蓝光对蔬菜烟粉虱的控制作用

利用灯光控制害虫是蔬菜害虫绿色防控的重要手段.本研究探讨了蓝光对黄瓜烟粉虱种群及黄瓜营养物质、次生代谢物、抗性相关酶的影响.结果 表明:在直接驱避试验条件下,蓝光对烟粉虱成虫有较强的驱避作用,光照强度越大、照射时间越长,对烟粉虱的驱避作用越强.在相同光强和光照时间下,直射光较透射光的驱避作用强.其中,1200 lx的蓝...     

Grazing on toxic cyanobacterial blooms by tadpoles of edible frog Rana grylio

Tadpoles of Rana grylio were raised as edible frogs in fishponds of Guanqiao in Wuhan City, Hubei, China, during cyanobacterial blooms from June to October. The dominant cyanobacterial species was Microcystis, which was found to be lethally toxic by intraperitoneal (i.p.) mouse bioassay. Little is known about the effect of tadpoles on toxic cyanobacterial blooms. To evaluate the potential of the tadpoles to graze on cyanobacterial blooms, the tadpoles were fed on Microcystis collected from the field in the laboratory. The Microcystis cells decreased from 1.19 × 10⁷ cells mL^?1 to 3.23 × 10⁶ cells mL^?1, with a sharp reduction of 73% of the initial Microcystis population observed in the first 24 h after introduction of the tadpoles. The ponds containing tadpoles had a markedly lower density of Microcystis than those lacking tadpoles. Tadpoles exposed to either cultured Microcystis aeruginosa (NIES–90, 2.768 µg microcystins mg^–1 dw^–1) cells or lysed M. aeruginosa cells grew well, however, indicating that they were unaffected by Microcystis toxins. We found a significant increase in tadpole body weight after feeding on either field Microcystis or cultured M. aeruginosa. The mean increase in individual body weight was 20 mg day^?1 when fed on Microcystis from the pond, and 7 mg day^?1 when fed on M. aeruginosa from culture. Our study strongly suggested that there is a direct trophic relationship between R. grylio tadpoles and toxic Microcystis blooms and they possess the potential to graze on toxic Microcystis. The results imply that R. grylio tadpoles may play an important ecological role in reducing toxic cyanobacterial blooms caused by Microcystis.     

Adrenergic Stimulation of Cyclic GMP Formation Requires NO-Dependent Activation of Cytosolic Guanylate Cyclase in Rat Pinealocytes

Abstract: Cyclic GMP (cGMP) formation in rat pinealocytes is regulated through a synergistic dual receptor mechanism involving β-and α₁-adrenergic receptors. The effects of N -monomethyl- l -arginine (NMMA), which inhibits nitric oxide (NO) synthase and NO-mediated activation of cytosolic guanylate cyclase, and methylene blue (MB), which inhibits cytosolic guanylate cyclase, were investigated in an attempt to understand the role of NO in adrenergic cGMP formation. Both NMMA and MB inhibited β-adrenergic stimulation of cGMP formation as well as α₁-adrenergic potentiation of β-adrenergic stimulation of cGMP formation, whereas they had no effect in unstimulated pinealocytes. The inhibitory action of NMMA was antagonized by addition of l -arginine. On the basis of these findings it can be concluded that the adrenergic stimulation of cGMP formation involves NO synthesis followed by activation of cytosolic guanylate cyclase.     

The extended Moran effect and large-scale synchronous fluctuations in the size of great tit and blue tit populations

1. Synchronous fluctuations of geographically separated populations are in general explained by the Moran effect, i.e. a common influence on the local population dynamics of environmental variables that are correlated in space. Empirical support for such a Moran effect has been difficult to provide, mainly due to problems separating out effects of local population dynamics, demographic stochasticity and dispersal that also influence the spatial scaling of population processes. Here we generalize the Moran effect by decomposing the spatial autocorrelation function for fluctuations in the size of great tit Parus major and blue tit Cyanistes caeruleus populations into components due to spatial correlations in the environmental noise, local differences in the strength of density regulation and the effects of demographic stochasticity. 2. Differences between localities in the strength of density dependence and nonlinearity in the density regulation had a small effect on population synchrony, whereas demographic stochasticity reduced the effects of the spatial correlation in environmental noise on the spatial correlations in population size by 21.7% and 23.3% in the great tit and blue tit, respectively. 3. Different environmental variables, such as beech mast and climate, induce a common environmental forcing on the dynamics of central European great and blue tit populations. This generates synchronous fluctuations in the size of populations located several hundred kilometres apart. 4. Although these environmental variables were autocorrelated over large areas, their contribution to the spatial synchrony in the population fluctuations differed, dependent on the spatial scaling of their effects on the local population dynamics. We also demonstrate that this effect can lead to the paradoxical result that a common environmental variable can induce spatial desynchronization of the population fluctuations. 5. This demonstrates that a proper understanding of the ecological consequences of environmental changes, especially those that occur simultaneously over large areas, will require information about the spatial scaling of their effects on local population dynamics.     

苔藓植物蓝光/紫外光-A 信号传导的研究

种子植物含有5个已分离的光受体和至少1个未鉴定的蓝光/紫外光-A受体。隐花色素(CRY1、CRY2和CRY3) 调节植物的生长发育,而向光蛋白(PHOT1和PHOT2) 调节植物对光的营养反应。黄素可以吸收蓝光和紫外光-A,是生色团。对这些光受体的结构和作用模式已了解很多。苔藓植物小立碗藓中含有2个已分离的隐花色素(CRY1a和CRY1b),负责调节侧枝形成和生长素代谢;有4个向光蛋白(PHOTA1,PHOTA2,PHOTB1,PHOTB2) 调节叶绿体的运动。苔藓细胞内蓝光/紫外光-A刺激引发的信号转导有Ca2+参与。     

Aqueous two-phase partition and detergent precipitation of a drug-responsive NADH oxidase from the HeLa cell surface

The partitioning behaviour of a drug (capsaicin)-responsive NADH oxidase (tNOX) activity released from HeLa ceIls by low pH treatment followed by heat and proteinase K was determined. When partitioned in a standard 6.4% PEG 3350/6.4% dextran T-500 two-phase system, the bulk of the tNOX activity was in the dextran-rich lower phase. The activity was inhibited by and bound to the triazine dye, Cibacron blue. Affinity partition, where the Cibacron blue was coupled to amino PEG 5000 and added to the first two-phase separation step, resulted in the partitioning of activity to the upper PEG phase. A second partition with PEG-salts resulted in the release of the tNOX from the Cibacron blue–amino PEG enriched phase into the salt-enriched lower phase. The phase-purified protein exhibited anomalous behavior and tended to multimerize in sodium dodecyl sulphate (SDS) prior to SDS-polyacrylamide gel electrophoresis (PAGE). Multimerization appeared to be enhanced by PEG. The multimerization was enhanced with the reduced protein in the presence of detergent prior to SDS–PAGE. In addition, the activity was precipitated by PEG 8000 at concentrations between 6 and 30% by weight. In the presence of or after exposure to PEG 3350 or PEG 8000, the protein could not be detected by Western blot analysis after SDS–PAGE suggesting that the protein failed to enter the gel even though other HeLa cell surface proteins were unaffected. The anomalous multimerization behavior has thus far precluded the use of phase partition as a practical purification step for the oxidase.     

Light control of extractable nitrate reductase activity in higher plants

Light regulation of extractable nitrate reductase (NR) activity of higher plants is complicated by: 1) involvement of several photoreceptors, 2) differences in the relative importance of the several photoreceptors among species and among developmental stages of the same species, 3) two types of effects – alteration of activity of existing NR and influences on de novo synthesis of NR, and 4) differing forms of NR within the same species. The interrelationships of all of these factors are not clear. It may be that each system will have to be understood separately before a general model can be developed. Immunochemical quantification of NR from systems exposed to varied light regimes may enhance our understanding of this area. Currently few general conclusions can be made; however, we think that the following statements are true or are usually true: (1) Phytochrome influences extractable NR activity by the low irradiance response and high irradiance response in etiolated tissues. (2) In de-etiolated tissues phytochrome can influence NR activity decay at the end of a light period by the low irradiance response. (3) The phytochrome equilibrium or the absolute level of P_fr influences extractable NR activity in green tissues under white light. (4) Blue light influences extractable NR activity through phytochrome and another, unknown, blue light-absorbing pigment. Flavins may be involved in vitro in reactivation of inactivated NR. (5) Photosynthesis does not directly influence the induction of the forms of NR that require substrate and light for induction. (6) In some tissues there appears to be a close link between nitrite-reducing and nitrate-reducing capabilities. (7) Much circumstantial evidence from kinetic and protein-synthesis-inhibitor studies and the only available immunochemical data indicate that light induces de novo synthesis of NR, resulting in increased extractable activity.