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D Ramón

Publications and source records attributed to D Ramón.

At least 19 recordsLinked to original sources
PubMed2006

An ITS-RFLP method to identify black Aspergillus isolates responsible for OTA contamination in grapes and wine.

Ochratoxigenic mycobiota in grapes from representative wine regions in Valencia was identified. Black aspergilli were predominant among the different Aspergillus spp. isolated. Restriction digestion analysis of the ITS products was tested as a rapid method to identify isolates of black Aspergillus species from grapes. Restriction endonuclease digestion of the ITS products using the endonucleases HhaI, NlaIII and RsaI, distinguished five types of restriction fragment length polymorphism (RFLP) corresponding to Aspergillus niger, Aspergillus tubingensis, Aspergillus carbonarius and Aspergillus aculeatus species. In addition, a new RFLP type in the A. niger aggregate was identified. The fragments obtained by digestion with the endonuclease NlaIII could be used to identify these new isolates. Black Aspergillus isolates were tested for their ability to produce OTA. Most of the isolates that produced ochratoxin A in YES medium belonged to A. carbonarius species. These results support evidence that A. carbonarious greatly contributes to OTA contamination in grapes and consequently in wine. The ITS-RFLP assay is proposed as a rapid and easy method to identify black Aspergillus species isolated from grapes, especially in studies that involve a large number of isolates.

Aspergillus↗
PubMed2006

[Chondroid syringoma: a clinical and histological review of eight cases].

INTRODUCTION: Chondroid syringoma is a rare skin tumor that presents as a slow growing, indolent lesion, that is more frequent in male adults and is usually benign. It is treated surgically and its diagnosis is histological. It can be classified as eccrine and apocrine according to its pathological characteristics. MATERIAL AND METHODS: Eight cases diagnosed of chondroid syringoma in our Department in the last eight years were reevaluated clinically and histologically and the epiluminiscence microscopy was used in one of them. RESULTS: Most of the cases occurred as well-defined nodular lesions, whose presumptive clinical diagnosis was adnexal or cystic pathology. All were treated surgically. The epiluminiscence microscopy showed a pattern of homogenous whitish-blue coloring. All the cases had a myxoid matrix and most also had a chondroid one. Five of the eight cases were apocrine, one of them with follicular and sebaceous differentiation. DISCUSSION: The chondroid syringoma is usually a small-sized skin tumor, frequently on the head and neck. The dermatoscopy does not seem to supply any specific trait to this lesion. The microscopic examination of these lesions reveals tubuloalveolar and glandular type structures positioned as islets within a fibroadipose, chondroid, myxoid or hyaline stroma. The final treatment of these tumors is surgical. As a general rule, it is a benign tumor. Some authors have proposed the term of atypical mixed tumor of the skin for those chondroid syringomas with histological traits of malignancy but without evidence of metastasis.

Adenoma, Pleomorphic↗
PubMed2006

[Necrotizing subcutaneous infection by Streptococcus agalactiae].

Necrotizing soft tissue infections constitute some of the most potentially threatening infections that may be acquired in the community or in the hospital milieu as they are associated with a high mortality rate. In most cases they are produced by Streptococcus pyogenes. We report a case of a necrotizing soft tissue infection caused by Streptococcus agalactiae (group B beta hemolytic streptococcus) that involved the leg of an elderly man with chronic lymphatic leukemia and diabetes mellitus. The lesions notably improved after initiating intravenous antibiotic treatment with amoxicillin-clavunate and clindamycin.

Aged↗
PubMed2006

Cutaneous plasmacytosis associated with lung and anal carcinomas.

Cutaneous plasmacytosis is a rare disorder characterized by a benign proliferation of mature plasma cells that appears as multiple dark-brown to purplish skin lesions, often associated with polyclonal hypergammaglobulinaemia. We present the case of a 55-year-old Caucasian man who suffered from a cutaneous plasmacytosis associated with two different carcinomas. Cutaneous plasmacytosis seems to be a reactive process because most cases reported are not associated with any apparent underlying disease. Nevertheless, because few reported cases were associated with malignancies, screening of additional neoplasms would be justified.

Anus Neoplasms↗
PubMed2004

Streptomyces lividans and Brevibacterium lactofermentum as heterologous hosts for the production of X22 xylanase from Aspergillus nidulans.

The Aspergillus nidulans gene xlnA coding for the fungal xylanase X22 has been cloned and expressed in two heterologous bacterial hosts: Streptomyces lividans and Brevibacterium lactofermentum. Streptomyces strains yielded 10 units/ml of xylanase when the protein was produced with its own signal peptide, and 19 units/ml when its signal peptide was replaced by the one for xylanase Xys1 from Streptomyces halstedii. B. lactofermentum was also able to produce xylanase X22, affording 6 units/ml upon using either the Aspergillus xlnA signal peptide or Streptomyces xysA. These production values are higher than those previously reported for the heterologous expression of the A. nidulans xlnA gene in Saccharomyces cerevisiae (1 unit/ml). Moreover, the X22 enzyme produced by Streptomyces lividans showed oenological properties, indicating that this Streptomyces recombinant strain is a good candidate for the production of this enzyme at the industrial scale.

Aspergillus nidulans↗
PubMed2004

Screening and typing of Patagonian wine yeasts for glycosidase activities.

AIMS: The purpose of this study was to select autochthonous glycosidase producer yeasts with potential use in industrial production of Patagonian red wines. METHODS AND RESULTS: The study was carried out in oenological autochthonous yeasts from Comahue region (Argentinean North Patagonia). A set of screenable yeast phenotypic characteristics indicative of their potential usefulness in more aromatic red wine production was defined and tested in both, Saccharomyces and non-Saccharomyces populations. Twelve isolates showing six different glycosidase phenotypes were selected and they were characterized at species and strain levels using molecular methods. A close correlation between molecular and phenotypic characteristics was observed. Five strains belonging to Candida guilliermondii, C. pulcherrima and Kloeckera apiculata with highest constitutive beta-glucosidase activity levels without anthocyanase activity were discriminated. Some of them also showed constitutive beta-xylosidase and inductive alpha-rhamnosidase activities. CONCLUSIONS: The extension of the selection of oenological yeast to non-Saccharomyces species provided strains possessing novel and interesting oenological characteristics which could have significant implications in the production of more aromatic young red wine. SIGNIFICANCE AND IMPACT OF THE STUDY: As these non-Saccharomyces are indigenous to wine, they can be used in mixed starters at the beginning or as pure cultures at the end fermentation to contribute in enhancing the wine nuance that is typical of this specific area.

Cluster Analysis↗
PubMed2004

pH control of the production of recombinant glucose oxidase in Aspergillus nidulans.

AIMS: Recombinant Aspergillus nidulans sVAL040, capable of synthesizing and secreting glucose oxidase derived from Aspergillus niger was used to study the influence of pH and carbon source on enzyme production. METHODS AND RESULTS: Glucose oxidase gene (goxC) was expressed under transcriptional regulation by using the promoter of A. nidulans xlnB gene (encoding an acidic xylanase). A maximum specific glucose oxidase activity of approx. 10 U mg(-1) protein and a maximum volumetric productivity of 29.9 U l(-1) h(-1) were obtained at pH 5.5, after 80 h of growth by using xylose as inducer. Enzyme volumetric productivity increased when xylans were used instead of xylose; however, specific glucose oxidase activity did not differ significantly. CONCLUSIONS: Specific GOX activity obtained at pH 5.5 are two to three times more than those previously described for goxC multicopy transformants of A. nidulans. Xylans were a more powerful inducer than xylose although fungal growth was lower when the polymers were used. SIGNIFICANCE AND IMPACT OF THE STUDY: The obtained results by using xlnB promoter in A. nidulans could be useful in improving heterologous enzyme production by using genetic- and process-engineering strategies.

Aspergillus nidulans↗
PubMed2002

Improving extracellular production of food-use enzymes from Aspergillus nidulans.

Filamentous fungi, and particularly those of the genus Aspergillus, are major producers of enzymatic activities that have important applications in the food and beverage industries. Prior to the availability of transformation systems improvement of industrial production strains was largely restricted to the strategy of mutagenesis, screening and selection. Aspergillus nidulans is a genetically amenable filamentous fungus the ease of handling and analysis of which has led to its use as a model system for the investigation of eukaryotic gene regulation. Although not used industrially it is able to produce a wide variety of extracellular enzymatic activities. As a consequence of half a century of study a considerable resource of characterised mutants has been generated in conjunction with extensive genetic and molecular information on various gene regulatory systems in this micro-organism. Investigation of xylanase gene regulation in A. nidulans as a model for the production of food-use extracellular enzymes suggests strategies by which production of these enzymes in industrially useful species may be improved.

Aspergillus nidulans↗
PubMed2002

Ultrastructural and immunohistochemical characterization of the so-called giant multinucleate cells in cutaneous collagenomas.

AIMS: This study was undertaken to compare the histopathological, immunohistochemical and ultrastructural features of the so-called giant multi nucleate cells in cutaneous collagenomas: giant-cell collagenoma and solitary sclerotic fibroma. METHODS AND RESULTS: We studied four collagenomas: one giant-cell collagenoma and three solitary sclerotic fibromas. All the cases showed an indolent clinical presentation and were histologically constituted by a well-demarcated dome-shaped proliferation of coarse collagen bundles with a varying number of interspersed giant multinucleate cells and stellate mononuclear cells. The immunohistochemical study on paraffin sections revealed that neoplastic cells in both collagenomas were vimentin and CD34-positive, whereas FXIIIa was only expressed in solitary sclerotic fibromas. In regard to the so-called giant multinucleate cells, we have ultrastructurally found that these cells were 'real' multinucleate cells in giant-cell collagenoma, whereas in solitary sclerotic fibromas they consisted of closely packed aggregates of individual stellate mononuclear cells. Moreover, perinuclear cisternae focally containing finely textured material of moderate density were unexpectedly found in giant cells of giant-cell collagenoma, a finding which was not observed in solitary sclerotic fibromas. Additionally, a characteristic cell-cell interaction between tumour cells and mast cells was encountered in all collagenomas. CONCLUSIONS: This study supports a distinctive immunohistochemical and overall ultrastructural profile of giant multinucleate cells in giant-cell collagenoma and solitary sclerotic fibroma, which suggests a different pattern of differentiation for these two related cutaneous lesions.

Adult↗
PubMed2001

Study of the authenticity of commercial wine yeast strains by molecular techniques.

mtDNA restriction analysis has been carried out with 45 different commercial Saccharomyces wine yeast strains. The analysis with Hinf I provided unique profiles for 17 of the 45 strains and can therefore be considered as individual strains. Nevertheless, among the remaining 28 strains, only eight mtDNA restriction patterns appeared. These strains were subjected to electrophoretic karyotyping and PCR amplification of delta sequences. We concluded that the maximum discriminatory power was obtained when the results of the three techniques were combined, giving 13 different composite patterns for the 28 strains under study. The results showed evidence of mistakes during production or fraudulent practices by yeast producers, since only 30 individual strains have been identified among the 45 Saccharomyces wine yeast strains commercialised by different companies. Additionally, commercial starters of Saccharomyces uvarum and Saccharomyces bayanus have been re-identified as Saccharomyces cerevisiae.

DNA, Bacterial↗
PubMed2001

A simplified procedure to analyse mitochondrial DNA from industrial yeasts.

A rapid method based on mtDNA restriction analysis is described for yeast strain identification. The method is an adaptation of that devised by Querol et a]. [Syst. Appl. Microbiol. 15 (1992) 439] for Saccharomyces cerevisiae wine strains, and consists of the standard miniprep isolation of yeast total DNA, and the use of restriction endonucleases that recognise a large number of sites in yeast nuclear DNA, but few sites in the mitochondrial DNA. In the adapted method, the propagation of yeast cells and restriction analysis were the steps mainly affected: cell growth was reduced to 36 h by using microfuge tubes, and the restriction analysis was carried out in just 33 min using a microwave oven for DNA digestion, and minigels for restriction fragment separation. The DNA extraction procedure was performed in the same way as in the original protocol. but slightly reducing the duration of each step and scaling down the volumes of the different solutions. enzymes and reagents used. As result, a large time reduction (52.5 h) was obtained compared to the original method. The DNA obtained can be directly digested with endonucleases displaying clear restriction patterns useful for S. cerevisiae yeast strain differentiation. In addition, strains belonging to other foodborne yeast species, including spoilage yeast species, can also be identified.

DNA Restriction Enzymes↗
PubMed2001

Molecular characterisation of Hanseniaspora species.

The sequences of the internal transcribed spacers (ITS regions) and the 5.8S rRNA gene, together with the electrophoretic karyotypes of 27 strains representative of the six species belonging to the genus Hanseniaspora, were examined. From the analysis of the 5.8S rRNA gene and the ITS regions, the genus Hanseniaspora is monophyletic and can be divided into two subgroups. This subdivision was supported by electrophoretic chromosome patterns. Hanseniaspora guilliermondii, H. uvarum and H. valbyensis show 6-7 bands (8 to 9 chromosomes), while the second group comprises the species H. occidentalis, H. osmophila and H. vineae which have only 5 chromosomes.

Chromosomes, Fungal↗
PubMed2001

The wide-domain carbon catabolite repressor CreA indirectly controls expression of the Aspergillus nidulans xlnB gene, encoding the acidic endo-beta-(1,4)-xylanase X(24).

The Aspergillus nidulans xlnB gene, which encodes the acidic endo-beta-(1,4)-xylanase X(24), is expressed when xylose is present as the sole carbon source and repressed in the presence of glucose. That the mutation creA(d)30 results in considerably elevated levels of xlnB mRNA indicates a role for the wide-domain repressor CreA in the repression of xlnB promoter (xlnBp) activity. Functional analyses of xlnBp::goxC reporter constructs show that none of the four CreA consensus target sites identified in xlnBp are functional in vivo. The CreA repressor is thus likely to exert carbon catabolite repression via an indirect mechanism rather than to influence xlnB expression by acting directly on xlnB.

Aspergillus nidulans↗
PubMed2000

The use of transgenic yeasts expressing a gene encoding a glycosyl-hydrolase as a tool to increase resveratrol content in wine.

Resveratrol, a phenolic compound produced in grapes, exhibits properties that may contribute to the reduction of the incidence of coronary heart disease and other human health related processes. Recombinant yeast strains expressing the Aspergillus niger abfB gene encoding an alpha-L-arabinofuranosidase or the Candida molischiana bgIN gene encoding a beta-glucosidase have been used in vinifications as tools to increase the resveratrol content of white wine. Glycosylated resveratrol isomers (trans- and cis-piceid) and free resveratrol isomers (trans- and cis-resveratrol) were detected and quantified in white wines. Wines fermented with the strain expressing BgiN showed an increased amount of total resveratrol derivatives, particularly the non-glycosylated forms.

Aspergillus niger↗
PubMed2000

Heterologous expression in Aspergillus nidulans of a Trichoderma longibrachiatum endoglucanase of enological relevance.

An Aspergillus nidulans transformant expressing the Trichoderma longibrachiatum endoglucanase 1 gene (egl1) has been constructed. The extracellular production of EGL1 in different culture media has been studied, and a medium has been found in which EGL1 is the predominant extracellular protein produced. The enzymatic properties of the heterologously produced EGL1 are very similar to those of the native enzyme. Grape maceration in the presence of culture filtrate enriched in EGL1 resulted in increased release of aroma precursors, particularly in the case of aromatic grapes. Cryoscanning electron microscopy of the flesh of grapes treated with EGL1-enriched culture filtrate revealed degradation of the cell wall matrix.

Aspergillus nidulans↗
PubMed2000

Purification and characterization of an alpha-L-rhamnosidase from Aspergillus nidulans.

An enzyme exhibiting alpha-L-rhamnosidase activity was purified by fractionating a culture filtrate of Aspergillus nidulans grown on L-rhamnose as the sole carbon source. The alpha-L-rhamnosidase was shown to be N-glycosylated and had a molecular mass of 102 kDa, of which approximately 7% was contributed by carbohydrate. The enzyme, optimally active at pH 4.5-6 and 60 degrees C, had an isoelectric point of 5. With rho-nitrophenyl-alpha-L-rhamnopyranoside as the substrate it showed Km and Vmax values of 0.27 mmol l-1 and 64.6 U mg-1, respectively. The enzyme was competitively inhibited by L-rhamnose (Ki 0.3 mmol l-1). Ca2+ (2 mmol l-1) stimulated the activity of the enzyme by 14%, whereas Mg2+ (2 mmol l-1) inhibited it by 63%. Substrate specificity studies showed the alpha-L-rhamnosidase to be active both on alpha-1,2 and alpha-1,6 linkages to beta-D-glucosides.

Aspergillus nidulans↗
PubMed1999

Aroma improving in microvinification processes by the use of a recombinant wine yeast strain expressing the Aspergillus nidulans xlnA gene.

A recombinant wine yeast strain has been constructed expressing the gene coding for beta-(1,4)-endoxylanase from Aspergillus nidulans under the control of the yeast actin gene promoter. The resulting recombinant strain is able to secrete active xylanase enzyme into the culture medium. Wines obtained by microvinification with the control and the recombinant wine yeast strain did not differ in their physicochemical characteristics although an increase in fruity aroma was organoleptically detected in the wine produced by the recombinant yeast. Also, an increase in the concentration of some esters, higher alcohols and terpenes was observed in the case of the recombinant strain.

Aspergillus nidulans↗