Studies of oogenesis in Urechis caupo. II. Accumulation during oogenesis of carbohydrate, RNA, microtubule protein, and soluble, mitochondrial, and lysosomal enzymes.
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The purine analogue, 8-azaguanine, was added to cultures of the parasporal crystal-forming organism Bacillus cereus var. alesti at different times during growth and synchronous sporulation. The effect of its incorporation has been studied with particular reference to cell growth, nucleic acid composition, cytology, and the synthesis of the spore and crystal protein. Additions of the analogue during any stage of growth prevented further cell proliferation and all spore and crystal formation. Since both nucleic acids continued to be formed, cells of an increased size developed, containing large masses of chromatin in the form of condensed balls or axial cords. Lipid-containing inclusions also appeared following these additions and were usually aggregated at the centre or poles of the cells. The analogue could be isolated as the ribonucleotide from both the acid soluble and RNA fractions of these inhibited cells. Additions of the analogue following commencement of sporulation did not prevent either spore or crystal formation or affect the nucleic acid content of the sporulating cells. However, as before, the 8-azaguanine was incorporated into both the acid soluble and RNA of the cells, but not into these fractions of the spores ultimately formed. The implications of these findings are discussed in relation to crystal protein synthesis.
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A therapeutic dose of labelled 5-fluorouracil (5-FU) was infused via the hepatic artery during 30 min with or without a simultaneous temporary clamping of the portal vein in a model of secondary liver cancer in Wistar rats. After another 60 min, the incorporation of 5-FU into the acid soluble fraction, RNA and DNA was determined in tumor, liver, small intestine, kidney, and bone marrow. The liver and intestinal nucleotide profiles were examined with isotachophoresis. Temporary portal vein clamping caused the following changes, as compared with the control group with intraarterial infusion only: in the liver, the incorporation of 5-FU into the acid soluble fraction increased without a concomitant increase into the RNA or of the level of (F)UTP. Liver ATP decreased. In the tumor, the ratio of RNA to acid soluble fraction labelling decreased. There was a generally decreased ratio of tumor to peripheral normal tissue (small intestine and kidney) labelling. In conclusion, portal vein clamping in conjunction with hepatic arterial administration of 5-FU led to a decreased anabolism of 5-FU in the liver and tumor, and increased systemic drug exposure. It is not known how this interferes with the therapeutic effect.
Gottlieb, David (University of Illinois, Urbana), and James L. Van Etten. Changes in fungi with age. I. Chemical composition of Rhizoctonia solani and Sclerotium bataticola. J. Bacteriol. 91:161-168. 1966.-The chemical composition of the mycelium of Rhizoctonia solani and Sclerotium bataticola was determined in cells of various ages. The percentage, per unit of dry weight, of soluble amino nitrogen, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), ergosterol, and protein decreased with age in both fungi. Total lipids and fatty acids increased with age in S. bataticola but remained constant in R. solani. Total carbohydrate increased with age in R. solani and decreased in S. bataticola. Fewer changes with age were observed when the results were calculated in ratio to DNA. There was no change in the ratios of protein, RNA, and soluble amino nitrogen to DNA with age in either fungus, but the ergosterol-DNA ratio decreased. The total lipid-DNA ratio and the total fatty acid-DNA ratio increased with age in both fungi, whereas the total carbohydrate-DNA ratio increased in R. solani but remained constant in S. bataticola. Both fungi contained myristic, palmitic, palmitoleic, stearic, oleic, and linoleic acids. In addition, R. solani contained pentadecanoic acid, and S. bataticola had myristoleic, linolenic, and arachidic acids. No marked change in the fatty acid pattern of S. bataticola was observed with age, whereas in R. solani the percentage of linoleic acid per total fatty acids decreased slightly when oleic acid increased.
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The effect of aflatoxin B1 on the DNA template and DNA-dependent RNA polymerases in buffalo liver was studied. Aflatoxin B1 inhibited both Mg2+- and Mn2+-activated RNA polymerases in a dose-dependent manner. At 10 micrograms the inhibition of both enzymes was almost complete. The inhibitory effect on the solubilized enzymes was higher than the chromatin-bound, suggesting a direct effect at the enzyme level. On the other hand, incubating DNA or deoxyribonucleoprotein (DNP) with 2 micrograms aflatoxin reduces its transcriptional capacity with a greater effect on the Mg2+-activated RNA polymerase than the Mn2+-activated enzyme. These results suggest that aflatoxin B1 inhibits in vitro transcription in buffalo liver at both enzyme and template levels.
The instability of RNA in solutions during storage and travel is an impediment to its utilization in routine diagnostics. A robust and simple approach to the problem of RNA protection and processing is offered by storage of RNA desiccated with processing procedures that do not solublize the RNA until the beginning of reverse transcription. The feasibility of this general approach was tested with coxsackievirus B4 (CVB-4) from blood or culture fluid held on a storage and transport medium (FTA(R)) and analysed by reverse transcriptase PCR (RT-PCR) without removing the RNA from the FTA(R) until reverse transcription. Phase-trapping techniques based on water-miscible solvents such as ethanol or phenol were compared with simple buffers and concentrated lithium chloride solutions. RT-PCR detection of viral RNA reached a sensitivity of approximately 0.1 fg, which is comparable with other non-nested PCR techniques. Whole blood as a virus vehicle significantly interfered with CVB-4 detection, but to an acceptable degree. Desiccation-storage of the RNA of CVB-4 appears to be unaffected by weeks on the storage medium under ambient conditions. These characteristics indicate that this approach forms a credible developmental base for RNA-based pathogen diagnostics with particular application to the problem of transporting potentially infectious body fluids to a centralized laboratory for analysis.
Human catechol-O-methyltransferase (hCOMT) cDNA was used to express the recombinant hCOMT enzyme in sufficient quantities in prokaryotic as well as in eukaryotic cells to allow kinetic studies. When human membrane-bound catechol-O-methyltransferase (MB-COMT; amino acids 1-271) and the soluble catechol-O-methyltransferase COMT (S-COMT; delta membrane anchor hCOMT; amino acids 27-271), with the latter lacking the first 26 hydrophobic amino acids, were expressed in Escherichia coli, a relatively high-level synthesis of catalytically active enzymes was obtained. Insertion of the human MB-COMT-coding sequence into an eukaryotic expression vector under transcriptional control of the cytomegalovirus (CMV) promoter and enhancer yielded large quantities of hCOMT in human kidney 293 cells. Subcellular fractionation of 293 cells transfected with pBC12/CMV-hCOMT showed hCOMT to be located predominantly in the membrane fraction. The catechol-O-methyltransferase (COMT) activity was measured in cytosolic and membrane fractions at 37 degrees C, giving values of 33 and 114 units/mg of protein, respectively (1 unit produces 1 nmol of guaiacol/h). Km values were 10 microM for MB-COMT and 108 microM for S-COMT, indicating that recombinant MB-COMT exhibits a higher affinity for catechol as the substrate than the soluble form. RNA blot analysis of human hepatome cells (Hep G2), kidney, liver, and fetal brain revealed only one species of hCOMT mRNA of approximately 1.4 kb. Its level in these various tissues was similar to those of COMT protein in each tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
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LéJohn, Herbert B. (Purdue University, Lafayette, Ind.), and James S. Lovett. Ribonucleic acid and protein synthesis in Rhizophlyctis rosea zoospores. J. Bacteriol. 91:709-717. 1966.-The uniflagellate zoospores of Rhizophlyctis rosea display active motility and a high endogenous respiratory metabolism, but neither growth nor net ribonucleic acid (RNA) or protein synthesis can be measured by ordinary procedures. Nevertheless, synthesis can be detected with isotopic precursors. Uracil-C(14) is incorporated slowly into both the soluble and ribosomal RNA. Analysis of zoospore extracts (on diethylaminoethyl cellulose columns or sucrose gradients) after various periods of labeling suggested that most of the uracil incorporation represents slow synthesis of ribosomal precursor RNA and, ultimately, ribosomes. Actinomycin D caused an 80% inhibition of uracil incorporation. The most rapidly labeled RNA was susceptible to extensive degradation in cells treated with actinomycin, but the percentage of stable RNA increased with the time of incorporation before addition of the antibiotic. Neither the effects of actinomycin nor the results of chase experiments have established unequivocally the existence of turnover or the presence of a short-lived "messenger" fraction in motile spores. Both leucine and methionine were slowly incorporated into a spectrum of cellular proteins. The methyl group of C(14)-methylmethionine also served as a methyl donor for the methylation of soluble RNA but not of ribosomal RNA. The observations that some of the newly synthesized RNA and protein occur in the intact 82S ribosomes and that actinomycin inhibits the low level of protein synthesis provide some indirect evidence for a very low rate of "messenger" synthesis and turnover in zoospores.
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To derive structural information about the vesicular stomatitis virus (VSV) nucleocapsid (N) protein, the N protein and the VSV phosphoprotein (P protein) were expressed together in Escherichia coli. The N and P proteins formed soluble protein complexes of various molar ratios when coexpressed. The major N/P protein complex was composed of 10 molecules of the N protein, 5 molecules of the P protein, and an RNA. A soluble N protein-RNA oligomer free of the P protein was isolated from the N/P protein-RNA complex using conditions of lowered pH. The molecular weight of the N protein-RNA oligomer, 513,879, as determined by analytical ultracentrifugation, showed that it was composed of 10 molecules of the N protein and an RNA of approximately 90 nucleotides. The N protein-RNA oligomer had the appearance of a disk with outer diameter, inner diameter, and thickness of 148 +/- 10 A, 78 +/- 9 A, and 83 +/- 8 A, respectively, as determined by electron microscopy. RNA in the complexes was protected from RNase digestion and was stable at pH 11. This verified that N/P protein complexes expressed in E. coli were competent for encapsidation. In addition to coexpression with the full-length P protein, the N protein was expressed with the C-terminal 72 amino acids of the P protein. This portion of the P protein was sufficient for binding to the N protein, maintaining it in a soluble state, and for assembly of N protein-RNA oligomers. With the results provided in this report, we propose a model for the assembly of an N/P protein-RNA oligomer.
Deproteinized globin poly(A) + mRNAs reassociate readily in vitro with soluble RNA-binding proteins of the cytosol; reconstituted messenger ribonucleoprotein complexes are obtained which are very similar to native globin polyribosomal-mRNP as far as bouyant density in Cs2SO4 and the composition of proteins which can be crosslinked to the mRNA are concerned. Proteins thus identified bind specifically to mRNA and not to ribosomal RNA or any synthetic oligonucleotides, with one exception: a 78-kDa protein could be cross-linked to poly(A).
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Association between RNAs with preprogrammed molecular recognition units can be quantified by using cationic, water-soluble conjugated polymers. The method uses a fluorophore-labeled probe RNA (RNA-F*), which is treated with a target structure (RNA-T). Heterodimer formation, (RNA-T/RNA-F*), increases the total negative charge on the F*-bearing macromolecule and reduces the number of negatively charged molecules (relative to unbound RNA-T+ RNA-F*). On the basis of electrostatic interactions, we anticipated more effective binding between CCP and (RNAT/RNA-F*), a reduction of the average CCP- - -F* distance, and more effective FRET upon excitation of the conjugated polymer. The resulting signals benefit from the optical amplification characteristic of emissive conjugated polymers. Solution dissociation constants can be determined by monitoring F* intensity changes as a function of [RNA-F*] and the ratio: [I(T) - I(NB)]/I(NB), where I(T) and I(NB) are the F* intensities in the presence of the target RNA (RNA-T) and a nonbinding RNA (RNA-NB), respectively, while keeping the concentration of the conjugated polymer constant. By focusing on [I(T) - I(NB)]/I(NB) as a function of RNA concentration, one can detect the concentration range wherein increased fluorescence is the result of dimerization.