Stress-induced RNASET2 overexpression mediates melanocyte apoptosis via the TRAF2 pathway in vitro

The recent genome-wide association study identified a link between vitiligo and genetic variants in the ribonuclease T2 (RNASET2) gene; however, the functional roles of RNASET2 in vitiligo pathogenesis or in melanocyte apoptosis have yet to be determined. The current study was designed to investigate the vitiligo-related expression pattern of RNASET2 and its molecular function involving apoptosis-related signaling proteins and pathways. The results showed overexpression of RNASET2 in epidermis specimens from 40 vitiligo patients compared with that from matched healthy controls. In addition, in vitro analyses indicated that overexpression of RNASET2 was inducible in cultured primary human melanocytes and keratinocytes by stress conditions, that is, exposure to UV irradiation, hydrogen peroxide, and inflammatory factors, respectively, and led to increased cell apoptosis via the tumor necrosis factor receptor-associated factor 2 (TRAF2)–caspases pathway through the physical interaction of RNASET2 with TRAF2. Thus, RNASET2 may contribute to vitiligo pathogenesis by inhibiting TRAF2 expression and, as such, RNASET2 may represent a potential therapeutic target of vitiligo.     

不同品种春小麦根系对低钾胁迫的生物学响应

采用水培法,以3个春小麦品种(加春1号、2号、4号)为试验材料,研究了低钾胁迫下不同品种春小麦根系的形态学与生理学特征。结果表明:(1)与对照相比,低钾胁迫下小麦的根重、根数、总根长、总吸收面积、根活力、根系SOD及POD活性、根系活性吸收面积均明显降低,但根冠比有所增加,不同春小麦品种间的变化趋势相似,但变化幅度存在明显差异。(2)供试品种小麦根系的形态与生理学特征在同一供钾水平下和不同供钾水平间均存在着明显的差异,表明这两种性状的差异是由基因型和环境因素共同决定的,因此,根系形态学和生理学特征可以作为筛选高效吸收钾小麦品种的参考指标。(3)供试的3个春小麦品种中‘加春4号’对低钾环境的适应性最强。     

The growth strategy of the Gram-positive rod

Abstract Bacteria grow by enlarging their envelope in such a way that osmotic pressure does not normally cause physical rupture. The strategy of Bacillus subtilis for both cylindrical elongation and pole formation is now substantially defined. Side-wall growth takes place by laying down new peptidoglycan, which is then displaced outwards, stretched and discarded; cross walls are laid down in the absence of stress, and then stretched and bulged outward as the septum is split and the pole is formed.     

CHANGES IN PHOTOSYNTHESIS IN RESPONSE TO COMBINED IRRADIANCE AND TEMPERATURE STRESS IN CYANOBACTERIAL SURFACE WATERBLOOMS1

Buoyant cyanobacteria, previously mixed throughout the water column, float to the lake surface and form a surface waterbloom when mixing subsides. At the surface, the cells are exposed to full sunlight, and this abrupt change in photon irradiance may induce photoinhibition; at the same time, temperature rises as well. This study investigated the damaging effects of this increase in temperature as well as the ecologically more relevant combination of both an increased temperature and a high photon irradiance. Analysis of surface blooms with oxygen microelectrodes showed that integrated oxygen contents that are dependent on the balance of photosynthetic oxygen evolution and respiratory oxygen uptake decreased when temperature was raised above the lake temperature. Gross rates of photosynthesis were unaffected by temperatures up to of 35°C; hence, a moderate increase in temperature mainly stimulated oxygen uptake. Preincubation of cells of the cyanobacterium Anabaena flos-aquae (Lyngb.) de Brébisson at temperatures up to 35°C did not affect the subsequent measurement of rates of net photosynthesis. Another 5°C rise in temperature severely damaged the photosynthetic apparatus. Failure to restore net rates of photosynthesis was coupled to a strong quenching of the ratio of variable to maximum fluorescence, F_v/F_m, that was the result of a rise in F_o. A combination of high temperature and high photon irradiance was more damaging than high temperature alone. In contrast, low photon irradiances offered substantial protection against heat injury of the photosynthetic apparatus. I conclude from this study that because cyanobacteria usually are acclimated to low average irradiance prior to bloom formation, there is a reasonable risk of chronic photoinhibition. The increase in temperature will enhance the photodamage of cells in the top layer of the bloom. Low photon irradiances in subsurface layers will offer protection against heat injury. If the high temperatures extend to the deepest, dark layers of the bloom, damage in those layers is likely to occur.     

Na/K-ATPase as an oligomeric ensemble

Differences in the kinetic behavior and properties of monomeric and oligomeric forms of membrane-bound Na/K-ATPase are analyzed. It is concluded that enzyme molecules within oligomeric complexes are affected by extrinsic signals that result in change of enzyme activity, whereas the individual (protomeric) state is insensitive to these signals. Some of the major factors of such regulation are microviscosity of the lipid environment, reactive oxygen species, and intracellular protein kinases.     

甘蔗抗逆细胞系选择及其生化特性的研究

利用脯氨酸类似物羟脯氨酸(Hyp)的生长抑制作用,筛选出抗Hyp的甘蔗(Saccha-rum sinensis Roxb)细胞变异系R932。抗性系体内游离脯氨酸含量超常积累(×3．2)。而且其体内脯氨酸合成途径中的关键酶γ－谷氨酸激酶对脯氨酸的反馈抑制较不敏感。R932抗PEG和低温能力较供体加强。实验结果表明γ－谷氨酸激酶特性的变化可能导致细胞内脯氨酸的过量积累,脯氨酸的过量积累有利于植物细胞对抗恶劣环境。     

Submarine pollination in the marine angiosperm Zostera marina (Zosteraceae). II. Pollen transport in flow fields and capture by stigmas

Flow chamber observations of the filamentous pollen of Zostera marina L. (Potamogetonales) revealed that pollen rotated and moved toward inflorescences where they were captured by stigmas. The mechanics of this abiotic pollination process were examined and found to be related to the flow environment around emergent flowers. The translational movement of pollen was imparted by the advection of the fluid (e.g., pollen kinetic energy, K, ranged from 0.8 x 10-14 to 2.4 x 10-14 J, and the average K of the fluid was _ 0.7 x 10-14 J), while the rotational motion was imparted by the fluid shear stress (tau) within the velocity gradient (e.g., pollen shear stress, sigmat = omegamu where omega is the rotational velocity and mu is the dynamic viscosity, ranged from 3.4 x 10-4 to 26 x 10-4 Pa, and the average fluid shear stress was tau _ 10 x 10-4 Pa; Ackerman, 1997, American Journal of Botany 84: 1099-1109). These results indicate that there is a greater potential for pollination by filamentous pollen relative to spherical pollen. Functionally, while spherical pollen needs to be directly upstream from stigmas to be captured, filamentous pollen need only be in the vicinity of inflorescences and flowers to be captured by stigmas. Thus, in addition to direct interception on stigmas, filamentous pollen can be captured while they rotate past flowers or when they are redirected through the velocity gradient towards flowers. Filamentous pollen is an adaptation to submarine pollination in seagrasses.