Benito Pereyra | Universidad Autónoma de Nuevo León (original) (raw)

Papers by Benito Pereyra

<b>Copyright information:</b>Taken from "Reduction of arsenic content in a compl... more <b>Copyright information:</b>Taken from "Reduction of arsenic content in a complex galena concentrate by "BMC Biotechnology 2004;4():22-22.Published online 13 Oct 2004PMCID:PMC526773.Copyright © 2004 Makita et al; licensee BioMed Central Ltd.

Periodontal disease has been associated with poor dental care, which promotes the accumulation of... more Periodontal disease has been associated with poor dental care, which promotes the accumulation of bacteria and the development of diseases of the mouth. Porphyromonas gingivalis are anaerobic Gram-negative bacteria found in the subgingival plaque. They are largely responsible for chronic periodontal disease. Streptococcus intermedius is a Gram positive coccus found in the supragingival plaque. The objective of the present work was to evaluate the expression of several virulence genes of P. gingivalis in a mixed culture with S. intermedius using qPCR and heterologous microarrays. P. gingivalis ATCC 33277 and W83 and S. intermedius ATCC 27335 strains were cultured and total RNA was extracted using the High Pure RNA isolation kit. Oligodeoxynucleotides were designed to make multiple comparisons with organisms. Microarray was performed to identify gene expression. To quantify gene expression, cDNA samples from three different P. gingivalis:S. intermedius ratios were diluted 10 -1 , 10 -...

Gene, 2013

Background: The aims of this population genetics study were: 1) to ascertain whether Mexicans wit... more Background: The aims of this population genetics study were: 1) to ascertain whether Mexicans with type 2 diabetes mellitus (DM) were genetically homogeneous and 2) to compare the genetic structure of this selected population with the previously reported data of four random populations (Nuevo León, Hispanics, Chihuahua, and Central Region of Mexico). Methods: A sample of 103 unrelated individuals with DM and whose 4 grandparents were born in five zones of Mexico was interviewed in 32 Medical Units in the Mexican Institute of Social Security (IMSS). The non-coding STRs D16S539, D7S820, and D13S317 were analyzed. Results: Genotype distribution was in agreement with Hardy-Weinberg expectations for all three markers. Allele frequencies were found to be similar between the selected population and the four random populations. Gene diversity analysis suggested that more than 99.57% of the total gene diversity could be attributed to variation between individuals within the population and 0.43% between the populations. Conclusions: According to the present and previous studies using molecular and non-molecular nuclear DNA markers not associated with any disease, the Mexican Mestizo population is found to be genetically homogeneous and therefore the genetic causes of DM are less heterogeneous, thereby simplifying genetic epidemiological studies as has been found in a previous study with the same design in Mexican women with breast cancer.

RESUMEN Se muestra la utilización del ensayo de polimerasa en cadena (PCR) múltiplex para la dete... more RESUMEN Se muestra la utilización del ensayo de polimerasa en cadena (PCR) múltiplex para la detección de Porphyromonas gin-givalis y Streptococcus intermedius en pacientes con periodontitis crónica. Se analizaron un total de 180 muestras de 65 adultos con periodontitis no tratada y 17 voluntarios sanos, las células se procesaron inicialmente colocándolas a baño María durante 10 min. El lisado celular fue usado como fuente de ADN para los ensayos del PCR múltiplex. Los primers fueron diseñados a partir de secuencias génicas de fracciones 16 rRNA obtenidas de la base de datos GenBank-EMBL y que mostraron especificidad para los patógenos mencionados. El sistema PCR múltiplex fue diseñado para identificar 8.2 células de P. gingivalis y S. intermedius. De los pacientes con periodontitis, sólo el 78.5 % fueron positivos para una o ambas bacterias. En el 37% se identificó única-mente P. gingivalis, en el 17% S. intermedius y en un 24.5% ambos. P. gingivalis fue detectada en el 23.5% de lo...

Journal of Invertebrate Pathology, 2004

Erratum to ''Characterization of Mexican Bacillus thuringiensis strains toxic for lepidopteran an... more Erratum to ''Characterization of Mexican Bacillus thuringiensis strains toxic for lepidopteran and coleopteran larvae'' [

World Journal of Microbiology & Biotechnology, 2004

A Paecilomyces fumosoroseus strain was mutagenized by u.v. Among 200 colonies, one mutant (M84), ... more A Paecilomyces fumosoroseus strain was mutagenized by u.v. Among 200 colonies, one mutant (M84), showed a large and stable chitin hydrolysis-halo. Glucose consumption and biomass production were similar for M84 and the parental strain. Chitinase was inducible by chitin and repressed by glucose in both strains but, when they were grown on minimal medium plus colloidal chitin as sole carbon source, the parental and M84 strains yielded 198 and 690 μmol N-acetylglucosamine, respectively. This results indicate that the mutant strain synthesized a chitinase with a higher activity. Bioassays against Bemisia tabaci nymph, showed that M84 incited a 2-fold higher incidence of disease compared to the parental strain.

Journal of Biotechnology, 2007

Biocontrol, 2004

Diatraea saccharalis (F.) (Lepidoptera: Pyralidae) is a pest that causes great economic losses to... more Diatraea saccharalis (F.) (Lepidoptera: Pyralidae) is a pest that causes great economic losses to sugarcane producers in Mexico. In order to obtain alternatives for control of this pest, several Bacillus thuringiensis strains (native and from the Howard Dulmage collection) were tested. In bioassays, strains HD-133, HD-551, GM-7, GM-10, and GM-34 caused more than 50% mortality with a 50 μg/ml spore-crystal complex concentration, and were selected as toxic strains. The lowest LC50 value corresponded to GM-34 (33.21 μg/ml). Cry1B and cry1C genes were detected by PCR analysis in the toxic strains. HD-133 and GM-10 habored cry1C gene, HD-551 and GM-7 strains harbored cry1B gene, while GM34 strain did not contain cry1B nor cry1C. An additional PCR analysis was performed to detect cry1A-type genes. All the toxic strains habor at least one cry1A-type gene. Immunoblotting revealed that all strains cross-reacted with an antiCry1A, and only the HD-551 gave a positive signal with antiCry1B polyclonal antisera. GM-7 crystal protein showed no cross-reaction with polyclonal Cry1B antiserum. The toxicity of these strains may be related to some member of the Cry1A toxin class.

Journal of Invertebrate Pathology, 2004

The iron concentrate from Hercules Mine of Coahuila, Mexico, which mainly contained pyrite and py... more The iron concentrate from Hercules Mine of Coahuila, Mexico, which mainly contained pyrite and pyrrhotite, was treated by the bioleaching process using native strain Acidithiobacillus ferrooxidans ( A. ferrooxidans) to determine the ability of these bacteria on the leaching of zinc. The native bacteria were isolated from the iron concentrate of the mine. The bioleaching experiments were carried out in shake flasks to analyze the effects of pH values, pulp density, and the ferrous sulfate concentration on the bioleaching process. The results obtained by microbial kinetic analyses for the evaluation of some aspects of zinc leaching show that the native bacteria A. ferrooxidans, which is enriched with a 9K Silverman medium under the optimum conditions of pH 2.0, 20 g/L pulp density, and 40 g/L FeSO4, increases the zinc extraction considerably observed by monitoring during15 d, i.e., the zinc concentration has a decrease of about 95% in the iron concentrate.

Molecular Microbiology, 1992

A computer-based analysis of hydropathy and surface probability of representative members of each... more A computer-based analysis of hydropathy and surface probability of representative members of each class of the Cry family of proteins was performed. A highly conserved hydrophobic motif within the previously described block, D2, is present not only In lepidopteran toxin genes but also in toxins active against diptera and coleoptera. An interesting feature of this hydrophobic motif is the presence of an aspartic residue (highly hydrophilic) in its middle part. Comparison with the amino acid sequence from diphtheria toxin showed that it also contains a hydrophobic motif similar to the one present in the Bacillus thuringiensis toxins. It also contains an aspartic residue in the middle part and some speculations are presented on the function of this specific region with regard to the toxic mechanism of action.

Journal of Invertebrate Pathology, 2004

The systemic immune response of Trichoplusia ni after Bacillus thuringiensis (Bt) exposure was ev... more The systemic immune response of Trichoplusia ni after Bacillus thuringiensis (Bt) exposure was evaluated by comparing the expression of genes encoding antimicrobial peptides (AMPs) in Bt-susceptible and -resistant T. ni strains that were either exposed or not to Xen-TariÒ (Bt-XT). AMP genes were detected by RT-PCR using primers for attacin, gloverin, lebocin, lysozyme, and peptidoglycan recognition peptide (PGRP). In general, AMP genes were detected more frequently in Mexican field strains previously exposed to Bt (SALX and GTOX) than in a Mexican laboratory strain (NL), but expression was similar to the AMP expression in USA laboratory strains (US and USX). Among the AMPs, transcripts for lebocin were the least detected (11.7%) and those for lysozyme were the most detected (84.8%) in all samples. Lebocin was detected only in 2nd instar and pupa. All untreated controls expressed attacin. Attacin and gloverin were not detected in any midgut sample, and their highest detection was in pupa. Lysozyme was rarely detected in 2nd instar larvae from any strain or treatment but was detected in almost all midgut and hemolymph samples. Overall, AMPs were found more in T. ni strains previously exposed to Bt-XT, especially lebocin and globerin (1.8-fold increase) and PGRP (3.8-fold increase). The data suggest that the expression of AMPs in T. ni correlates to previous Bt exposure.

Journal of Invertebrate Pathology, 2000

Toxicity tests were performed to find among Cry1 and Cry2 Bacillus thuringiensis crystal proteins... more Toxicity tests were performed to find among Cry1 and Cry2 Bacillus thuringiensis crystal proteins those with high activity against the cabbage looper. Tests were performed with neonate larvae on surface-contaminated artificial diet. The crystal proteins found to be toxic were, from higher to lower toxicity: Cry1Ac, Cry1Ab, Cry1C, Cry2Aa, Cry1J, and Cry1F (LC 50 of 1.1-4.1, 3.4 -4.4, 12, 34, 87, and 250 ng/cm 2 , respectively). Cry1B, Cry1D, and Cry1E can be considered nontoxic (LC 50 higher than 2500 ng/cm 2 ). Cry1Aa was moderately toxic to nontoxic, depending on the source (LC 50 of 420 ng/cm 2 from PGS and 8100 ng/cm 2 from Ecogen). In vitro binding assays with trypsin-activated 125 I-labeled Cry1Aa, Cry1Ab, and Cry1Ac crystal proteins and brush border membrane vesicles from midgut larvae showed a direct correlation between toxicity and binding affinity. Heterologous competition experiments indicated that Cry1Aa and Cry1F bind, though only at very high concentrations, to the Cry1Ab/ Cry1Ac shared high-affinity binding site.

BMC Biotechnology, 2004

Bioleaching is a process that has been used in the past in mineral pretreatment of refractory sul... more Bioleaching is a process that has been used in the past in mineral pretreatment of refractory sulfides, mainly in the gold, copper and uranium benefit. This technology has been proved to be cheaper, more efficient and environmentally friendly than roasting and high pressure moisture heating processes. So far the most studied microorganism in bioleaching is Acidithiobacillus ferrooxidans. There are a few studies about the benefit of metals of low value through bioleaching. From all of these, there are almost no studies dealing with complex minerals containing arsenopyrite (FeAsS). Reduction and/or elimination of arsenic in these ores increase their value and allows the exploitation of a vast variety of minerals that today are being underexploited.

Archivos De Medicina Veterinaria, 2008

Here we analyze GDF8 gene regions which are potential carriers of polymorphisms using both base e... more Here we analyze GDF8 gene regions which are potential carriers of polymorphisms using both base excision sequence scanning thymine-base (BESS-T) and a fluorescent technique based on temperatures of dissociation (Tm's) technique. The first one permitted us to detect five nucleotide changes located four in the flanking regions of introns 1 and 2 and one in exon II. All the sequence variations were grouped in 11 haplotypes, which were distributed in the population tested. In order to evaluate a highest number of animals, a Tm's technique was optimized to analyze the region harboring most of mutations previously detected with BESS-T. Validation of Tm's technique was achieved comparing both the BESS-T and Tm's technique results. We found a 93.5% of correlation between these techniques.

Periodontal disease has been associated with poor dental care, which promotes the accumulation of... more Periodontal disease has been associated with poor dental care, which promotes the accumulation of bacteria and the development of diseases of the mouth. Porphyromonas gingivalis are anaerobic Gramnegative bacteria found in the subgingival plaque. They are largely responsible for chronic periodontal disease. Streptococcus intermedius is a Gram positive coccus found in the supragingival plaque. The objective of the present work was to evaluate the expression of several virulence genes of P. gingivalis in a mixed culture with S. intermedius using qPCR and heterologous microarrays. P. gingivalis ATCC 33277 and W83 and S. intermedius ATCC 27335 strains were cultured and total RNA was extracted using the High Pure RNA isolation kit. Oligodeoxynucleotides were designed to make multiple comparisons with organisms. Microarray was performed to identify gene expression. To quantify gene expression, cDNA samples from three different P. gingivalis:S. intermedius ratios were diluted 10 -1 , 10 -2 and 10 -3 . The microarray experiment indicated that in P. gingivalis, 29 genes were upregulated. The putative function of upregulated genes was the biosynthesis of different metabolic pathways. Heterologous microarrays are a new approach that are useful for investigating gene expression.

Gene, 2013

Journal of Invertebrate Pathology, 2004

World Journal of Microbiology & Biotechnology, 2004

Journal of Biotechnology, 2007

Biocontrol, 2004

Journal of Invertebrate Pathology, 2004

Molecular Microbiology, 1992

Journal of Invertebrate Pathology, 2004

Journal of Invertebrate Pathology, 2000

BMC Biotechnology, 2004

Archivos De Medicina Veterinaria, 2008

Periodontal disease has been associated with poor dental care, which promotes the accumulation of... more Periodontal disease has been associated with poor dental care, which promotes the accumulation of bacteria and the development of diseases of the mouth. Porphyromonas gingivalis are anaerobic Gramnegative bacteria found in the subgingival plaque. They are largely responsible for chronic periodontal disease. Streptococcus intermedius is a Gram positive coccus found in the supragingival plaque. The objective of the present work was to evaluate the expression of several virulence genes of P. gingivalis in a mixed culture with S. intermedius using qPCR and heterologous microarrays. P. gingivalis ATCC 33277 and W83 and S. intermedius ATCC 27335 strains were cultured and total RNA was extracted using the High Pure RNA isolation kit. Oligodeoxynucleotides were designed to make multiple comparisons with organisms. Microarray was performed to identify gene expression. To quantify gene expression, cDNA samples from three different P. gingivalis:S. intermedius ratios were diluted 10 -1 , 10 -2 and 10 -3 . The microarray experiment indicated that in P. gingivalis, 29 genes were upregulated. The putative function of upregulated genes was the biosynthesis of different metabolic pathways. Heterologous microarrays are a new approach that are useful for investigating gene expression.