Effects of size and morphology on swimming performance in juvenile brown trout (Salmo trutta L.)

Abstract –  Our study assesses swimming capacity (speed and stamina) and possible morphometric determinants of locomotor performance of juvenile brown trout ( Salmo trutta L.). We addressed these issues at the individual level to have an approach of the functional significance of intraspecific variation in morphological design. Both swimming speed and endurance time showed significant positive relationships with fish length. Size-corrected values of speed and endurance time were negatively correlated suggesting a phenotypic trade-off between burst and prolonged swimming. Size was also highly correlated with all the morphological variables measured. Therefore, we used the residuals of the regressions of those variables on fish length to remove the effect of body size. A principal components analysis (PCA) summarised the 12 morphological variables into two factors, which accounted for 44.3% of the variance. PC1 combined several measures of body depth and width, whereas PC2 represented mainly postanal length relative to abdomen length. Relationships between the scores of the two factors and size-corrected values of maximum swimming speed and endurance time were weak. PC2 showed a significant positive relationship with endurance time; that is, individuals with longer caudal regions were able to swim against water flow for longer periods of time. Stoutness (PC1) showed a marginally significant negative correlation with endurance time. The lack of stronger relationships could be because of the low morphometric variability among the test individuals, all proceeding from the same population, reared in a common environment, and measured at the same ontogenetic stage.     

Trypanocidal activity of extracts and fractions of Bertholletia excelsa

Crude extracts and fractions of Bertholletia excelsa stem barks were tested for trypanocidal activity. Acetone and methanol extracts showed significant in vitro trypanocidal activity against trypomastigote form of Trypanosoma cruzi since in the concentration of 500 microg/ml, the parasites were reduced in 100% and 90.3% respectively, whereas the triterpene betulinic acid pure isolated from hexane extract presented 75.4%.     

Effects of two iron sources on iron and cadmium allocation in poplar (Populus alba) plants exposed to cadmium

Effects of 10 microM cadmium (supplied as Cd nitrate) on the utilization and allocation of iron (Fe) were investigated in poplar (Populus alba L.) plants grown in nutrient solution with Fe(III)-EDTA or Fe(III)-citrate as the Fe source. The effects of Cd were also compared with those of Fe deprivation. The accumulation of Fe in roots was 10-fold higher in plants grown with Fe-citrate than with Fe-EDTA. Cadmium decreased leaf chlorophyll concentrations and photosynthetic rates, and these decreases were more marked in plants grown with Fe-citrate than with Fe-EDTA. In both Fe treatments, addition of Cd caused large increases in root and shoot apoplasmic and non-apoplasmic Cd contents and increases in root Fe content; however, Cd decreased shoot Fe content, especially in plants grown with Fe-citrate. New leaves of plants grown with Fe-citrate had small cellular (non-apoplasmic) Fe pools, whereas these pools were large in new leaves of plants grown with Fe-EDTA. Non-apoplasmic Cd pools in new leaves were smaller in plants grown with Fe-citrate than with Fe-EDTA, indicating that inactivation of non-apoplasmic Cd pools is facilitated more by Fe-EDTA than by Fe-citrate. In the presence of Cd, Fe-EDTA was also superior to Fe-citrate in maintaining an adequate Fe supply to poplar shoots. Differences in plant responses to Fe-EDTA and Fe-citrate may reflect differences in long-distance transport of Fe rather than in acquisition of Fe by roots.     

Application of the pipe model theory to non-destructive estimation of leaf biomass and leaf area of pruned agroforestry trees

The relationship of branch cross sectional area (CS) to leaf biomass (LM) and leaf area (LA) was studied in three agroforestry tree species,Calliandra calothyrsus Maissn.,Erythrina berteroana Urban andErythrina poeppigiana (Walpers) O.F. Cook, to develop a non-destructive method for the estimation of LM and LA for trees managed with periodic pruning. Variation in these relationships was observed according to the bifurcation level and, in theErythrina spp., by clone. All the relationships were linear except the CS-LM relation in small branches ofE. poeppigiana, where it was initially exponential. At main branch level the relationship of CS to LM and LA was linear in all cases but the regression parameter values varied between species and clones, with determination coefficient (R²) 0.88–0.99. It was concluded that the ratio of main branch CS to LM and LA can be used for non-destructive estimation of the latter variables. The method has the additional benefit that the regression parameter value reflects the allocation of dry matter within a tree and, consequently, may give indications about its possible uses in different agroforestry systems.Work carried out at the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), Turrialba, Costa Rica.     

The influence of the ethanol pumping of wheat straw and of the beating of pulp on the resulting paper sheets

This paper reports on the influence of independent variables in the pulping of wheat straw (viz. cooking temperature and time, and ethanol concentration), and of the number of PFI beating revolutions to which the pulp is subjected, on the yield and Shopper-Riegler index of the pulp, and on the breaking length, stretch, burst index and tear index of the resulting paper sheets. By using a central composite factor design and the BMDP software suite, equations that relate each dependent variable to the different independent variables were obtained that reproduce the experimental results for the dependent variables with errors less than 25% at temperatures, times, ethanol concentrations and numbers of PFI beating revolutions in the ranges 140–180°C, 60–120 min, 40–80% and 0–1750, respectively. Ensuring the optimal Shopper-Riegler index for the pulp (73.18°SR), and also the optimal breaking length (6276 m), stretch (2.57%) and burst index (3.72 kN/g) for the papers sheets, entails using a high temperature (180°C), a large number of PFI beating revolutions (1750) and medium-to-high ethanol concentration and time values; these conditions, however, decrease the tear index for the paper sheets below the optimum level (4.60 mNm²/g). A high temperature and a large number of PFI beating revolutions, in conjunction with a low ethanol concentration (60%) and a short time (60 min), can be used to save solvent and increase the production; the values thus obtained for the dependent variables differ by less than 30% from their optimum levels in the worst case.     

Characteristics and decomposition rates of pruning residues from a shaded coffee system in Southeastern Brazil

In the Zona da Mata Mineira of Southeastern Brazil the development of sustainable land requires the integration of crops with trees. The objectives of this study then were to (i) characterize prunings from the main tree species in an agroforestry system; (ii) determine the effects of the physical and chemical characteristics of the prunings on their decomposition patterns in the laboratory; (iii) assess the effect of mixing leaves of different species on decomposition rates; and (iv) propose a decomposition index for the residues studied. The study was carried out with pruning residues from Cajanus cajan, Solanum variable, Cassia ferruginea, Piptadenia gonoacantha, Croton urucurana, and Melinis multiflora. The materials were characterized for total C, N, P, Ca, Mg and K contents; lignin, cellulose, hemicellulose and soluble polyphenols contents. The pruning residues had high polyphenols and lignin contents, high C:N and C:P ratios, and low contents of Ca, Mg, and K. The low decomposition rates of the prunings were related to the P, K, hemicellulose and polyphenol contents. The rates of N mineralization from most of the residues indicate that there is a potential to supply the needs of a crop of maize. The residues of some species, if decomposed alone, would not supply sufficient nutrients, and need to be mixed with leaves of other species.This revised version was published online in November 2005 with corrections to the Cover Date.     

银杏产量与气象因子相关性研究

以湖南省１３年的气象资料，按银杏果生长发育周期，分５个阶段统计了水、光、热诸方面的８个气象因子，采用多元逐步回归方法，筛选出传粉受精期平均最大风速、种实第二增长高峰期的最低气温和５月１日～６月３０日的总雨量３个对产量有重要影响的气象因子。相应时期较大的风速，较低的气温、充沛的雨量，可提高银杏产量。     

Assessing different stocking regimes in a plantation of Gmelina arborea in northern Colombia

New Forests - Monterrey Forestal Ltda conducted a study to determine the effects of different stocking on productivity of Gmelina arborea (gmelina) to age 6 years in Zambrano, Bolívar,...