Spatial and temporal relation rule acquisition of eutrophication in Da’ning River based on rough set theory

Since the mechanisms of eutrophication are complicated and many other factors affect these mechanisms, methods such as quantitative statistics and numerical simulation, have their limitations in analyzing the spatiotemporal relations of eutrophication. The rough set theory (RST) was used to describe the spatiotemporal relations of eutrophication in Da’ning River without any of other prior knowledge. Rules of relations in time and space affecting eutrophication in the Da’ning River backwater area were extracted by taking representation of relations in time and space among eutrophication at a long river section of Da’ning River backwater area, by taking nine sets of encrypted monitoring data in 2003 as example, and by making season, area and eutrophication level as the decision attributes, respectively, to represent specific features of the eutrophication phenomenon in the Da’ning River backwater area from the points of view of time, space, and level by analysis of spatiotemporal relationship rules. This study result shows that the temporal and spatial differences between eutrophication phenomena in the long river section of the Da’ning River backwater area are significant. Eutrophication for each section is less serious in autumn, more in spring and most in summer. Eutrophication degree gradually decreases from estuary to upstream, which is in conformity with reality. The RST of eutrophication in Da’ning River may inform environmental decision-makers and assist them in making more cost-effective decisions.     

肾性高血压大鼠左室等容峰压一容积关系及其对异丙肾上腺素的反应

本研究观察了肾血管性高血压大鼠(RHR)肥大左室的等容峰压-容积关系(PIPVR)和左室压力最大上升速率-容积关系(PRPVR)的曲线特征,并用两曲线的升支斜率E_(max)和dE/dt_(max)及曲线的特征参数评价了RHR(8周)左室的收缩能力及其对异丙肾上腺素的反应性。结果显示,大鼠高血压8周后左室发生明显肥大;与同龄假手术对照大鼠(SOR)相似,RHR的PIPVR和PRPVR也呈指数曲线形式;与SOR比较,RHR左室的PIPVR和PRPVR左上移位,E_(max)、dE/dt_(max)显著增大(P均<0.01),分别增加78％和97％,曲线的特征参数K_1、K_2、B_1和B_2也明显高于SOR(P均<0.05),分别增加37％、32％、25％和57％;灌注异丙肾上腺素(0.94μg/min)后,上述指标的增加幅度均较SOR低(P均<0.05)。结果提示,压力超负荷心肌肥大并不影响PIPVR的非线性特征,基础状态下,RHR肥大左室的收缩能力增强,但对异丙肾上腺素的反应性降低。     

Probing the Transition State of the Allosteric Pathway of the Shaker Kv Channel Pore by Linear Free-Energy Relations

Long-range coupling between distant functional elements of proteins may rely on allosteric communication trajectories lying along the protein structure, as described in the case of the Shaker voltage-activated potassium (Kv) channel model allosteric system. Communication between the distant Kv channel activation and slow inactivation pore gates was suggested to be mediated by a network of local pairwise and higher-order interactions among the functionally unique residues that constitute the allosteric trajectory. The mechanism by which conformational changes propagate along the Kv channel allosteric trajectory to achieve pore opening, however, remains unclear. Such conformational changes may propagate in either a concerted or a sequential manner during the reaction coordinate of channel opening. Residue-level structural information on the transition state of channel gating is required to discriminate between these possibilities. Here, we combine patch-clamp electrophysiology recordings of Kv channel gating and analysis using linear free-energy relations, focusing on a select set of residues spanning the allosteric trajectory of the Kv channel pore. We show that all allosteric trajectory residues tested exhibit an open-like conformation in the transition state of channel opening, implying that coupling interactions occur along the trajectory break in a concerted manner upon moving from the closed to the open state. Energetic coupling between the Kv channel gates thus occurs in a concerted fashion in both the spatial and the temporal dimensions, strengthening the notion that such trajectories correspond to pathways of mechanical deformation along which conformational changes propagate.     

Effect of diastolic pressure on MLC2v phosphorylation in the rat left ventricle

The effect of passive muscle stretch on the extent of MLC2v phosphorylation was investigated. We used an isolated rat heart preparation and controlled the passive pressure of the left ventricle (LV) at 0 or 15 mmHg. The hearts were flash frozen and the LV free wall was split into epicardial and the endocardial halves. The samples were solubilized using a novel method that minimizes changes in the phosphate content of MLC2v under non-denaturing conditions. The proteins were separated by urea glycerol PAGE and identified by mass spectrometry and Western blots. At 0 mmHg passive pressure, the extent of MLC2v phosphorylation of the epicardium (34.1+/-1.7%) was the same as that of the endocardium (35.3+/-3.4%). At 15 mmHg passive pressure, we found a significant increase in MLC2v phosphorylation in the epicardium (to 41.5+/-2.0%) and a significant reduction in the endocardium (to 24.2+/-1.2%), giving rise to a gradient in the extent of MLC2v phosphorylation from epicardium (high) to endocardium (low). These changes in MLC2v phosphorylation that take place in response to increased diastolic pressure are likely to impact on the calcium sensitivity of actomyosin interaction (with an increased sensitivity towards the epicardium) and may play a role in the Frank-Starling mechanism of the heart.     

Feedback controlled force enhancement and activation reduction of voluntarily activated quadriceps femoris during sub-maximal muscle action

Stretch of activated muscles leads to enhanced forces compared to isometric contractions at the same muscle length and the same level of activation. This so-called residual force enhancement (RFE) is thought to be a property of all muscles and preparations. However, observations concerning the existence, amount and duration of RFE are inconsistent, especially for voluntary activated large human muscles. Therefore, physiological relevance for daily activity is still questionable and the purpose of this study was to examine whether RFE is present in voluntary sub-maximal activated quadriceps femoris (QF). Seated in a rotational dynamometer with EMG attached to superficial parts of QF, 30 subjects performed isometric and isometric-eccentric-isometric contractions (20° stretch, ω = 60° s⁻¹) at 30% and 60% of maximum voluntary activation (MVA) and contraction (MVC). To account for the complexity of the multi-headed QF, a compensation model based on physiological cross-sectional area and individual EMG-torque relations was used to interpret EMG data. For both levels of intensity and both feedback control strategies, ANOVA identified significant RFE (at the same level of activation) and reduced activation (at the same level of torque). Against expectations, RFE was independent of the level of activation.     

Comprehensive evaluation of multiple cropping systems on upland red soil

According to the principles and methods of ecology and system engineering,we set up an evaluation indicator system for multi-component and multiple crop-ping systems,evaluated the comprehensive benefits of multi-component and multiple cropping systems using grey relation clustering analysis and screened out the opti-mized model based on research done in the upland red soil in Jiangxi Agricultural University from 1984 to 2004.The results show that the grey relation degree of "cabbage/ potato/maize-sesame" was the highest among 23 multi-component and multiple cropping systems and was clustered into the optimized system.This indicates that "cabbage/potato/maize - sesame" can bring the best social,economic and ecological benefits,increase product yield and farmers' income and promote sustainable development of agricultural production.Therefore,it is suitable for promotion on upland red soil.The grey rela-tion degree of "canola/Chinese milk vetch/maize/mung bean/maize" was second,which is suitable for imple-mentation at the city outskirts.In conclusion,these two planting patterns are expected to play important roles in the reconstruction of the planting structure and optimiza-tion of the planting patterns on upland red soil.     

Metabolic approaches to understanding climate change impacts on seasonal host‐macroparasite dynamics

Climate change is expected to alter the dynamics of infectious diseases around the globe. Predictive models remain elusive due to the complexity of host–parasite systems and insufficient data describing how environmental conditions affect various system components. Here, we link host–macroparasite models with the Metabolic Theory of Ecology, providing a mechanistic framework that allows integrating multiple nonlinear environmental effects to estimate parasite fitness under novel conditions. The models allow determining the fundamental thermal niche of a parasite, and thus, whether climate change leads to range contraction or may permit a range expansion. Applying the models to seasonal environments, and using an arctic nematode with an endotherm host for illustration, we show that climate warming can split a continuous spring‐to‐fall transmission season into two separate transmission seasons with altered timings. Although the models are strategic and most suitable to evaluate broad‐scale patterns of climate change impacts, close correspondence between model predictions and empirical data indicates model applicability also at the species level. As the application of Metabolic Theory considerably aids the a priori estimation of model parameters, even in data‐sparse systems, we suggest that the presented approach could provide a framework for understanding and predicting climatic impacts for many host–parasite systems worldwide.     

Phospholipase Dα1‐mediated phosphatidic acid change is a key determinant of desiccation‐induced viability loss in seeds

High sensitivity of seeds to water loss is a widespread phenomenon in the world's plant species. The molecular basis of this trait is poorly understood but thought to be associated with critical changes in membrane function. We profiled membrane lipids of seeds in eight species with varying levels of desiccation tolerance and found a close association between reducing seed viability and increasing phosphatidic acid (PA). We applied hydration–dehydration cycles to Arabidopsis seeds, which are normally desiccation tolerant, to mimic the onset of desiccation sensitivity with progression towards germination and examined the role of phospholipase D (PLD) in desiccation stress‐induced production of PA. We found that PLDα1 became more abundant and migrated from the cytosol to the membrane during desiccation, whereas PLDδ did not change, and that all desiccation‐induced PA was derived from PLDα1 hydrolysis. When PLDα1 was suppressed, the germination level after each hydration–dehydration cycle improved significantly. We further demonstrated that PLDα1‐mediated PA formation modulates desiccation sensitivity as applying its inhibitor improved seed desiccation tolerance and its suppression in protoplasts enhanced survival under dehydration. The insights provided by comparative lipidomics enable us to propose a new membrane‐based model for seed desiccation stress and survival.     

Insight into genetic relation and diversity of cultivated and semi-domesticated under-utilized Crotalaria species gained using start codon targeted (SCoT) markers

To augment conventional crop improvement approaches in cultivated sunnhemp (Crotalaria juncea L.) and other under-utilized Crotalaria species, genetic diversity of 94 genotypes from seven Crotalaria species was studied using 20 Start Codon Targeted (SCoT) markers. High allele number (1.32), polymorphism information content (0.37) and resolving power (6.59) established SCoT as a reliable marker system for genetic analysis in Crotalaria. All the species except Crotalaria retusa L. exhibited high number of SCoT amplicons. Analysis of molecular variance revealed significant variability between (24.0%) the species as well as within species (76.0%). A cluster analysis identified distinct groups corresponding to the seven species and also identified sub-groups within the species. The sunnhemp cultivars were distant from the landraces, suggesting the need of population improvement using distantly related genotypes. Species relationship identified Crotalaria pallida Aiton to be a close relative of C. juncea. The results of principal coordinate analysis were comparable to that of cluster analysis, revealing high genetic variability in sunnhemp and other semi-domesticated Crotalaria species. The study further suggests some measure for conservation of genetic resources and genetic improvement of these species based on the results of diversity analysis.     

Cytokinin Profiles in the Conifer Tree <Emphasis Type="Italic">Abies nordmanniana</Emphasis>: Whole-Plant Relations in Year-Round Perspective

Conifer trees are routinely manipulated hormonally to increase flowering, branching, or adjust crown shape for production purposes. This survey of internal cytokinin levels provides a background for such treatments in Abies nordmanniana, a tree of great economic interest. Reference points in the crown and root system were sampled destructively in 4- and 6-year-old trees and analyzed for a range of cytokinins by LC-MS/MS. No seasonal patterns were detected in the root samples, and a major portion of cytokinin was in conjugated forms. Dramatic and consistent seasonal changes occurred in the crown, at levels 17–65 times higher than in the root. Predominant among crown cytokinins was ZR, except in the needles where IPR was also prominent. Within the crown, cytokinin profiles in different organs differed consistently. The leader bud showed a pronounced mid-June minimum, and a maximum later in summer. Subapical buds showed the same June minimum but peaked in mid autumn at a much lower level. Maxima in these buds were preceded by peaks in the subapical stem. Parallel patterns were observed in homologous tissues on branches.This pattern is consistent with two surges beginning in the uppermost stem tissues leading to subsequent accumulation or stimulated production within the buds. Strong differential hormonal profiles between adjacent buds with different fates agree with recent evidence of localized cytokinin production. The data suggest a reduced role of root-derived cytokinins in crown development. Practical cytokinin treatments for crown-shape regulation require close attention to dosage as well as precise timing and positioning.