Vitamin B6s inhibit oxidative stress caused by Alzheimer's disease-related Cu(II)-β-amyloid complexes-cooperative action of phospho-moiety

Cu(II) complexes of Alzheimer's disease-related β-amyloid (Aβ) peptides exhibit metal-centered oxidation chemistry. The metallo-Aβ complexes are the hallmark of the disease and have been attributed to the generation of reactive oxygen species (ROS), causing oxidative stress. In this communication, the inhibitions of the oxidative activity of Cu(II)-Aβ by vitamin B6 compounds pyridoxamine (PM), pyridoxine (PN), pyridoxal (PL), and pyridoxal-5'-phosphate (PLP) are presented. These B6's are competitive inhibitors toward dopamine oxidation by Cu(II)-Aβ(1-20), with K(i) values of 1.4, 8.3, 1.2, and 0.2mM, respectively. The phospho-moiety in PLP seems to exhibit cooperative inhibition, affording a clue for future design of inhibitors.     

When it is too hot for photosynthesis: heat-induced instability of photosynthesis in relation to respiratory burst, cell permeability changes and H₂O₂ formation

Photosynthesis rate (A_n) becomes unstable above a threshold temperature, and the recovery upon return to low temperature varies because of reasons not fully understood. We investigated responses of A_n, dark respiration and chlorophyll fluorescence to supraoptimal temperatures of varying duration and kinetics in Phaseolus vulgaris asking whether the instability of photosynthesis under severe heat stress is associated with cellular damage. Cellular damage was assessed by Evans blue penetration (enhanced membrane permeability) and by H₂O₂ generation [3,3′‐diaminobenzidine 4HCl (DAB)‐staining]. Critical temperature for dark fluorescence (F₀) rise (T_F) was at 46–48 °C, and a burst of respiration was observed near T_F. However, A_n was strongly inhibited already before T_F was reached. Membrane permeability increased with temperature according to a switch‐type response, with enhanced permeability observed above 48 °C. Experiments with varying heat pulse lengths and intensities underscored the threshold‐type loss of photosynthetic function, and indicated that the degree of photosynthetic deterioration and cellular damage depended on accumulated heat‐dose. Beyond the ‘point of no return’, propagation of cellular damage and reduction of photosynthesis continued upon transfer to lower temperatures and photosynthetic recovery was slow or absent. We conclude that instability of photosynthesis under severe heat stress is associated with time‐dependent propagation of cellular lesions.     

欧报春二型花柱的繁育特性研究

二型花柱植物通常具有自交不亲和性,在不同植物中所表现的可育性不同。欧报春(Primula vulgaris)是典型的二型花柱植物,为了探究欧报春的繁育特性,通过温室栽培,对欧报春的长花柱和短花柱的花部特征、花粉和花柱形态、花粉活力、柱头可授性、花粉/胚珠比、杂交指数、杂交亲和性、花粉管观察进行研究。结果表明,(1)长花柱和短花柱的花冠直径、花冠筒长度、柱头高度、花药高度和花筒中部直径均表现出两型性;(2)花粉和柱头观察发现花粉极轴长、花粉赤道轴长、花柱直径、柱头乳突细胞和花粉数量均有差异;(3)长花柱的花粉/胚珠比为384.20,短花柱为369.70,属于兼性异交类型;长花柱和短花柱的花粉活力和柱头可授性能在较长时间内维持较高活力;(4)长花柱杂交指数值为5,短花柱为4,表明繁育系统类型为异交,部分自交亲和,需要传粉者;6种授粉组合均能结实,异型花间授粉的结实数明显高于同型自花授粉和异株同型授粉;短花柱为母本的异型花间授粉组合亲和性优于其他组合;欧报春存在自交不亲和性,长花柱的自交不亲和性低于短花柱。     

铜胁迫条件下土壤微生物对海州香薷光合特性和叶绿素荧光参数的影响

为探讨铜（Cu）胁迫条件下土壤微生物对海州香薷（Elsholtzia splendens）光合生理和叶绿素荧光参数的影响,实验设置添加Cu（Cu胁迫）、接种土壤微生物、添加Cu与接种土壤微生物等3个处理,以不添加Cu与不接种土壤微生物为对照（CK）。结果表明：接种土壤微生物处理的植株相对叶绿素含量、净光合速率（P_n）、水分利用效率（WUE）均显著高于CK;且对初始荧光（F_o）和最大光化学效率（F_v/F_m）均有显著性影响。与CK相比,添加Cu降低了海州香薷的P_n和气孔导度（G_s）,但胞间CO₂浓度（C_i）的变化与P_n相反,表明其对光合作用的影响主要是非气孔限制因素。添加Cu的植株相对叶绿素含量显著下降,但Cu胁迫下接种土壤微生物提高了植株相对叶绿素含量,差异显著。在Cu胁迫条件下,接种土壤微生物的植株具有较高的F_v/F_m及较低的F_o,显著提高了海州香薷的WUE、P_n、G_s。说明接种土壤微生物可通过提高相对叶绿素含量、改善叶绿素荧光和光合作用来减轻Cu胁迫对海州香薷植株造成的伤害,从而提高海州香薷耐受Cu胁迫的能力。     

Spread of beet necrotic yellow vein virus in infected seedlings and plants of sugar beet (Beta vulgaris)

Summary Infection of sugar beet roots by beet necrotic yellow vein virus (BNYVV) was investigated with transmission electron microscopy, immunogold labelling and enzyme linked immuno sorbent assay (ELISA). Here we show that infection of sugar beet roots is very fast, occurring during germination. Seedlings grown directly in infected soil showed higher BNYVV infection than plants transplanted into infected soil after seven days of initial growth in sterilized soil. The earlier the initial infection, the faster was its spread. The study showed that a few differentiated cells of the cortex and of the xylem parenchyma were the preferred sites of viral multiplication. The spread of viral infection was slow through differentiated tissues. Intact virions were frequently found in undifferentiated and mature vessel elements and xylem parenchyma, whereas they were rare in sieve elements. Virus particle number in the differentiating tracheary elements was high, suggesting that infection of the vessel elements preceded their differentiation. This would explain increased infection after early inoculation. Even the xylem tissue of the primary root was highly infected, the seedlings lacked virus particles in their hypocotyls and leaves.     

Multicolour Fluorescence Imaging of Sugar Beet Leaves with Different Nitrogen Status by Flash Lamp UV-Excitation

Fluorescence images of leaves of sugar beet plants (Beta vulgaris L. cv. Patricia) grown on an experimental field with different fertilisation doses of nitrogen [0, 3, 6, 9, 12, 15 g(N) m^–2] were taken, applying a new multicolour flash-lamp fluorescence imaging system (FL-FIS). Fluorescence was excited by the UV-range (280–400 nm, _max = 340 nm) of a pulsed Xenon lamp. The images were acquired successively in the four fluorescence bands of leaves near 440, 520, 690, and 740 nm (F₄₄₀, F₅₂₀, F₆₉₀, F₇₄₀) by means of a CCD-camera. Parallel measurements were performed to characterise the physiological state of the leaves (nitrogen content, invert-sugars, chlorophylls and carotenoids as well as chlorophyll fluorescence induction kinetics and beet yield). The fluorescence images indicated a differential local patchiness across the leaf blade for the four fluorescence bands. The blue (F₄₄₀) and green fluorescence (F₅₂₀) were high in the leaf veins, whereas the red (F₆₉₀) and far-red (F₇₄₀) chlorophyll (Chl) fluorescences were more pronounced in the intercostal leaf areas. Sugar beet plants with high N supply could be distinguished from beet plants with low N supply by lower values of F₄₄₀/F₆₉₀ and F₄₄₀/F₇₄₀. Both the blue-green fluorescence and the Chl fluorescence rose at a higher N application. This increase was more pronounced for the Chl fluorescence than for the blue-green one. The results demonstrate that fluorescence ratio imaging of leaves can be applied for a non-destructive monitoring of differences in nitrogen supply. The FL-FIS is a valuable diagnostic tool for screening site-specific differences in N-availability which is required for precision farming.     

Antihypertensive medications and survival in patients with cancer: A population-based retrospective cohort study

Background: The association between antihypertensive medications and survival in cancer patients remains unclear. Objectives: To explore the association between classes of antihypertensive drugs and survival in cancer patients. Methods: Provincial Cancer Registry data was linked with a Provincial Drug Program Information Network (DPIN) for patients with lung (n = 4241), colorectal (n = 3967), breast (n = 4019) or prostate (n = 3355) cancer between the years of 2004 and 2008. Cox regression analyses were used to compare survival of patients using beta blockers (BBs), angiotensin-converting enzyme inhibitors/receptor blockers (ACEi/ARB), calcium channel blockers (CCBs) or thiazide diuretics (TDs) to survival of patients who did not use any of these antihypertensive drugs. Survival of patients using only one class of antihypertensive drugs were compared to each other, with BBs as the reference class. Results: Compared to the antihypertensive drug non-user cohort, BBs had no effect on survival for any of the cancers. ACEi/ARBs use was weakly associated with increased deaths for breast cancer (HR: 1.22, 95% CI: 1.04–1.44) and lung cancer (HR: 1.11, 95% CI: 1.03–1.21) patients. Deaths were also increased with CCB use in patients with breast cancer (HR: 1.22, 95% CI: 1.02–1.47) and with TD use in lung cancer patients (HR: 1.1, 95% CI: 1.01–1.19). There was strong evidence (p-value <0.0001) of an increase in deaths with TD use for colorectal (HR: 1.28, 95% CI: 1.15–1.42), and prostate (HR 1.41, 1.2–1.65) cancer patients. When including only antihypertensive drug users prescribed one drug class, lung cancer patients receiving CCBs had improved survival compared to BBs (HR 0.79, 95% CI: 0.64–0.98). Conclusions: Some classes of antihypertensive agents are associated with a decreased survival in certain cancers. The decrease could be due to more comorbidities in antihypertensive drug users. However, CCB use was associated with improved survival in lung cancer patients.     

High-density algal photobioreactors using light-emitting diodes

Lack of high-density algal photobioreactors (PBR) has been a limitation in exploiting the biotechnological potential of algae. Recent developments of highly efficient light-emitting diodes (LED using gallium aluminum arsenide chips) have made the development of a small LED-based PBR possible. We have calculated theoretical values of gas mass transfer requirements and light-intensity requirement to support high-density algal cultures for the 680 nm monochromatic red light from LED as a light source. A prototype PBR has been designed based on these calculations. A cell concentration of more than 2 x 10(9) cells/mL (more than 6.6% v%sol;v), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/L culture/h were achieved using on-line ultrafiltration to periodically provide fresh medium. (c) 1994 John Wiley & Sons, Inc.     

夏枯草药材和种植土壤中农药及重金属残留分析

采用气相色谱及ICP-AES法测定了安徽庐江和江苏洪泽2个种植基地的土壤和夏枯草(Prunella vulgaris L.)果穗及全草中有机氯农药及重金属含量,并根据污染指数和相关标准对土壤及药材的安全性进行了评价.测定结果表明:来源于2个基地的土壤及药材中有机氯农药及重金属含量有明显差异.庐江产果穗和全草中Pb、Cd、Cu、Cr、As及BHC含量分别为3.361和3.953、0.172和0.190、8.258和7.722、3.423和2.658、0.284和0.355、0.003和0.004 mg·kg-1,Hg和DDT未检出;洪泽产果穗和全草中Pb、Cd、Cu、Cr、Hg及BHC含量分别为2.399和1.558、0.155和0.111、7.682和6.756、4.259和3.801、0.077和0.102、0.003和0.006 mg·kg-1,As未检出,果穗中也未检出DDT.庐江基地土壤中Cd、Cu、Cr、As、Hg、BHC和DDT含量分别为0.001、12.943、47.417、1.008、0.003、0.003和0.002 mg·kg-1,Pb未检出;洪泽基地土壤中Pb、Cd、Cu、Cr、As、Hg和BHC含量分别为3.443、0.002、18.655、63.385、3.701、0.141和0.004 mg·kg-1,DDT未检出.比较结果表明:夏枯草果穗中重金属残留量均高于全草,但均低于国家限量标准;土壤中有机氯农药及重金属单项污染指数均小于1,且庐江和洪泽基地土壤的综合污染指数分别为0.286和0.399,因此,土壤污染等级属安全级且污染水平为清洁级.