Cellulose depolymerization to glucose and other water soluble polysaccharides by shear deformation and high pressure treatment

The simultaneous action of shear deformation and high pressure (SDHP) creates changes in the structure of wood and its main components (cellulose, hemicelluloses, lignin). The formation of water and alkali soluble polysaccharides under SDHP action, proceeds in seconds in the solid state, without the use of any reagents and solvents. Therefore, SDHP seems to be a technologically safe method and friendly to the environment. The amorphization of cellulose crystallites and depolymerization of cellulose chains were observed under a wide range of pressures (1–6 GPa), both for cellulose samples and the cellulose part of wood. Similar depolymerization occurs in the hemicellulose part of wood. The decomposition of polysaccharides under SDHP causes the formation of the water soluble part, whose content increases with pressure and the applied shear deformation. A maximum solubility of 40% and 55% was registered at 6 GPa following treatment of cellulose and birch wood samples. A higher output in the case of wood can be explained by a specific role of lignin under SDHP, which acts as a ‘grinding stone’ during cellulose and hemicelluloses destruction. As shown by high-performance size exclusion chromatography, the water soluble fraction obtained from cellulose contained glucose (2.6%), cellobiose (9.6%), cellotriose (16.6%) and other higher water soluble oligomers (71%). Almost complete dissolution (98%) of the treated cellulose sample can be achieved by extraction with 10% NaOH solution. The SDHP treated birch wood was subjected to submerged fermentation (with Trichoderma viride), and a 13% output of proteins was obtained. In this case, the water soluble part played the role of the so called ‘start sugars’. Abbreviations: ASF, alkali soluble fraction; DP, degree of polymerization; EC, energy consumption; HP, high pressure; LMWS, low molecular weight sugars; MC, moisture content; MCC, microcrystalline cellulose; SD, shear deformation, SDHP, shear deformation under high pressure; SS, shear strength; WSF, water soluble fraction This revised version was published online in November 2006 with corrections to the Cover Date.     

Function2Form Bridge—Toward synthetic protein holistic performance prediction

Protein engineering and synthetic biology stand to benefit immensely from recent advances in silico tools for structural and functional analyses of proteins. In the context of designing novel proteins, current in silico tools inform the user on individual parameters of a query protein, with output scores/metrics unique to each parameter. In reality, proteins feature multiple “parts”/functions and modification of a protein aimed at altering a given part, typically has collateral impact on other protein parts. A system for prediction of the combined effect of design parameters on the overall performance of the final protein does not exist. Function2Form Bridge (F2F-Bridge) attempts to address this by combining the scores of different design parameters pertaining to the protein being analyzed into a single easily interpreted output describing overall performance. The strategy comprises of (a) a mathematical strategy combining data from a myriad of in silico tools into an OP-score (a singular score informing on a user-defined overall performance) and (b) the F2F Plot, a graphical means of informing the wetlab biologist holistically on designed construct suitability in the context of multiple parameters, highlighting scope for improvement. F2F predictive output was compared with wetlab data from a range of synthetic proteins designed, built, and tested for this study. Statistical/machine learning approaches for predicting overall performance, for use alongside the F2F plot, were also examined. Comparisons between wetlab performance and F2F predictions demonstrated close and reliable correlations. This user-friendly strategy represents a pivotal enabler in increasing the accessibility of synthetic protein building and de novo protein design.     

Efficient chemoenzymatic synthesis of (S)-α-amino-4-fluorobenzeneacetic acid using immobilized penicillin amidase

An efficient chemoenzymatic route was developed for synthesis of (S)-α-amino-4-fluorobenzeneacetic acid, a valuable chiral intermediate of Aprepitant, using immobilized penicillin amidase catalyzed kinetic resolution of racemic N-phenylacetyl-4-fluorophenylglycine. The optimum temperature, pH and agitation rate of the reaction were determined to be 40 °C, 9.5 and 300 rpm, respectively. Kinetic resolution of 80 g L⁻¹ N-phenylacetyl-4-fluorophenylglycine by immobilized amidase 20 g L⁻¹ resulted in 49.9% conversion and >99.9% e.e. within 3 h. The unreacted N-phenylacetyl-4-fluorophenylglycine can be easily racemized and then recycled as substrate. The production of (S)-α-amino-4-fluorobenzeneacetic acid was further amplified in 1 L reaction system, affording excellent conversion (49.9%) and enantioselectivity (99.9%). This chemoenzymatic approach was demonstrated to be promising for industrial production of (S)-α-amino-4-fluorobenzeneacetic acid.     

Power and limitation of soil properties as predictors of variation in peak plant biomass in a northern mixed-grass prairie

Soil properties are thought to affect annual plant productivity in rangelands, and thus soil variables that are consistently correlated with plant biomass may be general indicators of rangeland health. Here we measured several soil properties (e.g. aggregate stability, organic carbon, total nitrogen) and tested each as a would-be predictor of local variation in peak aboveground grassland biomass. Individual properties explained a slight (≤10%) amount of variation in plant biomass. Plant biomass was mainly (negatively) associated with two soil properties, subsurface soil carbonate concentration and the stability of soil macroaggregates near the soil surface. Less important predictive variables included: elevation, plant community composition, surface soil organic carbon, and soil carbon:nitrogen. Plot-to-plot variation in plant biomass is seemingly difficult to predict based on soil properties, including popular indicators of soil and rangeland health and even root biomass. While protection of soil is critical to overall rangeland ecosystem function, our findings suggest that the relationship between soil properties and plant biomass in natural grasslands is complex. Thus, there may not be one or even several soil properties that consistently predict appreciable variation in peak grassland biomass, especially variation within an ecosystem independent of precipitation.     

Impaired spermatogenesis associated with changes in spatial arrangement of Sertoli and spermatogonial cells following induced diabetes

The current study was conducted to assess the relationship between testicular cells in spermatogenesis, through which the production of healthy and mature sperm is essential. However, it seems necessary to obtain more information about the three-dimensional pattern of the testis cells arrangement, which is directly related to the function of the testis after induction of diabetes. Twelve adult mice (28-30 g) were assigned into two experimental groups: (1) control and (2) diabetic (40 mg/kg STZ). The epididymal sperm collected from the tail of the epididymis and testes samples were taken for stereology, immunocytochemistry and RNA extraction. Our data showed that diabetes could notably decrease the number of testicular cells, together with a reduction of total sperm count. In addition, the results from the second-order stereology indicated the significant changes in the spatial arrangement of Sertoli cells and spermatogonial cells in the diabetic groups, in comparison with the control (P < .05). Moreover, the immunohistochemistry results showed a significant reduction in Sex-determining Region Y (SRY) box 9 gene (SOX9), vimentin, occludin, and connexin-43 positive cells in the diabetic groups compared with the control (P < .05). Furthermore, our data showed that the expression of steroidogenic acute regulatory protein steroidogenic acute regulatory protein (StAR) and peripheral benzodiazepine receptor peripheral benzodiazepine receptor (PBR) was significantly reduced in the diabetic groups, in comparison with the control (P < .05). These findings suggest that structural and functional changes of testis cells after induction of diabetes cause the alterations in the spatial arrangement of Sertoli and spermatogonial cells, ultimately influencing the normal spermatogenesis in mice.     

Population and size-specific distribution of Atlantic salmon Salmo salar in the Baltic Sea over five decades

Population-specific assessment and management of anadromous fish at sea requires detailed information about the distribution at sea over ontogeny for each population. However, despite a long history of mixed-stock sea fisheries on Atlantic salmon, Salmo salar, migration studies showing that some salmon populations feed in different regions of the Baltic Sea and variation in dynamics occurs among populations feeding in the Baltic Sea, such information is often lacking. Also, current assessment of Baltic salmon assumes equal distribution at sea and therefore equal responses to changes in off-shore sea fisheries. Here, we test for differences in distribution at sea among and within ten Atlantic salmon Salmo salar populations originating from ten river-specific hatcheries along the Swedish Baltic Sea coast, using individual data from >125,000 tagged salmon, recaptured over five decades. We show strong population and size-specific differences in distribution at sea, varying between year classes and between individuals within year classes. This suggests that Atlantic salmon in the Baltic Sea experience great variation in environmental conditions and exploitation rates over ontogeny depending on origin and that current assessment assumptions about equal exploitation rates in the offshore fisheries and a shared environment at sea are not valid. Thus, our results provide additional arguments and necessary information for implementing population-specific management of salmon, also when targeting life stages at sea.     

Wildcat population density in NE Portugal: A regional stronghold for a nationally threatened felid

Population density data on depleted and endangered wildlife species are essential to assure their effective management and, ultimately, conservation. The European wildcat is an elusive and threatened species inhabiting the Iberian Peninsula, with fragmented populations and living in low densities. We fitted spatial capture–recapture models on camera-trap data, to provide the first estimate of wildcat density for Portugal and assess the most influential drivers determining it. The study was implemented in Montesinho Natural Park (NE Portugal), where we identified nine individuals, over a total effort of 3,477 trap-nights. The mean density estimate was 0.032 ± 0.012 wildcat/km², and density tended to increase with distance to humanized areas, often linked to lower human disturbance and domestic cat presence, with forest and herbaceous vegetation cover and with European rabbit abundance. Although, this density estimate is within the range of values estimated for protected areas elsewhere in the Iberian Peninsula, our estimates are low at the European level. When put in context, our results highlight that European wildcats may be living in low population densities across the Iberian Mediterranean biogeographic region. No phenotypic domestic or hybrid cats were detected, suggesting potentially low admixture rates between the two species, although genetic sampling would be required to corroborate this assertion. We provide evidence that Montesinho Natural Park may be a suitable area to host a healthy wildcat population, and thus be an important protected area in this species' conservation context.     

基于空间面板STIRPAT模型的水足迹影响因素分析——以山东省为例

随着中国水资源供需矛盾加剧，虚拟水成为地区水资源管理中不可或缺的一环，为提高地区水资源综合利用效率和探索水资源区域一体化管理提供了新思路。采用"自下而上"法核算了山东省17个城市农业、工业、生活、生态与灰水足迹，在分析2009-2018年水足迹时空分布规律基础上，综合运用探索性空间数据分析方法、面板数据STIRPAT模型和空间杜宾模型，揭示了水足迹的空间自相关特征，量化分析了人口数量、富裕程度、技术进步、城镇化和产业升级等影响因素对水足迹的本地影响效应与空间溢出效应。结果显示：①2009-2018年山东省水足迹总量均呈现波动上升的变化趋势；空间布局上呈现东部沿海和西部平原水足迹高，中部山地水足迹低的特点。②山东省水足迹具有正向的空间自相关性，相比地理位置相邻，水足迹的空间相关性受人口数量因素影响更大，表现出明显的"高高"聚集和"低低"聚集特征，但是受到经济因素的主要影响，区域间水足迹空间相关性随时间发展逐渐下降。③人口数量是山东省水足迹增长的重要来源，经济增长是推动各地区间水资源竞争关系的最重要因素。城镇化能够缓解本地水资源压力，技术进步和产业升级不仅能缓解本地水资源压力，而且通过空间溢出效应有效缓解临近地区水资源压力，是实施水资源区域一体化管理策略的重要着眼点。