The isolation of polyadenylate with unreacted cellulose

Octadecylsilyl silica column method for extraction of messenger RNA

We have developed a simple and rapid method for the purification of poly(A) tail-messenger RNA (mRNA) from total RNA by using a solid phase extraction column filled with a small amount of octadecylsilyl silica. The method is based on a hydrophobic interaction between the poly(A) tail and the octadecyl unit on the silica particle in a water/dimethyl sulfoxide mixed solution. By using this column, mRNA can be separated from 100 microg of total RNA in less than 10 min with high yields (>80%).

Defective protein synthesis of S-30 fraction of reticulocytes of anemic b/b rats

The preincubated S-30 fraction from reticulocytes of anemic b/b rats is not able to promote the synthesis of proteins in the presence of hemoglobin RNA provided either from the reticulocytes of phenylhydrazine-treated rats or from the reticulocytes of anemic b/b rats. It was observed that poly(U)-directed polyphenylalanine synthesis is negligible in the same system, suggesting the existence of some alteration in regulatory machinery for protein synthesis in the reticulocytes of the anemic b/b rats.

A micro-method for the assay of polyadenylate-containing ribonucleic acid by gel electrophoresis

A micro-method for the determination of the electrophoretic profile of the various poly(A)-containing RNA species in a RNA sample was developed. The method is simple to carry out and allows for great reproducibility. It combines the resolving power of electrophoresis in agarose with the specificity of binding of poly(A) to poly(U)-containing glass-fibre filters. It consists of the following steps. (1) The molecules in an RNA sample are first separated according to their molecular weight by electrophoresis in agarose, at low ionic strength. 2. The molecules thus seperated are then submitted to a second electrophoresis in 'binding buffer' in a direction perpendicular to the first one. In the course of this electrophoresis the poly(A)-containing RNA species are seperated from other RNA species as they bind to a poly(U)-containing glass-fibre filter which is placed across the electrophoresis path. The method was used to determine the electrophoretic profile of Rhynchosciara salivary-gland messenger RNA. It was found that the population of messenger RNA in the gland is dominated by forms moving as 18 and 158 S peaks, but there is also polydisperse RNA with slower mobility.

Search for nucleic acid sequences complementary to a murine oncornaviral genome in poly(A)-rich RNA of human leukemic cells

The presence of viral-like sequences in the RNA of various types of leukemic cells was investigated by hybridizing cellular poly(A)-containing RNA with cDNA synthesized in an endogenous system of purified Moloney murine sarcoma virus [M-MSV-(MLV)]. Poly(A)-RNA-cDNA hybrids were detected by assaying their resistance to S1 nuclease. Hybrids were found in 22 out of the 46 leukemias that were tested. None of the controls, including material obtained from buffy coats, bone marrow cells, and a continuous human cell line, was positive. Positive cases were found in all the different categories of leukemias with the exception of chronic myelogenous leukemias. There was no definite corelation between the category of leukemia and positivity. A few cases contained a very high proportion of poly(A)-RNA-cDNA hybrid.

A simple method for the purification of reticulocyte globin messenger ribonucleic acid

A relatively simple and inexpensive method has been developed for the preparation of highly purified rabbit reticulocyte globin mRNA. After phenol extraction, polysomal RNA was chromatographed on Sigmacell type 38 cellulose and Sepharose 4B. The resulting mRNA preparation has a purity in excess of 90%. No selective loss of either alpha or beta globin mRNA is observed.

A comparison of the chromatographic properties of various polyadenylate binding materials

The suitability of various materials for messenger RNA isolation and possible fractionation was examined by comparing the chromatographic behaviour of synthetic poly(riboadenylic acid) [poly(A)] and ribosomal RNA on each suport. The ratios of poly(A) to ribosomal RNA capacities of the various materials under different chromatographic conditions were used to estimate the potential selectivity of the columns for messenger RNA isolation. Using this criterion, benzoylated cellulose and oligo(deoxythymidylate)-cellulose should be the most selective materials of those studied. The elution conditions (temperature or salt gradient) used to obtain bound poly(A) were investigated to determine the optimum conditions for possible messenger RNA fractionation. It is concluded that oligo(deoxythymidylate)-cellulose appears to be the most suitable support of those investigated for messenger RNA isolation and possible fractionation.

Messenger activity of ribonucleic acid form yeast mitochondria

Total yeast mitochondrial RNA was shown to possess messenger RNA activity when injected into oocytes of the frog Xenopus laevis. The specific polypeptides formed were precipitated by mitochondrial antisera. A comparison was made of the molecular weights of the proteins obtained form this system with those made by mitochondria in vivo in the presence of cycloheximide. No RNA containing poly(A) sequences was detected in yeast mitochondria.

Isolation and characterization of casein mRNAs from lactating ewe mammary glands

RNA from bound polysomers of lactating ewe's mammary gland directs the synthesis of the three major milk proteins (alphas, beta and kappa-caseins) in a cell-free system derived from rabbit reticuyocytes. The "in vitro" product was identified by immunoprecipitation with specific antibodies and by electrophoresis in SDS polyacrylamide gel. Each of these messengers was purified from 20 to 25 fold from total membrane-bound polysomal RNA using poly U-Sepharose chromatography. This purified fraction assayed in a reticulocyte cell-free system is able to direct also the synthesis of 2 minor secretory proteins (beta-lactoglobulin and alpha-lactalbumin). The messenger RNAs purified by hybridization to poly U-Sepharose have a sedimentation coefficient of about 12 S and an apparent molecular weight of approximatively 3.5 s 10-5 daltons was observed by polyacrylamide gel electrophoresis under denaturing contitions. This value which correspond to about 900 nucleotides is significantly greater than the number expected for coding milk proteins.

Heterogeneous nuclear rna from lymphocytes of chronic lymphocytic leukaemia: adenylate-rich and double-stranded regions

Rapidly labelled high molecular weight nuclear RNA from lymphocytes of chronic lymphocytic leukaemia was analysed for ribonuclease-stable adenylate-rich and double-stranded regions. The polyadenylate content corresponds to 0.4-0.5 percent and the content of double-stranded sequences to 2-4 percent of the total nucleotides. Partial association of polyadenylate segments with double-stranded regions was found by comparative analysis of (3H)-adenosine and (3H)-uridine labelled ribonuclease-stable RNA before and after thermal denaturation. Comparison with normal lymphocytes shows lower proportions of polyadenylate-containing RNA binding to poly(U)-Sepharose in leukaemia cells than in normals. Partial degradation of rapidly labelled high molecular weight RNA was found in leukaemia cases with low white cell counts.

Messenger RNA metabolism of animal cells. Possible involvement of untranslated sequences and mRNA-associated proteins

The past several years have seen a virtual revolution in the study of eukaryotic mRNA. Among the notable recent achievements are the positive identification of mRNA precursors in HnRNA, the enumeration of the DNA sequences from which mRNA is transcribed, and the finding that mRNA in cultured cells is much more stable than was previously believed. One of most far-reaching discoveries has been the finding that mRNA in eukaryotes contains poly A. This discovery, aside from providing a powerful tool for mRNA isolation, has generated a large body of research into the properties and metabolism of poly A itself. In addition, the finding of a poly A-associated protein has given a renewed stimulus to the study of proteins associated with mRNA. This review is devoted to a discussion of these and related achievements, and some of their implications

Immunoglobulin heavy chain mRNA in mitogen-stimulated B cells

This paper relates the synthesis of DNA, immunoglobulin and heavy chain (H) mRNA in murine spleen cells following activation of B cells with lipopolysaccharide from E. coli (LPS). Spleen cells (CBA/H mice) were cultivated with 10% FCS and 10 mug LPS/ml. 4 h pulses with [3H]thymidine showed that DNA synthesis was stimulated within the first day following LPS activation and exhibited a sharp peak at 24 h. The shape of the DNA synthesis curve suggests that the cells susceptible to LPS stimulation are activated in a synchronous manner. Stimulation of H-chain mRNA (H-mRNA) synthesis proceeded rapidly (within 6 h of LPS addition) and peaked around 24 h, in parallel to DNA synthesis. The H-mRNA was isolated and quantitated by making use of its interaction with IgG[1, 2]. The actual level of H-mRNA in the culture increased threefold during the first 24 h and then doubled within the next 48 h. Estimates of the actual number of H-mRNA were approximately 200 molecules H-m-RNA/cell on day 0 rising to 1800/cell on day 3. In such a mixed cell population these figures will be accurate only within a factor of 2-3 (at least 35% B cells in spleen cell suspensions at the commencement of the culture, with up to 35-60% of plasma blasts by day 3 and 4 of LPS treatment). Translation of the lymphoid cell mRNA in oocytes from Xenopus laevis demonstrated that stimulation of H-mRNA synthesis was restricted to mu-mRNA, although some gamma-mRNA was present in the original spleen cells. High levels of synthesis of immunoglobulin followed after a lag period of about 24 h following LPS addition peaking after 48 and 72 h; the proportional Ig production relative to total protein synthesis reached 26% on days 3 and 4. Stimulation of Ig production was limited to IgM. Rapid stimulation of mitosis and H-mRNA synthesis thus precedes the maximum synthesis of Ig molecules, suggesting a translational block on H-mRNA during cell maturation. There was no apparent block on the transport of H-mRNA from the nucleus during early stages of activation.

Cell-free translation of paramyxovirus messenger RNA

Polypeptides corresponding in electrophoretic mobility to virion polypeptides 1, 3, and 5 were made in a reticulocyte cell-free system to which 18S RNA from Sendai virus-infected cells was added. Immune precipitation was used to select relevant polypeptides from endogenous products. The cell-free product corresponding to virion polypeptide 3 (the nucleocapsid structure unit) was the most abundant; its tryptic peptides comigrated electrophoretically with tryptic peptides of polypeptide 3 isolated from virions. Other sedimenting classes of RNA from infected cells were tested; only the 28S fraction showed slight activity. Virion 50S RNA was inactive. These findings support the hypothesis that complementary RNA transcripts of paramyxovirion RNA are the templates for viral proteins.

Synthesis of RNA-polyadenylic acid by isolated brain nuclei

Nuclei, isolated from mouse brain tissue at various stages of postnatal development and incubated under cell-free conditions, synthesized RNA molecules that were associated with polyadenylic acid [poly(A)]. The RNA synthesized by these nuclei was similar to the poly(A)-associated products described for intact eukaryotic cells. The brain nuclei synthesized a similar proportion of RNA-poly(A) in the presence either of Mg(2+) or of Mn(2+) with (NH(4))(2)So(4). The RNA from neonatal brain nuclei appeared to have a greater proportion of poly(A)-containing RNA than nuclear products obtained from more mature neural tissue.

A general method of gene isolation

A general method of gene isolation has been developed that involves the chemical linkage of RNA to cellulose by a water-soluble carbodiimide, and the continuous circulation of DNA containing specific sequences complementary to the RNA. The temperature of the cellulose matrix is maintained at 37 degrees (50% formamide, 0.3 M NaCl-0.03 M Na(3) citrate) to allow efficient DNA-RNA interaction in the stationary phase, while unreacted and any reassociated DNA is denatured at 90 degrees and then recirculated into the hybridization chamber. Between 40 and 45% of fragmented (32)P-labeled simian virus (SV)40 DNA was removed from the circulating solution when cellulosebound SV40-specific RNA, assymmetrically transcribed in vitro with Escherichia coli RNA polymerase, was used. In the presence of 10(4)-fold excess of sheared E. coli DNA, nearly half of the [(32)P]SV40 DNA was recovered from the mixture as a DNA-RNA hybrid with negligible contamination by bacterial DNA. The isolation procedure is almost quantitative for the complementary DNA. The efficiency and selectivity of this method permit the isolation of a defined DNA sequence from a large and complex genome.