佛冈县不同类型橘园柑橘木虱的种群动态

[目的] 明确佛冈县不同类型橘园柑橘木虱的种群动态,为当地柑橘木虱及柑橘黄龙病的防治工作提供科学依据。[方法] 通过2015-2016年的系统调查,对广东省佛冈县砂糖橘园的柑橘木虱种群消长动态进行研究,对比分析了不同处理措施对柑橘木虱种群数量的影响。[结果] 1-3月柑橘木虱发生危害较轻,随着嫩梢增多,其种群数量开始上升,6-9月为种群发生高峰期,期间出现多个发生高峰,10月之后种群数量逐渐进入消退期,种群数量维持在较低水平;2015、2016年佛冈县柑橘木虱的季节性消长动态基本一致,但种群发生量存在明显差别;3种不同类型橘园内柑橘木虱种群发生数量也存在显著差异,常年失管橘园柑橘木虱种群发生数量最高,常规水肥管理橘园次之,二者均显著高于常规水肥管理及化学防治橘园。[结论] 化学防治可在一定程度上控制柑橘木虱的种群数量,及时清理失管橘园对控制柑橘木虱和柑橘黄龙病传播至关重要。     

Inline noninvasive Raman monitoring and feedback control of glucose concentration during ethanol fermentation

Raman spectroscopy as a process analytical technology tool was implemented for the monitoring and control of ethanol fermentation carried out with Saccharomyces cerevisiae. The need for the optimization of bioprocesses such as ethanol production, to increase product yield, enhanced the development of control strategies. The control system developed by the authors utilized noninvasive Raman measurements to avoid possible sterilization problems. Real-time data analysis was applied using partial least squares regression (PLS) method. With the aid of spectral pretreatment and multivariate data analysis, the monitoring of glucose and ethanol concentration was successful during yeast fermentation with the prediction error of 4.42 g/L for glucose and 2.40 g/L for ethanol. By Raman spectroscopy-based feedback control, the glucose concentration was maintained at 100 g/L by the automatic feeding of concentrated glucose solution. The control of glucose concentration during fed-batch fermentation resulted in increased ethanol production. Ethanol yield of 86% was achieved compared to the batch fermentation when 75 % yield was obtained. The results show that the use of Raman spectroscopy for the monitoring and control of yeast fermentation is a promising way to enhance process understanding and achieve consistently high production yield.     

Effective bioreactor pH control using only sparging gases

pH control is critical in bioreactor operations, typically realized through a two-sided control loop, where CO₂ sparging and base addition are used in bicarbonate-buffered media. Though a common approach, base addition could compromise culture performance due to the potential impact from pH excursions and osmolality increase in large-scale bioreactors. In this study, the feasibility of utilizing control of sparge gas composition as part of the pH control loop was assessed in Chinese hamster ovary (CHO) fed-batch cultures. Fine pH control was evaluated in multiple processes at different setpoints in small-scale ambr®250 bioreactors. Desired culture pH setpoints were successfully maintained via air sparge feedback control. As part of the pH control loop, air sparging was increased to improve CO₂ removal automatically, hence increase culture pH, and vice versa. The effectiveness of this pH control strategy was seamlessly transferred from ambr®250 to 200 L scale, demonstrating scalability of the proposed methodology. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2743, 2019     

In vitro characterization bioassays of the nematophagous fungus Purpureocillium lilacinum: Evaluation on growth,extracellular enzymes,mycotoxins and survival in the surrounding agroecosystem of tomato

The effects of water stress and temperature on in vitro growth and enzymatic activity of Purpureocillium lilacinum (Sordariomycetes, Hypocreales, Ophiocordycipitaceae) isolates with demonstrated capacity to control Nacobbus aberrans (Secernentea, Tylenchida, Pratylenchidae) were evaluated in this study. Also, saprophytic and endophytic colonization in tomato plants were determined. P. lilacinum was able to grow under the evaluated levels of osmotic and matric stress, but the increase in water stress caused reductions in radial growth rates. Moreover, the fungal isolates produced chitinases, proteases, and leucinostatins under inductive conditions. The nematophagous fungi were able to develop saprophytically (10⁴ CFU g^?1 of soil). Meanwhile, only P. lilacinum SR38 demonstrated endophytic capacity. The results suggest that P. lilacinum can be effectively applied as biocontrol agents of phytoparasitic nematodes in tomatoes under variable agroecological conditions.     

Opposing effects of plant growth regulators via clonal integration on apical and basal performance in alligator weed

植物生长调节剂通过克隆整合对空心莲子草顶端和基部生长的不同作用 入侵植物不仅对全球生物多样性造成了巨大的威胁,同时也严重影响了农业生产与粮食安全。克隆整合使得相连植株进行资源共享,能促进入侵植物的生长从而获得优势。然而,入侵杂草 在植物调节剂(plant growth regulators, PGRs)影响下的克隆整合作用则很少有报道。PGRs被广泛应用于 农作物生产上,并能通过土壤淋溶、侵蚀和径流作用,影响分布在作物附近的农田杂草的生长。本 研究采用两种PGRs赤霉素(gibberellins, GA)和多效唑(paclobutrazol,PAC)处理恶性入侵杂草空心莲子草 (Alternanthera philoxeroides)基端,并保持或者通过剪切达到控制基端与顶端的连通,从而探究克隆整合作用在空心莲子草响应两种农业常用PGRs中的作用。研究结果表明,GA和PAC对空心莲子草生长的作用相反。GA通过克隆整合作用显著促进顶端植株的地上生长。相反地,PAC显著抑制基端和顶端的地 上生长,但是能够通过克隆整合作用显著促进基端和顶端的地下生长。这些研究结果解释了克隆整合作用能促进PGRs对空心莲子草生长的促进作用,这很可能是外来杂草能够成功入侵人为干扰较多的农业生态系统的重要原因之一。     

入侵植物筛选方法在我国口岸防控中的应用建议

入侵植物是生物入侵中数量最多的类群,给全世界造成了重大的经济和环境影响。植物入侵的预测研究是口岸防控工作中的重要技术环节之一。本文介绍了入侵植物筛选方法的概念,简述了与之相关的基础理论、研究情况以及3种植物入侵的预测方法。综合来看,入侵植物筛选方法主要采用植物自身的生物生态学特性作为评估指标来筛选外来植物,能快速可靠地将外来植物评判为严重入侵植物、非入侵植物以及介于二者之间的一般入侵植物,因此该方法能为我国口岸防范外来植物入侵的管理提供基础技术支撑。当前我国入侵植物筛选方法的研究和应用尚处起步阶段,通过本文的简述期望引起相关人员对此问题进行探讨,并为我国口岸入侵植物防控工作提供理论参考。     

Comparative analysis of the dynamics of human postural control during fixation and pursuit of a visual target

The properties of the system maintaining the upright posture were compared in different states of the oculomotor system: during target fixation and horizontal fast and slow pursuit (0.1 and 0.01 Hz), recording the trajectories of the center of pressure in the frontal and the sagittal planes. Methods of nonlinear analysis were applied to assess the similarity in pairwise comparisons. The overall similarity of the frontal plane dynamics proved to be higher than that of the sagittal plane dynamics. However, differences were revealed in fast pursuit versus slow pursuit or fixation in the frontal but not in the sagittal plane. Such differences may reflect the different inertia of the oculomotor and the balance control systems. In general, the results are consistent with the current notions on the two orthogonal subsystems of postural control.     

A general kinetic model for biological nutrient removal activated sludge systems: model development

In this article, a kinetic model is developed and presented for biological nutrient removal (BNR) activated sludge (BNRAS) systems in general, but for external nitrification (EN) BNRAS (ENBNRAS) systems in particular. The model is based on the UCTPHO model, but includes some significant modifications, such as anoxic P uptake and associated denitrification by phosphorus accumulating organisms (PAOs). Some key features of the model are described and discussed before the model is presented. Model evaluation will be addressed in another article (Hu et al., 2007).     

Effect of ferrous ion on the biological activity in a UASB reactor: mathematical modeling and verification

The effect of ferrous ion on the biological activity in a upflow anaerobic sludge blanket (UASB) reactor was studied. A mathematical model was developed and validated in order to simulate the dynamic behavior of a UASB reactor. This model took into consideration of all the biological and physicochemical reactions. The model was able to simulate the accumulation of iron in the sludge bed and its effect on the biological activity of the anaerobic sludge. A significant increase in the maximum uptake rate of methanogens and acidogens was revealed when iron was supplemented to the UASB reactor. The addition of ferrous iron induced a stable and excellent COD conversion rate. The model can be a useful tool for the prediction of process performance in the future and can be used to assist in the operation of biogas plants. The ferrous ion addition proved to enhance the biological activity of UASB sludge. Thus, the model can be used for the design of treatment plants that will take advantage of the benefits of iron addition.     

OPA1 cleavage depends on decreased mitochondrial ATP level and bivalent metals

OPA1, an intra-mitochondrial dynamin GTPase, is a key actor of outer and inner mitochondrial membrane dynamic. OPA1 amino-terminal cleavage by PARL and m-AAA proteases was recently proposed to participate to the mitochondrial network dynamic in a DeltaPsi(m)-dependent way, and to apoptosis. Here, by an in vitro approach combining the use of purified mitochondrial fractions and mitochondrial targeting drugs, we intended to identify the central stimulus responsible for OPA1 cleavage. We confirm that apoptosis induction and PTPore opening, as well as DeltaPsi(m) dissipation induce OPA1 cleavage. Nevertheless, our experiments evidenced that decreased mitochondrial ATP levels, either generated by apoptosis induction, DeltaPsi(m) dissipation or inhibition of ATP synthase, is the common and crucial stimulus that controls OPA1 processing. In addition, we report that ectopic iron addition activates OPA1 cleavage, whereas zinc inhibits this process. These results suggest that the ATP-dependent OPA1 processing plays a central role in correlating the energetic metabolism to mitochondrial dynamic and might be involved in the pathophysiology of diseases associated to excess of iron or depletion of zinc and ATP.