Effect of coumaphos on cholinesterase activity,hematology, and biochemical blood parameters of bovines in tropical regions of Mexico

To assess the effect of coumaphos [O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) O,O-diethyl phosphorothioate] exposure on physiological responses during bovine production, acetylcolinesterase (AChE) and butyrylcholinesterase (BuChE) activities were measured in whole blood, erythrocytes, and plasma of healthy male steers (Bos Taurus x Bos indicus) sprayed with coumaphos at a non-lethal dose of 1 mg kg^{? 1} body weight per day once every 14 (in vivo group) or 21 days (southern and central groups). Coumaphos topically administered at 1 mg/kg body weight per day to cattle under normal management practices in tropical areas produced a significant inhibition in erythrocyte (RBC) AChE and BuAChE activities when compared to baseline levels. RBC-AChE activity for the in vivo group decreased 71.3% (P < 0.05) and BuChE activity 59.1% (P < 0.05); RBC-AChE activity decreased 55.1% (P < 0.05) (southern group) and 43.4% (P < 0.05) (central group). Compared to the control specimens, steers from in vivo, southern, and central groups after 150 days of exposure had lower (P < 0.05) leukocyte count, absolute lymphocyte, erythrocyte, and platelet counts. Decreases in RBC-AChE activities correlated with decreased lymphocyte (r = 1.000, p = 0.01), erythrocyte (r = 1.000, p = 0.003), and platelet counts (r = 0.841, p = 0.036). Significantly increased BUN levels (P < 0.05) correlated with the decrease in RBC-AChE activities (r = ? 0.997, p = 0.047) and with the decrease in absolute red blood cell (r = ? 0.883, p = 0.020) and lymphocyte (r = ? 0.825, p = 0.043) counts; increased (P < 0.05) total plasma protein levels correlated with the decrease in RBC-AChE activities (r = ?0.998, p = 0.043), absolute red blood cell (r = ? 0.998, p = 0.040), lymphocyte (r = ? 0.893, p = 0.017), and platelet (r = -0.855, p = 0.030) counts. The physiological responses correlated with the erythrocyte acetylcholinesterase inhibition could be considered as early indicators or warning responses of bovine exposures to organophosphorus pesticides (OPs).     

Application of heterogeneous catalysis to biodiesel synthesis using microalgae oil

• Microalgae oil application for biodiesel synthesis is discussed. • Catalytic effectiveness of ferment preparations and chemical catalyst is disputed. • Application of heterogeneous catalysts for biodiesel synthesis is reviewed. • Possibilities of catalyst regeneration is shown. Recently, there is a growing interest in the use of microalga in various fields. Microalgae have properties such as rapid reproduction and high biomass accumulation, and under certain conditions, some are able to accumulate a large amount of oil. However, microalgae oil often contains more free fatty acids than the vegetable oil and is therefore unsuitable for biodiesel synthesis using alkaline catalysts. For this reason, some authors suggest the application of heterogeneous catalysis. A particular interest in the use of immobilized enzymes has developed. Other solid substances can also be used as heterogeneous catalysts are usually metal oxides, carbonates or zeolites. The use of these catalysts results in simpler biodiesel synthesis, especially purification processes, a cleaner end product and a less polluted environment. The molar ratio of alcohol to oil is lower during enzymatic transesterification, and more than 90% ester yield is obtained using a molar ratio of alcohol to oil of 3:1 to 4.5:1. The alcohols do not have a negative effect on the effectiveness of chemical catalysts, so it is possible to use alcohols in molar ratio from 4:1 to 12:1. The optimal temperature of enzymatic process is 30℃‒50℃. An ester yield of more than 95% was obtained in 12‒48 h. Using chemical catalysts, greater than a 95% yield of esters was obtained at higher temperatures in a shorter time. Material costs of enzymatic catalysis can be reduced by reusing the catalysts directly or after regeneration.     

Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes

Data from recent sediment and surface water surveys have been collated and mapped to illustrate the spatial distribution of contaminants across the entire Great Lakes basin. Information from historical surveys, together with data from surface water monitoring programs in three major connecting channels, has also been collated in order to evaluate temporal trends. In general, Lakes Superior and Michigan exhibited the lowest levels of sediment contamination while Lake Ontario had the highest. Contaminants such as gamma-HCH (lindane) and dieldrin were ubiquitous in surface waters across the entire basin, which was indicative of atmospheric sources. The distribution of other compounds including hexachlorobenzene, octachlorostyrene and mirex indicated the presence of local sources within the watersheds of the connecting channels. Surficial sediment contamination was found to have decreased markedly since the late 1960s and 1970s. Similarly, surface water contamination decreased over the period 1986-1997 with concentrations of dieldrin, hexachlorobenzene, octachlorostyrene and mirex reduced by over 50%. However, the spatial distributions of both sediment and surface water contamination indicate that further effort is warranted in reducing local sources of contaminants, particularly in Lake Ontario.     

Changes in photosynthesis, mesophyll conductance to CO2, and isoprenoid emissions in Populus nigra plants exposed to excess nickel

Poplar (Populus nigra) plants were grown hydroponically with 30 and 200 μM Ni (Ni₃₀ and Ni₂₀₀). Photosynthesis limitations and isoprenoid emissions were investigated in two leaf types (mature and developing). Ni stress significantly decreased photosynthesis, and this effect depended on the leaf Ni content, which was lower in mature than in developing leaves. The main limitations to photosynthesis were attributed to mesophyll conductance and metabolism impairment. In Ni-stressed developing leaves, isoprene emission was significantly stimulated. We attribute such stimulation to the lower chloroplastic [CO₂] than in control leaves. However chloroplastic [CO₂] did not control isoprene emission in mature leaves. Ni stress induced the emission of cis-β-ocimene in mature leaves, and of linalool in both leaf types. Induced biosynthesis and emission of isoprenoids reveal the onset of antioxidant processes that may also contribute to reduce Ni stress, especially in mature poplar leaves.