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L Mendoza

Publications and source records attributed to L Mendoza.

101 records · Page 6Linked to original sources
PubMedDate not supplied

Identification of the conserved coding sequences of three chitin synthase genes in Fonsecaea pedrosoi.

Primers having designs based on highly conserved stretches in the deduced amino acid sequences of chitin synthase (CHS) genes were used in PCR reactions to amplify 600 bp and 366 bp products from the genomic DNA of three major causal agents of chromoblastomycosis. Cloning and sequencing of the PCR products of one of these fungi, Fonsecaea pedrosoi, identified three CHS sequences designated as FpCHS1, FpCHS2 and FpCHS3. FpCHS1 and FpCHS2 were homologous to regions of CHS1 and CHS2 of Saccharomyces cerevisiae, and their derived amino acid sequences fell into chitin synthase classes I and II, respectively. FpCHS3 was homologous to a region of the CAL1/CSD2 gene of S. cerevisiae, which codes for the chitin synthase three (Chs3) enzyme in that fungus. Phylogenetic trees constructed using the deduced amino acid sequences of PCR-amplified CHS products from many fungi clustered F. pedrosoi with other dematiaceous fungi, providing new molecular evidence for the genetic relatedness of these organisms. The identification of these CHS genes in F. pedrosoi will facilitate future studies of the functional roles of chitin synthases in the unique in vivo dimorphism exhibited by chromoblastomycotic fungi.

Amino Acid Sequence↗
PubMedDate not supplied

Genetic control of flower morphogenesis in Arabidopsis thaliana: a logical analysis.

MOTIVATION: A large number of molecular mechanisms at the basis of gene regulation have been described during the last few decades. It is now becoming possible to address questions dealing with both the structure and the dynamics of genetic regulatory networks, at least in the case of some of the best-characterized organisms. Most recent attempts to address these questions deal with microbial or animal model systems. In contrast, we analyze here a gene network involved in the control of the morphogenesis of flowers in a model plant, Arabidopsis thaliana. RESULTS: The genetic control of flower morphogenesis in Arabidopsis involves a large number of genes, of which 10 are considered here. The network topology has been derived from published genetic and molecular data, mainly relying on mRNA expression patterns under wild-type and mutant backgrounds. Using a 'generalized logical formalism', we provide a qualitative model and derive the parameter constraints accounting for the different patterns of gene expression found in the four floral organs of Arabidopsis (sepals, petals, stamens and carpels), plus a 'non-floral' state. This model also allows the simulation or the prediction of various mutant phenotypes. On the basis of our model analysis, we predict the existence of a sixth stable pattern of gene expression, yet to be characterized experimentally. Moreover, our dynamical analysis leads to the prediction of at least one more regulator of the gene LFY, likely to be involved in the transition from the non-flowering state to the flowering pathways. Finally, this work, together with other theoretical and experimental considerations, leads us to propose some general conclusions about the structure of gene networks controlling development.

Arabidopsis↗
PubMedDate not supplied

Calcium regulates in vitro dimorphism in chromoblastomycotic fungi.

Cladosporium carrionii, Fonsecaea pedrosoi and Phialophora verrucosa, the three most important agents of chromoblastomycosis, produced large numbers of sclerotic bodies at 25 degrees C, and greater numbers at 37 degrees C, after inoculation into a defined pH 2.5 medium containing 0.1 mmol l-1 Ca2+. Higher concentrations of Ca2+ reversed this tendency and promoted maintenance of hyphal growth. Addition of the Ca2+ chelator EGTA to the same medium buffered at pH 6.5 also induced sclerotic bodies, but in a more concentration-dependent fashion. EGTA at 0.5-1.0 mmol l-1 induced maximum numbers of sclerotic bodies in Cl. carrionii, whereas 2 and 8 mmol l-1 concentrations were required for the same results with F. pedrosoi and P. verrucosa, respectively. These findings suggest that Ca2+ concentrations in human tissue may play a paramount role in the dimorphic switching between hyphae and sclerotic bodies among chromoblastomycotic agents during infection.

Calcium↗
PubMedDate not supplied

Dual mycotic infection in a chicken.

A double mycotic infection, caused by Aspergillus fumigatus and a zygomycete-like organism, was histopathologically demonstrated in the lungs of a 12-week-old chicken. A. fumigatus was isolated, but the zygomycete was not.

Animals↗
PubMedDate not supplied

Favus in a fighting cock caused by Microsporum gallinae.

The first diagnosis of favus in chickens in Costa Rica was made in a 1-year-old fighting cock that had lesions surrounding the comb. The etiologic agent was isolated and identified as Microsporum gallinae. The rooster recovered during topical treatment with tolnaftate and oral treatment with griseofulvin.

Animals↗
PubMedDate not supplied

[Esthesioneuroblastoma: experience from 4 cases treated with radiotherapy and neoadjuvant chemotherapy].

The esthesioneuroblastoma is an uncommon but curable disease in a high proportion of cases. The treatment is controversial. Radiotherapy, alone or combined with surgery, has demonstrated to be an effective treatment in early stages. Chemotherapy, associated to radiotherapy, can improve the outcome in advanced stages and reduce the morbidity related to surgery. Three cases treated with radiotherapy, and one case treated with chemotherapy followed by radiotherapy are reported. Diagnosis and treatment management are discussed.

Adult↗