Broadening the Scope of Enforced ATP Wasting as a Tool for Metabolic Engineering in Escherichia coli

The targeted increase of cellular adenosine triphosphate (ATP) turnover (enforced ATP wasting) has recently been recognized as a promising tool for metabolic engineering when product synthesis is coupled with net ATP formation. The goal of the present study is to further examine and to further develop the concept of enforced ATP wasting and to broaden its scope for potential applications. In particular, considering the fermentation products synthesized by Escherichia coli under anaerobic conditions as a proxy for target chemical(s), i) a new genetic module for dynamic and gradual induction of the F₁‐part of the ATPase is developed and it is found that ii) induction of the ATPase leads to higher metabolic activity and increased product formation in E. coli under anaerobic conditions, and that iii) ATP wasting significantly increases substrate uptake and productivity of growth‐arrested cells, which is vital for its use in two‐stage processes. To the best of the authors' knowledge, the glucose uptake rate of 6.49 mmol gCDW^?1 h^?1 achieved with enforced ATP wasting is the highest value reported for nongrowing E. coli cells. In summary, this study shows that enforced ATP wasting can be used to improve yield and titer (in growth‐coupled processes) as well as volumetric productivity (in two‐stage processes) depending on which of the performance measures is more crucial for the process and product of interest.     

Chemical Composition and Antimicrobial Activity of Achillea tenuifolia Lam. Essential Oil at Different Phenological Stages from Khoy

Achillea species and in particular Achillea tenuifolia Lam . is generally used as a food flavor and traditional remedies, especially in the initial developmental stage for medical conditions in the Mediterranean part of Iran. In this report, we extracted the essential oil from the aerial parts of A. tenuifolia (collected from Khoy), at various developmental stages (i. e., vegetative, flowering and fruiting), characterized them and studied their antibacterial activities. Of 46, 51 and 38 components found in the vegetative, flowering, and fruiting stages, respectively, 35 were present in all three stages, including oxygenated terpenes such as carvacrol (30.85–34.11), germacrene C (16.21–17.87), spathulenol (7.26–8.96), β‐sesquiphellandrene (4.11–4.25), τ‐muurolol (2.27–3.25) and α‐cadinol (2.01–3.29). We witnessed that the composition of the essential oils varies with phenological stages and geographic regions. The essential oil demonstrated substantial antibacterial properties against both Gram‐positive and Gram‐negative bacteria, indicated by disk method, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays. Except Pseudomonas aeruginosa, the essential oils of various phenological stages showed higher antibacterial activity against tested bacteria, with Bacillus anthracis as the most sensitive strain. Moreover, although antibacterial characteristics of the essential oil from the vegetative and flowering stages were similar (p=0.91), they were significantly different from those of fruiting stage (p<0.005 in both MIC and MBC tests). This emphasizes the importance of the developmental stage of the plant in the biological properties of its essential oil and justifies the widespread application of this plant in the vegetative stage.     

Quantitative Proteomic Analysis of Simian Primary Hepatocytes Reveals Candidate Molecular Markers for Permissiveness to Relapsing Malaria Plasmodium cynomolgi

A major obstacle impeding malaria research is the lack of an in vitro system capable of supporting infection through the entire liver stage cycle of the parasite, including that of the dormant forms known as hypnozoites. Primary hepatocytes lose their liver specific functions in long‐term in vitro culture. The malaria parasite Plasmodium initiates infection in hepatocyte. This corresponds to the first step of clinically silent infection and development of malaria parasite Plasmodium in the liver. Thus, the liver stage is an ideal target for development of novel antimalarial interventions and vaccines. However, drug discovery against Plasmodium liver stage is severely hampered by the poor understanding of host–parasite interactions during the liver stage infection and development. In this study, tandem mass tag labeling based quantitative proteomic analysis is performed in simian primary hepatocytes cultured in three different systems of susceptibility to Plasmodium infection. The results display potential candidate molecular markers, including asialoglycoprotein receptor, apolipoproteins, squalene synthase, and scavenger receptor B1 (SR‐BI) that facilitate productive infection and full development in relapsing Plasmodium species. The identification of these candidate proteins required for constructive infection and development of hepatic malaria liver stages paves the way to explore them as therapeutic targets.     

Census timing alters stage duration distributions in matrix population models

Matrix population models are widely used to study the dynamics of stage‐structured populations. A census in these models is an event monitoring the number of individuals in each stage and occurs at discrete time intervals. The two most common methods used in building matrix population models are the prebreeding census and postbreeding census. Models using the prebreeding and postbreeding censuses assume that breeding occurs immediately before or immediately after the censuses, respectively. In some models such as age‐structured models, the results are identical regardless of the method used, rendering the choice of method a matter of preference. However, in stage‐structured models, where the duration of the first stage of life varies among newborns, a choice between the prebreeding and postbreeding censuses may result in different conclusions. This is attributed to the different first‐stage duration distributions assumed by the two methods. This study investigated the difference emerging in the structures of these models and its consequence on conclusions of eigenvalue and elasticity analyses using two‐stage models. Considerations required in choosing a modeling method are also discussed.     

长柄双花木叶性状异速生长关系随发育阶段和海拔梯度的变化

长柄双花木(Disanthus cercidifolius var. longipes)是一种仅分布于我国东南地区的珍稀濒危植物。为研究该物种叶性状异速生长关系和叶片资源利用策略及其随发育阶段和海拔梯度的变化规律,该文以分布于江西省不同海拔梯度的长柄双花木群落为研究对象,调查分析了群落中不同发育阶段长柄双花木植株的叶片面积、叶片体积以及叶片含水量与叶片干重之间的异速关系。结果表明:不同发育阶段植株之间叶性状异速生长关系有着显著差异。成树叶片面积的增长速度低于或等于叶片干重的增长速度,幼树、幼苗叶片面积的增长速度低于叶片干重的增长速度; 成树叶片体积与叶片干重呈等速增长,幼树、幼苗叶片体积的增长速度高于叶干重的增长速度; 成树叶片含水量的增长速度低于叶干重的增长速度,幼树、幼苗两性状间保持等速增长。海拔梯度对长柄双花木叶性状异速生长关系也有影响,植株叶体积和叶含水量与叶干重的异速生长指数在不同海拔间有显著性差异。在低海拔区域,叶体积与叶干重呈等速增长,叶含水量的增长速度低于叶片干重的增长速度。在高海拔区域,叶体积的生长速度低于叶干重的生长速度,叶含水量和叶片干重呈等速增长。这说明长柄双花木叶片资源投资策略随着发育阶段和海拔梯度的不同发生变化。成树主要将叶生物量投资于光捕获面积和同化结构,幼树和幼苗则主要投资于维管组织的建设。由于海拔升高会引起风力增大、光强增强和土壤理化性质改变,长柄双花木在中低海拔倾向于增大叶体积以抢占资源,在高海拔倾向于加强机械组织和维管组织的建设来抵抗外界因子干扰。     

几种调控措施对龙眼顶芽激素及成花坐果的影响

以当地主栽龙眼品种‘泸丰一号’为材料,在龙眼花芽形态分化期开始前,采取树冠喷施不同比例的生理调节剂、骨干枝环割、断根等调控措施,定期测定花芽分化期顶芽内源激素,在花芽分化完成后统计成花坐果率,研究调控措施对龙眼顶芽激素含量动态变化和成花坐果率的影响。结果表明:几种措施处理都不同程度地提高了龙眼的成花坐果率,适当浓度(150 mg·L-1及100 mg·L-1)乙烯调节剂组合调控措施可以显著提高树体的雌花数、雌花率及坐果率,其中雌花率分别比对照提高了32.57%和38.22%;各处理的冲梢率显著低于对照,其中处理B(100 mg·L-1乙烯利调节剂组合)的冲梢率(18.58%)最低,比对照低34.18%,且芽轴增长率与冲梢率呈显著正相关,其中以150.00 mg·L-1多效唑+100.00 mg·L-1乙烯利+1.0 mg·L-1细胞分裂素配制好的药液均匀喷洒在树冠上的处理效果最优。几种措施对于龙眼顶芽中的激素及激素的平衡的影响表现为GA3含量和ABA含量在花序主轴分化期较高,在多级侧花序快速分化期则处于较低水平,整个形态分化期ZT始终保持较低水平,则利于防止龙眼成花逆转,从而促进龙眼花芽分化;IAA含量受各处理影响变化较为复杂,并未呈现出较强的规律性;从激素比例方面看,龙眼顶芽在花序主轴分化前期IAA/GA3比值较低,末期ZT/GA3比值较高则有利于成花,在整个形态分化期ZT/ABA及GA3/ABA都处在较低的水平,可有效抑制成花逆转。研究结果可为龙眼的成花机理以及四川泸州地区龙眼的优质丰产栽培提供理论依据。     

Pine sawfly Gilpinia albiclavata sp. nov. (Hymenoptera: Diprionidae) infesting Pinus pumila in the Japanese Alps

Gilpinia albiclavata Hara, sp. nov. is described from Honshu, Japan. Larvae feed on needles of Pinus pumila (Pinaceae). Since 2001, severe infestations of the sawfly have been often observed in the Japanese Alps. Notes on the immature stages and the life history are presented.     

冬麦春播小麦穗分化阶段对低温胁迫的响应及耐寒性

以长江中下游地区引进的10个冬小麦品种为材料,在忻定盆地春播条件下,于2013-2014年研究了低温胁迫对冬小麦穗分化阶段光合作用、渗透调节物质及膜系统产生的影响,并对其抗寒性能进行综合评价.结果表明:在低温胁迫下,不同品种小麦叶片的离子渗漏率、可溶性糖和可溶性蛋白质含量均不同程度地升高,总叶绿素含量明显下降.通过主成分分析和抗寒性度量值(D值)排序,不同品种冬小麦幼穗分化期间的抗寒性为:渝麦10、扬麦20、云麦42的抗寒性较差;扬麦13、渝麦12、宁麦13的抗寒性较强且年际稳定性好,D值分别为0.665 ～0.659、0.493～0.495、0.471 ～0.583;而作为对照的宁2038、新春30分别为0.368～0.397、0.328～0.330.扬麦13、渝麦12、宁麦13的两年籽粒产量显著高于其他品种,可作为忻定盆地的引种材料.     

Seasonal weather patterns drive population vital rates and persistence in a stream fish

Climate change affects seasonal weather patterns, but little is known about the relative importance of seasonal weather patterns on animal population vital rates. Even when such information exists, data are typically only available from intensive fieldwork (e.g., mark–recapture studies) at a limited spatial extent. Here, we investigated effects of seasonal air temperature and precipitation (fall, winter, and spring) on survival and recruitment of brook trout (Salvelinus fontinalis) at a broad spatial scale using a novel stage‐structured population model. The data were a 15‐year record of brook trout abundance from 72 sites distributed across a 170‐km‐long mountain range in Shenandoah National Park, Virginia, USA. Population vital rates responded differently to weather and site‐specific conditions. Specifically, young‐of‐year survival was most strongly affected by spring temperature, adult survival by elevation and per‐capita recruitment by winter precipitation. Low fall precipitation and high winter precipitation, the latter of which is predicted to increase under climate change for the study region, had the strongest negative effects on trout populations. Simulations show that trout abundance could be greatly reduced under constant high winter precipitation, consistent with the expected effects of gravel‐scouring flows on eggs and newly hatched individuals. However, high‐elevation sites would be less vulnerable to local extinction because they supported higher adult survival. Furthermore, the majority of brook trout populations are projected to persist if high winter precipitation occurs only intermittently (≤3 of 5 years) due to density‐dependent recruitment. Variable drivers of vital rates should be commonly found in animal populations characterized by ontogenetic changes in habitat, and such stage‐structured effects may increase population persistence to changing climate by not affecting all life stages simultaneously. Yet, our results also demonstrate that weather patterns during seemingly less consequential seasons (e.g., winter precipitation) can have major impacts on animal population dynamics.