RESUMEN
Several partial reactions of the Na(+)-K+ pump enzyme were studied in a microsomal fraction derived from the gill of carp (Cyprinus carpio Linneo). We tested the effect of three toxins [(i) microcystin-LR, (ii) microcystin-LR-like toxin component isolated from Microcystis aeruginosa culture and (iii) okadaic acid] on the phosphorylation, ouabain binding and ATPase activity of the Na(+)-K+ pump. The K(+)-dependent hydrolysis of the Na(+)-dependent phosphorylation of Na(+)-K+ pump, as well the release of bound ouabain were inactivated in direct proportion to the amount of each toxin treatment. These results indicate that these toxins not only block the hydrolysis of phosphorylated protein at serine and threonine residues, but also inhibit the aspartic dephosphorylation step of the sodium pump enzymes. This inactivation could disrupt the ion homeostasis of the internal medium by blocking the gill function. The blockage of gill activity could be the cause of the massive fish death during blooms of M. aeruginosa.
Asunto(s)
Inhibidores Enzimáticos/toxicidad , Branquias/efectos de los fármacos , Péptidos Cíclicos/toxicidad , Fosfoproteínas Fosfatasas/antagonistas & inhibidores , ATPasa Intercambiadora de Sodio-Potasio/efectos de los fármacos , Animales , Unión Competitiva , Carpas , Células Cultivadas , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/metabolismo , Inhibidores Enzimáticos/farmacología , Branquias/enzimología , Hidrólisis , Indicadores y Reactivos/metabolismo , Toxinas Marinas , Microcistinas , Microsomas/efectos de los fármacos , Microsomas/enzimología , Nitrofenoles/metabolismo , Octoxinol/química , Ácido Ocadaico/farmacología , Compuestos Organofosforados/metabolismo , Ouabaína/metabolismo , Ouabaína/farmacología , Fosforilación/efectos de los fármacos , ATPasa Intercambiadora de Sodio-Potasio/metabolismoRESUMEN
A microsomal fraction enriched in ion pump enzymes was isolated from the gill of the carp (Cyprinus carpio Linneo). Mg(2+)-dependent (Na+ + K+), Na+, HCO3- and Ca(2+)-stimulated ATPase activities were studied following treatment with microcystin-LR-like toxin, the major toxic component isolated from Microcystis aeruginosa culture. These enzyme activities were inhibited in a dose-dependent manner. The maximum inhibition of each enzyme, induced with nM concentration of the toxin, was similar to that produced by inhibitors specific for each ATPase activity. The Mg(2+)-ATPase activity and non-specific hydrolysis of ATP were unaffected. These results strongly suggest that the massive fish death during M. aeruginosa blooms may result from the loss of ion homeostatic processes produced by the inhibitory action of microcystin on the ion pumps of gill chloride cells.
Asunto(s)
Toxinas Bacterianas/farmacología , Branquias/enzimología , Bombas Iónicas/efectos de los fármacos , Microcystis/química , Animales , ATPasas Transportadoras de Calcio/metabolismo , Carpas , Branquias/microbiología , ATPasa Intercambiadora de Sodio-Potasio/metabolismoRESUMEN
Four hundred strains of enterobacteria, isolated before the introduction of trimethoprim as a single agent in Chile, were studied. One hundred and thirty six strains (34%) were resistant to greater than or equal to 8 mg/l of trimethoprim and 118 of these (87%) were also resistant to sulphamethoxazole (156 mg/l). Plasmids were detected in 79% of the trimethoprim-resistant strains; 56% of the strains carried two or more plasmids. Trimethoprim resistance could be transferred by conjugation in 66% of the plasmid-carrying strains; this resistance was co-transferred with a variety of other antibiotic resistance determinants.
Asunto(s)
Enterobacteriaceae/efectos de los fármacos , Resistencia al Trimetoprim/genética , Chile , ADN Bacteriano/aislamiento & purificación , Infecciones por Enterobacteriaceae/tratamiento farmacológico , Escherichia coli/efectos de los fármacos , Humanos , Klebsiella pneumoniae/efectos de los fármacos , Plásmidos/efectos de los fármacos , Valores de Referencia , Shigella/efectos de los fármacos , Sulfametoxazol/farmacología , Sulfametoxazol/uso terapéutico , Trimetoprim/farmacología , Trimetoprim/uso terapéuticoRESUMEN
An approach to correlate functions with cistrons in bacteriophage PM2 is presented. Two of the temperature-sensitive mutants obtained differed from the wild type in heat sensitivity and four differed in host range. Comparison of the electrophoretic patterns of DNA from cells infected at the restrictive temperature with those obtained in wildtype infection revealed that viral DNA bands were absent with three additional mutants. Complementation analysis assigned the four host range mutants to cistron I and the three mutants defective in DNA synthesis to cistron IV. Recombination frequencies were used to locate cistrons III and IV on the partial genetic map of PM2.
Asunto(s)
Bacteriófagos/genética , Bacteriófagos/fisiología , Replicación del ADN , ADN Superhelicoidal/biosíntesis , ADN Viral/biosíntesis , Prueba de Complementación Genética , Recombinación Genética , Temperatura , Replicación ViralAsunto(s)
Adolescente , Adulto , Humanos , Femenino , Amenorrea , Galactorrea , Hormona Folículo Estimulante , Laparoscopía , Hormona Luteinizante , ProlactinaRESUMEN
The DNA molecules isolated from mature bacteriophage PM2 are closed double-stranded rings of a molecular weight of six million. Direct evidence for the circularity and supercoiling of PM2 DNA was obtained by electron microscopy. Other properties, such as sedimentation behavior at neutral and alkaline pH, unusually high buoyant density in alkaline CsCl, and stability upon heating, are consistent with this structure. Only the four common nucleotides are found after hydrolysis and chromatographic analysis of PM2 DNA.
Asunto(s)
Bacteriófagos/análisis , ADN Viral/aislamiento & purificación , Peso Molecular , Centrifugación por Gradiente de Densidad , Microscopía Electrónica , Nucleótidos/análisisRESUMEN
Phosphatidylethanolamine is the only phosphatide present in purified bacteriophage PM2 when obtained from bacteria grown and infected in minimal medium. The growth cycle of bacteriophage PM2 shows the basic general features described for virulent bacteriophages. PM2 infection of Pseudomonas BAL-31 causes a pronounced increase in deoxyribonucleic acid synthesis, but no detectable effect on the incorporation of phosphorus into lipid. When (32)P-prelabeled bacteria are infected with PM2, the specific activity of the phosphatide phosphorus in the virus is almost the same as that in the host bacteria labeled before infection. It is concluded that the viral phosphatide is not synthesized de novo after infection, but it probably is derived from preexisting cellular phosphatidylethanolamine.
Asunto(s)
Bacteriófagos/análisis , Fosfatidiletanolaminas/análisis , Fósforo/análisis , Pseudomonas , Bacteriófagos/crecimiento & desarrollo , Cromatografía en Capa Delgada , Fosfolípidos/metabolismo , Isótopos de Fósforo , RadiometríaRESUMEN
A marine bacterium, which acts as host for bacteriophage PM2 isolated from the same environment, has been characterized as a Pseudomonas species. This Pseudomonas cannot be assigned to any of the subgeneric categories or "groups" described by Stanier, Palleroni, and Doudoroff. The psychrophilic and halophilic nature of the organism and its requirement for NaCl suggest an indigenous marine origin.