Brain μ-Calpain Autolysis During Global Cerebral Ischemia

Abstract: Proteolytic degradation of numerous calpain substrates, including cytoskeletal and regulatory proteins, has been observed during brain ischemia and reperfusion. In addition, calpain inhibitors have been shown to decrease degradation of these proteins and decrease postischemic neuronal death. Although these observations support the inference of a role for μ-calpain in the pathophysiology of ischemic neuronal injury, the evidence is indirect. A direct indicator of μ-calpain proteolytic activity is autolysis of its 80-kDa catalytic subunit, and therefore we examined the μ-calpain catalytic subunit for evidence of autolysis during cerebral ischemia. Rabbit brain homogenates obtained after 0, 5, 10, and 20 min of cardiac arrest were electrophoresed and immunoblotted with a monoclonal antibody specific to the μ-calpain catalytic subunit. In nonischemic brain homogenates the antibody identified an 80-kDa band, which migrated identically with purified μ-calpain, and faint 78- and 76-kDa bands, which represent autolyzed forms of the 80-kDa subunit. The average density of the 80-kDa band decreased by 25 ± 4 ( p = 0.008) and 28 ± 9% ( p = 0.004) after 10 and 20 min of cardiac arrest, respectively, whereas the average density of the 78-kDa band increased by 111 ± 50% ( p = 0.02) after 20 min of cardiac arrest. No significant change in the density of the 76-kDa band was detected. These results provide direct evidence for autolysis of brain μ-calpain during cerebral ischemia. Further work is needed to characterize the extent, duration, and localization of μ-calpain activity during brain ischemia and reperfusion as well as its role in the causal pathway of postischemic neuronal injury.     

Cooperation without Culture? The Null Effect of Generalized Trust on Intentional Homicide: A Cross-National Panel Analysis, 1995–2009

Sociologists, political scientists, and economists all suggest that culture plays a pivotal role in the development of large-scale cooperation. In this study, I used generalized trust as a measure of culture to explore if and how culture impacts intentional homicide, my operationalization of cooperation. I compiled multiple cross-national data sets and used pooled time-series linear regression, single-equation instrumental-variables linear regression, and fixed- and random-effects estimation techniques on an unbalanced panel of 118 countries and 232 observations spread over a 15-year time period. Results suggest that culture and large-scale cooperation form a tenuous relationship, while economic factors such as development, inequality, and geopolitics appear to drive large-scale cooperation.     

Vascular Immunotargeting to Endothelial Determinant ICAM-1 Enables Optimal Partnering of Recombinant scFv-Thrombomodulin Fusion with Endogenous Cofactor

The use of targeted therapeutics to replenish pathologically deficient proteins on the luminal endothelial membrane has the potential to revolutionize emergency and cardiovascular medicine. Untargeted recombinant proteins, like activated protein C (APC) and thrombomodulin (TM), have demonstrated beneficial effects in acute vascular disorders, but have failed to have a major impact on clinical care. We recently reported that TM fused with an scFv antibody fragment to platelet endothelial cell adhesion molecule-1 (PECAM-1) exerts therapeutic effects superior to untargeted TM. PECAM-1 is localized to cell-cell junctions, however, whereas the endothelial protein C receptor (EPCR), the key co-factor of TM/APC, is exposed in the apical membrane. Here we tested whether anchoring TM to the intercellular adhesion molecule (ICAM-1) favors scFv/TM collaboration with EPCR. Indeed: i) endothelial targeting scFv/TM to ICAM-1 provides ∼15-fold greater activation of protein C than its PECAM-targeted counterpart; ii) blocking EPCR reduces protein C activation by scFv/TM anchored to endothelial ICAM-1, but not PECAM-1; and iii) anti-ICAM scFv/TM fusion provides more profound anti-inflammatory effects than anti-PECAM scFv/TM in a mouse model of acute lung injury. These findings, obtained using new translational constructs, emphasize the importance of targeting protein therapeutics to the proper surface determinant, in order to optimize their microenvironment and beneficial effects.     

A meta-analysis of the ecological and evolutionary drivers of metabolic rates in brachyuran crabs

Metabolic rates provide an estimate of the cost of living for different organisms that can readily be compared across species to provide an estimate of their relative requirements for survival. As such, metabolic rates have been measured for decades on a wide range of organisms. Here, we review published estimates of metabolic rates for brachyuran crabs, a ubiquitous and ecologically and economically important group of consumers. Consistent with ecological theory and results in many other groups of animals, and after controlling for phylogenetic relationships, crab metabolic rates scale with body mass with a scaling exponent of 0.65. Similarly, as with other groups of poikilotherms, crab metabolic rates increase strongly with temperature, with a Q₁₀ of 1.26. Additionally, we found that metabolic rates were correlated with ecological niche, varying with both the diet strategy and the habitat occupied. These results help clarify the relative risk to crabs from environmental changes that impose metabolic stress, including climate change and the proliferation of hypoxic zones.     

Personality interacts with habitat quality to govern individual mortality and dispersal patterns

Individual phenotypic differences are increasingly recognized as key drivers of ecological processes. However, studies examining the relative importance of these differences in comparison with environmental factors or how individual phenotype interacts across different environmental contexts remain lacking. We performed two field experiments to assess the concurrent roles of personality differences and habitat quality in mediating individual mortality and dispersal. We quantified the predator avoidance response of mud crabs, Panopeus herbstii, collected from low‐ and high‐quality oyster reefs and measured crab loss in a caging experiment. We simultaneously measured the distance crabs traveled as well as the stability of personalities across reef quality in a separate reciprocal transplant experiment. Habitat quality was the primary determinant of crab loss, although the distance crabs traveled was governed by personality which interacted with habitat quality to control the fate of crabs. Here, crabs on low‐quality reefs rapidly emigrated, starting with the boldest individuals, and experienced modest levels of predation regardless of personality. In contrast, both bold and shy crabs would remain on high‐quality reefs for months where bolder individuals experienced higher predation risk. These findings suggest that personalities could produce vastly different population dynamics across habitat quality and govern community responses to habitat degradation.     

Habitat quality mediates personality through differences in social context

Assessing the stability of animal personalities has become a major goal of behavioral ecologists. Most personality studies have utilized solitary individuals, but little is known on the extent that individuals retain their personality across ecologically relevant group settings. We conducted a field survey which determined that mud crabs, Panopeus herbstii, remain scattered as isolated individuals on degraded oyster reefs while high quality reefs can sustain high crab densities (>10 m^?2). We examined the impact of these differences in social context on personality by quantifying the boldness of the same individual crabs when in isolation and in natural cohorts. Crabs were also exposed to either a treatment of predator cues or a control of no cue throughout the experiment to assess the strength of this behavioral reaction norm. Crabs were significantly bolder when in groups than as solitary individuals with predator cue treatments exhibiting severally reduced crab activity levels in comparison to corresponding treatments with no predator cues. Behavioral plasticity depended on the individual and was strongest in the presence of predator cues. While bold crabs largely maintained their personality in isolation and group settings, shy crabs would become substantially bolder when among conspecifics. These results imply that the shifts in crab boldness were a response to changes in perceived predation risk, and provide a mechanism for explaining variation in behavioral plasticity. Such findings suggest that habitat degradation may produce subpopulations with different behavioral patterns because of differing social interactions between individual animals.     

6-deoxyerythronolide B production through chromosomal localization of the deoxyerythronolide B synthase genes in E. coli

Chromosomal engineering was used to localize the deoxyerythronolide B synthase (DEBS) genes and propionyl-CoA carboxylase (PCC) genes to the BAP1 Escherichia coli chromosome creating the new strain YW9. YW9 then featured a plasmid-free heterologous pathway for the production of the polyketide product 6-deoxyerythronolide B (6dEB, a precursor to the antibiotic erythromycin) highlighted by the successful chromosomal integration of five genes total and three DEBS genes each approximately 10 kb in length. The new strain was tested for small-scale 6dEB biosynthesis and compared to 6dEB production from plasmid-derived gene expression at 22, 30, and 37 degrees C. YW9 produced 6dEB at each temperature tested; whereas, the current plasmid-based system could only produce 6dEB at 22 and 30 degrees C. As determined by MS analysis, average production levels for YW9 were 0.47 (22 degrees C), 0.52 (30 degrees C), and 0.11 (37 degrees C)mg/L.