RESUMEN
Carbon-flow-regulator A (CfrA) adapts carbon flux to nitrogen conditions in nondiazotrophic cyanobacteria. Under nitrogen deficiency, CfrA leads to the storage of excess carbon, which cannot combine with nitrogen, mainly as glycogen. cfrA overexpression from the arsenite-inducible, nitrogen-independent ParsB promoter allows analysis of the metabolic effects of CfrA accumulation. Considering that the main consequence of cfrA overexpression is glycogen accumulation, we examined carbon distribution in response to cfrA expression in Synechocystis sp. PCC 6803 strains impaired in synthesizing this polymer. We carried out a comparative phenotypic analysis to evaluate cfrA overexpression in the wild-type strain and in a mutant of ADP-glucose pyrophosphorylase (ΔglgC), which is unable to synthesize glycogen. The accumulation of CfrA in the wild-type background caused a photosynthetic readjustment although growth was not affected. However, in a ΔglgC strain, growth decreased depending on CfrA accumulation and photosynthesis was severely affected. An elemental analysis of the H, C, and N content of cells revealed that cfrA expression in the wild-type caused an increase in the C/N ratio, due to decreased nitrogen assimilation. Metabolomic study indicated that these cells store sucrose and glycosylglycerol, in addition to the previously described glycogen accumulation. However, cells deficient in glycogen synthesis accumulated large amounts of Calvin-Benson cycle intermediates as cfrA was expressed. These cells also showed increased levels of some amino acids, mainly alanine, serine, valine, isoleucine, and leucine. The findings suggest that by controlling cfrA expression, in different conditions and strains, we could change the distribution of fixed carbon, with potential biotechnological benefits.
Asunto(s)
Proteínas Bacterianas , Carbono , Nitrógeno , Fotosíntesis , Synechocystis , Carbono/metabolismo , Synechocystis/metabolismo , Synechocystis/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Nitrógeno/metabolismo , Glucógeno/metabolismo , Regulación Bacteriana de la Expresión GénicaRESUMEN
Introduction: Loss of Heterozygocity (LOH) in the short arm of human chromosome 3 (3p) is a frequent event in different types of sporadic tumors, including lung cancer (LC). Aim: To determine 3p LOH in LC samples using 17 microsatellite markers. Methodology: In a pilot study on volunteers, thirteen LC biopsies (tumor tissue) and 4 ml of blood (normal tissue) from the same patient were collected. DNA extraction and Polymerase Chain Reaction (PCR) were performed with 17 microsatellite markers to analyze LOH. Amplified fragments were run on 6% denaturalizing polyacrilamide gels and were visualized by using silver stain. Descriptive analysis was performed for each region on the 3p chromosome. Results: All tumors were informative for one or more of the analyzed markers. LOH was found in one or more loci in eleven samples (84.6%). The markers with major LOH were UBE1L (23.1%), D3S1317, D3S1300, D3S1284, D3S1274, D3S3049, and D3S1577 (15.4%). Three samples showed microsatellite instability (changes in the length of the microsatellite) in different loci. The percentages of LOH for the regions of 3p were: 17.6 % for 3p24-25, 11.62% for 3p21-22, 20% for 3p13-14, and 18.42% for the 3p12 region. Conclusions: Chromosomal regions with allelic loss were identified where probably other GSTs involved in the development of the LC are localized. It should increases sample size and marker number in order to narrow a minimal region and to identify a unknown gene involved in LC.
Introducción: La pérdida de heterocigocidad (LOH) en el brazo corto del cromosoma 3 (3p) humano es un evento frecuente en diferentes tipos de tumores esporádicos, incluyendo cáncer de pulmón (CP). Objetivo: Determinar la LOH de 3p en muestras de CP, con 17 marcadores microsatelitales. Metodología: En un estudio piloto en voluntarios, se recolectaron 13 biopsias de CP (tejido tumoral) y 4 ml de sangre periférica (tejido normal) del mismo paciente, se extrajo el ADN y se realizaron reacciones en cadena de la polimerasa (PCR) con 17 marcadores microsatelitales para analizar LOH. Los fragmentos amplificados se corrieron en geles de poliacrilamida desnaturalizante al 6% y se visualizaron por medio de la coloración de tinción de plata. El análisis descriptivo se realizó para cada región estudiada en el cromosoma 3p. Resultados: Todos los tumores fueron informativos para uno o más de los marcadores analizados. Se encontró LOH en uno o más loci en 11 muestras (84.6%). Los marcadores con mayores LOH fueron UBE1L (23.1%), D3S1317, D3S1300, D3S1284, D3S1274, D3S3049 y D3S1577 con 15.4%. Tres muestras presentaron inestabilidad microsatelital (cambios en la longitud del microsatélite) en diferentes loci. Los porcentajes de LOH para las regiones de 3p fueron: 17.6 % para 3p24-25, 11.6% para 3p21-22, 20% para 3p13-14 y 18.4% para la región 3p12. Conclusiones: Se identificaron regiones cromosómicas con pérdida alélica donde es probable que se localicen otros GST involucrados en el desarrollo de CP, diferentes de los ya identificados como VHL, RASSF1A, FHIT y DUTTI, entre otros. Se debe aumentar el número de muestras y de marcadores para delimitar una región mínima e identificar algún gen no descrito implicado en la carcinogénesis de pulmón.
Asunto(s)
Humanos , Pérdida de Heterocigocidad , Neoplasias Pulmonares , Reacción en Cadena de la PolimerasaRESUMEN
La histoplasmosis es una micosis de origen pulmonar primario, adquirida por vía inhalatoria. En la mayoría de los casos, la infección pasa inadvertida o se manifiesta por síntomas respiratorios leves. El histoplasmoma es una forma relativamente común de histoplasmosis pulmonar aguda, de aspecto nodular, generalmente acompañada de calcificación, la cual puede aumentar en tamaño y simular una neoplasia pulmonar. presenta un caso de un paciente inmunosuprimido con esta forma de micosis pulmonar.