Effects of nitrogen fertilizer and pesticide management on floodwater ecology in a wetland ricefield

Algal, zooplankton, and mollusc populations were monitored over a crop cycle in the floodwater of a tropical ricefield subject to various N-management and pesticide regimes. This paper gives the results on dynamics of microcrustanceans and dipteran larvae. Dominant groups developed in the succession mosquito+chironomid larvaeostracodscopepods+cladocerans. Populations of ostracods and mosquito+chironomid larvae expanded rapidly after broadcast N applications. Deep placement of N avoided the proliferation of ostracods and dipteran larvae. With the exception of chironomid larvae early in the crop cycle, aquatic invertebrates were generally less abundant in treatments where Azolla sp. was incorporated. When considered at the crop cycle level, aquatic invertebrate populations were not significantly affected by applications of butachlor and carbofuran.     

Analysis of rainwater quality variability on mesoscale: Case of the montreal island

During summer of 1989, a network for the analysis of spatial variability of rainwater quality was operated on Montréal Island. Six bulk samplers distributed on the territory were used for this purpose. A total of 97 storm-station events have been analyzed for pH, conductivity, Total Organic Carbon, nitrate, sulphate, calcium and magnesium. A canonical discriminant analysis shows that as a whole, there is no statistically significant discrimination between stations. However, Tukey's test for means shows that mean pH is significantly different between downtown and peripheric stations. The pH is higher in downtown. Finally, a variance analysis shows that variations with respect to time are greater than those on a spatial basis. Thus, the Montréal Island can be considered as spatially homogeneous for most rainwater quality parameters.     

Triacylglycerol and fatty acid compositions of French virgin olive oils. Characterization by chemometrics

There is no data concerning the fatty acid and triacylglycerol composition of French virgin olive oil. Thus, these compositions were determined using 564 samples coming from four olive harvests (1998-1999 to 2000-2001). Among these 564 samples, 372 came from the four main French cultivars (Aglandau, Cailletier, Picholine, and Salonenque) and from both of the oldest French protected designations of origin: "Nyons" (cv. Tanche) and "Vallée des Baux". The fatty acid compositions took the different isomeric monounsaturated fatty acids (C16:1 and C18:1) into account. The eicosenoic acid is gondoic acid (20:1n-9) and was determined by dimethyl disulfide adduct using GC/MS. The use of propionitrile as a mobile phase for the HPLC analysis of the triacylglycerols led to better resolutions between triacylglycerols than those resolutions obtained with the mix of solvents recommended by the normalized method (acetone/acetonitrile). Of the samples, 88 had a 9-heptadecenoic acid level (17:1n-8) higher than 0.3% and 33 had a linolenic acid level higher than 0.9%, which are maximal values accepted by the International Olive Oil Council and the European Union. A linear discriminant analysis was carried out on 372 samples with the SAS system and particularly with STEPISC and CANDISC procedures. Variables (n = 37) representing the different fatty acids, the sum of saturated, monounsaturated, and polyunsaturated fatty acids, squalene, and triacylglycerols were used, thus allowing us to classify samples into six groups defined with 100% of well classified samples. These results constitute an original data bank that can be used to identify the origin of virgin olive oils.     

Colza (Brassica napus, v. Jaguar) Responses to Low Level of Metal Inputs Through Sewage Sludge Application: Induction of phytochelatin synthesis (10 pp)

Background, Aim and Scope   Most studies of sewage sludge disposal effects on plants have focused on high metal loadings. Less attention has been paid to plant responses to trace metal loadings below the recommended limit values. Materials and Methods: Here, a lysimetric experiment was conducted to assess the uptake, distribution and binding of trace metals by metal-induced, sulfhydryl-rich peptides (phytochelatins) in colza (Brassica napus, v. Jaguar) grown on a clayey, silty soil amended with a sewage sludge compost containing trace metal contents far below the recommended limit values established by French legislation. Chemical fractionation of unamended and sludge-amended soils was performed using a sequential extraction technique. Results: Copper concentrations in plant tissues were not affected by compost disposal. Its application at a single rate equivalent to 30 t/ha stimulated the growth of plants. Lead was not detectable in the plant material (< 1 mg g-1 dry wt.). Plants grown on the amended soil accumulated significantly more zinc than control plants. These phytochelatin complexes detected in leaves had a lower molecular weight than those extracted from roots. Those extracted from roots were composed of one type of phytochelatins (PCs) such as in leaves or a mixture of glutathione, PC2 and PC4. In comparison with control plants, sewage sludge compost application caused the synthesis of longer chain PCs in roots and in leaves. Furthermore, in comparison with control roots, glutathione and phytochelatin mixtures of higher molecular weight were detected in roots produced on the amended soil, whereas no significant increase in \total\ Cu and Zn content was observed in these organs after sludge application. Discussion: Compost application induces a significant increase in the proportion of the most labile forms of zinc and especially its pH 4.7 acid-soluble forms and, as a consequence, a higher accumulation of zinc in plants. Effects of copper are limited due to its strong affinity for humic substances and lead does not seem to be transported in any organ of plants. The presence of phytochelatins, even in plants grown on the unamended soil, proved the ability of colza to synthesize them in the presence of zinc and copper. Conclusions: These primary results seem to prove, on one hand, ability of colza (Brassica napus, v. Jaguar) to synthesize phytochelatins as well as in roots, in leaves and, on the other hand, the sensitivity of the PC induction as suggested by their identification in plants grown on the control soil. Synthesis of longer chain PCs in roots and in leaves, and formation of glutathione and phytochelatin mixtures in roots, are plant responses to sewage sludge compost application. Recommendations and Perspectives: Phytochelatin analysis is thus supposedly able to be one of the bioindicators that may be used as an ecotoxicological risk assessment of wastes. Due to its ability to synthesize phytochelatins, colza could be chosen as a plant test. Phytochelatin analysis could also be limited to roots (more sensitive than leaves). However, further experiments are needed. Quantitative analysis of phytochelatins had not been carried out due to insufficient amounts of pure phytochelatin standards, that had allow us to better study relationships between trace metal amounts to vegetal response.     

No evidence of general decline in an amphibian community of Southern France

We investigated long term changes in an amphibian community in the Languedoc area of Southern France by comparing results of a survey of 56 ponds made in the early 1970s with results of a survey of the same localities in 2001. Based on the frequency of new occurrences and disappearances of species in the sample ponds, there is no sign of a general decline of amphibians in this area. Most species showed non-significant variation in frequency of occurrence or had increased. “Green frogs” (Rana perezi/ridibunda/kl. grafi) showed clear signs of decline, but this is a local phenomenon rather than a decline at the regional scale. Pelodytes punctatus probably declined also, possibly due to its sensitivity to fish introduction. The species richness in the ponds has also remained stable except in ponds where fish have been introduced. The only adverse impact of human activities that we could detect was thus the introduction of fish, which had a significantly adverse effect on amphibian species richness.     

Lactoferrin against Staphylococcus aureus Mastitis. Lactoferrin alone or in combination with penicillin G on bovine polymorphonuclear function and mammary epithelial cells colonisation by Staphylococcus aureus

Antibiotics should combine good antibacterial activity and the capacity to work in association with the host defence system. In this study, we have investigated the effects of bovine lactoferrin alone or in combination with penicillin G on the phagocytic activity of bovine polymorphonuclear leukocytes against Staphylococcus aureus. We have shown that susceptibility of S. aureus to phagocytosis was decreased in the presence of penicillin in the medium. In a kinetic study, lactoferrin alone did not affect phagocytosis but, when used with penicillin, it reversed the negative effect of this antibiotic on phagocytosis. In addition, in an epithelial invasion assay, lactoferrin alone or in combination with penicillin reduced the invasion of mammary epithelial cells in culture by S. aureus. Lactating female CD-1 mice were infected by intra-mammary delivery of a virulent penicillin-susceptible S. aureus strain and were then randomly assigned to treatments according to a 2 x 2 factorial design. In this mouse mastitis model, 2 days of systemic treatments with lactoferrin and/or penicillin did not lead to a total clearance of infection by S. aureus, but bacterial number was significantly reduced by treatments with lactoferrin or penicillin. These data suggest that bovine lactoferrin, alone or in combination with penicillin G, enhances S. aureus susceptibility to immuno-defense mechanisms, which can be beneficial in the treatment of S. aureus infections.     

Genetic diversity of Mycoplasma hyopneumoniae isolates of abattoir pigs

Mycoplasma hyopneumoniae, the causative agent of porcine enzootic pneumonia, is present in swine herds worldwide. However, there is little information on strains infecting herds in Canada. A total of 160 swine lungs with lesions suggestive of enzootic pneumonia originating from 48 different farms were recovered from two slaughterhouses and submitted for gross pathology. The pneumonic lesion scores ranged from 2% to 84%.Eighty nine percent of the lungs (143/160) were positive for M. hyopneumoniae by real-time PCR whereas 10% (16/160) and 8.8% (14/160) were positive by PCR for M. hyorhinis and M. flocculare, respectively. By culture, only 6% of the samples were positive for M. hyopneumoniae (10/160). Among the selected M. hyopneumoniae-positive lungs (n = 25), 9 lungs were co-infected with M. hyorhinis, 9 lungs with PCV2, 2 lungs with PRRSV, 12 lungs with S. suis and 10 lungs with P. multocida. MLVA and PCR-RFLP clustering of M. hyopneumoniae revealed that analyzed strains were distributed among three and five clusters respectively, regardless of severity of lesions, indicating that no cluster is associated with virulence. However, strains missing a specific MLVA locus showed significantly less severe lesions and lower numbers of bacteria. MLVA and PCR-RFLP analyses also showed a high diversity among field isolates of M. hyopneumoniae with a greater homogeneity within the same herd. Almost half of the field isolates presented less than 55% homology with selected vaccine and reference strains.     

Shape and temperature memory of nanocomposites with broadened glass transition

Shape-memory polymers can revert to their original shape when they are reheated. The stress generated by shape recovery is a growing function of the energy absorbed during deformation at a high temperature; thus, high energy to failure is a necessary condition for strong shape-memory materials. We report on the properties of composite nanotube fibers that exhibit this particular feature. We observed that these composites can generate a stress upon shape recovery up to two orders of magnitude greater than that generated by conventional polymers. In addition, the nanoparticles induce a broadening of the glass transition and a temperature memory with a peak of recovery stress at the temperature of their initial deformation.     

Effects of Mixing Conditions on Pasta Dough Development and Biochemical Changes

Mixing of commercial durum wheat semolina with water was performed under different conditions in a Brabender micromixer equipped with pastamaking shafts. Semolina filling of the mixing chamber was 30.4–42.9% (v/v), shaft speed was 10–110 rpm, temperature was 10–40°C, and hydration level was 47–52.5% (db). The blend of water and semolina evolved from individualized hydrated particles (HP) to a dough product (DP) as a function of these conditions. Torque values (T) and the specific mechanical energies (SME) were recorded during mixing as a function of time. Terms from these curves were defined to characterize the mixing process: t_o (starting time of dough development), t_d (time to reach the maximum dough consistency), T_m (mean torque value after dough development), and SME_f (total energy applied to the dough during mixing). Transformation of HP into DP and the mixing temperature were the main parameters affecting t_o, t_d, T_m, and SME_f. Protein aggregate distribution was measured by size-exclusion HPLC, protein solubility in 0.01N acetic acid, free -SH content, soluble arabinoxylans, reducing sugars, ferulic acid, carotenoid content, and oxidase activities to characterize the biochemical changes that occurred during pasta dough formation. DP was characterized by lower amounts of insoluble glutenin aggregates, lower protein solubility in dilute acetic acid, lower free -SH content, ferulic acid, carotenoid content, and lower oxidoreductase activities as compared to HP. Once the dough was developed, the effects of mixing speed, temperature, or hydration level on the biochemical composition of the blend were null or low compared to the modifications that were observed when the blends changed from HP to DP. The t_o and SME_f were the most significant parameters in characterizing the pasta dough mixing process in relation to biochemical changes.