids from polyacrylamide gels

A method is described for the recovery of RNA from ethylene diacrylate cross-linked polyacrylamide gels. The RNA is recovered undergraded in good yields under mild conditions and is free of soluble polyacrylamide gels.     

Relationship Between Sporulation-Specific 20S Ribonucleic Acid and Ribosomal Ribonucleic Acid Processing in Saccharomyces cerevisiae

The nature and properties of the 20S ribonucleic acid which accumulates only during the sporulation of Saccharomyces cerevisiae were examined. The 20S ribonucleic acid (RNA) has a base composition considerably different from ribosomal RNA species and is virtually unmethylated. The 20S RNA did, however, exhibit approximately 70% homology with 18S RNA by RNA-deoxyribonucleic acid filter hybridization competitions. The 20S RNA showed a hybridization saturation plateau level 30 to 40% higher than 18S, consistent with measurements of the size difference in polyacrylamide gels. Pulse-chase experiments in the presence and absence of cycloheximide indicate that the 20S RNA has a presumptive relationship to the 20S ribosomal RNA precursor normally observed only in short pulse-labeling in vegetative cells.     

Characterization of pre-messenger-RNA-containing nuclear ribonucleoprotein particles from avian erythroblasts.

Ribonucleoprotein particles have been isolated from duck erythroblast nuclei using a procedure designed to produce maximal cytoplasmic dispersion with minimal release of endogenous hydrolytic enzymes. The RNA extracted from the purified nuclear ribonucleoprotein fraction is shown to contain globin messenger RNA sequences at a concentration comparable to that present in total nuclear RNA. The polypeptide composition of this fraction revealed by electrophoresis in two dimensions is complex, consisting of at least 65 acidic species and 21 basic species. Several lines of evidence suggest that these are authentic components of nuclear ribonucleoprotein. The so-called 'core' proteins of nuclear ribonucleoprotein which were previously shown to migrate as a single band on low-pH urea gels, and as six bands on sodium dodecyl sulphate gels are here shown to be considerably more complex being resolved by two-dimensional electrophoresis into a group of 15 basic and 6 more and less neutral polypeptides. Isoelectric focusing of nuclear ribonucleoprotein under non-denaturing conditions suggests that these latter species are not uniformly distributed along the pre-messenger RNA molecule.     

Hybridization of DNA to RNA in methylmercuric hydroxide agarose gels

We describe a method for hybridization of cDNA probes to RNA directly in agarose gels which provides a practical alternative to methods involving transfer of the RNA out of the gel. Total cellular RNA is subjected to electrophoresis in agarose gels containing methylmercuric hydroxide as the denaturing agent. After removal of the methylmercuric hydroxide, the gel is dried and 32P-labeled DNA probes are hybridized to the immobilized RNA. This method is more economical in time and expense than methods involving transfer of the RNA out of the gel, while maintaining a level of sensitivity comparable to other procedures.     

One-step casting of Laemmli discontinued sodium dodecyl sulfate-polyacrylamide gel electrophoresis gel

A modified Laemmli sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protocol is described. The new method saves 30 min for gel casting without loss of the resolution power of Laemmli gel. In this method, both the upper and lower gels can be cast at the same time because the lower gel contains 10% glycerol, which generates higher density in the lower gel than in the upper gel.