Report on the fifth meeting of INRA’s national network of ecotoxicologists,ECOTOX

The fifth meeting of INRA’s national network of ecotoxicologists took place on 25 to 27 November 2014 in Biarritz, France. The main aim of the meeting was to bring together ecotoxicologists from INRA and associated partners, providing them ample opportunity to share and discuss their latest scientific results as well as the national policy of research in ecotoxicology and to precise perspectives for the network.     

Role of Amino Acids on <Emphasis Type="Italic">In Situ</Emphasis> Photografting of Jute Yarn with 3-(Trimethoxysilyl) Propylmethacrylate

To improve the mechanical performance of natural lignocellulosic jute yarn, grafting with [3-(trimethoxysilyl) propylmethacrylate] (TMSPM) monomer has been performed on in situ UV radiation and optimized the monomer concentration (30%) and irradiation time (30 min). Effect of various amino acids (1%) as additives in TMSPM with photografted jute yarn at optimized system has been studied. The polymer loading (PL) and tensile properties like tensile strength (TS) and elongation at break (Eb) of treated samples were enhanced by incorporation of amino acids and the highest properties (TS = 300% and Eb = 386%) achieved by the sample treated with l-Arginine (Arg) with 32.5% PL value. Weak acid like 3% acetic acid and inorganic acid like 1% sulfuric acid were also incorporated in the optimized system of TMSPM grafting and compared their effect on the tensile properties with amino acid treated samples. Water absorption and weathering resistance of treated and untreated samples were also performed and treated sample showed lesser water uptake as well as less weight loss and mechanical properties as compared to untreated samples.     

亚剂量抗生素诱导抗性基因水平迁移

为探究亚剂量抗生素诱导下编码广谱β-内酰胺酶(extended-spectrum β-lactamase,ESBL)基因的接合转移(conjugation),使用从新加坡主要医院的废水中直接分离的可合成ESBL的铜绿假单胞菌(P.aeruginosa)和大肠杆菌(E.coli)菌株作为ESBL编码质粒的供体,以携带绿色荧光蛋白(green fluorescent protein, GFP)基因的耐氯霉素(chloramphenicol,CHL)大肠杆菌SCC1(E.coli SCC1)作为受体,借助响应面分析,检测并分析了携带有ESBL编码基因的质粒在亚剂量水平的四环素(tetracycline,TC),磺胺甲噁唑(sulfamethoxazole,SMZ)和头孢他啶(ceftazidime,CAZ)单一暴露和共同暴露时,从供体菌株接合传递至受体菌株的特征.结果发现,ESBL编码质粒可在无诱导抗生素胁迫下,以平均0.001 5和0.004 2的频率分别由铜绿假单胞菌和大肠杆菌供体接合转移至受体大肠杆菌SCC1菌株,具有较低的"适应性代价",并在质量浓度低于最小抑菌浓度(minimum inhibitory concentration,MIC)的抗生素暴露下更易在大肠杆菌菌株之间传递.大肠杆菌菌株之间的接合转移显著发生在质量浓度低于0.03 mg·L~(-1)的TC与质量浓度低于0.002 mg·L~(-1)的CAZ单一暴露或共同暴露时,并可被亚MIC的TC显著抑制.铜绿假单胞菌与大肠杆菌间的接合转移可在5倍MIC的TC、CAZ共同暴露时被显著诱导,未检测到亚MIC水平抗生素对其的促进作用.     

A comparison of filtration rates among pelagic tunicates using kinematic measurements

Salps have higher filtration rates than most other holoplankton, and are capable of packaging and exporting primary production from surface waters. A method of kinematic analysis was employed to accurately measure salp feeding rates. The data were then used to explain how diverse body morphologies and swimming motions among species and lifecycle stages influence salp feeding performance. We selected five species, representing a range of morphologies and swimming styles, and used digitized outlines from video frames to measure body-shape change during a pulse cycle. Time-varying body volume was then calculated from the digitized salp outlines to estimate the amount of fluid passing through the filtering mesh. This non-invasive method produced higher feeding rates than other methods and revealed that body volume, pulse frequency and degree of contraction are important factors for determining volume filtered. Each species possessed a unique combination of these three characteristics that resulted in comparable filtration (range: 0.44–15.33 ml s⁻¹) and normalized filtration rates (range: 0.21–1.27 s⁻¹) across species. The convergence of different species with diverse morphologies on similar normalized filtration suggests a tendency towards a flow optimum.     

Two-year monitoring of Cryptosporidium parvum and Giardia lamblia occurrence in a recreational and drinking water reservoir using standard microscopic and molecular biology techniques

Starting in 2006, a monitoring of Giardia lamblia and Cryptosporidium parvum occurrence was conducted for 2 years in the largest drinking water reservoir of Luxembourg (Esch-sur-S?re reservoir) using microscopy and qPCR techniques. Parasite analyses were performed on water samples collected from three sites: site A located at the inlet of the reservoir, site B located 18 km downstream site A, at the inlet of the drinking water treatment plant near the dam of the reservoir and site C where the finished drinking water is injected in the distribution network. Results show that both parasites are present in the reservoir throughout the year with a higher occurrence of G. lamblia cysts compared to C. parvum oocysts. According to our results, only 25% of the samples positive by microscopy were confirmed by qPCR. (Oo)cyst concentrations were 10 to 100 times higher at site A compared to site B and they were positively correlated to the water turbidity and negatively correlated to the temperature. Highest (oo)cyst concentrations were observed in winter. In contrast, no relationship between the concentrations of (oo)cysts in the reservoir and rain events could be established. Though a correlation has been observed between both parasites and faecal indicators in the reservoir, some discrepancies highlight that the latter do not represent a reliable tool to predict the presence/absence of these pathogenic protozoa. In summer 2007, the maximal risk of parasite infection per exposure event for swimmers in the reservoir was estimated to be 0.0015% for C. parvum and 0.56% for G. lamblia. Finally, no (oo)cysts could be detected in large volumes of finished drinking water.     

A prospective study of amniotic fluid cholinesterases: Comparison of quantitative and qualitative methods for the detection of open neural tube defects

The value of quantitative and qualitative methods of cholinesterase (ChE) analysis in the detection of open neural tube defect (NTD) has been assessed in a prospective survey of 1495 mid-trimester amniotic fluids. Using a quantitative method the mean ChE values were much lower in fluids from pregnancies of normal outcome but it was not possible to discriminate these fluids completely from those associated with NTD pregnancies. particularly when the specimens were contaminated with blood. Similarly, measurement of acetylcholinesterase (AChE) activity alone by three different methods also failed to eliminate the overlap between the two groups. In contrast, polyacrylamide gel electrophoresis revealed only a single band of ChE activity in 1408 out of 1410 fluids from pregnancies with a normal outcome whilst amniotic fluids from all 60 cases of open NTD. 6 out of 7 cases of exomphalos and 3 out of 4 cases of intra-uterine death gave the characteristic second faster-running AChE band. A qualitative gel method which requires the same amount of ChE activity to be loaded from each amniotic fluid is an effective method for pre-natal diagnosis of NTDs.     

A 25-year record of polycyclic aromatic hydrocarbons in soils amended with sewage sludges

We studied polycyclic aromatic hydrocarbons (PAHs) in crop soils amended with 1000 tonnes dry weight of sewage sludges per 10,000 m² from 1974 to 1992, then after sludges addition from 1993 to 1999. The absence of variations of total PAHs levels of control soils, averaging at 123 μg/Kg, shows the absence of horizontal contamination. During sludges addition, the total PAHs levels in amended soils increased from 232 to 402 μg/Kg. Seven years after sludges addition, it decreased to 275 μg/Kg, which is still more than twice –the levels of control soils. This finding shows that sludges PAHs are preserved in crop soils for long periods of time, on a human scale.     

Solitary and eusocial nests in a population of Augochlorella striata (Provancher) (Hymenoptera; Halictidae) at the northern edge of its range

Summary Augochlorella striata was studied at the northern limit of its range. The study population contained a mixture of solitary and social nest foundresses. Eusocial foundresses produced 1 or 2 workers before switching to a male biased brood. Solitary foundresses produced males first. Cells vacated by eclosed offspring were reused late in summer. A female biased brood resulted from cell reuse in both solitary and eusocial nests. Workers were slightly smaller than their mothers and were sterile although most of them mated. In comparison to published data from a Kansas population of this species, the Nova Scotia population had i) a lower proportion of multiple foundress nests, ii) a smaller worker brood and iii) a briefer period of foraging activity but iv) comparable overall nest productivity.