ABSTRACT
The ChrA membrane protein belongs to the CHR superfamily of chromate ion transporters, which includes homologues from bacteria, archaea and eukaryotes. Bacterial ChrA homologues confer chromate resistance by exporting chromate ions from the cell's cytoplasm. The Neurospora crassa strain 74-A chr-1 gene encodes a putative CHR-1 protein of 507 amino acid residues, which belongs to the CHR superfamily. RT-PCR assays showed that expression of the chr-1 gene was up-regulated by chromate exposure of N. crassa cultures. Introduction in N. crassa of sense and antisense fragments of the chr-1 gene, as part of a silencing module within the pSilent-1 vector, produced transformants with a phenotype of resistance to chromate and diminished accumulation of chromium, as compared with the control strain containing only the vector. A chromate-resistance phenotype was also observed in N crassa strains deleted in the genomic chr-1 gene, thus confirming that the absence of CHR-1 protein confers chromate resistance to the fungus. The cDNA from N. crassa chr-1 gene (Ncchr-1) was cloned into the pYES2 vector under the control of a GAL promoter and the resulting recombinant plasmid was transferred to the yeast Saccharomyces cerevisiae. Galactose-induced S. cerevisiae transformants expressing Ncchr-1 were more sensitive to chromate and accumulated 2.5 times more chromium than the induced strain containing only the vector. Excess sulfate, a chromate analog, was unable to protect S. cerevisiae chr-1 transformants from chromate toxicity. These data indicate that the N. crassa CHR-1 protein functions as a transporter that takes up chromate; it also appears that this transport occurs in a sulfate-independent fashion. This is the first report assigning a role as a chromate transporter to a nonbacterial CHR protein.
Subject(s)
Chromates/metabolism , Fungal Proteins/metabolism , Gene Expression Regulation, Fungal , Genes, Fungal , Neurospora crassa/metabolism , Biological Transport , Chromates/pharmacology , Cloning, Molecular , Culture Media/metabolism , DNA, Complementary/genetics , DNA, Complementary/metabolism , Fungal Proteins/genetics , Gene Silencing , Genetic Vectors/genetics , Genetic Vectors/metabolism , Membrane Transport Proteins/genetics , Membrane Transport Proteins/metabolism , Neurospora crassa/drug effects , Neurospora crassa/genetics , Phenotype , Plasmids/genetics , Plasmids/metabolism , Promoter Regions, Genetic , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Sequence Analysis, Protein , Spores, Fungal/drug effects , Spores, Fungal/metabolism , Transformation, GeneticABSTRACT
Estudiamos los factores asociados al estrés psicosocial en pacientes con diabetes mellitus tipo 2. Se realizó un estudio en sección transversal en 105 pacientes, 27 hombres y 78 mujeres, cuya edad media es de 51.5 años (50.2-52.5, IC 95 por ciento) con 8.6 años desde el diagnóstico (7.3-9.8, IC 95 por ciento). Los pacientes tenían sobrepeso con índice de masa corporal (IMC) de 27.6 y la mayoría tenía descontrol metabólico aunque sin síntomas (media de glucosa 10.6 nmol/L y HbA1c de 9.2 por ciento). La hemoglobina glucosilada se asoció con el IMC (negativamente, p = 0.002). Dentro de los grupos, esta asociación con el IMC se encontró sólo en las mujeres y se explicó porqué la mujer obesa tiene menos años desde el diagnóstico que es un factor relacionado a mejor control metabólico. En el análisis de regresión múltiple el estrés percibido se asoció además con el por ciento de grasa corporal y con la glucosa en el grupo total, en las mujeres con años desde el diagnóstico (p = 0.02), y en los hombres con IMC (p = 0.03). No se encontró asociación entre estrés percibido y adherencia al tratamiento. Concluimos que en nuestro grupo, el estrés percibido se asoció con la obesidad y con el control metabólico.
