Fluorescence-force spectroscopy maps two-dimensional reaction landscape of the holliday junction

Despite the recent advances in single-molecule manipulation techniques, purely mechanical approaches cannot detect subtle conformational changes in the biologically important regime of weak forces. We developed a hybrid scheme combining force and fluorescence that allowed us to examine the effect of subpiconewton forces on the nanometer scale motion of the Holliday junction (HJ) at 100-hertz bandwidth. The HJ is an exquisitely sensitive force sensor whose force response is amplified with an increase in its arm lengths, demonstrating a lever-arm effect at the nanometer-length scale. Mechanical interrogation of the HJ in three different directions helped elucidate the structures of the transient species populated during its conformational changes. This method of mapping two-dimensional reaction landscapes at low forces is readily applicable to other nucleic acid systems and their interactions with proteins and enzymes.     

Improved climate control for potato stores by fuzzy controllers

The main tasks for climate controllers in potato bulk stores are to keep the storage climate in an appropriate condition for quality conservation. To avoid extra energy costs by using cooling systems the internal climate of potato bulk stores is controlled with outdoor air. A conventionally designed controller is difficult to adapt for an optimal climate control to reduce quality loss. However, a controller designed with fuzzy logic is found as advantageous for adapting control parameters to improve the control process. A test stand is built to ventilate and to control two samples of potato bulks simultaneously with the same outdoor weather conditions for comparisons. Several experiments were carried out to compare climate controllers with different control algorithms, i.e. conventional to a different conventional and conventional to fuzzy.     

Scaling in the time domain: universal dynamics of order fluctuations in Fe3Al

By focusing a highly brilliant synchrotron x-ray beam to a micrometer spot on a sample, we measured in real time the x-ray intensity fluctuations associated with order fluctuations in crystalline materials. We applied this method to the binary alloy Fe3Al near its continuous A2-B2 phase transformation and determined a specific four-point time correlation function for the order parameter. From a detailed theoretical analysis, dynamical scaling in the time domain with a transition from noncritical to critical dynamics is disclosed.     

Differences between tight and loose cultures: a 33-nation study

With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated multilevel system that comprises distal ecological and historical threats (e.g., high population density, resource scarcity, a history of territorial conflict, and disease and environmental threats), broad versus narrow socialization in societal institutions (e.g., autocracy, media regulations), the strength of everyday recurring situations, and micro-level psychological affordances (e.g., prevention self-guides, high regulatory strength, need for structure). This research advances knowledge that can foster cross-cultural understanding in a world of increasing global interdependence and has implications for modeling cultural change.     

A spatially explicit height�Cdiameter model for Scots pine in Estonia

This contribution presents an approach to model individual tree height?Cdiameter relationships for Scots pine (Pinus sylvestris) in multi-size and mixed-species stands in Estonia using the Estonian Permanent Forest Research Plot Network. The dataset includes 22,347 trees. The main focus of the study was to use an approach that is spatially explicit allowing for high accuracy prediction from a minimum set of predictor variables that can be easily derived. Consequently, the height?Cdiameter relationship is modeled as a function of only the stand quadratic mean diameter (dg) and the plot geographical coordinates. A specific generalized additive model gam is employed that allows for the integration of a varying coefficient term and 2-dimensional surface estimators representing a spatial trend and a spatially varying coefficient term. The high flexibility of the model is needed due to the very few predictor variables that subsume a variety of potential influential factors. Subsequently, a linear mixed model is used that quantifies the random variation between plots and between measurement occasions within plots, respectively. Hence, our model is based on the theory of structured additive regression models (Fahrmeir et al. 2007) and separates a structured (correlated) spatial effect from an unstructured (uncorrelated) spatial effect. Additionally, the linear mixed model allows for calibration of the model using height measurements as pre-information. Model bias is small, despite the somewhat irregular distribution of experimental areas within the country. The overall model shows some similarity with earlier applications in Finland. However, there are important differences involving the model form, the predictors and the method of parameter estimation.     

Does tree seedling growth and survival require weeding of Himalayan balsam (Impatiens glandulifera)?

The effect of Himalayan balsam (Impatiens glandulifera) on survival and growth of naturally regenerated silver birch (Betula pendula) and planted Norway spruce (Picea abies) and silver fir (Abies alba) seedlings was studied in a weeding experiment over 3 years. Three different treatments were applied: control, mowing, and hand weeding by pulling out the entire plant. There were no consistent treatment effects on height and diameter of the tree seedlings. The coverage of Rubus fruticosus had a negative impact on diameter increment of Norway spruce and silver fir. As opposed to growth, treatment effects on seedling survival could be found for planted Norway spruce and silver fir. However, it is very likely that these effects, namely higher seedling survival after mowing, have to be attributed to the control of bramble (Rubus fruticosus) rather than to that of Himalayan balsam. It is concluded that Himalayan balsam is not able to seriously affect the growth of already established seedlings.     

Effects of the aglycone of ascaulitoxin on amino acid metabolism in Lemna paucicostata

Ascaulitoxin and its aglycone (2,4,7-triamino-5-hydroxyoctanoic acid, CAS 212268-55-8) are potent phytotoxins produced by Ascochyta caulina, a plant pathogen being developed for biocontrol of weeds. The mode of action of this non-protein amino acid was studied on Lemna paucicostata. Ascaulitoxin is a potent growth inhibitor, with an I₅₀ for growth of less than 1 μM, almost completely inhibiting growth at about 3 μM. Its action is slow, starting with growth inhibition, followed by darker green fronds, and then chlorosis and death. Most amino acids, including non-toxic non-protein amino acids, reversed the effect of the toxin when supplemented in the same medium. Supplemental sucrose slightly increased the activity. d-Amino acids were equally good inhibitors of ascaulitoxin activity, indicating the amino acid effects may not be due to inhibition of amino acid synthesis. Oxaloacetate, the immediate precursor of aspartate, also reversed the activity. LC-MS did not detect interaction of the compound with lysine, an amino acid that strongly reversed the effect of the phytotoxin. Metabolite profiling revealed that the toxin caused distinct changes in amino acids. Reduction in alanine, paralleled by enhanced levels of the branched chain amino acids valine, leucine and isoleucine and nearly unchanged levels of pyruvate, might indicate that the conversion of pyruvate to alanine is affected by ascaulitoxin aglycone. In addition, reduced levels of glutamate/glutamine and aspartate/asparagine might suggest that synthesis and interconversion reactions of these amino group donors are affected. However, neither alanine aminotransferase nor alanine: glyoxylate aminotransferase were inhibited by the toxin in vitro. Our observations might be explained by three hypotheses: (1) the toxin inhibits one or more aminotransferases not examined, (2) ascaulitoxin aglycone affects amino acid transporters, (3) ascaulitoxin aglycone is a protoxin that is converted in vivo to an aminotransferase inhibitor.     

Probing mode of action in plant cell cycle by the herbicide endothall, a protein phosphatase inhibitor

The mode of action of endothall, an herbicide which was reported to inhibit plant protein phosphatases 1 (PP1) and 2A (PP2A), was investigated. For initial characterization, a series of bioassays was used for comprehensive physiological profiling of endothall effects which suggested a phytotoxic mode of action similar to mitotic disrupter herbicides. Unlike known microtubule disrupters, endothall did not inhibit soybean tubulin polymerization in vitro. As shown in meristematic corn root tips, endothall distorted the orientation of cell division plane and microtubule spindle structures which led to cell cycle arrest in prometaphase. In tobacco BY-2 cells, malformed spindles together with prometaphase arrest of nuclei and abnormal perinuclear microtubule patterns were detected as early as 4 h of endothall treatment. These effects were also observed after treatment with other protein phosphatase inhibitors, cantharidin and okadaic acid, which phenocopied the mitotic changes described in tonneau1 (ton1) and tonneau2 (ton2) Arabidopsis mutants. These mutants are defective in TONNEAU2 (TON2) protein, a regulatory subunit of PP2A, which governs cell division plane and microtubule orientation. Therefore, PP2A/TON2 phosphatase complex is suggested to be an in planta molecular target of endothall. However, in BY-2 cells, additional effects of endothall, including inhibition of S-phase initiation and DNA synthesis, detected by 5-ethynyl-2′-deoxyuridine (EdU) incorporation, and condensed nuclei arrested in late mitosis were observed which were not reported in Arabidopsiston1 and ton2 mutants. This result indicates that two additional checkpoints in cell cycle were blocked by endothall which are probably not associated with TON2-pathway inhibition. Possibly, inhibition of PP1 and/or other PP2A protein phosphatases are involved in the regulation of these cell cycle phenomena.