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R Serrano

Publications and source records attributed to R Serrano.

At least 19 recordsLinked to original sources
PubMed2006

Antimicrobial and general toxicity activities of Gymnosperma glutinosum: a comparative study.

Gymnosperma glutinosum (Spreng.) Less (Asteraceae) is an important, and an effective herbal medicine which is wide used for the treatment of diarrhoea in Mexico. We examined and compared the antibacterial and antifungal activities through the dilution method and for general toxicity activity by the brine shrimp lethality assay of two samples of Gymnosperma glutinosum from two localities of Mexico: San Rafael-Coxcatlan (Puebla State) and Tepeji del Rio (Hidalgo State). In addition, two bioactive compounds (-)-17-hydroxy-neo-clerod-3-en-15-oic acid (1) and 5,7-dihydroxy-3,6,8,2',4',5'-hexamethoxyflavone (2) were isolated. From the hexane extract from both places was obtained a MeOH partition M(2). M(2) of Tepeji del Rio showed the least MICs (<125 microg/ml) in the majority of the bacterial strains. Sarcina lutea was the most sensitive bacteria (MIC< 125 microg/ml). The hexane extract of both localities showed antifungal activity against all tested fungi. San Rafael's hexane extract was significant more activity than Tepeji del Rio. Aspergillus niger (IC(50)=23.79 microg/ml) and Trichophyton mentagrophytes (IC(50)=90.25 microg/ml) were the more sensitive fungus strains. The strongest general toxicity activity was observed with the M(2) partition from Tepeji del Rio (LC(50)=503.7 microg/ml). The results obtained in this investigation, showed differences between the antimicrobial activities of the samples of plants collected in San Rafael (Puebla) and Tepeji del Rio (Hidalgo).

Animals↗
PubMed2006

Assessment of the efficacy of Artemia sp (Crustacea) cysts chorion as barrier to chlorpyrifos (organophosphorus pesticide) exposure. Effect on hatching and survival.

In order to reveal the efficacy of the Artemia cysts chorion as barrier to the organophosphorus pesticide chlorpyrifos, whole and decapsulated cysts have been exposed to 10 mg L(-1) chlorpyrifos in sea water during hydration and hatching phase, separately. The concentration of chlorpyrifos in capsulated and decapsulated cysts after exposure has been determined in order to elucidate the efficacy of chorion as protection to the embryo. The results obtained demonstrate the ability of the cysts chorion to obstruct the pass of chlorpyrifos molecules through this protection structure. Thus, the concentration of chlorpyrifos in exposed decapsulated cysts is higher than in exposed whole cysts. Moreover, after removing the chorion of exposed cysts, the concentration of chlorpyrifos in the embryo was lower than that of cysts exposed, what would demonstrate the retention of chlorpyrifos molecules by the shell. Hatching was not severely affected by exposure to the insecticide whereas survival at 44 h of the nauplii exposed to chlorpyrifos was significantly different from the controls. Survival of nauplii hatched from exposed decapsulated cysts was higher than that from those hatched from exposed whole cysts, probably because of the lower vitality of the latter, due to depletion of energy reserves during hatching.

Animals↗
PubMed2005

Development of a citrus genome-wide EST collection and cDNA microarray as resources for genomic studies.

A functional genomics project has been initiated to approach the molecular characterization of the main biological and agronomical traits of citrus. As a key part of this project, a citrus EST collection has been generated from 25 cDNA libraries covering different tissues, developmental stages and stress conditions. The collection includes a total of 22,635 high-quality ESTs, grouped in 11,836 putative unigenes, which represent at least one third of the estimated number of genes in the citrus genome. Functional annotation of unigenes which have Arabidopsis orthologues (68% of all unigenes) revealed gene representation in every major functional category, suggesting that a genome-wide EST collection was obtained. A Citrus clementina Hort. ex Tan. cv. Clemenules genomic library, that will contribute to further characterization of relevant genes, has also been constructed. To initiate the analysis of citrus transcriptome, we have developed a cDNA microarray containing 12,672 probes corresponding to 6875 putative unigenes of the collection. Technical characterization of the microarray showed high intra- and inter-array reproducibility, as well as a good range of sensitivity. We have also validated gene expression data achieved with this microarray through an independent technique such as RNA gel blot analysis.

Citrus↗
PubMed2005

Differential gene expression of insulin receptor isoforms A and B and insulin receptor substrates 1, 2 and 3 in rat tissues: modulation by aging and differentiation in rat adipose tissue.

The insulin receptor (IR) occurs as two alternatively spliced isoforms, IR-A (exon 11-) and IR-B (exon 11+), which exhibit functional differences and are expressed in a tissue-specific manner. The IR substrate (IRS) proteins 1, 2 and 3 also differ in function and tissue distribution. Here we show the differential gene expression of IRs and IRSs in several rat target tissues of insulin action. IR-B is significantly higher than IR-A in epididymal white adipose tissue and adipogenesis induces a shift in the alternatively spliced species of IR from the A to the B isoform. Moreover, since aging in the rat is associated with the development of insulin resistance we looked for alterations of expression of these proteins in adipocytes from old rats. Our results reveal that there is a specific decrease in the expression of the IR-B isoform, as well as both mRNA and protein levels of IR, IRS-1 and IRS-3 being significantly decreased, in epididymal adipose tissue from old compared with adult rats. It is concluded that the down-regulation of early components of the insulin transduction pathway in a primary insulin target tissue could be related to the insulin resistance of aging.

Adipose Tissue↗
PubMed2004

The quotient of number of nodes and tumour size (N/T) from primary breast cancer predicts the clinical course after diagnosis of distant relapse.

INTRODUCTION: Breast cancer is a disease with a very variable progression. Primary tumour size and metastatic lymph node involvement are the best indicators of the likelihood of relapse. However, their value in predicting progression following relapse is not clear. AIM: The aim of this study was to asses whether the relationship between tumour size and the number of lymph nodes involved had any value as predictive factors of post-relapse progression. METHOD: We established an index defined as the quotient between the number of diseased lymph nodes and the tumour size (in cm). RESULTS: Applying this index in 230 consecutive patients with metastatic breast cancer, we observed that there was a significant inverse relation between the index and post-relapse progression. CONCLUSION: We conclude that, at the time of initial diagnosis, the quotient of tumour size and the number of diseased lymph nodes could be a good predictor of time-to-progression following the diagnosis of the metastatic disease.

Adult↗
PubMed2003

The expression of the Saccharomyces cerevisiae HAL1 gene increases salt tolerance in transgenic watermelon [Citrullus lanatus (Thunb.) Matsun. & Nakai.].

An optimised Agrobacterium-mediated gene transfer protocol was developed in order to obtain watermelon transgenic plants [Citrullus lanatus (Thunb.) Matsun. & Nakai.]. Transformation efficiencies ranged from 2.8% to 5.3%, depending on the cultivar. The method was applied to obtain genetically engineered watermelon plants expressing the Saccharomyces cerevisiae HAL1 gene related to salt tolerance. In order to enhance its constitutive expression in plants, the HAL1 gene was cloned in a pBiN19 plasmid under control of the 35S promoter with a double enhancer sequence from the cauliflower mosaic virus and the RNA4 leader sequence of the alfalfa mosaic virus. This vector was introduced into Agrobacterium tumefaciens strain LBA4404 for further inoculation of watermelon half-cotyledon explants. The introduction of both the neomycin phosphotransferase II and HAL1 genes was assessed in primary transformants (TG1) by polymerase chain reaction analysis and Southern hybridisation. The expression of the HAL1 gene was determined by Northern analysis, and the diploid level of transgenic plants was confirmed by flow cytometry. The presence of the selectable marker gene in the expected Mendelian ratios was demonstrated in TG2 progenies. The TG2 kanamycin-resistant plantlets elongated better and produced new roots and leaves in culture media supplemented with NaCl compared with the control. Salt tolerance was confirmed in a semi-hydroponic system (EC=6 dS m(-1)) on the basis of the higher growth performance of homozygous TG3 lines with respect to their respective azygous control lines without the transgene. The halotolerance observed confirmed the inheritance of the trait and supports the potential usefulness of the HAL1 gene of S. cerevisiae as a molecular tool for genetic engineering of salt-stress protection in other crop species.

Blotting, Northern↗
PubMed2003

Rapid multiresidue determination of organochlorine and organophosphorus compounds in human serum by solid-phase extraction and gas chromatography coupled to tandem mass spectrometry.

A rapid analytical method for the multiresidue determination of several organochlorine and organophosphorus pesticides and polychlorinated biphenyls in human serum samples has been developed. Analytes were isolated by solid-phase extraction using C18 cartridges with subsequent analysis by GC-MS/MS using a glass liner packed with CarboFrit in the GC injection port. Labelled surrogate internal standards (fenitrothion D6, HCB (13)C6, p, p'-DDE D8 and PCB 138 (13)C12) were added to the samples before the extraction and were used for quantitation and for quality control in the analysis of real-world samples. Accuracy and precision were evaluated by using serum samples fortified at two concentration levels for the three families of compounds, with satisfactory results in the majority of cases. The high selectivity and sensitivity of GC-MS/MS allowed low detection limits of 0.05-0.5 ng mL(-1) for most of the analytes investigated. The developed procedure improves other current methodologies for the analysis of pesticides and PCBs in biological fluids, especially as regards to analysis time and simplicity of sample treatment. The method was applied to several serum samples obtained from farmers devoted to citrus crop production. Chlorpyrifos, HCB, p, p'-DDE and the higher chlorinated PCBs (153, 138 and 180) were the most frequently detected compounds.

Gas Chromatography-Mass Spectrometry↗
PubMed2002

Crystal structure of an enzyme displaying both inositol-polyphosphate-1-phosphatase and 3'-phosphoadenosine-5'-phosphate phosphatase activities: a novel target of lithium therapy.

Lithium cations exert profound and selective psychopharmacological effects on ameliorate manic-depressive psychosis. Although lithium is an effective drug for both treatment and prophylaxis of bipolar disorder, the precise mechanism of action is not well understood. Lithium acts as both an uncompetitive and non-competitive inhibitor of several lithium- sensitive phosphatases with regard to substrate and magnesium cofactor, respectively. In this work, we report the crystal structure and reaction mechanism of Rattus norvegicus 3'-phosphoadenosine 5'-phosphate and inositol 1,4-bisphosphate phosphatase (RnPIP), a recently identified target of lithium therapy. This Li(+)-sensitive enzyme plays a crucial role in several cellular processes, such as RNA processing, sulphation reactions and probably inositol recycling. RnPIP specifically removes the 3'-phosphate group of 3'-phosphoadenosine 5'-phosphate (PAP) and the 1'-phosphate group of inositol 1,4-bisphosphate (I(1),(4)P(2)) producing AMP and inositol 4'-phosphate, respectively. The crystal structure of RnPIP complexed with AMP, Pi and magnesium ions at 1.69 A resolution provides insight into the reaction mechanism of the hydrolysis of PAP. The core fold of the enzyme is equivalent to that found in other Li(+)-sensitive phosphatases, such as inositol monophosphatase, but molecular modelling of I(1),(4)P(2) in the RnPIP active site reveals important structural determinants that accommodate this additional substrate. RnPIP is potently inhibited by lithium and, as the accumulation of PAP inhibits a variety of proteins, including sulphotransferases and RNA processing enzymes, this dual specificity enzyme represents a potential target of lithium action, in addition to inositol monophosphatases.

Adenosine Diphosphate↗
PubMed2002

Bioaccumulation of chlorpyrifos through an experimental food chain: study of protein HSP70 as biomarker of sublethal stress in fish.

The accumulation and transfer of the organophosphorus pesticide chlorpyrifos has been studied in an experimental aquatic two-level food chain using two species of the crustacean Artemia (A. franciscana and A. parthenogenetica) and the small fish Aphanius iberus. Artemia adults contaminated by exposure to the pesticide in water were used as live prey for Aphanius, the next trophic level. During the experimental bioaccumulation phase, fish were fed chlorpyrifos-contaminated Artemia pools with concentrations between 6.5 and 14.5 ng/g fresh weight for 32 days. Both concentrations accumulated in fish, and biomagnification factor (BMF) values showed a continuous decrease during the bioaccumulation phase, probably due to the physicochemical characteristics of the organophosphorus pesticide, to the biotransformation ability of fish and to the progressive adaptation of fish metabolism to toxic exposure. The first day that fish were fed uncontaminated preys, the pesticide accumulated via food was rapidly eliminated and was not detected. The effect of chlorpyrifos exposure through the food chain on stress protein (HSP70) synthesis was measured as a general biochemical response of stress in the fish (A. iberus). The levels of HSP70 were significantly higher in fish fed on contaminated Artemia than in the control fish fed on uncontaminated Artemia. Results showed that the HSP70 induction in fish could be associated to exposure of chlorpyrifos via food.

Animals↗
PubMed2002

Multiresidue determination of endosulfan and metabolic derivatives in human adipose tissue using automated liquid chromatographic cleanup and gas chromatographic analysis.

A multiresidue method based on normal-phase liquid chromatography (LC) cleanup and gas chromatography-electron capture detection-mass selective detection (GC-ECD-MSD) analysis has been developed for the determination of endosulfan and its main metabolic derivatives in human adipose tissues. Analytes were extracted by dissolving the fat samples in n-hexane, and the hexanic extracts were directly injected onto the silicagel column of the automated LC cleanup system. Purified LC extracts were analyzed by GC-ECD or GC-MSD, without any solvent exchanges or preconcentration steps. The high efficiency of the high-performance liquid chromatographic cleanup for the elimination of fats allowed to reach detection limits for all analytes at low nanograms-per-gram concentration levels. The optimized overall analytical procedure was applied to 18 selected human mammary adipose and abdominal fat tissue samples. p,p'-DDE, hexachlorobenzene, and beta-HCH were the most frequently detected compounds, and residues of endosulfan-sulfate and -ether were also found in several samples. All findings were confirmed by an additional GC-MS-MS analysis of the LC sample extracts.

Adipose Tissue↗
PubMed2001

Multiple levels of control regulate the yeast cAMP-response element-binding protein repressor Sko1p in response to stress.

The Sko1p transcriptional repressor regulates a subset of osmoinducible stress defense genes in Saccharomyces cerevisiae by binding to cAMP-responsive elements. We have reported previously that in response to stress Sko1p is phosphorylated by the stress-activated Hog1p mitogen-activated protein kinase, which disrupts its interaction with the Ssn6p x Tup1p corepressor. Here we report that other mechanisms are essential for the regulation of the Sko1p repressor activity upon stress. The nuclear localization of Sko1p depends on the stress-inhibited protein kinase A (PKA). Sko1p is localized in the nucleus of unstressed cells, and it redistributes to the cytosol upon severe salt stress (1 m NaCl). Yeast mutants with low PKA activity localize Sko1p to the cytoplasm in the absence of stress and exhibit deregulated expression of cAMP-responsive element-regulated genes. The central part (315) of Sko1p, containing the PKA phosphorylation sites and the basic domain-leucine zipper domain, is essential for its nuclear localization. Salt-induced export of Sko1p from the nucleus is independent of Hog1p and of the Bcy1p regulatory subunit of PKA. Furthermore, phosphorylation by PKA slightly enhanced DNA binding affinity of Sko1p in vitro, whereas Sko1p dimerization in vivo is not regulated by stress. Sko1p repressor activity is associated to its binding to the Ssn6p x Tup1p complex. Interestingly, the Sko1p NH(2) terminus (1), containing the Hog1p phosphorylation sites, associates in vivo with Tup1p in the absence of Ssn6p, suggesting that Sko1p represses gene transcription by interacting directly with the Tup1p subunit of the Ssn6p x Tup1p complex.

Basic-Leucine Zipper Transcription Factors↗
PubMed2001

The protein kinase Gcn2p mediates sodium toxicity in yeast.

Phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF2alpha) is a conserved mechanism regulating protein synthesis in response to various stresses. A screening for negative factors in yeast salt stress tolerance has led to the identification of Gcn2p, the single yeast eIF2alpha kinase that is activated by amino acid starvation in the general amino acid control response. Mutation of other components of this regulatory circuit such as GCN1 and GCN3 also resulted in improved NaCl tolerance. The gcn2 phenotype was not accompanied by changes in sodium or potassium homeostasis. NaCl induced a Gcn2p-dependent phosphorylation of eIF2alpha and translational activation of Gcn4p, the transcription factor that mediates the general amino acid control response. Mutations that activate Gcn4p function, such as gcd7-201, cpc2, and deletion of the translational regulatory region of the GCN4 gene, also cause salt sensitivity. It can be postulated that sodium activation of the Gcn2p pathway has toxic effects on growth under NaCl stress and that this novel mechanism of sodium toxicity may be of general significance in eukaryotes.

Amino Acids↗
PubMed2001

Regulation of the Sko1 transcriptional repressor by the Hog1 MAP kinase in response to osmotic stress.

Exposure of yeast to increases in extracellular osmolarity activates the Hog1 mitogen-activated protein kinase (MAPK), which is essential for the induction of gene expression required for cell survival upon osmotic stress. Several genes are regulated in response to osmotic stress by Sko1, a transcriptional repressor of the ATF/CREB family. We show by in vivo coprecipitation and phosphorylation studies that Sko1 and Hog1 interact and that Sko1 is phosphorylated upon osmotic stress in a Hog1-dependent manner. Hog1 phosphorylates Sko1 in vitro at multiple sites within the N-terminal region. Phosphorylation of Sko1 disrupts the Sko1-Ssn6-Tup1 repressor complex, and consistently, a mutant allele of Sko1, unphosphorylatable by Hog1, exhibits less derepression than the wild type. Interestingly, Sko1 repressor activity is further enhanced in strains with high protein kinase A (PKA) activity. PKA phosphorylates Sko1 near the bZIP domain and mutation of these sites eliminates modulation of Sko1 responses to high PKA activity. Thus, Sko1 transcriptional repression is controlled directly by the Hog1 MAPK in response to stress, and this effect is further modulated by an independent signaling mechanism through the PKA pathway.

Amino Acid Sequence↗
PubMed2001

Identification of Candida tropicalis HSR1, a gene of the heat-shock factor-related family, which confers salt tolerance in Saccharomyces cerevisiae.

A genomic library of Candida tropicalis in a yeast multicopy plasmid has been screened for clones conferring salt tolerance upon transformation into S. cerevisiae. The best halotolerance clone contained an open reading frame encoding a predicted protein of 728 amino acids with homology to transcription factors of the heat-shock family. This novel gene was named HSR1 and is present in single copy in the C. tropicalis genome. Upon transformation into S. cerevisiae it increases the expression of ENA1, a major determinant of salt tolerance encoding a cation-extrusion pump. The sequence of CtHSR1 has been deposited in the EMBL data library under Accession No. AJ296093.

Adenosine Triphosphatases↗
PubMed2001

Multiresidue determination of organophosphorus and organochlorine pesticides in human biological fluids by capillary gas chromatography.

Two multiresidue analytical methods for the simultaneous determination of organophosphorus and organochlorine pesticides in human urine and serum samples are described. The first approach is based on liquid-liquid microextraction with dichloromethane, and the second uses solid-phase extraction with C18. In both methods, the extracts are analyzed by capillary gas chromatography using nitrogen-phosphorus detection (NPD) and electron-capture detection (ECD). Limits of detection of the overall procedure of analysis are at the low ng mL(-1) level. Stability experiments have been performed with spiked urine and serum samples stored at 4 degrees C for 1 month. Finally, the solid-phase extraction procedure was applied to real-world samples. Quantification was performed by NPD or ECD, and peak identity was confirmed by use of mass-selective detection (MSD).

Chromatography, Gas↗
PubMed2001

Promoter sequences regulated by the calcineurin-activated transcription factor Crz1 in the yeast ENA1 gene.

In Saccharomyces cerevisiae the transcription of the ENA1 gene is modulated by multiple transduction pathways that respond to osmotic, ionic and nutrient stresses. We have investigated the molecular mechanisms involved in ENA1 induction by the calcium-calcineurin-activated transcription factor Crzl/Tcn1. We found in the ENA1 promoter a calcium-responsive, Crzl-dependent upstream activating region (UASENA1) located between -713 bp and 826 bp relative to the translation start. This region contains two separate control elements: the upstream element (5'-GAATGGCTG-3') between -813 and -821 binds Crzlp with lower affinity and mostly contributes to basal ENA1 expression, whereas the downstream element (5'-GGGTGGCTG-3') between 727 and 719 binds Crz1p with higher affinity and is a major determinant of the induction response to calcium.

Adenosine Triphosphatases↗