The global carbon storage regulator (Csr) system is conserved in bacteria and functions as a regulator in the exponential and stationary phases of growth in batch culture. The Csr system plays a role in the central carbon metabolism, virulence, motility, resistance to oxidative stress, and biofilm formation. Although the Csr was extensively studied in Gram negative bacteria, it has been reported only in the control of motility in Bacillus subtilis among Gram positive bacteria. The goal of this study was to explore the role of the csrA gene of Bacillus licheniformis M2-7 on motility and the bacterial ability to use hydrocarbons as carbon source. We deleted the csrA gene of B. licheniformis M2-7 using the plasmid pCsr-L, harboring the spectinomycin cassette obtained from the plasmid pHP45-omega2. Mutants were grown on culture medium supplemented with 2% glucose or 0.1% gasoline and motility was assessed by electron microscopy. We observed that CsrA negatively regulates motility by controlling the expression of the hag gene and the synthesis of flagellin. Notably, we showed the ability of B. licheniformis to use gasoline as a unique carbon source. Our results demonstrated that CsrA is an indispensable regulator for the growth of B. licheniformis M2-7 on gasoline.
The aim of this work was to isolate pulp (PH) and seed hydrocolloids (SH) of the fruit of Hymenaea corbaril L. and determinate chemical, functional and rheological properties, as a proposal of a new attractive product for functional applications in food systems. Both hydrocolloids have a high content of carbohydrates, minerals and fiber. The solubility of PH was higher 94.1%. The emulsifying capacity of SH, PH and GG increases with the hydrocolloid concentration. The emulsions showing a good stabilization stability with drop sizes of 5-20 μm. The emulsions PH and SH at 1% were higher stability than guar gum (GG), due to slower down the cremation index after 3 days of storage at 35 and 40°C. The hydrocolloids exhibited a pseudoplastic behavior at concentrations of 0.5-2%. The elastic behavior suggests its application to edible films, while the viscous behavior suggests its incorporation in food systems.
Benzopyrene is a high molecular weight polycyclic aromatic hydrocarbon with highly recalcitrant and develops carcinogenic effects. CsrA is a conserved regulatory protein, which controls the translation and stability of its target transcripts, having negative or positive effects depending on the target mRNAs. It is known that Bacillus licheniformis M2-7 has the ability to grow and survive in concentrations of hydrocarbons as benzopyrene, which prompted in part by CsrA, as it occurs in the presence of gasoline. However, there are a few studies that reveal the genes involved in that process. In order to know the involved genes in the Bacillus licheniformis M2-7 degradation pathway, the plasmid pCAT-sp containing a mutation in the catEgen was constructed and used to transform B. licheniformis M2-7 and generate the CAT1 strain. We determined the capacity of the mutant B. licheniformis(CAT1) to grow in the presence of glucose and benzopyrene as a carbon source. We observed that CAT1 strain presented an increase in growth in the presence of glucose, but a statistically considerable decrease in the presence of benzopyrene with respect to the wild strain M2-7. Also we demonstrated that the Csr system regulates its expression positively since it was observed that the expression of the gene in the mutant strain LYA12 (M2-7 csrA:: Sp, SpR) decreased considerably with respect to the wild strain. This allowed to characterize the metabolic pathway that Bacillus licheniformis M2-7 implements in the presence of benzopyrene.
La propagación de los Agaves spp. en México es muy extensa y el país cuenta con 151 especies endémicas. Sin embargo, prácticas como la construcción, el desarrollo de fibras, la elaboración de alimentos y bebidas alcohólicas, así como la elaboración de productos ornamentales han ocasionado una considerable disminución entre las poblaciones silvestres. En este sentido, el presente trabajo tiene como objetivo realizar la caracterización morfométrica por el método de I.S.T.A de las semillas de Agave spp. colectadas en los diferentes municipios del estado de Guerrero (Agave cupreata Trel. & A. Berger y Agave angustifolia Haw.). Los resultados obtenidos se sometieron a análisis de varianza y pruebas de medias (Tukey, p ≤ 0.05), tomándose el largo, ancho, grosor de las semillas y su volumen. El sitio de muestreo que presentó el mayor número de semillas por kilogramo (233,590) fue Lamazintla. Por otra parte, las semillas de mayor longitud, anchura y grosor se encontraron en el municipio de Alpoyeca (8.6; 6.4; 0.62 mm, respectivamente). Además el análisis de pureza demostró que la muestra obtenida en Amojileca cuenta con el mayor número de semillas maduras con un promedio del 57%.
Introducción. Los efectos adversos de los químicos en la reproducción masculina es un área de preocupación creciente, actualmente el Tl es utilizado principalmente en la fabricación de dispositivos electrónicos, interruptores y cierres; así como en plantas generadoras de energía, fábricas de cemento y fundiciones. Objetivo. Evaluar la calidad espermática y el daño genético de los espermatozoides en ratones expuestos oralmente a Tl. Materiales y métodos. Se utilizaron ratones macho y dosis de Tl de 5, 15 y 25 mg/kg/5d, se evaluaron los parámetros de calidad espermática y el daño al ADN por la técnica de SCSA. Resultados. La exposición a Tl afecto la motilidad, la viabilidad y la morfología espermática. Se observaron alteraciones en la estructura del ADN (%DFI y %HSD) de los espermatozoides. El Tl se podría considerar reprotóxico, ya que altera capacidad reproductiva.
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