Sperm-depleted males influence the reproductive behaviour of conspecifics

In many insect species, sperm-depleted males (SDMs, i.e. males that have exhausted their sperm after a given number of matings) remain sexually active and continue to mate females. Here, we investigated the behavioural modifications that occur in both sexes of the parasitoid Asobara tabida Nees (Hymenoptera: Braconidae), after matings by fertile males and sperm-depleted males. We show that (i) virgin females, mated females and females mated to a SDM exhibited different behaviours and that (ii) males responded differently to females depending on whether the females had previously mated with an SDM or not. Our findings demonstrate that SDM influenced the reproductive behaviour of both males and females, especially with regard to male responsiveness and female attractiveness. These findings are discussed in the context of adaptive behaviour and fitness maximization in both males and females.     

Unusually high-pitched neonate distress calls of the open-habitat Mongolian gazelle (<Emphasis Type="Italic">Procapra gutturosa</Emphasis>) and their anatomical and hormonal predictors

In neonate ruminants, the acoustic structure of vocalizations may depend on sex, vocal anatomy, hormonal profiles and body mass and on environmental factors. In neonate wild-living Mongolian gazelles Procapra gutturosa, hand-captured during biomedical monitoring in the Daurian steppes at the Russian-Mongolian border, we spectrographically analysed distress calls and measured body mass of 22 individuals (6 males, 16 females). For 20 (5 male, 15 female) of these individuals, serum testosterone levels were also analysed. In addition, we measured relevant dimensions of the vocal apparatus (larynx, vocal folds, vocal tract) in one stillborn male Mongolian gazelle specimen. Neonate distress calls of either sex were high in maximum fundamental frequency (800–900 Hz), but the beginning and minimum fundamental frequencies were significantly lower in males than in females. Body mass was larger in males than in females. The levels of serum testosterone were marginally higher in males. No correlations were found between either body mass or serum testosterone values and any acoustic variable for males and females analysed together or separately. We discuss that the high-frequency calls of neonate Mongolian gazelles are more typical for closed-habitat neonate ruminants, whereas other open-habitat neonate ruminants (goitred gazelle Gazella subgutturosa, saiga antelope Saiga tatarica and reindeer Rangifer tarandus) produce low-frequency (<200 Hz) distress calls. Proximate cause for the high fundamental frequency of distress calls of neonate Mongolian gazelles is their very short, atypical vocal folds (4 mm) compared to the 7-mm vocal folds of neonate goitred gazelles, producing distress calls as low as 120 Hz.     

Leaf accumulation of trace elements and polycyclic aromatic hydrocarbons (PAHs) in Quercus ilex L

Quercus ilex L. leaves were collected four times in one year at six urban sites and one remote area in order to determine trace element and PAH accumulation through concomitant analyses of unwashed and water-washed leaves. Both unwashed and washed leaves showed the highest amounts of trace elements and PAHs in the urban area. Unwashed leaves showed greater differences between urban and remote areas and among the urban sites than washed leaves for trace element and PAH concentrations. Water-washing resulted in a significant (P<0.001) decrease in leaf concentrations of Cr, Cu, Fe, Pb, V and Zn. By contrast, Cd and total PAH concentrations showed no differences between unwashed and washed leaves.     

A model for estimating the potential biomagnification of chemicals in a generic food web: Preliminary development

GOAL, SCOPE AND BACKGROUND: Bioaccumulation and biomagnification of organic pollutants have been increasingly assessed and modeled during the last years. Due to the complexity of these processes and the large variability of food webs, setting generic assessments for these parameters is really difficult. Equilibrium models, based on a compound's lipophylicity, are the main tool in regulatory proposals, such as for identifying Persistent, Bioaccumulative and Toxic Substances (PBTs), although a refinement has been claimed by the scientific community. Toxicokinetic studies offer an alternative for these estimations, where biomagnification is modeled as a succession of bioaccumulation processes, each one regulated by toxicokinetic parameters. METHODS: A review of kinetic models covering species belonging to different trophic levels and with different ecological behavior has been conducted. The results were employed for setting a conceptual model for estimating the biomagnification potential in a generic food web, which was mathematically implemented through system dynamic models developed under data sheet software. Crystal Ball was then employed for allowing Monte Carlo based probabilistic calculations. Bioaccumulation laboratory assays have been performed to estimate toxicokinetic parameters in mussels (Mytilus edulis) with two PAHs (chrysene and benzo[a]pyrene). The contamination was delivered via food. The exposure period lasted more than one month followed then by a depuration phase. The contaminant content was determined on an individual basis on five replicates. RESULTS AND DISCUSSION:. The reviewed information suggested the development of a tiered conceptual biomagnification model, starting with a simplified food chain which can be refined to more realistic and complex models in successive levels. CONCLUSIONS: The mathematical implementation of the conceptual model offers tools for estimating the potential for bioaccumulation and biomagnification of chemicals under very different conditions. The versatility of the model can be used for both comparative estimations and for validating the model. RECOMMENDATIONS AND PERSPECTIVES: Since bioaccumulation and biomagnification processes are crucial elements for a proper risk assessment of chemicals, their estimation by mathematical models has been widely tested. However, inregulatory assessments, too simplistic models are still being used quite often. The biomagnification model presented in this study should be amore accurate alternative to these models. In comparison to other previously published biomagnification models, the present one covers the time variation of bioaccumulation using just a few toxicokinetic parameters.     

Formation of aerobic granules in the presence of a synthetic chelating agent

This paper examines the development of aerobic granular sludge in the presence of a synthetic chelating agent, nitrilotriacetic acid (NTA), in sequencing batch reactors (SBR). The growth of seed sludge at 0.26 mM, 0.52 mM and 1.05 mM of NTA was found to be significantly lower as compared to that in the absence of NTA. Aerobic granulation was significantly enhanced in the three SBRs (R2, R3 and R4), which were fed with 0.26 mM, 0.52 mM and 1.05 mM of NTA as a co-substrate, in comparison to the acetate-alone fed SBR (R1). After 2 months of operation, the mean diameter of the biomass stabilized at 0.35 mm in R1 (acetate alone), as compared to 2.18 mm in R4 (1.05 mM NTA+acetate). NTA degradation was established in SBRs, with almost complete removal during the SBR cycle. Batch experiments also showed efficient degradation of NTA by the aerobic granules.     

Variation of MCPA, metribuzine, methyltriazine-amine and glyphosate degradation, sorption, mineralization and leaching in different soil horizons

Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28 km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils. One-dimensional MACRO modeling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2 m depth calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater was below the administrative limit of 0.1 μg/l in all tested profiles while metribuzine always exceeded the 0.1 μg/l threshold value.     

固定化混合菌修复油污染地表水的研究

从辽河油田受石油污染的河床底泥中筛选出一株芽孢杆菌(Bacillus sp.)和一株黄杆菌(Flavobacterium sp.),采用二次交联化学方法对2株细菌单独及混合固定,分别进行了不同接种量的固定化细菌对油的降解,以及固定化混合菌对环境的耐受性和在自然地表水中对油的降解进行研究,结果表明,在相同时间内固定化混合菌对油的降解效果明显优于固定化单株菌,而且都优于游离菌。固定化混合菌pH在6～10、温度在20～40℃范围内能保持较好的活性。在120 h时,固定化混合菌对自然地表水中油的降解率达94.5%,对地表水中COD的去除率达89.6%。扫描电子显微镜分析显示,固定化载体的微观结构适合细菌的生长,固定化混合菌在载体内部形成高密度的菌群。以上的研究为固定化微生物应用于油污染地表水的生物修复提供了一定的理论基础。     

The historical record of PCB and PCDD/F deposition at Greifensee, a lake of the Swiss plateau, between 1848 and 1999

Dated sediment cores provide an excellent way to investigate the historical input of persistent organic pollutants into the environment and to identify possible sources of pollution. The vertical distribution of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCB) was investigated in a sediment core from Greifensee to elucidate the historical trends of PCDD/F and PCB inputs between 1848 and 1999. Concentrations of PCB and PCDD/F increased by more than one order of magnitude between 1930 and 1960. PCB and PCDD/F concentrations were 5700 ng/kg dry weight (dw) and 160 ng/kg dw, respectively, in sediments originating from the late 1930s and reached a maximum of 130,000 ng/kg dw and 2400 ng/kg dw, respectively, in the early 1960s. From 1960 on, concentrations decreased to the 1930s level by the mid 1980s. A remarkable shift in the PCDD/F pattern was observed after the early 1940s. Before 1940, the PCDD/F pattern was PCDF dominated (ratio of PCDD to PCDF=0.41+/-0.11), while the PCDD started to be the major species after the early 1940s (ratio of PCDD to PCDF=1.46+/-0.38). The temporal trends of PCB and PCDD/F correlate surprisingly well with each other. This might be due to the coincidence of two factors. The introduction of PCB on the market in the 1930s resulted in emissions due to the widespread use of these industrial chemicals. In the same time period, waste incineration became an increasingly popular way to get rid of garbage, boosting the PCDD/F emissions significantly. The rapid decline of PCDD/F and PCB concentrations in the sediment starting in the early 1960s reflects the result of better emission control techniques in thermal processes and the improvement of waste water treatment in the catchment of Greifensee.     

Organochlorinated contaminants in decapod crustaceans from the coasts of Brittany and Normandy (France)

The contamination and distribution of organochlorinated compounds were considered in three crustacean species (edible crab, Cancer pagurus; spider crab, Maja brachydactyla; velvet swimming crab, Necora puber) from five sites along the coasts of Brittany and Normandy (Western and North-Western France). PCBs (16 single congeners), pp'-DDE and HCB were measured in hepatopancreas, gonads and muscle: in all, 175 samples were analysed. The spider crab was the only species found in the five sampling sites, thus enabling comparison between areas. Specimens from Antifer were much more contaminated (summation operator 16 PCBs in hepatopancreas=2000-4000 ng g(-1) dry weight) than those from other sites (50-1000 ng g(-1) d.w.). Among all the three species, the spider crab appeared more contaminated by PCBs than the edible crab, by a factor 2-3, probably in relation with specific differences in their life cycle. There was no difference due to the gender of the species. Within the different analysed tissues, contamination levels increased from muscle to gonads and hepatopancreas in relation with the fat content. A very similar PCB composition was observed in all samples, PCB fingerprints being characterised by the relative importance of the more persistent PCB congeners: CB153, 138, 180, 187, and 118. Finally, these results were compared to recent food regulations first of maximum marker PCB intake and secondly of maximum dioxin-like PCB intake. By considering the muscle, all samples were far below the regulatory limits; for hepatopancreas and gonads, however, some samples were unfit for human consumption.     

Atrazine sorption and fate in a Ultisol from humid tropical Brazil

This study combined laboratory based microcosm systems as well as field experiments to evaluate the mobility of atrazine on a Ultisol under humid tropical conditions in Brazil. Results from sorption experiments fit to the Freundlich isotherm model [K(f) 0.99 mg kg(-1)/(mg l(-1))(1/n)], and indicate a low sorption capacity for atrazine in this soil and consequently large potential for movement by leaching and runoff. Microcosm systems using (14)C-atrazine to trace the fate of the applied herbicide, showed that 0.33% of the atrazine was volatilized, 0.25% mineralized and 6.89% was recorded in the leachate. After 60 d in the microcosms, 75% of the (14)C remained in the upper 5 cm soil layer indicating atrazine or its metabolites remained close to the soil surface. In field experiments, after 60 d, only 5% of the atrazine applied was recovered in the upper soil layers. In the field experiments atrazine was detected at a depth of 50 cm indicating leaching. Simulating tropical rain in field experiments resulted in 2.1% loss of atrazine in runoff of which 0.5% was adsorbed onto transported soil particles and 1.6% was in solution. Atrazine runoff was greatest two days after herbicide application and decreased 10 fold after 15 d. The use of atrazine on Ultisols, in the humid tropics, constitutes a threat to water quality, causing surface water and ground water pollution.