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At least 1,639 records · Page 91Linked to original sources
PubMed1981

Unusual pattern of ribonucleic acid components in the ribosome of Crithidia fasciculata, a trypanosomatid protozoan.

In a previous study from this laboratory, presumptive ribosomal ribonucleic acid (RNA) species were identified in the total cellular RNA directly extracted from intact cells of the trypanosomatid protozoan Crithidia fasciculata (M. W. Gray, Can. J. Biochem. 57:914-926, 1979). The results suggested that the C. fasciculata ribosome might be unusual in containing three novel, low-molecular-weight ribosomal RNA components, designated e, f, and g (apparent chain lengths 240, 195, and 135 nucleotides, respectively), in addition to analogs of eucaryotic 5S (species h) and 5.8S (species i) ribosomal RNAs. In the present study, all of the presumptive ribosomal RNAs were indeed found to be associated with purified C. fasciculata ribosomes, and their localization was investigated in subunits produced under different conditions of ribosome dissociation. When ribosomes were dissociated in a high-potassium (880 mM K+, 12.5 mM Mg2+) medium, species e to i were all found in the large ribosomal subunit, which also contained an additional, transfer RNA-sized component (species j). However, when subunits were prepared in a low-magnesium (60 mM K+, 0.1 mM Mg2+) medium, two of the novel species (e and g) did not remain with the large subunit, but were released, apparently as free RNAs. Control experiments have eliminated the possibility that the small RNAs are generated by quantitative and highly specific (albeit artifactual) ribonuclease cleavage of large ribosomal RNAs during isolation. In terms of RNA composition and dissociation properties, therefore, the ribosome of C. fasciculata is the most "atypical" eucaryotic ribosome yet described. These observations raise interesting questions about the function and evolutionary origin of C. fasciculata ribosomes and about the organization and expression of ribosomal RNA genes in this organism.

Animals↗
PubMed1994

Human fallopian tube expresses transforming growth factor (TGF beta) isoforms, TGF beta type I-III receptor messenger ribonucleic acid and protein, and contains [125I]TGF beta-binding sites.

Reverse transcription-polymerase chain reaction analysis of total ribonucleic acid (RNA) from human fallopian tubes revealed that transforming growth factor-beta 1 (TGF beta 1), TGF beta 2, and TGF beta 3 as well as TGF beta type I-III messenger RNA (mRNA) are expressed in this tissue. In situ hybridization and immunohistochemical observations using TGF beta isoform-specific [35S]40-mer oligonucleotide probes and polyclonal antibodies indicate that all the tubal cell types express TGF beta isoforms and TGF beta type II receptor mRNA and protein. The tubal epithelial cells appeared to express more TGF beta 1 mRNA and TGF beta 1-3 proteins than other cell types, whereas TGF beta 2 and TGF beta 3 mRNA appeared to be equally expressed in the epithelial and other tubal cell types. In the epithelial lining, both ciliated and nonciliated cells in the ampullary and isthmus regions appeared to express mRNA and protein for TGF beta s and TGF beta type II receptor at a similar level. The intensity of immunostaining of TGF beta s in tubal epithelial cells was lower during the early proliferative and late secretory than the mid- to late proliferative and early to midsecretory phases of the menstrual cycle and reduced during the postmenopausal period. However, the intensity of immunoreactive TGF beta type II receptor in these cells did not vary during the cycle as much as that seen with TGF beta s. Quantitative autoradiography of [125I]TGF beta 1 indicates that fallopian tubes contain specific binding sites for TGF beta 1. Net grain density per 100 microns 2, calculated for different cell types, indicates that the epithelial cells had a significantly higher grain density than other tubal cell types (P < 0.05), with similar densities in the late proliferative and early secretory phases of the cycle. These results provide the first evidence that human fallopian tubes express mRNA and protein and contain specific binding sites for TGF beta system, suggesting an autocrine/paracrine role for TGF beta in a variety of tubal functions.

Autoradiography↗
PubMed1993

Localization of the placental form of glutathione S-transferase messenger ribonucleic acid in human glioma cell lines.

Localization of the placental form of glutathione S-transferase (GST-pi) messenger ribonucleic acid (mRNA) in three human glioma cell lines (A172, T98G, and Tc77) was studied by in situ hybridization with digoxigenin-labeled GST-pi complementary DNA followed by immunocytochemistry with antidigoxigenin antibody. A172 glioma cells showed hardly any GST-pi mRNA. GST-pi mRNA was recognized in the cytoplasm of T98G and Tc77 glioma cells. Tc77 cells especially had a strong expression of GST-pi mRNA. GST activity and the expression of GST-pi protein were also investigated for these cell lines. Cytosolic GST activity was determined with 1-chloro-2,4-dinitrobenzene as substrate, and the results were as follows: A172, 24.3 +/- 2.0; T98G, 60.8 +/- 4.9; Tc77, 84.0 +/- 1.7 (mean +/- standard deviation, in nanomoles per minute per milligram of protein). The expression level of GST-pi protein analyzed by Western blotting with anti-GST-pi antibody as a primary antibody was compatible with the results of both in situ hybridization of GST-pi mRNA and GST activity. A172 cells possessing the lowest GST activity showed a weak expression of both GST-pi mRNA and protein. Tc77 cells with the highest GST activity had the strongest expression of GST-pi mRNA and protein in three cell lines. The GST-pi expression of T98G cells was moderate. These findings indicate that some human glioma cells have GST-pi expression and that GST-pi in glioma cells is the major isozyme of GSTs for the significant activity of glutathione conjugation.

Blotting, Western↗
PubMed2002

Multiple messenger ribonucleic acid transcripts and revised gene organization of the human TSH receptor.

Northern blot analysis of human TSH receptor (hTSHR) messenger ribonucleic acid (mRNA) expression has previously demonstrated multiple species of transcripts in the thyroid gland, suggesting the presence of multiple transcription initiation sites, alternatively spliced forms or alternate polyadenylation (poly(A)) sites. The first two have already been reported elsewhere. To clarify alternate poly(A) sites in the hTSHR gene, the present study was designed to characterize three full-length hTSHR cDNAs with distinct poly(A) signals that we have previously cloned. The comparison of the nucleotide sequencing data on the 3'UTR of these three clones to the Draft Human Genome in NCBI database revealed that the 3' segment of exon 10 of hTSHR gene contains three tandem repeats of the poly(A) sites, from which are expressed three full-length TSHR mRNAs with distinct 3'UTR length. The longest one appears to be a predominant transcript. From these data, together with (i) the previously reported organization of hTSHR genome and (ii) use of the Draft Human Genome to localize the unidentified sequence in the alternatively spliced form of truncated hTSHR, we propose the complete structure of hTSHR gene. Rather than 10 exons, our analysis suggests that hTSHR gene seems to contain 13 exons and 12 introns. At least three full-length TSHR mRNAs with distinct poly(A) sites and five alternatively spliced forms of TSHR mRNAs are expressed from the single hTSHR gene.

Alternative Splicing↗
PubMed2001

Guidelines for laboratory test result reporting of human immunodeficiency virus type 1 ribonucleic acid determination. Recommendations from a CDC working group. Centers for Disease Control.

Monitoring human immunodeficiency virus type 1 (HIV-1) ribonucleic acid levels (also known as HIV viral load) has become the standard of care for monitoring response to therapy in HIV-infected patients. In 1999, CDC published updated surveillance case definitions for HIV infection and acquired immunodeficiency syndrome (AIDS) reporting, including positive results of HIV-1 viral detection tests (CDC. Guidelines for national human immunodeficiency virus case surveillance, including monitoring for human immunodeficiency virus infection and acquired immunodeficiency syndrome. MMWR 1999;48[No. RR-131:1-28). Since 1996, an increased number of public and private laboratories have begun performing viral load tests. Results obtained with available test methods are variable, and laboratories present these results in different ways, indicating that guidelines to promote standard practice in reporting of test results are warranted. This report provides guidelines for standardized reporting of viral load test results by licensed laboratories to health-care providers and facilities for public health case reporting of HIV infection and AIDS. Recommended standards were developed through data review, input involving a working group of physicians and laboratorians experienced in viral load testing, and an assessment of laboratory practices. These guidelines were discussed, refined, and endorsed at the annual Human Retrovirus and Hepatitis C Laboratory Testing Conference, held March 6-9, 2000, in Charlotte, North Carolina, with participation of representatives from public health, hospital, independent, and blood-collection-facility laboratories. Adoption of these guidelines by all public and private laboratories that perform HIV viral load testing will improve the quality and usefulness of viral load test results for the physician ordering the test and for reporting to public health departments.

Clinical Laboratory Techniques↗
PubMed1977

[Change in the hybridization characteristics of rapidly-labelled ribonucleic acids during tumor "progression"].

The hybridization properties of in vivo rapidly labeled with 14C-orotate both nuclear and mitochondrial ribonucleic acids from the MD hepatoma were investigated. During tumour progression the repression of nuclear genome found at its early stages (5th to 6th passages) is replaced by the increase of hybridizability of nuclear DNA with a population of 14C-RNA's as well as by the appearance of new classes of pulse labeled RNA's. In other words, at late stages of tumour progression (60th passage) there occur a de-repression of nuclear genome. The hybridizability of mitochondrial RNA with nuclear DNA remains almost the same at different tumour progression stages. The results obtained are discussed in the light of literature data available.

Animals↗
PubMed1995

Developmental expression and anatomical localization of endothelin-1 messenger ribonucleic acid and immunoreactivity in the rat placenta: a northern analysis and immunohistochemistry study.

Endothelin-1 (ET-1) immunoreactivity and messenger ribonucleic acid (mRNA) have previously been identified in the mammalian placenta. In the present study we examined the developmental expression of ET-1 mRNA and the localization of ET-1 mRNA and immunoreactivity within the rat placenta. Placental tissues were removed from primiparous Sprague-Dawley rats on gestational days 14, 18, and 21 and processed for blot hybridization of ET-1 mRNA and immunohistochemistry of ET-1 immunoreactive peptide. Placental tissue contained a 2.3 kb size ET-1 mRNA transcript. Placental ET-1 mRNA abundance increased approximately five-fold from day 14 to 21 of gestation (p = 0.02). To localize ET-1 mRNA within the rat placenta, day 18 placentas were dissected into the basal and labyrinth layers and processed separately for blot hybridization of ET-1 mRNA. ET-1 mRNA localized to the labyrinth zone. This was confirmed by immunohistochemical staining of day 18, 20, and 21 placental tissues with an antiserum specific to ET-1. The presence of ET-1 immunoreactivity and the stage-specific increase in ET-1 mRNA in the rat placenta suggest that ET-1 may exert paracrine effects on the placenta or uterus of the pregnant rat.

Animals↗
PubMed1979

Degradation of ribonucleic acid by immobilized ribonuclease.

An immobilized enzyme (pancreatic ribonuclease bound to porous titania) was investigated for the degradation of purified yeast ribonucleic acid as a substrate. The immobilized enzyme is active and stable in the pH range 4--8. Dependence of enzymatic activity on ionic strength, pH, temperature, fluid flow rate, and substrate concentration were investigated. A cumulative fluid residence time of 6 sec is sufficient for 50% substrate conversion at 25 degrees C and pH 7.0. The critical flow rate (i.e., the fluid flow rate necessary to remove film diffusion resistance) approximately doubles with each 10 degree C rise in reaction temperature. The critical flow rates obtained in this study are about 40 times greater than those obtained for a similar study on immobilized glucose oxidase. Arrhenius plots gave activation energies of -9.6 and -7.1 kcal/g mol at pH 4.6 and 7.0, respectively. The work reported herein is a bench-scale investigation of an immobilized enzyme with primary emphasis on the mass transfer and kinetic characteristics of the system. The rapid reaction rates obtainable at relatively low temperatures offer a potential alternative method of purifying yeast single cell protein (SCP) with miminum loss of desired protein. The key questions are how such a system would react in a yeast homogenate, what conditions in such a system must be controlled, and what type of immobilized reactor should be utilized, if such further work continued to show promise.

Ceramics↗
PubMed1988

A study of pituitary thyrotropin, its subunits, and messenger ribonucleic acids in nonthyroidal illness.

We studied serum TSH, pituitary TSH and alpha and beta-subunits of TSH and their messenger ribonucleic acids (mRNAs) in three models of nonthyroidal illness (NTI) in the rat, ie diabetes mellitus (1 wk after 65 micrograms streptozotocin/g BW IP), turpentine oil-injection (8 to 48 hours after after a dose of 5 microliter/g bw SC), and complete fasting for 72 hours. Euthyroid, hypothyroid (two months after thyroidectomy) and hyperthyroid rats (30 micrograms T4/d X 7, SC) were also studied for comparison. Pituitary TSH, alpha and beta subunits and serum TSH, T4, and T3 were measured by RIA. Pituitary mRNAs coding for common delta and TSH-beta subunits were determined by cytoplasmic dot hybridization technique using specific [32P]-cDNA probes. In all NTI models there were significant decreases in serum levels of TSH, T4, and T3, but no significant changes were observed in the pituitary content of TSH, and alpha and TSH-beta subunits. Hypothyroid rats had an increase in serum TSH, pituitary TSH, and pituitary TSH-beta subunit and a decrease in pituitary alpha subunit. On the other hand, hyperthyroid rats showed a decrease in serum TSH, pituitary TSH, and pituitary TSH-beta subunit, while there was no change in the alpha subunit. A significant reduction in the pituitary TSH-beta mRNA levels was observed in all NTI models and hyperthyroidism, while TSH-beta mRNA was increased in thyroidectomized rats. alpha-mRNA was increased only in the pituitary of hypothyroid rats; there was no appreciable change in the pituitary alpha-mRNA in the various other pituitary groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

Inhibitory effect of calcium-binding protein regucalcin on ribonucleic acid synthesis in isolated rat liver nuclei.

The effect of regucalcin, a Ca2+-binding protein isolated from rat liver cytosol, on ribonucleic acid (RNA) synthesis in the nuclei of normal rat liver and of regenerating rat liver was investigated. The liver weight at 1 day after partial hepatectomy was increased about 50% of that of sham-operated (control) rats. Calcium chloride (1.0-20 microM Ca2+ as final concentration) was added into the reaction mixture of nuclear RNA synthesis. RNA synthesis was established by incorporation of [3H]-uridine 5'-triphosphate (UTP) into the nuclear RNA. Addition of Ca2+ (5 and 10 microM) caused a significant increase of RNA synthesis in the nuclei from control rat liver. Such effect of Ca2+ was potentiated in the nuclei of regenerating liver; nuclear RNA synthesis was increased about 2 fold by the 1.0 and 2.5 microM Ca2+ addition. The stimulatory effect of Ca2+ was significantly inhibited by the presence of alpha-amanitin (10(-8) M), an inhibitor of RNA polymerase II. The presence of regucalcin (0.25 and 0.5 microM) significantly inhibited RNA synthesis in the nuclei from control rat liver and from regenerating rat liver. The inhibitory effect of regucalcin was remarkable in the presence of EGTA (0.5 mM), and it was weakened by the addition of Ca2+ (5 microM). Such regucalcin effect was not seen in the presence of alpha-amanitin. The presence of anti-regucalcin IgG in the reaction mixture significantly increased RNA synthesis in the nuclei from control rat liver, indicating that the endogenous regucalcin may be involved in nuclear RNA synthesis. The present results demonstrate that regucalcin can inhibit nuclear RNA synthesis in rat liver. Regucalcin may have an inhibitory role in the regulation of liver nuclear RNA synthesis.

Amanitins↗
PubMed1974

Effects of some antiviral isatinisothiosemicarbazones on cellular and viral ribonucleic acid synthesis in Mengovirus-infected FL cells.

Three antiviral isatinisothiosemicarbazones strongly inhibited the incorporation of [(3)H]uridine into the ribonucleic acid (RNA) of FL cells as a consequence of the inhibition of uridine transport. After prelabeling of cells at a low temperature (1 h at 16 C) with uptake of [(3)H]uridine into the acid-soluble nucleotide pool, the later addition of the test compounds revealed only a small or negligible influence on host-directed RNA synthesis. The pulse-labeled soluble nucleotide pool of FL cells was sufficient to give a gradual increase in incorporation into RNA over a period of 7 h. With the same method of prelabeling at the beginning of the experiment, it was also possible to detect virus-induced RNA synthesis in the presence of actinomycin D. In this way the specific inhibitory action of the three isatinisothiosemicarbazones on viral RNA synthesis could be demonstrated.

Animals↗
PubMed1972

Ribosomal ribonucleic acid synthesis and maturation in the blue-green alga Anacystis nidulans.

Methods are described for preparation of pulse-labeled ribonucleic acid (RNA) from the blue-green alga Anacystis nidulans. Synthesis of labeled RNA was found to be in part dependent on concurrent photosynthesis and was inhibited by the antibiotic streptolydigin. Mature 23S ribosomal RNA (rRNA) appeared before mature 16S rRNA. Formation of either molecule was inhibited by chloramphenicol, and RNA species of lesser mobility accumulated. These species may be precursors of the mature forms. Maturation of 16S rRNA was also inhibited by streptolydigin. (The effect of this antibiotic on 23S rRNA maturation was not examined). In many respects, ribosomal RNA synthesis and maturation in this blue-green alga appear to follow the pattern already established for bacteria.

Anti-Bacterial Agents↗
PubMed1973

Stable ribonucleic acid synthesis in stringent (rel+) and relaxed (rel-) polyamine auxotrophs of Escherichia coli K-12.

The relationship of polyamines to stable ribonucleic acid (RNA) synthesis under conditions of amino acid withdrawal or chloramphenicol treatment was examined with the use of a closely related rel(+), rel(-) pair conditionally incapable of synthesizing putrescine. Under conditions of polyamine starvation, the cellular sperimidine level fell to one-third to one-half of the value observed in putrescine-supplemented cultures and putrescine became undetectable; cadaverine was synthesized by both strains, but the relaxed strain, MA 252, accumulated less cadaverine per cell than its stringent twin, MA 254. Upon amino acid withdrawal, the stringent strain remained stringent whether starved of or supplemented with polyamines. Similarly, the relaxed strain was capable of making RNA either with or without polyamine starvation. On the addition of chloramphenicol or upon amino acid withdrawal in the relaxed strain, supplementation with spermidine had no effect on the initial rate of RNA synthesis, although RNA accumulation was greater in the presence of added spermidine. Spermidine added at the conclusion of RNA synthesis prompted additional synthesis, although preincubation with spermidine again had no effect on the initial rate. All forms of stable RNA species were made with polyamine supplementation. The present data appear to rule out the possibility that polyamines are primary causative agents in stimulating RNA synthesis, but rather suggest an indirect or secondary role for spermidine in which the polyamines "stimulate" stable RNA synthesis probably by relieving RNA product inhibition of RNA synthesis.

Amino Acids↗
PubMed1976

Escherichia coli mutants with altered ribosomal ribonucleic acid metabolism.

This paper reports the partial characterization of two temperature-sensitive mutants of Escherichia coli with alterations in ribosomal ribonucleic acid (rRNA) metabolism at the restrictive temperature. Both mutants continue to synthesize deoxyribonucleic acid and protein at 42 C but showed little or no accumulation of RNA. Both strains are inducible for beta-galactosidase at the restrictive temperature, showing that messenger RNA synthesis continues and that the messenger RNA is translated into functional protein. One of the strains, 2S474, shows a rather severe depression (sevenfold) in the synthesis of all classes of RNA at 42 C. In addition, the synthesis of rRNA is selectively depressed, with the percentage of rRNA synthesis. However, there appears to be a selective depression in the rate of rRNA synthesis and, possibly, in the conversion of p16S rRNA to m16S rRNA.

Bacterial Proteins↗
PubMed1977

Regulation of glnA messinger ribonucleic acid synthesis in Klebsiella aerogenes.

We examined wild-type and mutant strains of Klebsiella aerogenes for the relative amounts of ribonucleic acid (RNA) hybridizing specifically to deoxyribonucleic acid from a transducing phage carrying glnAK, the structural gene for glutamine synthetase. Our data showed a positive correlation between the intracellular level of glutamine synthetase and the level of glnA messenger RNA; we were unable to detect glnA messinger RNA in strains devoid of glutamine synthetase protein. Therefore, it is possible that transcription of glnA is not regulated simply by repression mediated through the glutamine synthetase protein; rather, autogenous control in this system may involve activation of transcription. Our experiments also suggest that the promotor of the glnA gene is located at the rha proximal end of the gene.

Genes↗