This lack of data may be related to the fact that evaluation of the energy releasing processes in swimming is difficult to perform in most exercise physiology laboratories. However, new methods have been developed which allow the determination of VO2 and blood lactate concentration in response to different swimuning velocities with the collection of expired air and blood samples in the recovery period'3' . These methods present the advantage of estimating the contribution of anaerobic and aerobic processes at submaximal and maximal intensities while swimuing, and relating these findings to training intensities'0' 15. Thus, the present study was conducted to evaluate the capacity of metabolic indices derived from these new methods to predict the performance in the 400 metres swimming event.The results indicate that some of these factors may be important determinants of middle distance swimming performance. MethodFifteen competitive swimmers participated in the study. Their physical characteristics are described in Table 1. They were participating in intense physical training, they were all used to swimming the 400 metres freestyle swimming event, but not all of them were specialists in such an event. The athletes were informed about the risks involved in the participation in the experiments and signed an informed consent. 196 Br.

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ResumenCon el objetivo de establecer la biomasa de carbono contenida en el fitoplancton eucariota del embalse Riogrande II (Antioquia, Colombia), entre agosto de 2011 y agosto de 2012, la porción de esa biomasa disponible para el zooplancton filtrador y la calidad de alimento que podría representar para dicho grupo, el fitoplancton se clasificó en dos rangos de longitud correspondientes a nanoplancton (5 a 20 µm) y microplancton (>20 µm). Para ambos grupos se calculó el contenido de carbono celular y la biomasa total en contenido de carbono. Además, para el nanoplancton, el cual corresponde a la fracción filtrable, se estimaron las concentraciones de nitrato y de fosfato. Los altos niveles de biomasa de organismos fototróficos evidenciaron el papel fundamental del fitoplancton eucariótico en la fijación de carbono. Sin embargo, debido a la eutrofización del sistema y a que la talla del zooplancton dominante es pequeña, el flujo de carbono y de nutrientes parece estar dirigido principalmente hacia la vía detrítica y las sustancias disueltas, y no directamente al zooplancton filtrador, cuya principal fuente de alimento en el fitoplancton eucariótico la constituyen los organismos nanoplanctónicos mixotróficos (Cryptophyta y Euglenophyta), que en función de un mayor volumen poseen concentraciones más elevadas de nitrato y fosfato y, por lo tanto, pueden proveer alimento de mejor calidad que el resto del nanoplancton. © Acad. Colomb. Cienc. Ex. Fis. Nat. 2016.Palabras clave: biomasa, carbono, fitoplancton, microplancton, nanoplancton, zooplancton. Eukariotic phytoplankton biomass and its availability for the food web at Riogrande II reservoir (Antioquia, Colombia) AbstractIn order to establish the carbon biomass content in the eukaryotic phytoplankton at Riogrande II reservoir (Antioquia, Colombia) from August 2011 to August 2012, as well as the portion of this available biomass for filter-feeding zooplankton and the quality of food it could represent for each group, we classified phytoplankton considering two length ranges corresponding to nanoplankton (5 to 20 µm) and microplankton (>20 µm). We estimated the cellular carbon content and the total biomass represented as carbon content for both groups. We also estimated nitrate and phosphate concentrations for the nanoplankton, which corresponds to the filterable fraction. The high levels of phototrophic organisms biomass showed the essential role of eukaryotic phytoplankton in carbon fixation; however, due to the eutrophication of this reservoir and to the small size of dominant zooplankton, the carbon flux and nutrients seemed to be directed mainly to the detrital track and to dissolved substances and not directly to the filter-feeding zooplankton, whose main food source among eukaryotic phytoplankton is constituted by mixotrophic nanoplanktonic organisms (such as Cryptophyta and Euglenophyta), that according to their greater volume have higher concentrations of nitrate and phosphate and, therefore, can provide better quality food than the remaining nanoplankton.

Se determinó la bioconcentración del insecticida clorpirifos en plantas de pasto Cenchrus clandestinus cultivadas hidropónicamente, el pesticida fue aplicado en la solución de cultivo, se realizó el seguimiento de la concentración del pesticida en los tejidos del follaje y de la raíz, durante 72 h de exposición a la solución nutritiva con 96, 192 y 288 mg L-1 de clorpirifos. Los muestreos en tejidos se realizaron a las 4, 24, 48 y 72 h. Para la extracción del clorpirifos del follaje y raíz del pasto se empleó el método MI 48640 con una sensibilidad de 0,01 ppm y la cuantificación se realizó por cromatografía de gases. Durante el estudio se evidenció que el clorpirifos se transporta a través del sistema vascular de plantas de C. clandestinus en cultivo hidropónico, desde la raíz hasta el follaje. Además, se evidenció bioacumulación creciente en los tejidos de raíz y follaje. La bioacumulación del clorpirifos fue mayor en la raíz 39,4 µg g-1 que en el follaje 1,1 µg g-1. Por lo anterior, la utilización de este insecticida en los sistemas ganaderos de trópico alto representa un riesgo para los bovinos y para los demás integrantes de la cadena alimenticia láctea.

Genotoxic evaluation of Río Grande (Antioquia, Colombia) water using micronucleus frequency in erythrocytes of Brycon henni (Characiformes: Characidae). The permanent monoculture of bananas and plantains farming in the middle of Río Grande (Turbo -Antioquia) requires the application of a variety of pesticides. Inappropriate banana production practices in this region, have often led to waterbody pollution by agrochemicals from leachate and runoff processes. Currently, fish are the most common vertebrates used as bioindicators of water quality, because they are very sensitive to the presence of contaminants. Our main goal with this study was to compare the frequency of micronucleated erythrocytes (MNE) in peripheral blood specimens of fish Brycon henni, from two locations (polluted and unpolluted) in the Rio Grande. We evaluated the frequency of MNE in peripheral blood samples of fish B. henni from each location during two rainy seasons in 2010 and two dry seasons in 2011. Blood samples were collected, fixed for 24 h, and then were stained with Giemsa. Among results, we found that the median frequency of MNE was higher in the polluted site by agrochemical discharges (0.15±0.18), than in the unimpacted site (0.06±0.08). Furthermore, the frequency of MNE in B. henni during the dry season was highly significant for both locations. The results of this study indicated that the analysis of MNE in B. henni could be recommended as a suitable method for in situ detection of environmental genotoxins. Rev. Biol. Trop. 65 (1): 405-414. Epub 2017 March 01.