Retrospective serological study on hepatitis E infection in pigs from 1985 to 1997 in Spain

The objective of the present work was to ascertain the date in which hepatitis E virus (HEV) was introduced in the Spanish pig population. For this, a serological retrospective study was carried out using archived sera. A total of 2871 serum samples gathered between 1985 and 1997 and collected in 208 farms of Spain were tested for anti-HEV IgG by an in-house ELISA. Of the 2871 sera analyzed by ELISA, 1390 were positive for anti-HEV antibodies (48.4%, 95% CI: 46.9-49.9%) and that corresponded to 204/208 farms (98%, 95% CI: 96.1-99.9%) having at least one positive pig. Our results show that HEV was present and widespread in Spanish swine farms at least since 1985. Any significant changes in prevalence were detected from 1 year to another and therefore, HEV infection in swine should be considered endemic in Spain.     

Modeling bleaching of tomato derivatives at subzero temperatures

This work was addressed to obtain a predictive model of the rate of bleaching in tomato derivatives at subzero temperatures. To this aim, a tomato puree was freeze-dried and equilibrated at increasing solid fractions. The bleaching rate was assessed by measuring tomato color during storage for up to 18 months at temperatures from -30 to 0 degrees C. The temperature dependence of the tomato-bleaching rate was neither predictable using the Arrhenius equation nor simply related to tomato physical state. The lack of a clear Arrhenius relation was attributed to the occurrence of temperature-dependent phenomena, such as ice crystallization and oxygen solubility modifications, which strongly changed the local concentration of reactants. A modified Arrhenius equation predicting the tomato-bleaching rate in the entire temperature range was proposed. Tomato concentration, and hence its physical state, affected the temperature dependence of bleaching, modifying apparent activation energy and frequency factor of the modified Arrhenius equation. In light of these considerations, a mathematical model was set up and validated to accurately predict the tomato-bleaching rate on the basis of only its concentration and storage temperature.     

Ranking temperate woody species along a gradient of browsing by deer

As a result of diverse management policies, densities of red and roe deer have varied considerably for the last few decades in Europe. Their selective browsing on woody species can modify the interactions between competing species and thus change overall patterns of plant diversity in forests. However, no classification of woody species according to browsing by deer yet exists in Europe. The selectivity index, which measures the balance between availability and consumption of plant species by herbivores, could be used for such a classification. The aim of this study was, first, to rank woody species according to this selectivity index, then to test whether their rank changed when browsing pressure varied in space or time. We also explored morphological and ecological life traits (Ellenberg indicator values) that might explain differences in selectivity.In 2006, we re-sampled a network of 217 coupled floristic and browsing survey plots, which had been previously described twice (1976, 1981). The plots were located in the forest of Arc-en-Barrois (France), a large woodland area divided into a North and a South Forest which have had different histories of browsing pressure.For the three samples and the two forests, we calculated a selectivity index for 19 woody species. Dogwood (Cornus sp.) and field rose (Rosa arvensis) appeared to be the most selected species whereas beech (Fagus sylvatica), common mezereon (Daphne mezereum) and wild-service tree (Sorbus torminalis) were always avoided. The rank order of species according to their selectivity index remained stable over the three sample years and between the two forests (Spearman's rank correlations: ρ ≈ 0.8 spatially, and range from 0.3 to 0.8 temporally). This indicates that variations in browsing pressure did not strongly modify deer selectivity patterns. Selectivity was positively correlated with wood density and negatively correlated with maximum height of the species, but unrelated to other plant traits. Finally, selectivity can be seen as an intrinsic characteristic of those woody species, and could be used as an additional life trait when analyzing vegetation communities.     

Potential productivity of forested areas based on a biophysical model. A case study of a mountainous region in northern Spain

? Today’s forest managers face a number of important challenges involving an increasing need for precise estimates of forest structure and biomass, potential productivity or forest growth. The objective is to develop a model for potential productivity in a mountainous region of Spain. The model combines climatic, topographic and lithological data using a variant of a traditional biophysical model: the Paterson index.

? In a first approach, the climatic productivity is assessed by modelling the required parameters using different geostatistical techniques and software supported by GIS. A second approach includes the correction of the former productivity classes considering the different lithological facies. The potential forest productivity model involves the integration of both models.

? Finally, data from the National Forest Inventory (NFI) are used to compare the real and potential yield data within different regions of the studied area.

? The results of these analyses demonstrate the usefulness of the model, particularly in mountainous regions, where no significant differences are found between the data from the NFI and the model, but they also show the discrepancies between the estimates and real data when the latter are considered for different tree species, diameter classes or management.

     

Biodegradability of Disinfectants in Surface Waters from Buenos Aires: Isolation of an Indigenous Strain Able to Degrade and Detoxify Benzalkonium Chloride

Biodegradability of chlorhexidine (CH), triclosan (TC), and benzalkonium chloride (CBA) has been tested in 18 surface water sampling points in the urban area of Buenos Aires. Sampling points were located in both the Reconquista and the Matanza-Riachuelo basins as well as in the La Plata River. High tolerance to the three disinfectants was found and indigenous strains capable of degrading CBA and TC were isolated. Neither tolerance nor biodegradation were correlated with sewage pollution. A strain that degrades CBA was identified as belonging to the genus Pseudomonas using the API20NE system and 16SRNA sequencing. In batch assays, the strain was capable of degrading 100, 200, and up to 500 mg L^?1 of CBA in 10, 25, and 46 h respectively with specific growth rates (μ) of 0.56, 0.30, and 0.14 h^?1. The efficiency of the process was between 99.5–98.0% in terms of compound removal and between 93.8–89.1% in terms of chemical oxygen demand (COD). The detoxification of the compound as a result of the biodegradation was assessed using Pseudokirchneriella subcapitata, Vibrio fischeri, and Lactuca sativa as test organisms.     

Effects of continuous spectrum LEDs used in indoor cultivation of two coniferous species Pinus sylvestris L. and Abies borisii-regis Mattf

The effects of four different continuous spectrum LED light qualities on the growth characteristics of Pinus sylvestris L. (PS) and Abies borisii-regis Mattf. (AB) seedlings were studied. The seedlings were exposed for 35 days inside growth chambers to G2 (high in red and far-red), AP67 (high in blue and far-red), AP67-ARCH (high in green), and NS2 (high in blue including a small percentage in the UV area) LEDs, as well as fluorescent light (FL) as Control. Each species showed a unique light-adapted response. G2 treatment stimulated needle formation of PS seedlings, while AB seedlings were unaffected. Hypocotyl elongation was promoted by FL; however, LEDs resulted in compact plants with greater root development, especially under the AP67-ARCH and AP67 spectra for PS and AB, respectively. In PS, AP67-ARCH and G2 significantly increased dry weight, while AB was affected significantly by AP67 and NS2. Furthermore, root growth potential of both species was better after LED pre-cultivation than the FL. Therefore, the use of continuous spectrum LEDs can enhance desirable quality characteristics of seedlings, which may be advantageous in large scale seedling production for reforestation.     

Species proportions by area in mixtures of Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) and European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) dominate many of the European forest stands. Also, mixtures of European beech and Scots pine more or less occur over all European countries, but have been scarcely investigated. The area occupied by each species is of high relevance, especially for growth evaluation and comparison of different species in mixed and monospecific stands. Thus, we studied different methods to describe species proportions and their definition as proportion by area. 25 triplets consisting of mixed and monospecific stands were established across Europe ranging from Lithuania to Spain in northern to southern direction and from Bulgaria to Belgium in eastern to western direction. On stand level, the conclusive method for estimating the species proportion as a fraction of the stand area relates the observed density (tree number or basal area) to its potential. This stand-level estimation makes use of the potential from comparable neighboring monospecific stands or from maximum density lines derived from other data, e.g. forest inventories or permanent observations plots. At tree level, the fraction of the stand area occupied by a species can be derived from the proportions of their crown projection area or of their leaf area. The estimates of the potentials obtained from neighboring monospecific stands, especially in older stands, were poorer than those from the maximum density line depending on the Martonne aridity index. Therefore, the stand-level method in combination with the Martonne aridity index for potential densities can be highly recommended. The species’ proportions estimated with this method are best approximated by the proportions of the species’ leaf areas. In forest practice, the most commonly applied method is an ocular estimation of the proportions by crown projection area. Even though the proportions of pine were calculated here by measuring crown projection areas in the field, we found this method to underestimate the proportion by 25% compared to the stand-level approach.     

抗重金属植物根际细菌的植物促生长特征以及它们对黑芥种子萌发的影响

Phytoremediation is an emerging technology that uses plants and their associated microbes to clean up pollutants from the soil, water, and air. In order to select the plant growth-promoting rhizobacteria(PGPR) for phytoremediation of heavy metal contamination, 60 bacterial strains were isolated from the rhizosphere of two endemic plants, Prosopis laevigata and Spharealcea angustifolia, in a heavy metal-contaminated zone in Mexico. These rhizobacterial strains were characterized for the growth at different pH and salinity, extracellular enzyme production, solubilization of phosphate, heavy metal resistance, and plant growth-promoting(PGP) traits, including production of siderophores and indol-3-acetic acid(IAA). Overall, the obtained rhizobacteria presented multiple PGP traits. These rhizobacteria were also resistant to high levels of heavy metals(including As as a metalloid)(up to 480 mmol L(-1)As(V), 24 mmol L(-1)Pb(Ⅱ), 21 mmol L(-1)Cu(Ⅱ), and 4.5 mmol L(-1)Zn(Ⅱ)). Seven rhizobacterial strains with the best PGP traits were identified as members of Alcaligenes, Bacillus, Curtobacterium, and Microbacterium, and were selected for further bioassay.The inoculation of Brassica nigra seeds with Microbacterium sp. CE3R2, Microbacterium sp. NE1R5, Curtobacterium sp. NM1R1,and Microbacterium sp. NM3E9 facilitated the root development; they significantly improved the B. nigra seed germination and root growth in the presence of heavy metals such as 2.2 mmol L(-1)Zn(Ⅱ). The rhizobacterial strains isolated in the present study had the potential to be used as efficient bioinoculants in phytorremediation of soils contaminated with multiple heavy metals.     

Evaluation of ground grain versus pre- and post-pellet whole grain additions to poultry diets via a response surface design

1. The objective of this study was to compare the effects of pre- and post-pellet whole grain wheat additions to diets on growth performance, gizzard and pancreas development, nutrient utilisation and starch and protein (N) digestibility coefficients in broiler chickens via an equilateral triangle response surface design.

2. The three apical treatments of the equilateral triangle comprised (1A) a standard diet containing 600 g/kg ground wheat, (2B) the same diet containing 600 g/kg pre-pellet whole wheat and (3C) the same diet containing 300 g/kg ground wheat and 300 g/kg post-pellet whole wheat. Seven blends of the three apical diets were located within the triangle to complete the design and a total of 360 male Ross 308 chicks were offered the ten experimental diets from 7 to 28 d post-hatch. Model prediction and response surface plots were generated with R 3.0.3 software.

3. The most efficient FCR of 1.466 was observed in birds offered an almost equal mixture of the pre- and post-pellet whole grain apical dietary treatments, which corresponded to 172 g/kg ground grain, 256 g/kg pre-pellet whole grain, 172 g/kg post-pellet whole grain in a diet containing 600 g/kg wheat.

4. The most efficient energy utilisation (ME:GE ratio of 0.766) was observed in birds offered a blend of the ground grain and pre-pellet whole grain apical dietary treatments which corresponded to a mixture of 384 g/kg pre-pellet whole grain and 216 g/kg ground grain.

5. Pre-pellet whole grain feeding generated the most pronounced responses in increased relative gizzard contents, reduced gizzard pH and increased relative pancreas weights. Consideration is given to the likely differences between pre- and post-pellet whole grain feeding.