Correlated evolution of male and female testosterone profiles in birds and its consequences

Circulating levels of testosterone in adults have mainly evolved as a consequence of selection on males for increased levels, while levels of circulating testosterone in females may be an indirect consequence of selection on males. A review of the literature revealed that intense directional selection for high levels of circulating testosterone in birds is likely to be mainly due to direct selection on males. A comparative study of testosterone levels in birds revealed a strong positive relationship between peak testosterone levels in adult females and peak levels in males. The slope of this relationship was significantly less than unity, implying that the testosterone levels in females have been reduced in species with high levels in males. An analysis of the order of evolutionary events suggested that peak concentration of testosterone in females changed after peak concentrations of testosterone in males. Females in colonial species of birds had significantly higher circulating peak testosterone levels compared to females of solitary species, and relative levels after controlling for the effects of peak levels in males were also larger, suggesting that any costs of high testosterone levels in females are particularly likely in colonial birds. Direct selection on male circulating testosterone levels may increase the costs that females incur from high testosterone titers. For example, high female levels may negatively affect ovulation and laying and may also affect the levels of testosterone that females deposit in their eggs and hence the exposure of pre- and post-hatching offspring to testosterone. This in turn may affect not only offspring behavior, but also offspring development and the trade-offs between growth, development of immune function, and behavior in offspring.     

Antigenic characterization of hemocyte subpopulations in the mussel Mytilus edulis by means of monoclonal antibodies

In order to characterize in more detail hemocytes from Mytilus edulis and establish links between histological and cytological featues, monoclonal antibodies (MABs) were prepared using hybridoma technology. Five MABs were identified and their reactivity patterns were analyzed with both immunoperoxidase and ultrastructural immunogold labelling. Four MAB classes were identified by their immunostaining patterns. Optical and ultrastructural examination revealed that Class I MAB reacted specifically with basophilic granulocytes (granulocytes containing small granules). Class II and III MABs differed in the intensity of their indirect immunofluorescence and degree of immunoperoxidase labelling, but all recognized both basophilic and eosinophilic granulocytes. Epitopes recognized by Class IV MABs were not always present in basophilic granulocytes, whereas they were always expressed in the eosinophilic granulocytes (granulocytes containing large granules) and could constitute differentiation antigens which progressively form during the maturation process. Molecular weights of the proteins recognized by these MABs were determined by Western blotting. It is concluded that immunostaining can identify at least three hemocyte types in M. edulis.     

Bioavailability of zinc in runoff water from roofing materials

Corrosion and runoff from zinc-coated materials and outdoor structures is an important source for the dispersion of zinc in the environment. Being part of a large inter-disciplinary research project, this study presents the bioavailability of zinc in runoff water immediately after release from the surface of 15 different commercially available zinc-based materials exposed to the urban environment of Stockholm, Sweden. Runoff water was analysed chemically and evaluated for its possible environmental impact, using both a biosensor test with the bacteria Alcaligenes eutrophus (Biomet^®) and the conventional 72 h growth inhibition test with the green alga Raphidocelis subcapitata. Chemical speciation modelling revealed that most zinc (94.3–99.9%) was present as the free Zn ion, the most bioavailable speciation form. These findings were confirmed by the results of the biosensor test (Biomet^®) which indicated that all zinc was indeed bioavailable. Analysis of the ecotoxicity data also suggested that the observed toxic effects were due to the presence of Zn²⁺ ions. Finally, regression analysis showed that, for this type of runoff samples, the rapid screening biosensor was capable of predicting (a) the total amount of zinc present in the runoff samples (R² of 0.93–0.98; p<0.05) and (b) the observed 72 h-EbC₅₀s (R² of 0.69–0.97; p<0.05).     

Application of rough sets analysis to identify polluted aquatic sites based on a battery of biomarkers: a comparison with classical methods

The evaluation of toxicological effects at the cellular and molecular levels in organisms are often used to determine sites subjected to contamination problems that pose a threat to the long-term survival of organisms. However, the integration of multiple measurements on the health status of organisms into a model for site discrimination is challenging. This study compares two discrimination methods which are based on rule inference: rough sets (RS) analysis and classification trees (CT) with classical multivariate discriminant analysis (DA). Site classification was attempted with six biomarkers of effects: metallothionein levels, lipid peroxidation, DNA damage, levels of lipophosphoproteins (i.e., vitellins), phagocytosis activity and haemocyte cell viability on clam (Mya arenaria) populations from the Saguenay River fjord (Quebec, Canada). Rule based methods have the advantage of complete independence from data distribution constraints in contrast to the classification methods from multivariate analysis that are more commonly used in ecotoxicology. Results show that RS and CT gave better classifications than DA because they do not require strong distributional assumptions. Moreover, RS provided classification rules that could identify the most important biomarker(s) for site discrimination. RS and CT were shown to be simple and efficient methods for classifying multivariable ecotoxicological data. This methodology would be especially useful when freedom from distributional assumptions is required.     

An analytical method to determine Henry's law constant for selected volatile organic compounds at concentrations and temperatures corresponding to tap water use

Henry's law constants (H) are needed to model human exposure to Volatile Organic Compounds (VOCs) in indoor air resulting from the use of tap water. This paper presents an experimental method to determine Hs for several common tap water pollutants at concentrations and temperatures used in household water. For 5 VOCs Henry's law constants were obtained simultaneously over the 25 degrees C to 45 degrees C temperature range, providing data on H beyond the currently available data (up to 35 degrees C). Henry's law constants were obtained as the ratio of equilibrium concentrations of VOCs in air and water, using simultaneous sampling from sealed bottles kept at constant temperatures. Air and water samples were concentrated by a purge-and-trap method, thermally desorbed from a Tenax trap, and analyzed with a gas chromatograph with an electron capture detector (GC-ECD). Experimental results agreed well with available literature data.     

Migration of contaminants through the unsaturated zone overlying the Hesbaye chalky aquifer in Belgium: a field investigation

This paper presents the results of a detailed field investigation that was performed for studying groundwater recharge processes and solute downward migration mechanisms prevailing in the unsaturated zone overlying a chalk aquifer in Belgium. Various laboratory measurements were performed on core samples collected during the drilling of boreholes in the experimental site. In the field, experiments consisted of well logging, infiltration tests in the unsaturated zone, pumping tests in the saturated zone and tracer tests in both the saturated and unsaturated zones. Results show that gravitational flows govern groundwater recharge and solute migration mechanisms in the unsaturated zone. In the variably saturated chalk, the migration and retardation of solutes is strongly influenced by recharge conditions. Under intense injection conditions, solutes migrate at high speed along the partially saturated fissures, downward to the saturated zone. At the same time, they are temporarily retarded in the almost immobile water located in the chalk matrix. Under normal recharge conditions, fissures are inactive and solutes migrate slowly through the chalk matrix. Results also show that concentration dynamics in the saturated zone are related to fluctuations of groundwater levels in the aquifer. A conceptual model is proposed to explain the hydrodispersive behaviour of the variably saturated chalk. Finally, the vulnerability of the chalk to contamination issues occurring at the land surface is discussed.     

Removal of hydrocarbons from wastewater using treated bark

This paper explores the possibility of removing hydrocarbons (HCs) and trace elements from synthetic and industrial effluents using treated bark as biosorbent. Coniferous bark was treated either chemically (Tc) or biologically (Tb) to eliminate soluble organic compounds of bark. The removal efficiency (RE) of the HCs from a synthetic oil-water mixture containing spent diesel motor oil exceeds 95% using 2 g/L of treated bark mixed with a synthetic oil-water mixture containing 2 g/L of spent oil. Under these conditions, the retention capacity (RC) was approximately 1 g HC/g dry substrate. The sorption reaction seems to be quasi-instantaneous, and the retention capacity of spent oil on treated bark increases as the temperature augments. This implies that the retention mechanism is related to the capillary action. Results of Fourier transform infrared (FTIR) spectroscopy indicate that spent oil is mainly composed of alkanes. They also suggest that no chemical bonds between Tc and spent oil were established. Measurement of the surface tension of spent oil and the wetting index of the bark suggests that only spent oil will be retained by the substrate. Treatment of an industrial effluent containing 14.4 g/L of total HCs was performed using Tc. It was possible to remove 97% of HCs and retain some trace elements such as Al, Ca, Fe, Mg, S, and so on.     

What attracts juvenile coral reef fish to mangroves: habitat complexity or shade?

The value of mangroves for fish species is usually explained in terms of high food abundance or shelter against predators as a result of high turbidity and structural complexity. In a field experiment, artificial mangrove units (AMUs) were designed as open cages, each of which was provided with a different degree of structural complexity and shade. Fish species that were attracted to the AMUs were identified and counted and the effects of shade and structural complexity, as well as the interaction between the two factors, were tested. Diurnal fish showed a preference for the greatest structured complexity and for a moderate increase in shade. Two nocturnal species common in local mangroves as well as seagrass beds showed statistically significant effects: densities of Haemulon sciurus were positively related to both shade and structural complexity, whereas only shade had a significant positive effect on densities of Ocyurus chrysurus. The experiment indicated that the attractiveness of mangrove vegetation for H. sciurus may be influenced by the structural complexity of the habitat as well as by the degree of shade, and that both factors are equally and separately important. Individuals of O. chrysurus that are attracted to mangroves are more likely to be influenced by the presence of shade than by the degree of structural complexity. The data thus indicated that the positive relationship between fish densities in mangrove habitats and the degree of shade and structural complexity, or both, is species-specific.Communicated by O. Kinne, Oldendorf/Luhe     

北极苔原和森林地区的稳定性及脆弱性与社会和环境变化

北极苔原带和北方森林(北部地区)因其分布广阔并远离农业土地利用变化及工业发展的影响,而一度被认为是地球上最后的净土.但如今这些地区如同地球上任何别的地区一样,也正经受着环境和社会变化的影响.本文总结了北部地区在全球系统中所起的作用,并提出方案以便对导致该地区对社会和环境变化敏感的那些因子进行评价.     

AZ31B镁合金挤压工艺研究

在油炉中熔炼AZ31B镁合金 ,用熔剂保护 ,石墨模铸造圆锭。铸锭经 40 0℃× 1 2h的均匀化处理后 ,进行热挤压 ,其挤压温度为 40 0℃ ,挤压速度为 1～ 2 .5m/min ,挤压比为 1 0～ 45。共挤出了 1 1种规格的棒材、管材、型材 (工字型、槽型、角形、方形、T形等 ) ,挤压过程中均发生了动态再结晶 ,其抗拉强度σb 在 2 75～ 2 85MPa之间 ,屈服强度σ0 .2　在 2 2 0～ 2 2 5MPa之间 ,延伸率δ在 1 5 %～ 1 7%之间。所制订的工艺合理 ,挤压出的棒材、管材、型材有较好的力学性能