Post-Golgi protein traffic in the plant secretory pathway

The Golgi apparatus in plants is organized as a multitude of individual stacks that are motile in the cytoplasm and in close association with the endoplasmic reticulum (ER) (Boevink et al. in Plant J 15:441–447, 1998). These stacks operate as a sorting centre for cargo molecules, providing modification and redirection to other organelles as appropriate. In the post-Golgi direction, these include vacuole and plasma membrane, and specialized transport routes to each are required to prevent mislocalization. Recent evidence in plant cells points to the existence of post-Golgi organelles that function as intermediate stations for efficient protein traffic, as well as to the influence of small GTPases such as Rabs and ARFs on post-Golgi trafficking. This review focuses on the latest findings on post-Golgi trafficking routes and on the involvement of GTPases and their effectors on the trafficking of proteins in the plant secretory pathway. Sally L. Hanton and Loren A. Matheson have contributed equally to this work.     

Neuroendocrine effect of sex hormones

The paper provides a generalization of data and the results of own experiments on influence ovarian steroids on the hypothalamus and other brain areas related to reproduction. Ovarian hormones have widespread effects throughout the brain: on catecholaminergic neurons and serotonergic pathways and the basal forebrain cholinergic system, as well as the hipocampus, spinal cord, nigrostriatal and mesolimbic system, in addition to glial cells and blood-brain barrier. The widespread influences of these various neuronal systems ovarian steroids have measurable effects on mood and affect as well as on cognition, with implications for dementia. There are developmentally programmed sex differenced in hippocampal structure that may help to explain differences in the strategies which male and female rats use to solve spatial navigation problems. The multiple sites and mechanisms of estrogen action in brain underlie a variety of importants effects on cognitive and other brain functions--coordination of movement, pain, affective state, as well as possible protection in Alzheimer's disease. Estrogen withdrawal after natural or surgical menopause can lead to a host of changes in brain function and behavior.     

Addiction,Heroin‐Assisted Treatment and the Idea of Abstinence: A reply to Henden

In our previous article on the question whether heroin addicts are able to give informed consent voluntarily to research on heroin‐assisted treatment, we criticized the ongoing bioethical discussion of a flawed conceptualization of heroin addicts' options. As a participant in this discussion, Edmund Henden defends the conceptualization as sufficient for determining whether heroin addicts are able to give informed consent to the research on heroin‐assisted treatment voluntarily. This discussion on research on heroin‐assisted treatment seems to go astray in several respects. In his reply to our article Henden maintains some of the biases, such as the necessity of abstinence in recovery, that seem to prevail in addiction research on a more general level as well. These biases run the danger of having implausible ethical implications on stakeholders in addiction research and treatment. In our reply to him, we will further clarify and discuss the importance of describing the relevant issues in plausible terms that do justice to the realities of the cases of informed consent in research on heroin‐assisted treatment and also raise a wider issue of the ethics of wording as well as of the narrow scope, or ‘tunnel vision’, in addiction research as currently conducted.     

Integrating hormones into the floral-transition pathway of Arabidopsis thaliana

The transition from vegetative to reproductive growth is a major phase change in angiosperms. In annual plants such as Arabidopsis thaliana (Arabidopsis), this change is irreversible, and as such, the regulation of its timing must be tightly controlled. Plant hormone (phytohormone) signalling is known to regulate suites of morphogenic processes in Arabidopsis a role in flowering-time control is starting to emerge as one key-controlling step. This review focuses on experimental evidence in the Arabidopsis that both classical and newly described phytohormones serve within the signal network leading to a reproductive phase transition, as both positive and repressive elements, depending on the phytohormone and growth conditions. Examples of genetic and pharmacological experiments that implicate phytohormones as components of the floral-timing syndrome will be described. I hope that this review will serve as a primer for future research on the mechanisms of action for each respective phytohormone on the floral transition in Arabidopsis, and lead to further experimentation on the crosstalk that likely bridges between them.     

Effects of 19-hydroxy-prostaglandins on oviductal and uterine motility.

The effects of 19-hydroxyprostaglandins (19-OH-PGs) were tested in vivo on the rabbit oviduct and uterus and on the rhesus monkey (Macaca mulatta) uterus. The 19-OH-PGEs suppressed spontaneous oviductal and uterine activity in the rabbit. The qualitative effect on the rabbit oviduct of 19-OH-PGEs was similar to that of PGE2. However, the typical response of the rabbit uterus to PGE2 was an increase in muscle activity. With regard to the rabbit oviduct, 19(R)-OH-PGE2 was as potent as PGE2, but 19(S)-OH-PGE2 was approximately 1/2 as potent as PGE2. Based on the dose of 19-OH-PGEs usually required to cause a minimal suppression and the dose of PGE2 required to cause a minimal stimulation of rabbit uterine activity, 19(R)-OH-PGE2 was twice as potent as PGE2 while 19(S)-OH-PGE2 was 1/2 as potent as PGE2. Stimulatory effects on the rabbit oviduct and uterus were observed following administration of 19-OH-PGFs and PGF2alpha. The potency on the rabbit oviduct of 19(S)-OH-PGF2alpha was about 1/5 to 1/10 that of PGF2alpha; the potency of 19(R)-OH-PGF2alpha was about 1/10 to 1/20 that of PGF2alpha. Both 19-OH-PGFs were approximately 1/5 to 1/10 as potent as PGF2alpha on the rabbit uterus. At the doses tested 19-OH-PGFs were inactive on the monkey uterus. Thus, these compounds are at least 1/5 as active as PGF2alpha. In contrast, 19(R)-OH-PGE2 had approximately the same potency as PGE2 in stimulating monkey uterine activity; but 19(S)-OH-PGE2 was approximately 1/3 as potent as PGE2.     

Regression commonality analyses on hierarchical genetic distances

Landscape genetics is emerging as an important way of supporting decision‐making in landscape management, in response to the deterioration of matrix permeability due to habitat loss and fragmentation. In line with unremitting methodological developments in landscape genetics, a new analytical procedure was recently proposed as a way of evaluating the effects of landscape gradients on genetic structures. This procedure is based on the computation of inter‐individual hierarchical genetic distances (HGD), a metric of genetic differentiation taking into account the hierarchical structure in populations as inferred from clustering algorithms. HGD can be used as dependent variables in multivariate regressions to assess the effects of various landscape predictors on spatial patterns of genetic differentiation. However, multicollinearity may obscure the interpretation of multivariate regressions. We illustrate how regression commonality analyses (CA), a detailed variance partitioning procedure that can be used to deal with multicollinearity issues, can thoroughly improve our understanding of landscape connectivity when HGD are used as a dependent variable, with the red deer Cervus elaphus as an empirical example. Using logistic regression commonality analyses on HGD, we showed that semi‐natural open areas, transportation infrastructures and, to a lesser extent, urban areas and rivers, were associated with an increase in hierarchical genetic differentiation in red deer. Regressions based on HGD provided detailed results that could not have been obtained with regressions based on standard genetic distances, with notably additional insights as to the possible influence of linear features such as roads and highways on landscape connectivity. Furthermore, CA helped identify synergistic associations among variables as well as suppressors, thus resolving inconsistencies among hierarchical levels and revealing spurious correlations that may have gone unnoticed in the course of classical regression analyses. We thus recommend the use of regression commonality analysis on hierarchical genetic distances as a promising statistical tool for landscape geneticists.     

The effect of acetate on population heterogeneity in different cellular characteristics of Escherichia coli in aerobic batch cultures

Acetate as the major by-product in industrial-scale bioprocesses with Escherichia coli is found to decrease process efficiency as well as to be toxic to cells, which has several effects like a significant induction of cellular stress responses. However, the underlying phenomena are poorly explored. Therefore, we studied time-resolved population heterogeneity of the E. coli growth reporter strain MG1655/pGS20PrrnBGFPAAV expressing destabilized green fluorescent protein during batch growth on acetate and glucose as sole carbon sources. Additionally, we applied five fluorescent stains targeting different cellular properties (viability as well as metabolic and respiratory activity). Quantitative analysis of flow cytometry data verified that bacterial populations in the bioreactor are more heterogeneous in growth as well as stronger metabolically challenged during growth on acetate as sole carbon source, compared to growth on glucose or acetate after diauxic shift. Interestingly, with acetate as sole carbon source, significant subpopulations were found with some cells that seem to be more robust than the rest of the population. In conclusion, following batch cultures population heterogeneity was evident in all measured parameters. Our approach enabled a deeper study of heterogeneity during growth on the favored substrate glucose as well as on the toxic by-product acetate. Using a combination of activity fluorescent dyes proved to be an accurate and fast alternative as well as a supplement to the use of a reporter strain. However, the choice of combination of stains should be well considered depending on which population traits to aim for.     

Role of 4-aminobutyrate aminotransferase in the arginine metabolism of Pseudomonas aeruginosa.

4-Aminobutyrate aminotransferase (GABAT) from Pseudomonas aeruginosa was purified 64-fold to apparent electrophoretic homogeneity from cells grown with 4-aminobutyrate as the only source of carbon and nitrogen. Purified GABAT catalyzed the transamination of 4-aminobutyrate, N2-acetyl-L-ornithine, L-ornithine, putrescine, L-lysine, and cadaverine with 2-oxoglutarate (listed in order of decreasing activity). The enzyme is induced in cells grown on 4-guanidinobutyrate, 4-aminobutyrate, or putrescine as the only carbon and nitrogen source. Cells grown on arginine or on glutamate contained low levels of the enzyme. The regulation of the synthesis of GABAT as well as the properties of the mutant with an inactive N2-acetyl-L-ornithin 5-aminotransferase suggest that GABAT functions in the biosynthesis of arginine by convertine N2-acetyl-L-glutamate 5-semialdehyde to N2-acetyl-Lornithine as well as in catabolic reactions during growth on putrescine or 4-guanidinobutyrate but not during growth on arginine.     

Emerging role of relaxin in renal and cardiovascular function

Although traditionally associated with reproductive processes, relaxin is emerging as an important player in renal and cardiovascular function. Much of our recently acquired understanding of relaxin in this new context has arisen from studies of maternal renal and cardiovascular adaptations to pregnancy in rats where the hormone is turning out to be an important mediator. First, we highlight the influence of relaxin on renal hemodynamics and glomerular filtration rate, as well as on other peripheral circulations. Second, we discuss the effect of relaxin on both the steady and pulsatile systemic arterial load, as well as on the heart, in particular, coronary blood flow. Third, we consider the impact of the hormone on cultured endothelial and vascular smooth muscle cells. Fourth, we address the interaction of relaxin with renal and cardiac disease, as well as its role in angiogenesis. Finally, in Perspectives, we point out several key research questions in need of investigation that relate to a potential autocrine/paracrine role of relaxin in renal and cardiovascular tissues. Furthermore, on the basis of its potent vasodilatory and matrix-degrading attributes, we speculate about the therapeutic potential of relaxin in renal and cardiovascular diseases.     

芽胞气溶胶表面滞留抗力预测模型研究

针对生物威胁的现场处置工作,建立气溶胶芽胞表面滞留抗力的智能预测模型,以准确预测环境表面芽胞污染状况,为大规模的现场洗消任务提供重要依据,有利于实现及时反应、恰当反应和准确防护的目标。以枯草杆菌芽胞为试验菌,在气溶胶实验室进行芽胞的环境因素暴露及活力测定,以模拟环境中芽胞抗力变化规律数据为依据,采用Matlab6.1软件包中的神经网络工具箱进行抗力预测模型研究。根据研究目的、模拟环境条件和数据训练的平滑曲线等特征,设定了5个输入神经元,8个隐层节点和1个输出神经元。‘tansig’、‘purelin’为传递函数,trainlm为训练函数,网络迭代100次。模型回顾预测效率达到100%,前瞻预测效率达到91%。以实验室数据为依据,利用Matlab平台中的BP神经网络建立的芽胞气溶胶表面滞留抗力预测模型能利用环境因素信息有效预测芽胞抗力。     

Impact Assessment of Biodiversity and Carbon Pools from Land Use and Land Use Changes in Life Cycle Assessment,Exemplified with Forestry Operations in Norway

There is a strong need for methods within life cycle assessment (LCA) that enable the inclusion of all complex aspects related to land use and land use change (LULUC). This article presents a case study of the use of one hectare (ha) of forest managed for the production of wood for bioenergy production. Both permanent and temporary changes in above‐ground biomass are assessed together with the impact on biodiversity caused by LULUC as a result of forestry activities. The impact is measured as a product of time and area requirements, as well as by changes in carbon pools and impacts on biodiversity as a consequence of different management options. To elaborate the usefulness of the method as well as its dependency on assumptions, a range of scenarios are introduced in the study. The results show that the impact on climate change from LULUC dominates the results, compared to the impact from forestry operations. This clearly demonstrates the need to include LULUC in an LCA of forestry products. For impacts both on climate change and biodiversity, the results show large variability based on what assumptions are made; and impacts can be either positive or negative. Consequently, a mere measure of land used does not provide any meaning in LCA, as it is not possible to know whether this contributes a positive or negative impact.     

Methylocella species are facultatively methanotrophic

All aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carbon-carbon bonds. Here we demonstrate that members of the recently discovered genus Methylocella are an exception to this. These bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. To conclusively verify facultative growth, acetate and methane were used as model substrates in growth experiments with the type strain Methylocella silvestris BL2. Quantitative real-time PCR targeting the mmoX gene, which encodes a subunit of soluble methane monooxygenase, showed that copies of this gene increased in parallel with cell counts during growth on either acetate or methane as the sole substrate. This verified that cells possessing the genetic basis of methane oxidation grew on acetate as well as methane. Cloning of 16S rRNA genes and fluorescence in situ hybridization with strain-specific and genus-specific oligonucleotide probes detected no contaminants in cultures. The growth rate and carbon conversion efficiency were higher on acetate than on methane, and when both substrates were provided in excess, acetate was preferably used and methane oxidation was shut down. Our data demonstrate that not all methanotrophic bacteria are limited to growing on one-carbon compounds. This could have major implications for understanding the factors controlling methane fluxes in the environment.     

The peroxisome: an update on mysteries

Peroxisomes contribute to several crucial metabolic processes such as β-oxidation of fatty acids, biosynthesis of ether phospholipids and metabolism of reactive oxygen species, which render them indispensable to human health and development. Peroxisomes are highly dynamic organelles that rapidly assemble, multiply and degrade in response to metabolic needs. In recent years, the interest in peroxisomes and their physiological functions has significantly increased. This review intends to highlight recent discoveries and trends in peroxisome research, and represents an update as well as a continuation of a former review article. Novel exciting findings on the biological functions, biogenesis, formation and degradation of peroxisomes, on peroxisomal dynamics and division, as well as on the interaction and cross-talk of peroxisomes with other subcellular compartments are addressed. Furthermore, recent findings on the role of peroxisomes in the brain are discussed.     

苹果蠹蛾成虫产卵特性

苹果蠹蛾Cydia pomonella(L.)是全球温带地区果园主要害虫之一,是中国的重要检疫性有害生物,对我国苹果、梨等水果的安全生产造成极大危害及威胁。为详细了解苹果蠹蛾的产卵特性,从而为进行有效的监测与防控提供基础信息,作者于2006年在甘肃省山丹县梨果园中对树冠不同高度与朝向的蛀果率进行了调查,并于2010在内蒙古阿拉善左旗对梨树果枝上不同部位的产卵量进行了详细调查。主要研究结果如下:1)树冠2.5m以上的蛀果率显著高于2.5m以下的蛀果率,树冠东面的蛀果率最高,南面的蛀果率最低;2)在整个果园中,靠近北侧的果树上果实受害程度要高于南侧果树上的果实受害程度,整个果园中蛀果率由北向南逐渐降低;3)叶片上的卵数最多,占总卵数的73.1%,果实上的卵数次之,占总卵数的14.6%,枝条上的卵数最少,占总卵数的12.2%;4)在产卵的叶片上,卵主要产在叶背面,叶片背面卵量是叶正面的6.65倍。鉴于以上研究结果,在开展化学防治或颗粒体病毒防治时,应注意充分喷施果树上层树冠,且在对果实进行处理的同时,叶片和枝条也需要充分喷药。     

步甲作为指示生物的研究进展

步甲是鞘翅目的重要类群之一,几乎分布于所有陆生生境。步甲与环境关系密切,不少学者认为可将其作为指示生物。目前国外关于步甲作为指示生物的研究很多,内容主要集中在探索生态系统的可持续管理和对整体环境质量的评估,而国内关于步甲的研究主要是区系分类和群落多样性研究,很少关于步甲对环境的指示作用报道。因此,深入研究步甲与环境的相互关系,在此基础上进一步研究其指示作用并应用于生态环境监测和评估之中十分重要。文章对近年来国内外关于步甲作为指示生物的相关研究工作进行概括和总结,对步甲作为指示生物的优点、环境因子对步甲的影响、步甲对环境变化的响应等进行简要评述,同时讨论步甲作为指示生物的研究中存在的一些问题以及该研究领域的发展前景。     

Control of benzylamine oxidase activity in Kluyveromyces fragilis grown on primary amines as nitrogen source

Abstract After growth on a mixture of ammonium and either methylamine or n -butylamine as nitrogen sources, benzylamine oxidase activity in yeasts from a number of different genera was found to be repressed to a lesser extent by ammonium than was methylamine oxidase. Catalase activity was better repressed by ammonium with methylamine as the nitrogen source than with n -butylamine. During growth of Kluyveromyces fragilis on equimolar mixtures of ammonium and an amine as nitrogen sources, benzylamine oxidase synthesis began during the period of exclusive growth on ammonium, and a period of simultaneous use of both nitrogen sources was observed just before the ammonium was exhausted. Addition of ammonium to cultures growing on n -butylamine as nitrogen source had no immediate repressive effect on benzylamine oxidase or catalase synthesis. However, growth on limiting ammonium in the absence of amines did give rise to low levels of amine oxidase and derepression of catalase activity. It is concluded that benzylamine oxidase in yeasts is induced strongly by amines as well as being less strongly repressed by ammonium than methylamine oxidase.     

“He’s so Fluffy I’m Gonna Die!” Cute Responses by Hikers to Autonomous Animals on the Appalachian Trail

The Appalachian Trail is a more than 2,000-mile-long wilderness trail in the Eastern United States. Every year, aspiring long-distance hikers travel from across the US and abroad, intending to hike the entire length of the trail, which takes around 6 months to complete. Numerous species of wildlife dwell on and around the trail. The aim of this study was to explore how long-distance hikers perceived the nonhuman animals that they encountered on their trek, and how they described navigating these encounters. Due to a thriving online community of hikers who blogged about their experiences on the trail, it was possible to retrieve a substantial amount of rich data detailing first hand encounters between hikers and animals on the trail. It was found that just under a third of all hiker narratives mentioning wild animals on the trail indicated that the author had responded to the animal as being cute. Despite cuteness frequently being perceived as trivial or banal, this paper argues that a hiker’s perception of an animal as cute is more complex and meaningful to their overall experience of the animal than might initially be assumed. Both the aesthetic of cuteness and the effect of cuteness on an observer are considered in light of existing research on the subject. Some specific accounts of a hiker perceiving and responding to cuteness in animals on the trail are then explored, which leads on to a consideration of why so many animals on the trail might have been perceived as being cute. Finally, the paper discusses what being seen as cute meant for the animal involved, as hikers stared at, approached, followed, and frequently made attempts at touching or feeding animals that they found cute. The paper concludes that, far from being inconsequential, the perception of cuteness in an animal was meaningful for the human observer, as well as having consequences for the animal in question.     

Considerations on influence of charge distribution on determination of biomolecules and microorganisms and tailoring the monolithic (continuous bed) materials for bioseparations

The importance of continuous beds (monoliths) as separation materials is connected with their better chromatographic properties and easier preparation in comparison to particulate-packed columns. Moreover the tuning of porosity as well as surface chemistry can lead to obtaining of highly selective materials, especially useful in separation of biologically important compounds or even microorganisms. To obtain high selectivity for such analytes as e.g. proteins, it is often important to have a knowledge about their shape, size, charge and finally charge distribution. This article presents our considerations on the charge distribution on the monolithic stationary phase and surface of such species as proteins or microorganisms as well as its eventual influence on the separation or sample preparation processes and tuning of their selectivity.     

Evaluating gene flow using selected markers: a case study.

The extent to which an organism is locally adapted in an environmental pocket depends on the selection intensities inside and outside the pocket, on migration, and on the size of the pocket. When two or more loci are involved in this local adaptation, measuring their frequency gradients and their linkage disequilbria allows one to disentangle the forces-migration and selection-acting on the system. We apply this method to the case of a local adaptation to organophosphate insecticides in the mosquito Culex pipiens pipiens in southern France. The study of two different resistance loci allowed us to estimate with support limits gene flow as well as selection pressure on insecticide resistance and the fitness costs associated with each locus. These estimates permit us to pinpoint the conditions for the maintenance of this pocket of adaptation as well as the effect of the interaction between the two resistance loci.