Tropic failure of Phyllactinia corylea contributes to the mildew resistance of mulberry genotypes

Different mulberry genotypes show great variation in their resistance to the powdery mildew Phyllactinia corylea. Conidial germination and hyphal growth of P. corylea on the leaf surface of two susceptible mulberry genotypes, viz., Kanva 2 (K2) and Victory 1 (V1) varieties of Morus indica, and on two resistant species, viz., M. laevigata and M. serrata were studied by scanning electron microscopy. Conidial germination and growth of germ tubes were normal on all the leaves. The hyphae of P. coryleaidentify stomata on host leaves by their topographical features to produce the stomatopodia precisely over them. The holes and/or the grooves of stomata appear to provide the signals for the initiation of stomatopodia and similar structures are erratically developed over many local depressions or grooves on leaf surface. The abaxial surface of K2 leaf is smooth without prominent undulations of epidermal cell surface, and the stomata are flush with the leaf surface. Although successful penetration is also achieved on V1 leaf, its slightly undulated surface occasionally provides inaccurate tropic signals to the hyphae, inducing the development of stomatopodia away from the stomata. The leaf surfaces of M. laevigata and M. serrata are very rough with highly sculptured cuticle and abundant epidermal outgrowths. Stomata mostly remain sunken or hidden amidst the cuticular ornamentations and the hyphae fail to recognise the precise signals from them. As the surface architecture of the leaves provides many immense sources of tropic signals, stomatopodia are often produced over local depressions or grooves. In these cases the fungus fails to penetrate the leaf, does not develop beyond 24 h and penetration is rarely achieved on the leaves of the resistant plants. The study indicates that the stimulatory effect of the leaf surface topography of resistant varieties misleads the pathogen from successful penetration, thus contributing to the plant's resistance.This revised version was published online in October 2005 with corrections to the Cover Date.     

加味真武汤对慢性心衰大鼠心肌结构及炎症因子的影响

目的:观察加味真武汤对慢性心力衰竭大鼠心肌组织结构以及炎症因子水平情况,并探讨其作用机理。方法:雄性SD大鼠48只随机分为空白组、模型组、地高辛组、加味真武汤组。采用盐酸阿霉素腹腔注射的方法建立慢性心力衰竭大鼠模型。各组分别给药治疗后,光镜观察心肌细胞结构并进行病理评分;酶联免疫法测定白介素-1(IL-1)、白介素-6(IL-6)以及血清脑钠肽(BNP)水平情况。结果:模型组大鼠心肌纤维断裂,伴炎性浸润,模型组病理评分显著高于空白组,有统计学差异(P0.05);地高辛组和加味真武汤组病理评分显著低于模型组,有统计学差异(P0.05);加味真武汤组与地高辛组病理评分比较无统计学差异(P0.05)。与模型组相比,加味真武汤组和地高辛组血清IL-6、IL-1、BNP水平明显减低,加味真武汤组效果更显著,差异具有统计学意义(P0.05)。结论:加味真武汤可能有增加心肌收缩力,抑制炎症因子的释放,减慢心室重构,保护心肌细胞的作用。     

Cardiac and neuroprotection regulated by α1-adrenergic receptor subtypes

Sympathetic nervous system regulation by the α₁-adrenergic receptor (AR) subtypes (α_1A, α_1B, α_1D) is complex, whereby chronic activity can be either detrimental or protective for both heart and brain function. This review will summarize the evidence that this dual regulation can be mediated through the different α₁-AR subtypes in the context of cardiac hypertrophy, heart failure, apoptosis, ischemic preconditioning, neurogenesis, locomotion, neurodegeneration, cognition, neuroplasticity, depression, anxiety, epilepsy, and mental illness.     

EEG-based communication and control: speed-accuracy relationships

People can learn to control mu (8–12 Hz) or beta (18–25 Hz) rhythm amplitude in the EEG recorded over sensorimotor cortex and use it to move a cursor to a target on a video screen. In our current EEG-based brain–computer interface (BCI) system, cursor movement is a linear function of mu or beta rhythm amplitude. In order to maximize the participant's control over the direction of cursor movement, the intercept in this equation is kept equal to the mean amplitude of recent performance. Selection of the optimal slope, or gain, which determines the magnitude of the individual cursor movements, is a more difficult problem. This study examined the relationship between gain and accuracy in a 1-dimensional EEG-based cursor movement task in which individuals select among 2 or more choices by holding the cursor at the desired choice for a fixed period of time (i.e., the dwell time). With 4 targets arranged in a vertical column on the screen, large gains favored the end targets whereas smaller gains favored the central targets. In addition, manipulating gain and dwell time within participants produces results that are in agreement with simulations based on a simple theoretical model of performance. Optimal performance occurs when correct selection of targets is uniform across position. Thus, it is desirable to remove any trend in the function relating accuracy to target position. We evaluated a controller that is designed to minimize the linear and quadratic trends in the accuracy with which participants hit the 4 targets. These results indicate that gain should be adjusted to the individual participants, and suggest that continual online gain adaptation could increase the speed and accuracy of EEG-based cursor control.     

Acid-base equilibria of air-water monolayers ofN-hexadecyl-8-hydroxy-2-quinolinecarboxamide

The surface pressure-area (-A) isotherms ofN-hexadecyl-8-hydroxy-2-quinolinecarboxamide (HHQ) monolayers at an air-water interface on subphases with different pH values were investigated. The monolayer of HHQ was expanded and unstable on acidic subphases, while it was condensed and stable on basic subphases. The acid-base equilibrium of HHQ was investigated in an aqueous dioxane solution and at the air-water interface. The association-dissociation of HHQ with H⁺ ions in the interfacial region was very different from that in the aqueous dioxane solution. Some information regarding the packing density, phase transition and degree of ionization of the head group under different experimental conditions has been obtained.     

Relationship between mechanical dysfunction and depression of sarcolemmal Ca2+-pump activity in hearts perfused with oxygen free radicals

Although in vitro studies have shown that oxygen free radicals depress the sarcolemmal Ca²⁺-pump activity and thereby may cause the occurrence of intracellular Ca²⁺ overload for the genesis of contractile failure, the exact relationship between changes in sarcolemmal Ca²⁺-pump activity and cardiac function due to these radicals is not clear. In this study we examined the effects of oxygen radicals on sarcolemmal Ca²⁺ uptake and Ca²⁺-stimulated ATPase activities as well as contractile force development by employing isolated rat heart preparations. When hearts were perfused with medium containing xanthine plus xanthine oxidase, the sarcolemmal Ca²⁺-stimulated ATPase activity and ATP-dependent Ca²⁺ accumulation were depressed within 1 min whereas the developed contractile force, rate of contraction and rate of relaxation were increased at 1 min and decreased over 3–20 min of perfusion. The resting tension started increasing at 2 min of perfusion with xanthine plus xanthine oxidase. Catalase showed protective effects against these alterations in heart function and sarcolemmal Ca²⁺-pump activities upon perfusion with xanthine plus xanthine oxidase whereas superoxide dismutase did not exert such effects. The combination of catalase and superoxide dismutase did not produce greater effects in comparison to catalase alone. These results are consistent with the view that the depression of heart sarcolemmal Ca²⁺ pump activities may result in myocardial dysfunction due to the formation of hydrogen peroxide and/or hydroxyl radicals upon perfusing the hearts with xanthine plus xanthine oxidase.