Adenine-rich polymer associated with rabbit reticulocyte messenger RNA

Terminal sequence studies of high-molecular-weight ribonucleic acid. The 3' termini of rabbit globin messenger ribonucleic acid

Haemoglobin mRNA isolated from EDTA-treated polyribosomes has an apparent molecular weight of 120000-180000 estimated by condensation with (3)H-labelled isoniazid after periodate oxidation. Analysis of the ribonuclease digests of isoniazid-labelled RNA by paper electrophoresis and column chromatography enables the amount of contaminating 18S, 7S, 5S and 4S RNA to be estimated, and a corrected molecular weight of globin mRNA as the acid is 161000 or 500 nucleotides in length. This molecule contains two groups of 3'-terminal sequences in equal yield; G-Y-A(6) and G-Y-A(7) in the ratio 3:2, and G-N(9-16)-Y-A(2) and G-N(9-16)-Y-N(3) in the ratio 3:2. The significance of these sequences is discussed in relation to the poly(A) content of globin mRNA, the specificity of the sequences, and possible function in processing and biosynthesis of mRNA.

Cytoplasmic adenylylation and processing of maternal RNA

Molecular hybridization between [(3)H]-poly(U) and unlabeled RNA prepared from sea urchin eggs and embryos has been used to contrast the subcellular localization as well as the size distribution of adenylylated maternal RNA preexisting in the unfertilized egg with that adenylylated as a function of fertilization. Evidence reported establishes that such preadenylylated genetic messages are predominantly located in the ovum's subribosomal fraction and that fertilization elicits a rapid reallocation of these latent transcripts into the zygote's ribosomal fraction. Examination of the size distribution of the adenylylated RNA further demonstrates that the unfertilized egg contains a substantial population of RNA transcripts of exceptionally high molecular weight that are used as primers for the 2-fold net synthesis of poly(A) that follows fertilization. The poly(A)-rich tracts are shown to be covalently bonded to RNA. Assessment of the poly(A) content of nuclear and cytoplasmic fractions suggests that the function of poly(A) is not confined to the transport of genetic messages from the nucleus.

Interaction between polyuridylic acid and rabbit globin messenger ribonucleic acid

Poly(U) binds to globin mRNA in 0.1m-NaCl. Studies with ribonuclease digestion of this complex suggest that there are polyadenylate-rich sequences in the mRNA containing about 30-40 adenylate residues. The sequences appear to be homogenous and of approximately the same length for both alpha- and beta-globin mRNA. They are most likely located at the 3' terminus of the molecule.

[RNA-Synthesis in telotrophic meroistic ovarioles of dysdercus intermedius DIST. (heteroptera, pyrrhoc.)]

RNA in insect ovaries was investigated by polyacrylamide gel electrophoresis to study site of synthesis, transportation and incorporation in mature eggs. Telotrophic-meroistic ovarioles ofDysdercus intermedius were selected for this work since they could be dissected in distinct portions: the apical one with polyploid nurse cells and the vitellarium with oocytes covered by a follicular epithelium. RNA was labeled by injecting radioactive precursors or incubating isolated ovarioles in vitro.In nurse cells labeled rRNA, tRNA and non-ribosomal RNA were found and evidence was presented for the processing of a 39s rRNA precursor molecule in 2 steps (36s and 32s) into 28s rRNA while the 18s rRNA was directly derived from the 36s molecule. A low concentration (0.5 Μg/ml) of α-Amanitin inhibited synthesis of non-ribosomal RNA thereby revealing a more distinct processing pattern for rRNA, while a high concentration (5 Μg/ml) blocked processing at the 36s molecule and led to its accumulation. Appropriate concentrations of Actinomycin D inhibited rRNA synthesis while distinct peaks of non-ribosomal RNA became apparent.RNA synthesized in the follicular cells was similar to the RNA made in the nurse cells only in the high molecular weight RNA. Some material, tentatively named "nucleotide fraction", with a mobility higher than tRNA was detected and could be localized in yolk granules. It was separable from RNA by chromatography on Sephadex G 100 and had an absorption maximum at 255 run. The "nucleotide fraction" could be rapidly labeled. It seemed to be utilized in RNA synthesis during embryogenesis. Mature eggs contained a relatively high amount of the "nucleotide fraction". If a single injection with precursor was done 4 days before analysing the RNA of mature eggs most of the label was found in the "nucleotide fraction". Eggs collected 5-8 days after injection contained only high molecular labeled RNA. This observation correlated well with the timing of egg maturation. It takes 4 days for a group of oocytes to reach the distal part of the vitellarium where yolk production and maturation go on for another 4 days. It is apparent, therefore, that the follicular epithelium contributes the "nucleotide fraction" to the oocyte, while most of the other RNA, including a stable polydisperse class of RNA, is made in the nurse cells and is transported into the oocyte.

A particle associated with the polyadenylate segment in mammalian messenger RNA

A structure consisting of poly(A) complexed with other components is released from polysomes by ribonuclease treatment. The poly(A) complex has a sedimentation value of 12-15, while the corresponding sedimentation value for free poly(A) is 4. The complex does not appear to represent an artifact formed by interaction of free poly(A) with either cytoplasmic or polysomal proteins. The polynucleotide released from the complex by treatment with sodium dodecyl sulfate shows the same electrophoretic mobility as that of poly(A) isolated from deproteinized polysomal RNA. The poly(A) in the complex is partially protected from digestion by T(2) ribonuclease. At least part of the poly(A) is available for base pairing with poly(U). The components associated with the poly(A) cause it to bind to Millipore filters at low ionic strength. These components are removed from the complex by Pronase digestion. The findings indicate that the poly(A) segment in messenger RNA serves as a binding site for a particle. This particle appears to consist of proteins.

Hemoglobin switching in sheep and goats: change in functional globin messenger RNA in reticulocytes and bone marrow cells

ANEMIA CAUSES A CHANGE IN THE TYPE OF CIRCULATING HEMOGLOBIN IN GOATS AND CERTAIN SHEEP: HbA (alpha(2)beta(2) (A)) is replaced by HbC (alpha(2)beta(2) (C)). We have isolated globin mRNA from erythroid cells of anemic and nonanemic animals to investigate the mechanism whereby anemia causes this switch. To study several stages in transition from beta(A) to beta(C) synthesis, active globin mRNA was isolated from bone marrow cells, as well as from reticulocytes. By assaying these globin mRNAs in a rabbit reticulocyte cell-free system, we have demonstrated that the switch from beta(A) to beta(C) globin synthesis is mediated via a change in functional globin mRNA.

Control of transcription of RNA rich in polyadenylic acid in human lymphocytes

Rapidly labeled polyribosomal RNA rich in poly(A) has been isolated from cultures of highly purified human peripheral blood lymphocytes. Messenger RNA function for this RNA is suggested by its ability to direct [3H]Met-tRNA binding to ribosomes and incorporation of amino acids into protein in a cell-free preparation. Phytohemagglutinin and low concentrations of dibutyryl cAMP (40 nM) increase poly(A)-rich RNA synthesis 40% within 2 hr, and 100-300% by 12 hr; the percent poly(A) content and the size of the poly(A)-rich portion remain constant. Higher concentrations of dibutyryl cAMP (1 nM), which prevent morphological transformation of lymphocytes by phytohemagglutinin, inhibit synthesis of poly(A)-rich RNA in phytohemagglutinin-treated lymphocytes without damaging cells. Cortisol (0.1 mM), which also prevents lymphocyte transformation, inhibits poly(A)-rich RNA synthesis by 80%. Cycloheximide (5 micro/ml), which decreases protein synthesis by 90%, decreases poly(A)-rich RNA synthesis 80% in cells stimulated by phytohemagglutinin. These studies demonstrate that, as part of the early molecular events of their action, phytohemagglutinin and cortisol regulate transcription of adenylate-rich RNA in human lymphocytes, and that similar transcriptional effects can be produced by dibutyryl cAMP.

Polyadenylic acid at the 3'-terminus of poliovirus RNA

Poliovirus RNA that has been derivatized at the 3'-end with NaIO(4)-NaB(3)H(4) yields, after hydrolysis with alkali or RNase T2, predominantly labeled residues of modified adenosine; no labeled nucleoside derivative is produced by digestion with RNase A or RNase T1. The 3'-terminal bases of the RNA are, therefore,...ApA(OH). Hydrolyzates of poliovirus [(32)P]RNA, after exhaustive digestion with RNase T1 or RNase A, contain, besides internal oligonucleotides, polynucleotides resistant to further action of ribonucleases T1 and A, respectively; these polynucleotides were isolated by membrane-filter binding or ion-exchange chromatography. The sequence of the T1-resistant polynucleotide was determined to be (Ap)(n)A(OH), that of the RNase A-resistant polynucleotide was GpGp(Ap)(n)A(OH). The chain length (n) of the polyadenylic acid, as analyzed by different methods, averages 89 nucleotides. Gel electrophoresis revealed heterogeneity of the size of poly(A). Poliovirus RNA, when labeled in vitro at the 3'-end, contains [3'-(3)H]poly(A); when labeled in vivo with [(3)H]A, it contains [(3)H](Ap)(n)A(OH). The data establish that... YpGpGp(Ap)([unk])A(OH) is the 3'-terminal sequence of poliovirus RNA, Type 1 (Mahoney). Since this mammalian virus reproduces in the cell cytoplasm, these observations may modify prior interpretations of the function of polyadenylate ends on messenger RNAs.

Purification and properties of biologically active messenger RNA for a myeloma light chain

A cell-free system derived from Krebs II ascites tumor has been used to assay biologically active mRNA for myeloma (MOPC-41) light chain during its purification by oligothymidylate-cellulose chromatography and sucrose gradient centrifugation. The purified mRNA directs the synthesis of a product that yields tryptic peptides corresponding to those derived from authentic myeloma protein and that forms a specific immunoprecipitate with antibody directed against the MOPC-41 protein. The fact that the light-chain mRNA anneals to oligothymidylic acid-cellulose suggests that it, like several other eukaryotic mRNAs, contains a region rich in adenylic acid residues. The most active fractions of light-chain mRNA, representing about 0.1% of the RNA originally extracted from membrane-bound myeloma polysomes, sediment as a discrete peak with an s(20,w) of about 13, roughly corresponding to an RNA molecule containing 850 bases. The results suggest that the light-chain mRNA is monocistronic and that it contains about 200 more bases than would be necessary to encode the variable and constant regions of a single light-chain molecule.

Correlation of messenger RNA function with adenylate-rich segments in the genomes of single-stranded RNA viruses

Oligonucleotides enriched in adenylate residues have been demonstrated in the genomes of two positive-strand RNA viruses, Sindbis and Columbia SK. Such oligonucleotides were not found in the genome of vesicular stomatitis virus, a negative-strand virus. The adenylate-rich oligonucleotides from Sindbis and Columbia SK viruses appeared similar when analyzed by zonal sedimentation in sucrose-sodium dodecyl sulfate.

Purification of biologically active globin messenger RNA by chromatography on oligothymidylic acid-cellulose

A convenient technique for the partial purification of large quantities of functional, poly(adenylic acid)-rich mRNA is described. The method depends upon annealing poly(adenylic acid)-rich mRNA to oligothymidylic acid-cellulose columns and its elution with buffers of low ionic strength. Biologically active rabbit globin mRNA has been purified by this procedure and assayed for its ability to direct the synthesis of rabbit globin in a cell-free extract of ascites tumor. Inasmuch as various mammalian mRNAs appear to be rich in poly(adenylic acid) and can likely be translated in the ascites cell-free extract, this approach should prove generally useful as an initial step in the isolation of specific mRNAs.

A novel DNA polymerase activity found in association with intracisternal A-type particles

A DNA polymerase activity that promotes the synthesis of poly(dT) has been found in association with intracisternal A-type particles isolated from several mouse tumors. The poly(dT) synthesis activity requires a DNA or RNA primer, is optimal at high salt concentration, prefers magnesium over manganese, and is stimulated by poly(rA). No significant incorporation of dAMP, dGMP, or dCMP was detected in the presence of several RNA and DNA template-primers. The enzyme activity differs in several of its properties from the poly(rA)-directed DNA polymerase activity associated with Rauscher murine leukemia virus.

Polyadenylic acid sequences in the virion RNA of poliovirus and Eastern Equine Encephalitis virus

Poliovirus virion RNA contains a single covalently bound sequence of polyadenylic acid which is approximately 49 nucleotides long. A single, slightly longer polyadenylic acid sequence is contained in Eastern Equine Encephalitis virus RNA. Since these viruses are otherwise dissimilar these sequences may play a common role in viral replication, possibly in translation of the viral RNA.