Habitat and community structure modulate fish interactions in a neotropical clearwater river

Species interactions can modulate the diversity and enhance the stability of biological communities in aquatic ecosystems. Despite previous efforts to describe fish interactions in tropical rivers, the role of habitat characteristics, community structure, and trophic traits over these interactions is still poorly understood. To investigate among-habitat variation in substratum feeding pressure and agonistic interactions between fishes, we used remote underwater videos in three habitats of a clearwater river in the Central Western, Brazil. We also performed visual surveys to estimate the abundance and biomass of fishes and proposed a trophic classification to understand how these variables can affect fish interactions. Community structure was the main factor affecting the variation in the interactions among the habitats. Biomass was the main variable determining which habitat a fish will feed on, while species abundance determined with how many other species it will interact in the agonistic interaction networks for each habitat. Specific habitats are not only occupied, but also used in distinct ways by the fish community. Overall, our results demonstrate the importance of the heterogeneity of habitats in tropical rivers for the interactions performed by the fishes and how the intensity of these interactions is affected by community structure

Liquid chromatography-mass spectrometry for simultaneous determination of spironolactone and canrenone in plasma samples

In our study, we aimed to validate a method based on liquid chromatography-mass spectrometry (LC-MS) to quantify spironolactone (SPI) and its active metabolite canrenone (CAN) simultaneously in plasma samples to support in vivo experiments. Compounds were separated by using a C18 column with the isocratic elution of a mobile phase composed of 0.1% (v/v) formic acid in methanol-water (60:40 v/v) at a flow rate of 0.4 mL min−1. SPI and CAN were detected in na electrospray interface operating in a positive ionization mode and quantified using the selective ion mode monitoring of mass-charge ratios (m/z) of 439.0 for SPI and 363.1 for CAN. After calculating the matrix effect using theoretical equations, we observed the strong interference of plasma in the equipment-generated signal, which required creating analytical curves using the matrix as a solvent. The method was nevertheless linear (r 2 > 0.999) in a concentration range of 0.4-5.0 μg mL−1, as well as precise, with a coefficient of variation less than 5%. SPI’s and CAN’s recovery rates from the plasma ranged from 87.4% to 112.1%, while their limits of detection (i.e., 0.07 μg mL−1 and 0.03 μg mL−1, respectively) and quantification (i.e., 0.20 μg mL−1 and 0.08 μg mL−1, respectively) in the presence of plasma contaminants were low. Therefore, the bioanalytical method seems to be feasible for quantifying SPI and CAN in plasma

Body yield and quality of fresh and post-freezing filet of Nile tilapia (Oreochromis niloticus) genetic groups

Abstract The aim of this study was to evaluate the body yield and quality of fresh and post-freezing filet of male and female fish of inbred and non-inbred AquaAmérica genetic group and the hybrid between the AquaAmérica and Tilamax varieties. Forty fish (20 males and 20 females) of each genetic group were housed in four 48-m3 hapa net cages, getting 120 fish per cage. The fish were housed at 51 days of age and farmed for 269 days. Pre-slaughter weight was higher (P<0.05) in the AquaAmérica × Tilamax males (0.805±0.204 kg) than in the inbred AquaAmérica male (0.643±0.115 kg). Filet yield percentage was higher (P<0.05) in the AquaAmérica × Tilamax males (32.14±4.72%) than in the inbred AquaAmérica (28.15±2.67%) and non-inbred AquaAmérica (29.06±2.80%) males. Head and viscera yield percentages, pH, color values (L*, a* and b*), shear force, drip loss and cooking loss did not differ significantly between the genetic groups and sexes. Alterations in meat quality were observed after freezing. In conclusion, inbreeding in the AquaAmérica variety resulted in reduced slaughter weight for males; AquaAmérica × Tilamax males have a higher filet yield; and filet quality is not influenced by crossing, inbreeding, or sex, but is changed after freezing

Blind Testing: DNA Barcoding Sheds Light Upon the Identity of Plant Fragments as a Subsidy for Cave Conservation

Plants living above and around caves represent an important, albeit poorly studied, resource within cave ecosystems. The presence of plant material (root-like structures or rhizothemes, saplings, seeds, and seedlings) correlates positively with the biodiversity of the cave dwelling animals as shown for iron-ore caves in Carajás, Pará, Brazil. Plant material collected in caves has proven to be difficult to identify by traditional botanical methods, thus this research aims to provide a qualitative insight into the taxonomy and morphology of rhizothemes and other plant fragments found in the caves. The identification process used a combination of different molecular markers (ITS2, rbcL, and trnH-psbA) followed by a comparison of the sequences obtained against publicly available databases. The rhizothemes were submitted to micromorphological analysis to ascertain their putative root or stem origin and to compare their anatomy with known patterns found in the plant families or genera recovered through molecular matches. All studied samples were Angiosperms, mostly belonging to subclass Rosideae, within four orders: Malpighiales (Euphorbiaceae, Hypericaceae), Sapindales (Anacardiaceae and Sapindaceae), Myrtales (Myrtaceae), Fabales (Fabaceae), and only two belonging to subclass Asteridae, order Gentianales (Apocynaceae). Some of the samples were matched to generic level, with ITS2 being the best marker to identify the fragments because it shows high degree of sequence variation even at specific level and result reliability. All rhizothemes turned out to be roots, and correspondence was found between the existing literature and the individual anatomical patterns for the families and genera retrieved. DNA barcode has proved to be a useful tool to identify plant fragments found in this challenging environment. However, the existence of well curated, authoritatively named collections with ample biological information has proven to be essential to achieve a reliable identification

Psicología Y educación a distancia : una revisión de la literatura

O presente estudo investigou as contribuições da Psicologia para a educação a distância – EAD. Para isso, realizou-se revisão bibliográfica de publicações nacionais, entre 1999 e 2009, nas bases de dados SciELO, Lilacs, PsycINFO, BVS e Google Acadêmico. Foram selecionados 69 estudos, dos quais se excluíram 15, por não serem compatíveis com a pesquisa. Os resultados evidenciaram nove eixos temáticos: (1) tecnologia educacional a distância com fundamentos psicológicos, (2) afeição, (3) papel do tutor/professor, (4) teorias psicológicas, (5) interatividade, (6) evasão, (7) relatos de experiências, (8) avaliação de treinamento, desenvolvimento e educação a distância e (9) outros. Os temas tecnologia educacional a distância com fundamentos psicológicos e afeição obtiveram maior frequência nas publicações. Neste estudo, registrou-se, também, que, embora em ascensão desde 2006, os anos de maiores publicações da Psicologia na educação a distância foram 2008 e 2009. Sugere-se que estudos futuros ampliem esta pesquisa para incluir bases de dados internacionais.This study investigated the contributions of Psychology to Distance Learning. A literature review of national publications between 1999 to 2009 was made in the electronic databases SciELO, LILACS, PsycINFO, BVS and Google Scholar. From the 69 studies selected, 15 were excluded because they were not compatible with the research. The results showed nine themes: (1) the distance learning technology with psychological grounding, (2) affection, (3)the role of the tutor/professor, (4) psychological theories, (5) interactivity, (6) dropout, (7) reports of experiences, (8) assessment of distance training, development and education and (9) others. The topics distance education technology with psychological grounding and affection had a larger frequency in the publications. Since 2006, there was an increasing number of publications in psychology distance education, but the years of major publications were from 2008 to 2009. It is suggested that future studies expand this research including international databases.El presente estudio investigó las contribuciones de la Psicología para la Educación a Distancia – EAD. Para eso, fue realizada una revisión bibliográfica de publicaciones nacionales, entre 1999 y 2009 en las bases de datos SciELO, Lilacs, PsycINFO, BVS y Google Académico. Fueron seleccionados 69 estudios, de los cuales se excluyeron 15, por no ser compatibles con la pesquisa. Los resultados evidenciaron nueve ejes temáticos (1) tecnología educacional la distancia con fundamentos psicológicos; (2) afección; (3) papel del tutor/profesor; (4) teorías psicológicas; (5) interactividad; (6) evasión; (7) relatos de experiencias, (8) evaluación de entrenamiento, desarrollo y educación distancia y (9) otros. Los temas tecnología educacional a distancia con fundamentos psicológicos y afección obtuvieron mayor frecuencia en las publicaciones. En ese estudio se registró, también, que, aunque en ascensión desde 2006, los años de mayores publicaciones de la psicología en la educación a distancia, fueron 2008 y 2009. Se sugiere que estudios futuros amplíen esa pesquisa para incluir bases de datos internacionales