RESUMEN En el trabajo se estudió un consorcio microbiano metanogénico de una mina de carbón de la cuenca de Bogotá en Colombia. Se establecieron cultivos de enriquecimiento de carbón ex situ para el crecimiento y la producción de gas de novo. El gas biogénico producido por los cultivos se analizó mediante cromatografía de gases con detectores de ionización de llama y conductividad térmica. Los cultivos se utilizaron para aislar estirpes microbianas y para generar bibliotecas del gene 16S rARN empleando de cebadores de bacteria y de arquea. El análisis de cromatografía de gases mostró producción de metano a 37 oC, pero no a 60 oC, donde el CO2 fue el componente principal del gas biogénico. El análisis de la secuencia del gen 16S rARN de estirpes microbianos y de las bibliotecas de clones, estableció que el consorcio microbiano metanogénico estuvo formado por especies de bacterias de los géneros Bacillus y Gracilibacter más la arquea del género Methanothermobacter. El consorcio microbiano metanogénico identificado es potencialmente responsable de la generación de gas biogénico en la mina de carbón La Ciscuda. Los resultados sugirieron que los metanógenos de este consorcio producían metano por vía hidrogenotrófica o de reducción de CO2.

ABSTRACT The work studied the methanogenic microbial consortium in a coal mine from the Bogotá basin in Colombia. Ex situ coal-enrichment cultures were established for in vitro growth and de novo gas production. Biogenic gas produced by cultures was analyzed by gas chromatography using thermal conductivity and flame ionization detectors. Cultures were used to isolate microbial specimens and to generate 16S rRNA gene libraries employing bacterial and archaeal primer sets. The gas chromatographic analysis showed methane production at 37 oC, but not at 60 oC, where CO2 was the major component of the biogenic gas. 16S rRNA gene sequence analysis of microbial isolates and clone libraries established that the methanogenic microbial consortium was formed by bacteria species from Bacillus and Gracilibacter genera plus archaea from the Methanothermobacter genus. This meth-anogenic microbial consortium was potentially responsible for biogenic gas generation in La Ciscuda coal mine. The results suggested that these methanogens produced methane by hydrogenotrophic or CO2 reduction pathways.

Water resources have significant importance in countries with water scarcity. Part of this problem is attributed to the lack of relatedness between ecosystems service suppliers and users, and schemes of payment for hydrological ecosystem services (PHES) are emerging as a strategy to connect them. However, in the development of a scheme of PHES, one critical point is to find out if the protective land uses are adequately generating the service to sell. The aim of this study was to determine the hydrologic behaviour of land uses located in a hydrological recharge area of Sierra de Ocontepec. The land uses were secondary regeneration forest (SRF), African star grasslands (GWT), African star grasslands with shrubs (GS), disturbed Quercus oleoides forest (QF) and natural grasslands (NG). Indicators were precipitation, throughfall, runoff, soil moisture changes, evapotranspiration and percolation. Hydrological balances showed that percolation was higher in GWT (1 608 mm), GS (1 744 mm) and NG (1 314 mm), than in SRF (1 19 mm) and QF (974 mm). Results indicate that groundwater recharge during the study period generated adequate water shed services; however, the demand for piped water supply in the lowlands is at a maximum. This implies that the use of water should be regulated, more efficiently distributed, rather than relying on the increased availability.

Los recursos hidrológicos tienen significativa importancia en países con problemas de escasez de agua, parte de los cuales se atribuyen a la inexistencia de una relación entre los proveedores de servicios ambientales y de los usuarios. Los esquemas de pago por servicios ambientales hidrológicos (PSAH) surgen como una estrategia para conectarlos. El desarrollo de este esquema debería garantizar que los usos de la tierra de protección generen el servicio que se va a vender correctamente. Este estudio determinó el comportamiento hidrológico de los usos del suelo ubicados en un área de recarga de la Sierra de Otontepec, que correspondieron a: regeneración de bosques secundarios (SRF), pastizales estrella africana (GWT), pasto estrella africana y terrenos con arbustos (GS); bosque perturbado de Quercus oleoides (QF) y pastizales naturales (NG). Los indicadores fueron: precipitación, escorrentía, cambios de humedad del suelo, evapotranspiración y percolación. Los saldos hidrológicos mostraron que la percolación fue mayor en GWT (1 608 mm), GS (1 744 mm) y NG (1 314 mm), que en SRF (1 19 mm) y QF (974 mm). Los resultados indican que la recarga de agua subterránea durante el período de estudio proporcionó servicios ambientales hidrológicos convenientes, aun cuando la demanda del suministro de agua corriente en las tierras bajas está en un nivel máximo. Lo anterior implica que el uso del agua debe ser regulado y distribuido de manera más eficiente, en lugar de basarse en el aumento de la disponibilidad.

In this work, the toxicity and genotoxicity of organic solvents (acetone, carbon tetrachloride, dichloromethane, dimethylsulfoxide, ethanol, ether and methanol) were studied using the SOS chromotest. The influence of these solvents on the direct genotoxicity induced by the mutagens mitomycin C (MMC) and 4-nitroquinoline-1-oxide (4-NQO) were also investigated. None of the solvents were genotoxic in Escherichia coli PQ37. However, based on the inhibition of protein synthesis assessed by constitutive alkaline phosphatase activity, some solvents (carbon tetrachloride, dimethylsulfoxide, ethanol and ether) were toxic and incompatible with the SOS chromotest. Solvents that were neither toxic nor genotoxic to E. coli (acetone, dichloromethane and methanol) significantly reduced the genotoxicity of MMC and 4-NQO. When these solvents were used to dissolve vitamin E they increased the antigenotoxic activity of this compound, possibly through additive or synergistic effects. The relevance of these results is discussed in relation to antigenotoxic studies. These data indicate the need for careful selection of an appropriate diluent for the SOS chromotest since some solvents can modulate genotoxicity and antigenotoxicity.

The present work evaluated the chemical composition and the DNA protective effect of the essential oils (EOs) from Lippia alba against bleomycin-induced genotoxicity. EO constituents were determined by Gas Chromatography/Mass Spectrometric (GC-MS) analysis. The major compounds encountered being citral (33% geranial and 25% neral), geraniol (7%) and trans-β-caryophyllene (7%) for L. alba specimen COL512077, and carvone (38%), limonene (33%) and bicyclosesquiphellandrene (8%) for the other, COL512078. The genotoxicity and antigenotoxicity of EO and the compounds citral, carvone and limonene, were assayed using the SOS Chromotest in Escherichia coli. The EOs were not genotoxic in the SOS chromotest, but one of the major compound (limonene) showed genotoxicity at doses between 97 and 1549 mM. Both EOs protected bacterial cells against bleomycin-induced genotoxicity. Antigenotoxicity in the two L. alba chemotypes was related to the major compounds, citral and carvone, respectively. The results were discussed in relation to the chemopreventive potential of L. alba EOs and its major compounds.

The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM) and 4-nitroquinoline-1-oxide (4NQO) was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 !g/mL) yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay) to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV < 10%). The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies.

The analysis of DNA damage by mean of Comet or single cell gel electrophoresis (SCGE) assay has been commonly used to assess genotoxic impact in aquatic animals being able to detect exposure to low concentrations of contaminants in a wide range of species. The aims of this work were 1) to evaluate the usefulness of the Comet to detect DNA strand breakage in dolphin leukocytes, 2) to use the DNA diffusion assay to determine the amount of DNA strand breakage associated with apoptosis or necrosis, and 3) to determine the proportion of DNA strand breakage that was unrelated to apoptosis and necrosis. Significant intra-individual variation was observed in all of the estimates of DNA damage. DNA strand breakage was overestimated because a considerable amount (~29%) of the DNA damage was derived from apoptosis and necrosis. The remaining DNA damage in dolphin leukocytes was caused by factors unrelated to apoptosis and necrosis. These results indicate that the DNA diffusion assay is a complementary tool that can be used together with the Comet assay to assess DNA damage in bottlenose dolphins.

Microsatellite polymorphism was studied in a sample of 39 traditional rice (Oryza sativa L.) varieties and 11 improved varieties widely planted in Cuba. The study was aimed at assessing the extent of genetic variation in traditional and improved varieties and to establish their genetic relationship for breeding purposes. Heterozygosity was analyzed at each microsatellite loci and for each genotype using 10 microsatellite primer pairs. Between varieties genetic relationship was estimated. The number of alleles per microsatellite loci was 4 to 8, averaging 6.6 alleles per locus. Higher heterozygosity (H) was found in traditional varieties (H TV = 0.72) than in improved varieties (H IV = 0.42), and 68% of the total microsatellite alleles were found exclusively in the traditional varieties. Genetic diversity, represented by cluster analysis, indicated three different genetic groups based on their origin. Genetic relationship estimates based on the proportion of microsatellite loci with shared alleles indicated that the majority of traditional varieties were poorly related to the improved varieties. We also discuss the more efficient use of the available genetic diversity in future programs involving genetic crosses.