Modulation of alpha-thrombin function by distinct interactions with platelet glycoprotein Ibalpha

Thrombin bound to platelets contributes to stop bleeding and, in pathological conditions, may cause vascular thrombosis. We have determined the structure of platelet glycoprotein Ibalpha (GpIbalpha) bound to thrombin at 2.3 angstrom resolution and defined two sites in GpIbalpha that bind to exosite II and exosite I of two distinct alpha-thrombin molecules, respectively. GpIbalpha occupancy may be sequential, as the site binding to alpha-thrombin exosite I appears to be cryptic in the unoccupied receptor but exposed when a first thrombin molecule is bound through exosite II. These interactions may modulate alpha-thrombin function by mediating GpIbalpha clustering and cleavage of protease-activated receptors, which promote platelet activation, while limiting fibrinogen clotting through blockade of exosite I.     

Meltwater pulse 1A from Antarctica as a trigger of the Bølling-Allerød warm interval

Meltwater pulse 1A (mwp-1A) was a prominent feature of the last deglaciation, which led to a sea-level rise of approximately 20 meters in less than 500 years. Concurrent with mwp-1A was the onset of the B?lling-Aller?d interstadial event (14,600 years before the present), which marked the termination of the last glacial period. Previous studies have been unable to reconcile a warm Northern Hemisphere with mwp-1A originating from the Laurentide or Fennoscandian ice sheets. With the use of a climate model of intermediate complexity, we demonstrate that with mwp-1A originating from the Antarctic Ice Sheet, consistent with recent sea-level fingerprinting inferences, the strength of North Atlantic Deep Water (NADW) formation increases, thereby warming the North Atlantic region and providing an explanation for the onset of the B?lling-Aller?d warm interval. The established mode of active NADW formation is then able to respond to subsequent freshwater forcing from the Laurentide and Fennoscandian ice sheets, setting the stage for the Younger Dryas cold period.     

Rheology,Microstructure, and Baking Characteristics of Frozen Dough Containing Rhizopus chinensis Lipase and Transglutaminase

The beneficial effects of a new recombinant lipase (Rhizopus chinensis lipase [RCL]) and transglutaminase (TG) were investigated on frozen dough systems and their breadmaking quality. Rheological properties and microstructure of doughs were measured using a dynamic rheometer, rheofermentometer F3, and scanning electron microscopy (SEM). Measurements of viscoelastic properties showed that both G′ and G″ of dough containing RCL and TG were greater than those of the control after 35 days of frozen storage. The SEM micrographs showed that dough containing RCL and TG had the most starch granules embedded in or attached to the gluten network, and the gluten seemed more powerful and resilient than for the control dough after 35 days of frozen storage. Results of the gas production and dough development tests indicated that RCL and TG improved the rheofermentative characteristics of frozen dough. RCL and TG could improve water‐holding capacity and significantly increase the glycerol content of the control dough. Image analyses showed that bread crumbs containing RCL and TG had a more open network and uniform crumb structure, which resulted in higher specific volume. This combination also yielded a product with higher sensory scores for test breads.     

Contrasting methods for estimating evapotranspiration in soybean

Crop scientists are often interested in canopy rather than leaf water estimates. Comparing canopy fluxes for multiple treatments using micrometeorological approaches presents limitations because of the large fetch required. The goal of this study was to compare leaf-scale to field-scale data by summing soil water evaporation (E) and leaf transpiration (T) versus ET using tower eddy covariance (EC) and scaling leaf transpiration to the canopy level using a two-step scaling approach in soybean [Glycine max (L.) Merr.]. Soybean transpiration represented 89-96% of E + T when combining the soil water evaporation with leaf transpiration on the five measurement days during reproductive growth. Comparing E + T versus ET from the EC system, the E + T method overestimated ET from 0.68 to 1.58 mm. In terms of percent difference, the best agreement between the two methods was 15% on DOY 235 and the worst agreement occurred on DOY 234 (41%). A two-step scaling method predicted average ET within 0.01 mm of the EC ET between 10:00 and 14:15 on an hourly time-step on DOY 227 under uniform sky conditions and average ET within 0.03 mm of the EC ET on DOY 235 under intermittent sky conditions between 10:00 and 15:15. Pooling the scaled-leaf data and comparing them with the measured EC ET data exhibited a strong linear relationship (r = 0.835) after accounting for bias (6%). Findings from this study indicate satisfactory results comparing absolute differences are likely not obtainable by summing leaf transpiration with soil water evaporation to calculate canopy water fluxes. However, scaling leaf transpiration provided a robust measure of canopy transpiration during reproductive growth in soybean under these conditions and merits additional study under different climatic and crop conditions.     

A preliminary watershed scale soil quality assessment in north central Iowa, USA

Soil quality assessment has been recognized as an important step toward understanding the long-term effects of conservation practices within agricultural watersheds. Our objective was to assess soil quality within the South Fork watershed of the Iowa River using various indicators and assessment approaches. Soil samples were collected during 2003 and 2004 from 29 areas of 32 ha (80 acres) each along two transects traversing the watershed. Soil pH, Mehlich III extractable P, K, Ca and Mg, electrical conductivity (EC), total organic carbon (TOC), and total N (TN) were measured. The Soil Management Assessment Framework (SMAF) was used to compute a soil quality index (SQI), while soil loss, the soil tillage intensity rating (STIR), N-leaching potential, and soil conditioning index (SCI) were determined for each sampling area using the 2003 version of the Revised Soil Loss Equation (RUSLE2). Overall, there were no soil fertility limitations within the watershed based on an average pH of 6.96 and extractable P and K levels of 36 and 162 mg kg⁻¹, respectively. Soil loss, STIR, N-leaching, and SCI averaged 1.13 Mg ha⁻¹, 68, 3, and 0.4, respectively. The SMAF analysis indicated soils within the watershed were functioning at 87% of their full potential. The lowest indicator score was associated with TOC (0.60) because the average value was only 28.4 g kg⁻¹. The SCI and SQI indices were positively correlated although since it used measured data, the SMAF appears to provide more information about the effects of management practices within the watershed. Soils in upper landscape positions had lower TOC and C:N ratios indicating an increased risks for both erosion and for nitrate leaching. Management of soils on hilltops may be the most effective way to minimize N and P losses within the watershed.     

Modeling Perceived Risk from Coyotes Among Chicago Residents

This article examined the influence of urban homeowners’ general wildlife value orientations (i.e., mutualism, domination) and their specific positive beliefs about coyotes on perceived risk from coyotes. Data were obtained from a mail survey of residents in the Greater Chicago Metropolitan Region during 2012 (n = 1,624, response rate = 34%). As predicted, general wildlife value orientations were related to specific positive beliefs about coyotes. Mutualism had a positive relationship with these beliefs, and domination had a negative relationship. As specific beliefs became more positive, perceived risk decreased. Although mutualism was not related to perceived risk, a significant and positive relationship was observed between domination and perceived risk. Residents with a domination orientation were more fearful of coyotes. The two value orientations explained 64% of the variance in specific positive beliefs, and both domination and these beliefs accounted for 20% of the variance in perceived risk. Implications for managing coyotes in an urban setting are discussed.