Structure and function of methanogenic microbial communities in sediments of Amazonian lakes with different water types.

Tropical lake sediments are a significant source for the greenhouse gas methane. We studied function (pathway, rate) and structure (abundance, taxonomic composition) of the microbial communities (Bacteria, Archaea) leading to methane formation together with the main physicochemical characteristics in the sediments of four clear water, six white water and three black water lakes of the Amazon River system. Concentrations of sulfate and ferric iron, pH and δ13 C of organic carbon were usually higher, while concentrations of carbon, nitrogen and rates of CH4 production were generally lower in white water versus clear water or black water sediments. Copy numbers of bacterial and especially archaeal ribosomal RNA genes also tended to be relatively lower in white water sediments. Hydrogenotrophic methanogenesis contributed 58 ± 16% to total CH4 production in all systems. Network analysis identified six communities, of which four were comprised mostly of bacteria found in all sediment types, while two were mostly in clear water sediment. Terminal restriction fragment length polymorphism (T-RFLP) and pyrosequencing showed that the compositions of the communities differed between the different sediment systems, statistically related to the particular physicochemical conditions and to CH4 production rates. Among the archaea, clear water, white water, and black water sediments contained relatively more Methanomicrobiales, Methanosarcinaceae and Methanocellales, respectively, while Methanosaetaceae were common in all systems. Proteobacteria, Deltaproteobacteria (Myxococcales, Syntrophobacterales, sulfate reducers) in particular, Acidobacteria and Firmicutes were the most abundant bacterial phyla in all sediment systems. Among the other important bacterial phyla, clear water sediments contained relatively more Alphaproteobacteria and Planctomycetes, whereas white water sediments contained relatively more Betaproteobacteria, Firmicutes, Actinobacteria, and Chloroflexi than the respective other sediment systems. The data showed communities of bacteria common to all sediment types, but also revealed microbial groups that were significantly different between the sediment types, which also differed in physicochemical conditions. Our study showed that function of the microbial communities may be understood on the basis of their structures, which in turn are determined by environmental heterogeneity.

Methane emissions from Pantanal, South America, during the low water season: toward more comprehensive sampling.

Freshwater environments contribute 75% of the natural global methane (CH(4)) emissions. While there are indications that tropical lakes and reservoirs emit 58-400% more CH(4) per unit area than similar environments in boreal and temperate biomes, direct measurements of tropical lake emissions are scarce. We measured CH(4) emissions from 16 natural shallow lakes in the Pantanal region of South America, one of the world's largest tropical wetland areas, during the low water period using floating flux chambers. Measured fluxes ranged from 3.9 to 74.2 mmol m(-2) d(-1) with the average from all studied lakes being 8.8 mmol m(-2) d(-1) (131.8 mg CH(4) m(-2) d(-1)), of which ebullition accounted for 91% of the flux (28-98% on individual lakes). Diel cycling of emission rates was observed and therefore 24-h long measurements are recommended rather than short-term measurements not accounting for the full diel cycle. Methane emission variability within a lake may be equal to or more important than between lake variability in floodplain areas as this study identified diverse habitats within lakes having widely different flux rates. Future measurements with static floating chambers should be based on many individual chambers distributed in the various subenvironments of a lake that may differ in emissions in order to account for the within lake variability.

Câncer de mama: da descoberta à recorrência da doença / Breast cancer: of the discovery to the recurrence of the illness / Cáncer de mama: de la descubierta a la recurrencia de la enfermedad

Estudo exploratório e descritivo que objetivou compreender o sentimento da mulher mastectomizada desde o diagnóstico até a possibilidade da recorrência do câncer de mama, desenvolvido com 15 mulheres com as idades compreendidas entre 30 a 75 anos, participantes do Grupo de Auto-ajuda, Ensino, Pesquisa e Assistência à Mulher Mastectomizada da Universidade Federal do Ceará. Os dados foram coletados entre os meses de agosto e setembro/2004, mediante entrevista semi-estruturada. Dos dados analisados identificamos as seguintes categorias: a descoberta do câncer e a realização da mastectomia, a expectativa de cura diante do câncer, convivendo com o temor da recorrência e a significação do grupo de auto-ajuda em suas vidas. Constatamos que o diagnóstico do câncer de mama se apresenta como algo irreal em suas vidas, se constituindo em doença letal e assustadora, trazendo surpresa, medo e desespero. O grupo de auto-ajuda surge como apoio, onde essas mulheres interagem, trocam e compartilham experiências, tornando-se mais conscientes, superando juntas o temor da recorrência do câncer de mama.

This in an exploratory and descriptive study, which aimed to understand the feelings of the mastectomized woman due to the possibility of breast cancer recurrence since the diagnosis, it was developed with 15 mastectomized women with the average of age between 30 and 75 years, participants of GEPAM (Self-Help, Teaching, Research and Attendance to the mastectomized woman Group) from the Department of Nursing of UFC. The data were collected in 2004, between August and September, with a semi-structured interview. We identified the following categories: the discovery of cancer and the accomplishment of the mastectomy; the cure expectation before the cancer; living with the fear of the recurrence and the significance of the group of self-help in their lives. We verified that the breast cancer diagnosis presents itself as something unreal in their lives, consisting of a lethal and frightening disease, bringing surprise, fear and despair. The self-help group appears as support, where those women interact, change and share experiences, becoming more conscious, overcoming together the fear of the recurrence of breast cancer.

Estudio exploratorio y descriptivo, objetivo comprehender el sentimiento de la mujer mastectomizada desde el diagnóstico hasta la posibilidad de la recurrencia del cáncer de mama, desarrollado con 15 mujeres mastectomizadas con edades comprehendidas entre 30 a 75 años, participantes del Grupo de Auto ayuda, Enseñanza, Investigación y Asistencia a la Mujer Mastectmomizada, del Departamiento de Enfermería de la Universidad Federal de Ceará. Los datos fueron colectados en agosto y septiembre/ 2004, através de entrevista estructura en parte. De los datos analizados, identificamos las seguientes categorías: la descubierta del cáncer y la realización de la mastectomía; la expectativa de cura delante del cáncer, viviendo junto al miedo de la recurrencia y a la significación del grupo de auto ayuda en sus vidas. Constatamos que el diagnóstico del cáncer de mama se presenta como algo que no es real en sus vidas, constuyéndose en una enfermedad asustadora, lo que trae surpresa, miedo y además desespero. El grupo de auto ayuda surge como apoyo, en que esas mujeres interagen, cambian experiencias, lo que resultan en mujeres más conscientes, superando todavia juntas el miedo de la recurrencia del cáncer de mama.