Nitrogenase complexes: multiple docking sites for a nucleotide switch protein

Adenosine triphosphate (ATP) hydrolysis in the nitrogenase complex controls the cycle of association and dissociation between the electron donor adenosine triphosphatase (ATPase) (Fe-protein) and its target catalytic protein (MoFe-protein), driving the reduction of dinitrogen into ammonia. Crystal structures in different nucleotide states have been determined that identify conformational changes in the nitrogenase complex during ATP turnover. These structures reveal distinct and mutually exclusive interaction sites on the MoFe-protein surface that are selectively populated, depending on the Fe-protein nucleotide state. A consequence of these different docking geometries is that the distance between redox cofactors, a critical determinant of the intermolecular electron transfer rate, is coupled to the nucleotide state. More generally, stabilization of distinct docking geometries by different nucleotide states, as seen for nitrogenase, could enable nucleotide hydrolysis to drive the relative motion of protein partners in molecular motors and other systems.     

Wood properties and their among-family variations in 10 open-pollinated families of Picea jezoensis

This study aimed to evaluate radial and among-family variations of wood properties in Picea jezoensis. A total of 174 trees were randomly selected from 10 open-pollinated families in a progeny trial for measuring stem diameter, dynamic Young’s modulus of log (DMOE_log), annual ring width (ARW), air-dry density (AD), modulus of elasticity (MOE), and modulus of rupture (MOR). Mean values of DMOE_log, AD, MOE, and MOR were 9.60 GPa, 0.41 g/cm³, 9.44 GPa, and 76.6 MPa, respectively. Significant differences among families were observed in all properties. F values obtained by analyzing variance in wood properties were higher than those generally observed in growth traits. In addition, F values in wood properties remained relatively higher from the 1st to 25th annual ring from the pith, although F value in ARW rapidly decreased with each increase in annual ring number. These results indicate that genetic factors largely contributed to the variance in wood properties compared with the growth traits.     

Importance of capital cost reduction of chippers and their required productivity

The productivity and chipping cost of a low-investment small mobile chipper were investigated. The effect of capital cost on chipping cost reduction was analyzed by changing the service life of the chipper when assuming a target operational chipping cost set at 250 yen m^?3. Productivity of the investigated chipper was found to be at 23.7 m³ h^?1 in chip volume with fuel consumption at 14.6 L h^?1. The results showed that the chipping cost of the investigated chipper was lower than that of a higher priced and more productive grinder. Neither chipper nor grinder, however, could achieve the assumed target cost of 250 yen m^?3 even if their service lives were extended. It was necessary to withstand the initial grapple loader and the labor costs or raise the grinder’s productivity to 33 m³ h^?1 in order to reach a comparable operational cost target with that of the investigated chipper. Similarly, the grinder would have to reduce its capital cost and fuel consumption to maintain the chipping cost of 250 yen m^?3 ifproductivity could not be improved. Net chipping cost of the investigated chipper was relatively small compared to that of the tub grinder, especially under a shorter service lifespan. The investigation shows that it is feasible for small-scale forestry to introduce a low-investment mobile chipper because it does not require a large amount of material and has a low chipping cost. Moreover, lowering the capital cost or the price of chippers is a more realistic cost savings in the long term.     

Pine heartwood formation as a maturation phenomenon

The inverse of the relative increment rate of size is proposed as a measure of the maturity of a forest tree. The heartwood content within bole cross sections is modeled semiempirically using asymptotic fitting. It is shown that the present proposal for a definition of maturity statistically explains heartwood content far better than age or size. The heartwood content appears to be independent on growth rate and tree size.     

The accumulation of glycinebetaine during cold acclimation in early and late cultivars of barley

Summary Barley plants are able to accumulate glycinebetaine (betaine) at high levels in their leaves in response not only to water and salt stress but also to cold stress. Such accumulation of betaine during acclimation to cold is associated to some extent with freezing tolerance in leaves of barley plants, as previously demonstrated with near-isogenic lines that differed only in a single gene for the spring type of growth habit (Plant, Cell and Enyironment 17: 89–95, 1994). We now present evidence that the levels of betaine accumulated during cold acclimation might be associated with the earliness or lateness of the maturity of cultivars, namely, that late cultivars accumulate more betaine than early cultivars. Moreover, the grade of the vermalization requirement of the cultivars seemed unlikely to be associated with the level of betaine acumulated during cold acclimation. However, the trait that controlled accumulation of betaine during cold acclimation was not linked with the earliness or lateness of the maturity of cultivars. The higher levels of betaine in the late cultivars might have resulted from co-selection for lateness of maturity and freezing tolerance, which is generally a requirement in the areas of Japan where such late cultivars were originally cultivated.     

Electrokinetic Copper and Iron Migration in Anaerobic Granular Sludge

The application of low-level direct electric current (0.15 mA cm^?2) as an electrokinetic technique to treat copper-contaminated mesophilic anaerobic granular sludge was investigated. The sludge was obtained from a full scale UASB reactor treating paper-mill wastewater and was artificially contaminated by Cu(NO₃)₂ or CuEDTA^2? with initial copper concentrations of 1000 mg . kg^?1 wet sludge. The effect of different electrokinetic cell layouts, pH and EDTA concentrations on the migration of copper and iron during electrokinetic treatment were evaluated. Both, the pH of the sludge cake or the copper complexation with EDTA significantly affected the migration direction of copper. In an ‘open’ cell (sludge cake in direct contact with air), the highest copper mobility was observed at pH 2.5 in both Cu(NO₃)₂ or CuEDTA^2? amended sludge. The highest copper accumulation was at the cathode (22 ± 2)% with CuEDTA^2? as contaminant. In a ‘closed’ cell (sludge cake not in contact with air), the highest accumulation was obtained for CuEDTA^2? at the anode and amounted to 4(± 0.5)% and 2(± 0.05)%, respectively, at a final pH of 4.2 and 7.7 in the sludge cake.     

Rapid time-resolved fluoroimmunoassay for the screening of narasin and salinomycin residues in poultry and eggs

Anticoccidial drugs are extensively used in the poultry industry to control the infection of the single-cell protozoa of the genus Eimeria. The most commonly used coccidiostats in poultry are the polyether ionophores such as narasin and salinomycin. This paper presents a rapid and simple method for the screening of residues of these two coccidiostatic compounds in poultry and eggs. The method is based on time-resolved fluoroimmunoassay. Sample preparation of eggs consists only of one extraction and evaporation step, and a solid phase extraction step is needed only for the muscle sample preparation. Mean recoveries were 91.0% from muscle tissue and 81.1% from eggs for both narasin and salinomycin. The performance of the assay was evaluated only for narasin because salinomycin had a cross-reactivity of 100% in the assay, and the recoveries of the compounds were not significantly different (P >0.05). The limits of detection [mean + 3 x standard deviation (SD)] of narasin were 0.56 and 0.28 microg/kg, and the limits of quantification (mean + 9 x SD) were 1.80 and 0.57 microg/kg for muscle and eggs, respectively. The coefficients of variation (CV) of the interassay precision of the method, evaluated by five replicate analyses of muscle samples spiked with 2 microg/kg of narasin and egg samples spiked with 1 microg/kg of narasin, were 4.1 and 6.4%, respectively. The CVs of intra-assay precision tests, determined by 10 replicate analyses at the above-mentioned concentration levels, were 3.8 and 4.5%, respectively.     

Development and intercalibration of methods in nordic freshwater fish monitoring

The awareness of the effects of transboundary pollution has increased the necessity to use comparable methods and to initiate joint studies between countries in environmental monitoring. In freshwater fish monitoring a number of different methods have been used, strongly reducing the possibilities to comparative assessments between countries. In 1990, a workshop on freshwater fish sampling was initiated in order to develop and intercalibrate methods used in freshwater fish studies in the Nordic countries. During a three year period, a new type of multi-mesh gillnet to be used for fish monitoring in Norway, Finland and Sweden have been developed. Comparative studies and gillnet-selectivity assessments show that these new multi-mesh gillnets better describe the actual population structure of European perch (Perca fluviatilis), roach (Rutilus rutilus) and Arctic char (Salvelinus alpinus) than do the traditional gillnet series used in the Nordic countries. Ageing of fish is central in most environmental studies, however, the comparability of analyses performed at different laboratories may be low. Comparative age analyses between the three countries have been performed for a number of fish species. The results of ageing E. perch, whitefish (Coregonus sp.) and roach indicate that differences between laboratories can be reduced by intercalibration. In the future, the workgroup will be focused on a further development of joint methods within studies of freshwater fish and on joint intemordic assessments on species distribution, abundance and life history characteristics in relation to airborne pollutants and liming.     

Using analogies from soil science for estimating solar radiation

Using analogies from soil science a new global radiation estimation method was developed and tested on a large North-American meteorological database. The newly developed procedure was compared to the well-known, Donatelli-Campbell method. Both the overall indicators and the more detailed analysis of the model performance confirmed that the new method is more efficient than the Donatelli-Campbell method. The improved performance is due to the greater number of parameters, as well as to the more adequate function type it uses during the calculation. Results suggest that it is sufficient to have 2 year-long data series for parameterizing the new method to provide at least as accurate radiation estimates as provided by the Donatelli-Campbell method. The new method can be efficiently used for locations with no radiation measurement by combining it with a simple spatial interpolation technique.