Acetic acid and acidification accelerate chronological and replicative aging in yeast

Comment on: Murakami C, et al. Cell Cycle 2012; 11:3087-96.     

Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock

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林农复合经营生态体系的研究

林农复合经营以生态经济学的原理,运用现代生物和生态工程方法技术,组成林、农、牧、副、渔有机结合的复合生产体系。它突破了传统林业的单一生产方式,形成以林为主的一个复合的、开放的、具有整体效应的生态系统。这种复合系统能有效地提高土地资源利用率,促进太阳能和有关物质在系统内的多次循环利用,实现整个系统在空间和时间上的高效利用。多年来的研究表明,这种由多种产业部     

Solid cultures of thrips-pathogenic fungi Isaria javanica strains for enhanced conidial productivity and thermotolerance

Entomopathogenic fungi have great potential to control agricultural and horticultural insect pests, however optimizing conidial production systems to demonstrate high productivity and stability still needs additional efforts for successful field application and industrialization. Although many virulent entomopathogenic fungal isolates have been viewed as potential candidates in a laboratory environment, very few of the isolates are being used in practice for application in agricultural fields as commercial products. I. javanicus is an entomopathogenic fungus that is parasitic to various diverse coleopteran and lepidopteran insects and thought good candidate as biopesticdes. In this work, the basic characteristics of two entomopathogenic fungi, I. javanica FG340 and Pf04, were investigated in morphological examinations, genetic identification, and virulence against Thrips palmi, and then the feasibility of various grains substrates for conidial production was assessed, particularly focusing on conidial productivity and thermotolerance. Isaria javanica FG340 and Pf04 conidia were solid-cultured on 12 grains for 14?days in a Petri dish. Of the tested Italian millet, perilla seed, millet and barley-based cultures showed high conidial production. The four-grain media yielded >1?×?10⁹ conidia/g of I. javanica FG340 and Pf04. Pf04 strain had enhanced thermotolerance up to 45?°C when cultured on Italian millet. In application, it was easy to make a conidial suspension using the cultured grains, and several surfactants were tested to release the conidia. This work suggests several possible inexpensive grain substrates by which to promote conidial production combined with enhanced stability against exposure to high temperature.     

Rebound effects of price differences

Goal, Scope and Background  Traditionally, comparative life cycle assessments (LCA) have not considered rebound effects, for instance in case of significant price differences among the compared products. No justifications have been made for this delimitation in scope. This article shows that price differences and the consequent effects of marginal consumer expenditure may influence the conclusions of comparative LCA significantly. We also show that considerations about rebound effects of price differences can be included in LCAs. Methods  The direct rebound effect of a price difference is marginal consumption. Based on statistical data on private consumption in different income groups (Statistics Denmark 2005a, 2005b), the present article provides an estimate of how an average Danish household will spend an additional 1 DKK for further consumer goods, when the household has gained money from choosing a cheaper product alternative. The approach is to use marginal income changes and the following changes in consumption patterns as an expression for marginal consumption. Secondly, the environmental impact potentials related to this marginal consumption are estimated by the use of environmental impact intensity data from an IO-LCA database (Weidema et al. 2005). Finally, it is discussed whether, and in which ways the conclusions of comparative LCAs can be affected by including the price difference between product alternatives. This is elucidated in a case study of a comparative LCA screening of two different kinds of Danish cheese products (Fricke et al. 2004). Results  Car purchase and driving, use and maintenance of dwelling, clothing purchase and insurance constitutes the largest percentages of the marginal consumption. In a case study of two cheeses, the including the impact potentials related to the price difference results in significant changes in the total impact potentials. Considering the relatively small price difference of the two products, it is likely also to have a significant influence on the results of comparative LCAs more generally. Discussion  The influence of marginal consumption in comparative LCAs is relevant to consider in situations with large differences in the price of the product alternatives being compared, and in situations with minor differences in the impact potentials related to the alternatives. However, different uncertainties are linked to determining the pattern for marginal consumption and the environmental impact potential related to this. These are first of all related to the method used, but also include inaccurate data of consumption in households, aggregation and weighting of income groups, aggregation of product groups, estimation and size of the price difference, and the general applicability of the results. Conclusion  Incorporating marginal consumption in consequential LCAs is possible in practice. In the case study used, including the rebound effects of the price difference has a significant influence on the result of the comparative LCA, as the result for the impact categories acidification and nutrient enrichment changes in favour of the expensive product. Recommendations and Perspectives  It is recommended that the rebound effects of price differences should be included more frequently in LCAs. In order to ensure this, further research in marginal consumption and investment patterns and IO data for different countries or regions is required. Furthermore, this study does not consider the economic distributional consequences of buying an expensive product instead of a cheaper product (e.g. related to how the profit is spent by those who provided the product). It should also be noted, that more expensive products not necessarily result in less consumption, as those who provided the product also will spend the money they have earned from the sale. Ideally, these consequences should also be further investigated. Likewise, the development of databases to include marginal consumption in PC-tools is needed. In general, considerations of marginal consumption would favour expensive product alternatives, depending, however, on the type of consumer. ESS-Submission Editor: Dr. David Hunkeler (david.hunkeler@aquaplustech.ch)     

哺乳动物主要嗅觉系统和犁鼻系统信息识别的编码模式

哺乳动物具有两套嗅觉系统, 即主要嗅觉系统和犁鼻系统。前者对环境中的大多数挥发性化学物质进行识别, 后者对同种个体释放的信息素进行识别。本文从嗅觉感受器、嗅球、嗅球以上脑区三个水平综述了这两种嗅觉系统对化学信息识别的编码模式。犁鼻器用较窄的调谐识别信息素成分, 不同于嗅上皮用分类性合并受体的方式识别气味; 副嗅球以接受相同受体输入的肾丝球所在区域为单位整合信息, 而主嗅球通过对肾丝球模块的特异性合并编码信息; 在犁鼻系统, 信息素的信号更多地作用于下丘脑区域, 引起特定的行为和神经内分泌反应。而在主要嗅觉系统, 嗅皮层可能采用时间模式编码神经元群, 对气味的最终感受与脑的不同区域有关。犁鼻系统较主要嗅觉系统的编码简单, 可能与其执行的功能较少有关。     

High-level expression of murine terminal deoxynucleotidyl transferase inEscherichia coli grown at low temperature and overexpressingargU tRNA

Terminal deoxynucleotidyl transferase (TdT) is a highly conserved vertebrate enzyme that possesses the unique ability to catalyze the random addition of deoxynucleoside 5′-triphosphates onto the 3′-hydroxyl group of a single-stranded DNA. It plays an important role in the generation of immunoglobin and T-cell receptor diversity. TdT is usually obtained from animal thymus gland or produced in a baculovirus system, but both procedures are rather tedious, and proteolysis occurs during purification. Attempts to overexpress TdT in bacteria have been unsuccessful or have yielded an enzyme with a lower specific activity. A dearth of TdT has thus hampered detailed structural and functional studies. In the present study, we report that by lowering growth temperature and overexpressing a rare arginyl tRNA, it is possible to boost the production inEscherichia coli of murine TdT with minimal proteolysis and high specific activity.     

Earthworm effect on root morphology in a split root system

Plants respond to their environment through adaptations such as root proliferation in nutrient-rich patches. Through their burrows and casts production in soil, earthworms create heterogeneity which could lead to local root adaptations or systemic effects. To investigate the effect of earthworms on root system morphology and determine whether earthworm effect is local or systemic, we set up two independent split root experiments with rice or barley, (i) without earthworm (CC), (ii) with earthworms in both compartments (EE), and (iii) with earthworms in one single compartment (CE). Earthworms had an effect on belowground plant biomass. The relative length of thick roots decreased with an increasing abundance of earthworms. Some root diameter classes responded to earthworm number in a linear or curvilinear way, making simple conclusions difficult. We found no difference in root biomass or morphology between the two compartments of the split root system in the CE treatment, but a positive effect of earthworm biomass on root biomass, volume, surface area, and length at the whole plant level. Results supported a systemic effect dependent on earthworm abundance. Modification of nutrient mineralization, soil physical structure, and/or the concentration of signal molecules could all be responsible for this systemic effect.     

In vitro chiral nematic ordering of chitin crystallites

Microfibrillar fragments of purified crab and shrimp chitin were prepared by hydrolysis in 3 HCl at its boiling point (104°C). After removal of the acid by centrifugal washing and dialysis, an ultrasound treatment converts the residual product to a colloidal suspension stabilized by NH₃⁺ charges. When dewatered to a critical concentration, spontaneous formation of a two-phase equilibrium system occurs. The upper phase (lower concentration) is isotropic and the lower phase is anisotropic. The latter displays chiral nematic order and dries to a solid film which mimics the helicoid organization characteristic of the chitin microfibrils in the cuticle of arthropods.     

Plant physiology in theory and practice: An analysis of the WBE model for vascular plants

The theoretical model of West, Brown and Enquist (hereafter WBE) proposed the fractal geometry of the transport system as the origin of the allometric scaling laws observed in nature. The WBE model has either been criticized for some restrictive and biologically unrealistic constraints or its reliability debated on the evidence of empirical tests. In this work, we revised the structure of the WBE model for vascular plants, highlighting some critical assumptions and simplifications and discuss them with regard to empirical evidence from plant anatomy and physiology. We conclude that the WBE model had the distinct merit of shedding light on some important features such as conduit tapering. Nonetheless, it is over-simplistic and a revised model would be desirable with an ontogenetic perspective that takes some important phenomena into account, such as the transformation of the inner sapwood into heartwood and the effect of hydraulic constraints in limiting the growth in height.