<Superscript>13</Superscript>C-Methyl isocyanide as an NMR probe for cytochrome P450 active sites

The cytochromes P450 (CYPs) play a central role in many biologically important oxidation reactions, including the metabolism of drugs and other xenobiotic compounds. Because they are often assayed as both drug targets and anti-targets, any tools that provide: (a) confirmation of active site binding and (b) structural data, would be of great utility, especially if data could be obtained in reasonably high throughput. To this end, we have developed an analog of the promiscuous heme ligand, cyanide, with a ¹³CH₃-reporter attached. This ¹³C-methyl isocyanide ligand binds to bacterial (P450cam) and membrane-bound mammalian (CYP2B4) CYPs. It can be used in a rapid 1D experiment to identify binders, and provides a qualitative measure of structural changes in the active site. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Cofilin-linked changes in actin filament flexibility promote severing

The actin regulatory protein, cofilin, increases the bending and twisting elasticity of actin filaments and severs them. It has been proposed that filaments partially decorated with cofilin accumulate stress from thermally driven shape fluctuations at bare (stiff) and decorated (compliant) boundaries, thereby promoting severing. This mechanics-based severing model predicts that changes in actin filament compliance due to cofilin binding affect severing activity. Here, we test this prediction by evaluating how the severing activities of vertebrate and yeast cofilactin scale with the flexural rigidities determined from analysis of shape fluctuations. Yeast actin filaments are more compliant in bending than vertebrate actin filaments. Severing activities of cofilactin isoforms correlate with changes in filament flexibility. Vertebrate cofilin binds but does not increase the yeast actin filament flexibility, and does not sever them. Imaging of filament thermal fluctuations reveals that severing events are associated with local bending and fragmentation when deformations attain a critical angle. The critical severing angle at boundaries between bare and cofilin-decorated segments is smaller than in bare or fully decorated filaments. These measurements support a cofilin-severing mechanism in which mechanical asymmetry promotes local stress accumulation and fragmentation at boundaries of bare and cofilin-decorated segments, analogous to failure of some nonprotein materials.     

Oxytocin infusion increases charitable donations regardless of monetary resources

This study examined if the prosocial effects of oxytocin (OT) extend from individuals to a generalized other who is in need. Participants played a series of economic games to earn money and were presented with an opportunity to donate a portion of their earnings to charity. OT did not significantly increase the decision to donate, but among the 36% of participants who did donate, people infused with OT were found to donate 48% more to charity than those given a placebo. The amount of money earned in the experiment had no effect on whether or not a donation was made or the size of a donation. This is the first study showing that OT increases generosity in unilateral exchanges directed toward philanthropic social institutions, as opposed to immediate benefits directed at individuals or groups.     

Evaluation of Agrilus planipennis (Coleoptera: Buprestidae) control provided by emamectin benzoate and two neonicotinoid insecticides, one and two seasons after treatment

Effective methods are needed to protect ash trees (Fraxinus spp.) from emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive buprestid that has killed millions of North American ash (Fraxinus spp.) trees. We randomly assigned 175 ash trees (11.5-48.1 cm in diameter) in 25 blocks located in three study sites in Michigan to one of seven insecticide treatments in May 2007. Treatments included 1) trunk-injected emamectin benzoate; 2) trunk-injected imidacloprid; 3) basal trunk spray of dinotefuran with or 4) without Pentra-Bark, an agricultural surfactant; 5) basal trunk spray of imidacloprid with or 6) without Pentra-Bark; or (7) control. Foliar insecticide residues (enzyme-linked immunosorbent assay) and toxicity of leaves to adult A. planipennis (4-d bioassays) were quantified at 3-4-wk intervals posttreatment. Seven blocks of trees were felled and sampled in fall 2007 to quantify A. planipennis larval density. Half of the remaining blocks were retreated in spring 2008. Bioassays and residue analyses were repeated in summer 2008, and then all trees were sampled to assess larval density in winter. Foliage from emamectin benzoate-treated trees was highly toxic to adult A. planipennis, and larval density was < 1% of that in comparable control trees, even two seasons posttreatment. Larval densities in trees treated with trunk-injected imidacloprid in 2007 + 2008 were similar to control trees. Dinotefuran and imidacloprid were effectively translocated within trees treated with the noninvasive basal trunk sprays; the surfactant did not appreciably enhance A. planipennis control. In 2008, larval densities were 57-68% lower in trees treated with dinotefuran or imidacloprid trunk sprays in 2007 + 2008 than on controls, but densities in trees treated only in 2007 were similar to controls. Highly effective control provided by emamectin benzoate for > or = 2 yr may reduce costs or logistical issues associated with treatment.     

Submersion as a tactic to prevent emergence of emerald ash borer Agrilus planipennis from black ash logs

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Effects of different mesenchymal stromal cell sources and delivery routes in experimental emphysema

We sought to assess whether the effects of mesenchymal stromal cells (MSC) on lung inflammation and remodeling in experimental emphysema would differ according to MSC source and administration route. Emphysema was induced in C57BL/6 mice by intratracheal (IT) administration of porcine pancreatic elastase (0.1 UI) weekly for 1 month. After the last elastase instillation, saline or MSCs (1×10⁵), isolated from either mouse bone marrow (BM), adipose tissue (AD) or lung tissue (L), were administered intravenously (IV) or IT. After 1 week, mice were euthanized. Regardless of administration route, MSCs from each source yielded: 1) decreased mean linear intercept, neutrophil infiltration, and cell apoptosis; 2) increased elastic fiber content; 3) reduced alveolar epithelial and endothelial cell damage; and 4) decreased keratinocyte-derived chemokine (KC, a mouse analog of interleukin-8) and transforming growth factor-β levels in lung tissue. In contrast with IV, IT MSC administration further reduced alveolar hyperinflation (BM-MSC) and collagen fiber content (BM-MSC and L-MSC). Intravenous administration of BM- and AD-MSCs reduced the number of M1 macrophages and pulmonary hypertension on echocardiography, while increasing vascular endothelial growth factor. Only BM-MSCs (IV > IT) increased the number of M2 macrophages. In conclusion, different MSC sources and administration routes variably reduced elastase-induced lung damage, but IV administration of BM-MSCs resulted in better cardiovascular function and change of the macrophage phenotype from M1 to M2.     

Multi-Platform Compatible Software for Analysis of Polymer Bending Mechanics

Cytoskeletal polymers play a fundamental role in the responses of cells to both external and internal stresses. Quantitative knowledge of the mechanical properties of those polymers is essential for developing predictive models of cell mechanics and mechano-sensing. Linear cytoskeletal polymers, such as actin filaments and microtubules, can grow to cellular length scales at which they behave as semiflexible polymers that undergo thermally-driven shape deformations. Bending deformations are often modeled using the wormlike chain model. A quantitative metric of a polymer''s resistance to bending is the persistence length, the fundamental parameter of that model. A polymer''s bending persistence length is extracted from its shape as visualized using various imaging techniques. However, the analysis methodologies required for determining the persistence length are often not readily within reach of most biological researchers or educators. Motivated by that limitation, we developed user-friendly, multi-platform compatible software to determine the bending persistence length from images of surface-adsorbed or freely fluctuating polymers. Three different types of analysis are available (cosine correlation, end-to-end and bending-mode analyses), allowing for rigorous cross-checking of analysis results. The software is freely available and we provide sample data of adsorbed and fluctuating filaments and expected analysis results for educational and tutorial purposes.     

2D:4D ratios predict hand grip strength (but not hand grip endurance) in men (but not in women)

In humans, the ratio of the second digit to the fourth digit — the 2D:4D ratio — is a sexually dimorphic trait (men, on average, exhibit lower 2D:4D ratios than do women) that is influenced by prenatal testosterone exposure, but not by circulating testosterone levels in adulthood. Consequently, 2D:4D ratios are commonly used as indirect measures of prenatal testosterone exposure. Many studies have examined the associations of 2D:4D ratios with sexually dimorphic adaptations that are thought to be influenced by such exposure, including physical prowess. The existing literature, however, remains unclear as to (1) whether 2D:4D ratios are more closely linked to strength or to endurance; and (2) whether 2D:4D ratios are linked with physical prowess for both men and women. In 100 men and 122 women, the relationship of 2D:4D ratios with maximum voluntary contraction (MVC) scores (hand grip strength) and maximum endurance time (MET) scores (local muscular endurance) using a hand dynamometer was examined. Controlling for age, height, weight, and average digit length, we found that 2D:4D ratios significantly predicted MVC scores in men, but not in women. 2D:4D ratios did not significantly predict MET scores for either sex. These results suggest that prenatal testosterone exposure in this sample is significantly related to hand grip strength in men, but not in women (and to local muscular endurance in neither sex), and, therefore, that strength, rather than local muscular endurance, potentially drives the relationship between 2D:4D ratios and physical prowess.     

Pulmonary hypertension and pulmonary vascular reactivity in beagles at high altitude

It is unclear whether dogs develop pulmonary hypertension (PH) at high altitude. Beagles from sea level were exposed to an altitude of 3,100 m (PB 525 Torr) for 12-19 mo and compared with age-matched controls remaining at low altitude of 130 m (PB 750 Torr). In beagles taken to high altitude as adults, pulmonary arterial pressures (PAP) at 3,100 m were 21.6 +/- 2.6 vs. 13.2 +/- 1.2 Torr in controls. Likewise, in beagles taken to 3,100 m as puppies 2.5 mo old, PAP was 23.2 +/- 2.1 vs. 13.8 +/- 0.4 Torr in controls. This PH reflected a doubling of pulmonary vascular resistance and showed no progression with time at altitude. Pulmonary vascular reactivity to acute hypoxia was also enhanced at 3,100 m. Inhibition of prostaglandin synthesis did not attenuate the PH or the enhanced reactivity. Once established, the PH was only partially reversed by acute relief of chronic hypoxia, but reversal was virtually complete after return to low altitude. Hence, beagles do develop PH at 3,100 m of a severity comparable to that observed in humans at the same or even higher altitudes.