Indirect effect of nitrogen enrichment modified invertebrate herbivory through altering plant community composition in an alpine meadow

Aims Nitrogen enrichment may affect ‘community invertebrate herbivory’ (hereafter ‘herbivory’) directly by changing plant species’ specific herbivory, or indirectly by altering the composition of natural plant communities. Here, we investigated how community composition altered the community herbivory in natural ecosystems and compared the relative importance of direct and indirect effects of nitrogen addition on community herbivory.     

A structured analysis of risk to important wildlife elements in three Australian Wildlife Conservancy sanctuaries

Where data and information are lacking, structured expert risk assessments can provide a powerful tool to progress natural resource planning. In many situations, practitioners make informal assessments of risk within small groups that typically constitute employees. In this study, we report on three small (in terms of experts) structured expert‐based risk assessment case studies conducted by expert employees of a not‐for‐profit organisation (Australian Wildlife Conservancy) to demonstrate the utility of the approach. The case studies were carried out for three wildlife sanctuaries managed by AWC: Faure Island, Karakamia and Paruna. The likelihood that a set of direct risk factors would cause management failure for sets of important wildlife elements in the three sanctuaries was elicited from the small group of ecological experts. The analysis was couched in terms of a management aim to not lose species from each wildlife element over the management period of 25 years with current management. The experts believed, in particular, that increasing temperature and decreasing water availability associated with climate change were likely to impact significantly upon the vegetation elements and water‐reliant fauna associated with the sanctuaries. Some vegetation elements were also thought likely to be at risk of over‐grazing, unsuitable fire regimes and, in some cases, disease. In addition to predation by exotic predators at one sanctuary, the experts identified additional direct risk factors for various fauna elements associated with expected changes to the vegetation elements, including reduction in food availability, nesting habitat, and generally important life media. From the risk analyses, a preliminary conceptual model was developed to underpin monitoring and to indicate areas for possible management intervention and research. The case studies demonstrate that even in a small workplace team, structured risk assessments can be efficiently accomplished and can provide expedient and transparent information that effectively captures and aggregates the views of the experts.     

Factors affecting plantlet regeneration from in vitro cultured immature embryos and cotyledons of Prunus mume “Xue mei”

Using immature embryos and cotyledons as explants, a successful immature embryo culture and efficient plant direct regeneration via organogenesis from cotyledons, which showed different patterns, was established for the “Xuemei” cultivar of Prunus mume. For immature embryo culture, high frequency plantlet forming (89.5%) from embryo axis was obtained on half-strength Murashige and Skoog (½MS) medium supplemented with 13.2 μM 6-benzyladenine (BA) and 2.7 μM 1-naphthaleneacetic (NAA). At the same time, shoots direct differentiation from cotyledons with the embryo axis development was also observed on ½MS medium containing 2.2 μM BA together with different combinations of NAA (2.7, 5.4 μM) and indole-3-butyric acid (IBA) (0, 2.5, 5.0 μM). Better results were achieved when embryo axes were removed from cotyledons and cultured on ½MS medium supplement with 13.2 μM BA, 2.7 μM NAA (72.9%) or 2.2 μM BA, 2.2 μM thidiazuron (TDZ), and 2.7 μM NAA (84.2%), respectively. Regenerated shoots were successfully rooted on ½MS or Woody Plant medium (WPM) supplemented with 2.5–5.0 μM IBA. The effect of embryo axes, BA and TDZ, on cotyledons’ regeneration were investigated in detail. The rooted plantlets were transferred to soil successfully with normal morphology.     

Sparse networks of directly coupled,polymorphic, and functional side chains in allosteric proteins

Recent studies have highlighted the role of coupled side‐chain fluctuations alone in the allosteric behavior of proteins. Moreover, examination of X‐ray crystallography data has recently revealed new information about the prevalence of alternate side‐chain conformations (conformational polymorphism), and attempts have been made to uncover the hidden alternate conformations from X‐ray data. Hence, new computational approaches are required that consider the polymorphic nature of the side chains, and incorporate the effects of this phenomenon in the study of information transmission and functional interactions of residues in a molecule. These studies can provide a more accurate understanding of the allosteric behavior. In this article, we first present a novel approach to generate an ensemble of conformations and an efficient computational method to extract direct couplings of side chains in allosteric proteins, and provide sparse network representations of the couplings. We take the side‐chain conformational polymorphism into account, and show that by studying the intrinsic dynamics of an inactive structure, we are able to construct a network of functionally crucial residues. Second, we show that the proposed method is capable of providing a magnified view of the coupled and conformationally polymorphic residues. This model reveals couplings between the alternate conformations of a coupled residue pair. To the best of our knowledge, this is the first computational method for extracting networks of side chains' alternate conformations. Such networks help in providing a detailed image of side‐chain dynamics in functionally important and conformationally polymorphic sites, such as binding and/or allosteric sites. Proteins 2015; 83:497–516. © 2014 Wiley Periodicals, Inc.     

DNA测序技术概述

DNA测序技术作为现代生命科学研究的核心技术之一,自上世纪70年代中期DNA发明以来发展迅速。我们简要综述现有的几代DNA测序技术的原理及其发展历程,并对未来可能出现的第三代测序进行预测。     

Insect attraction to synthetic herbivore‐induced plant volatile‐treated field crops

• 1 Plants produce natural enemy‐attracting semiochemicals known as herbivore‐induced plant volatiles (HIPV) in response to herbivore damage. Deployment of synthetic HIPV in crops could enhance the biological control of pests. To test this, six HIPV [methyl salicylate (MeSA), methyl anthranilate (MeA), methyl jasmonate (MeJA), benzaldehyde (Be), cis‐3‐hexenyl acetate (HA), cis‐hexen‐1‐ol (He)] in three concentrations (0.5%, 1.0% and 2.0% v/v) mixed with a vegetable oil adjuvant, Synertrol® (Organic Crop Protectants Pty Ltd, Australia), were sprayed onto winegrape, broccoli and sweet corn plants.
• 2 The relative abundance of insects within treated plots was assessed with non‐attracting, transparent sticky traps at varying time intervals up to 22 days after spraying.
• 3 In the vineyard experiment, Trichogrammatidae responded to Be and MeA (0.5%) and Be (1.0%); Encyrtidae and Bethylidae responded to MeA (1.0%); Scelionidae responded to all compounds at 1.0% and 2.0%; and predatory insects responded to MeA. In sweet corn, parasitoids as a group and Encyrtidae responded to MeA (0.5%); Braconidae responded to all compounds at 0.5% and Synertrol‐only; thrips responded to all compounds at 0.5% and 1.0%; while all parasitoids responded to all compounds at 0.5% and 1.0% and Synertrol‐only. In broccoli, parasitoids as a group and Scelionidae responded to Be, HA, He and Synertrol‐only; Trichogrammatidae responded to Be (0.5%), He (0.5% and 1.0%), MeJA (1.0%) and MeSA (0.5%); and thrips responded to all compounds at to 0.5% and 1.0%.
• 4 Significant attraction of insects occurred up to 6 days after the HIPV application, suggesting that plants may have been induced to produce endogenous volatiles that attracted insects over an extended period.
• 5 The results obtained are discussed in relation to the potential utility of synthetic HIPV to enhance the biological control of pests.

     

Essential requirement of cytochrome c release for caspase activation by procaspase-activating compound defined by cellular models

Mitochondrial cytochrome c (cyt. c) release and caspase activation are often impaired in tumors with Bcl-2 overexpression or Bax and Bak-defective status. Direct triggering of cell death downstream of Bax and Bak is an attractive strategy to kill such cancers. Small molecule compounds capable of direct caspase activation appear to be the best mode for killing such tumors. However, there is no precise model to screen such compounds. The currently employed cell-free systems possess the inherent drawback of lacking cellular contents and organelles that operate in integrating cell death signaling. We have developed highly refined cell-based approaches to validate direct caspase activation in cancer cells. Using this approach, we show that PAC-1 (first procaspase-activating compound), the first direct activator of procaspases identified in a cell-free system, in fact requires mitochondrial cyt. c release for triggering caspase activation similar to other antitumor agents. It can induce significant caspase activation and cell death in the absence of Bax and Bak, and in cells overexpressing Bcl-2 and Bcl-xL. This study for the first time defines precise criteria for the validation of direct caspase-activating compounds using specialized cellular models that is expected to accelerate the discovery of potential direct caspase activators.