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Biomedical subjects

R Muñoz

Publications and source records attributed to R Muñoz.

At least 91 records · Page 5Linked to original sources
PubMed1994

Cusativin, a new cytidine-specific ribonuclease accumulated in seeds of Cucumis sativus L.

Dry seeds of Cucumis sativus L. were found to contain a heat-sensitive endoribonuclease of a novel type which we have named cusativin. It was purified to apparent electrophoretic homogeneity by chromatography through S-Sepharose Fast Flow, Sephadex G-75, CM-Sepharose, Superdex 75-FPLC (fast protein liquid chromatography) and Mono S-FPLC. It is a single unglycosylated polypeptide chain with an apparent molecular mass (M(r)) of 22900. Polyclonal anti-cusativin antibodies raised in rabbits only reacted with melonin, the translation inhibitor from Cucumis melo L. Functional, Western blot and enzyme-linked immunosorbent assay (ELISA) analyses indicated that cusativin is present in the coat and cotyledons of dry seeds, but not in embryonic axes. Cusativin is accumulated in maturing seeds. By contrast, after seed germination there is degradation of the cusativin present in cotyledons but not that present in the seed coat. The preference of cusativin for polynucleotide cleavage was poly(C) >> poly(A) acids, poly(U) and poly(G) being unaffected by cusativin. Under the denaturing conditions used for RNA sequencing, cusativin acted only on poly(C). Cusativin proved to be useful for RNA sequencing, in particular, complementing the data obtained with RNase CL3. Cusativin represents a new class of plant RNase and, as far as we are aware, is the first plant enzyme that shows cleavage specificity for cytidine under the denaturing conditions of RNA sequencing.

Amino Acid Sequence↗
PubMed1994

Isolation and characterization of two new N-glycosidase type-1 ribosome-inactivating proteins, unrelated in amino-acid sequence, from Petrocoptis species.

Two new N-glycosidase type-1 ribosome-inactivating proteins (RIPs), denoted petroglaucin 1 and petrograndin, respectively, were isolated from the plants Petrocoptis glaucifolia (Lag.) Boiss sp. viscosa (Rothm.) Lainz and Petrocoptis grandiflora Rothm. These new RIPs do not share H2N-terminal amino-acid sequence homology with petroglaucin (now denoted as petroglaucin 2), the only other type-1 RIP to be isolated from P. glaucifolia (Arias et al. (1992) Planta 186, 532-540). Petroglaucin 1 shares amino-acid sequence homology with RIPs from Cucurbitaceae while petroglaucin 2 and petrograndin do so with saporins and dianthin 30 (Caryophyllaceae). The new RIPs strongly inhibited protein synthesis at subnanomolar concentrations in rabbit reticulocyte lysates and other eukaryotic cell-free systems, but they were inactive on bacterial ribosomes.

Amino Acid Sequence↗
PubMed1994

Burkitt lymphoma with a duplication of der(8)t(2;8). Interpretation of a complex karyotype by chromosome painting.

A 51-year-old male patient was diagnosed with Burkitt lymphoma 3 months after cardiac transplantation. The bone marrow karyotype was very complex, and to better define the complex karyotype we used the in situ suppression hybridization technique. Previously we interpreted this karyotype to be: 48,XY,t(2;8)(p11;q24), +der(2)t(2;8)(p11;q24),del(2)(q23), +7, +der(8)t(2;8)(p11;q24), +12, -13, -18, by G banding techniques, with a duplication of the t(2;8) derivatives. After in situ hybridization we changed to a: 48,XY,t(2;8)(p11;q24),t(2;18)(q23;q22), +7, +der(8)t(2;8)(p11;q24), +12, -13, which implies duplication of only one t(2;8) derivative.

Burkitt Lymphoma↗
PubMed1994

Molecular basis of the optochin-sensitive phenotype of pneumococcus: characterization of the genes encoding the F0 complex of the Streptococcus pneumoniae and Streptococcus oralis H(+)-ATPases.

The gene responsible for the optochin-sensitive (OptS) phenotype of Streptococcus pneumoniae has been characterized. Sequence comparisons indicated that the genes involved encoded the subunits of the F0 complex of an H(+)-ATPase. Sequence analysis and transformation experiments showed that the atpC gene is responsible for the optochin-sensitive resistant (OptS/OptR) phenotype. Our results also show that natural as well as laboratory OptR isolates have arisen by point mutations that produce different amino acid changes at positions 48, 49 or 50 of the ATPase c subunit. The nucleotide sequence of the F0 complex of the Streptococcus oralis ATPase has also been determined. In addition, comparison of the sequence of the atpCAB genes of S. pneumoniae R6 (OptS) and M222 (an OptR strain produced by interspecies recombination between pneumococcus and S. oralis), and S. oralis revealed that, in M222, an interchange of atpC and atpA had occurred. We also demonstrate that optochin specifically inhibited the membrane-bound ATPase activity of the S. pneumoniae wild-type (OptS) strains, and found a 100-fold difference between OptS and OptR strains, both in growth inhibition and in membrane ATPase resistance.

Amino Acid Sequence↗
PubMed1993

Ebulin 1, a nontoxic novel type 2 ribosome-inactivating protein from Sambucus ebulus L. leaves.

A novel type 2 ribosome-inactivating protein (RIP) that we named ebulin 1 has been isolated from leaves of Sambucus ebulus L. (Caprifoliaceae). In vitro ebulin 1 strongly inhibited protein synthesis by rabbit reticulocyte lysates, rat brain, and rat liver cell-free systems but did not affect in vitro plant nor bacterial protein synthesis. Ebulin 1 is composed of two subunits, a catalytic A subunit (M(r) 26,000) and a D-galactose-binding lectin B subunit (M(r) 30,000). Amino-terminal amino acid sequence homology revealed the novelty that the ebulin 1 A-chain shares a high degree of homology not with the A-chain of other type 2 RIPs but rather with the Cucurbitaceae type 1 RIP briodin S and the anti-human immunodeficiency virus type I proteins trichosanthin and TAP 29. Upon treatment with acid aniline the rRNA from ebulin 1-treated rabbit reticulocyte ribosomes released the RNA fragment which is diagnostic of RIP catalytic action. Ebulin 1 was nontoxic to mice up to 2 mg/kg of body weight and did not inhibit protein synthesis in cultured NHC human epithelial cells which are highly sensitive to ricin.

Amino Acid Sequence↗
PubMed1993

Isolation and partial characterization of nigrin b, a non-toxic novel type 2 ribosome-inactivating protein from the bark of Sambucus nigra L.

The bark of Sambucus nigra L. contains a non-toxic novel type 2 ribosome-inactivating protein that we named nigrin b. In vitro, nigrin b strongly inhibited mammalian protein synthesis but did not affect plant nor bacterial protein synthesis. The protein (M(r) 58,000) contains two subunits, A (M(r) 26,000) and B (M(r) 32,000); linked by disulphide bridge(s). Nigrin b was found to be an rRNA N-glycosidase of the rRNA of intact mammalian ribosomes and shares a very good N-terminal amino-acid sequence homology with the anti-HIV-1 proteins TAP 29 and trichosanthin.

Amino Acid Sequence↗
PubMed1993

Messenger-dependent action of the pokeweed antiviral protein and fusidic acid on in vitro Vicia sativa L. translation.

Plant ribosome sensitivity to either pokeweed antiviral protein (PAP) or fusidic acid has been investigated using a highly coupled translation system obtained from Vicia sativa L., a plant that lacks ribosome-inactivating protein activity. Protein synthesis directed by endogenous messengers was more sensitive to PAP than synthesis of polyphenylalanine directed by polyuridylic acid. Conversely, the effects of fusidic acid were the highest in polyphenylalanine synthesis. Additionally, the concentration of magnesium ions during translation also played a determinant role in the extent of inhibition by both PAP and fusidic acid. The effects seem to be exerted on the interaction of the translational elongation factor 2 with the ribosome.

Cell-Free System↗
PubMed1992

Oxidation of hydroquinone by both cellular and extracellular grapevine peroxidase fractions.

The oxidation of hydroquinone by two peroxidase (EC 1.11.1.7) fractions obtained from the cells and spent medium of cell cultures of grapevine (Vitis vinifera cv Monastrell) has been studied, and their comparative efficacy (kcat/KM ratio) studied in both the H2O2-consuming and hydroquinone-consuming reactions. While the efficacy in the H2O2-consuming reaction is practically identical for both enzyme fractions, the cellular peroxidase has five-fold more efficacy in the hydroquinone-consuming reaction than the peroxidase located in the spent medium. Screening of cellular peroxidases capable of oxidizing hydroquinone on polyacrylamide gels, by means of a staining reaction based on the nucleophilic attack of 4-aminoantipyrine on p-benzoquinone in acidic media, reveals that all the cellular peroxidase isoenzymes are capable of oxidizing hydroquinone, probably yielding a quinone-diimine as a product of the staining reaction. Since isoperoxidases found in cellular fractions are also present in the spent medium, the values found for the different efficacies in the hydroquinone-consuming reaction must be considered as the results of the different proportions in which each peroxidase isoenzyme was found in the two fractions. The localization of a benzoquinone-generating system of high efficacy inside the plant cell, and probably located in vacuoles, is discussed with respect to the harmful role which the quinone/semiquinone pair might play in cell death, as part of the hypersensitive response expressed within the mechanism of plant disease resistance.

Ampyrone↗
PubMed1992

Genetics of resistance to third-generation cephalosporins in clinical isolates of Streptococcus pneumoniae.

Resistance to third-generation cephalosporins in a clinical isolate of Streptococcus pneumoniae was shown to be due to the production of altered forms of penicillin-binding proteins (PBPs) 2X and 1A. The cloned PBP2X gene from the resistant strain was able to transform a susceptible strain to an intermediate level of resistance. The resulting transformant could be transformed to the full level of resistance of the clinical isolate using the cloned PBP1A gene from the latter strain. Chromosomal DNA from the resistant strain (and from other resistant strains) could readily transform a susceptible strain to the full level of resistance to third-generation cephalosporins (greater than 250-fold for cefotaxime; greater than 100-fold for ceftriaxone) in a single step (transformation frequency of about 10(-5)). The resistant transformants obtained with chromosomal DNA were shown by gene fingerprinting to have gained both the PBP1A and PBP2X genes from the DNA donor.

Bacterial Proteins↗
PubMed1992

Hammett rho sigma correlation for the inhibition by indoles of coniferyl alcohol oxidation catalyzed by cell wall peroxidases.

The inhibitory effect of indole-3-acetic acid, and of its peroxidase-mediated degradation products of an indole nature, on the oxidation rate of coniferyl alcohol catalyzed by cell wall peroxidases has been studied. The results show that the inhibitory effect of indole-3-acetic acid and indole-3-carbinol may be explained, in part, by their properties as peroxidase substrates. However, I50 values for a series of indole compounds not regarded as peroxidase substrates show a good correlation with the electron-donating or electron-withdrawing nature of the 3-substituents, as judged by the linearity of the Hammett rho sigma plot. These results suggest that although the properties of indole compounds as peroxidase substrates may be responsible, in part, for their inhibitory effects on the peroxidase-mediated oxidation of coniferyl alcohol, the inhibitory effect appears to be mainly determined by the acidity of the imino group of the indole nucleus.

Catalysis↗
PubMed1992

Presence of single-chain ribosome-inactivating protein-like activities in several plant species.

The present screening work was devoted to the search for new ribosome-inactivating proteins (RIPs) in 21 plant species. Eight plants proved to be very active, inhibiting protein synthesis in eukaryotic in vitro systems (rat liver, Vicia sativa and wheat germ). They fulfil the major requirements for consideration as type 1 RIPs. Also, eight plants were found to contain haemagglutinating activity of human red cells but this was not related to the simultaneous presence of RIPs.

Animals↗
PubMed1992

[Mortality from Parkinson's disease in Spain (1980-1985). Distribution by age, sex and geographic areas].

An approximation of Parkinson's disease in Spain was carried out based on the data of mortality by this disease over the period 1980-1985. The annual number of deaths by Parkinson's disease as well as its distribution by sex, age groups and Spanish provinces was obtained from information published annually by the National Institute of Statistics in the Natural Movement of the Spanish Population. The global mortality rate during the period studied was of 2.14 per 100,000 inhabitants. The specific mortality rate by Parkinson's disease in males was slightly higher than that of females. A specific mortality rate was also observed by age groups being higher in the older age groups. From the point of geographical distribution, higher rates were observed in the northern provinces with respect to the south and in rural areas compared to provinces capitals. Following the analysis of the results obtained and upon comparing the findings published in other countries it was concluded that place of residence may be related to the development of Parkinson's disease. From these data new epidemiological studies are required oriented to the identification of the environmental factors which may play a role in the etiology of this entity.

Age Factors↗
PubMed1991

Effect of L-azetidine 2-carboxilic acid on the activity of the general amino-acid permease from Saccharomyces cerevisiae var. ellipsoideus.

Addition of the L-proline analogue L-azetidine 2-carboxylic acid to growing cultures of Saccharomyces cerevisiae var. ellipsoideus promoted fast deactivation of the general aminoacid permease, measured as L-valine uptake, without an immediate decrease in the growth rate. Cells preincubated with the analogue for 3 h were unable to restore either growth ability or general aminoacid permease activity in analogue-free medium. Eadie-Hofstee plots of L-valine uptake in the presence of the analogue are consistent with a strong reduction in the number of active molecules of the general amino-acid permease located in the plasma membrane. Inhibitory effects on protein synthesis were seen after preincubations of the yeast with the analogue for 3 h although a 30 min preincubation had no effect.

Amino Acid Transport Systems↗
PubMed1991

Changes in sensitivity of in vitro rat brain protein synthesis to the acute action of ethanol and isopropanol as a consequence of the long-term ingestion of isopropanol.

Long-term treatment of rats with isopropanol in the drinking water results in a change or process of adaptation occurring in in vitro brain protein synthesis which increases the resistance of the ribosomal machinery to the acute effect of either ethanol or isopropanol. Such an increase was observed both in the system coded by endogenous messenger and in the system coded by polyuridylic acid. In both translation systems, the adaptation seems to affect the ribosomal step of polypeptide chain elongation. The increase in resistance to the alkanols apparently did not affect the inhibitory action of puromycin, fusidic acid and cycloheximide on the ribosome.

Adaptation, Physiological↗