Photochemical degradation of chromophoric-dissolved organic matter exposed to simulated UV-B and natural solar radiation

Photochemical degradation of chromophoric-dissolved organic matter (CDOM) by UV-B radiation decreases CDOM absorption in the UV region and fluorescence intensity, and alters CDOM composition. CDOM absorption, fluorescence, and the spectral slope indicating the CDOM composition were studied using 0.22-μm-filtered samples of Meiliang Bay water from Lake Taihu that were exposed to short-term (0–12 h) simulated UV-B radiation and long-term (0–12 days) natural solar radiation in summer. CDOM absorption coefficient and fluorescence decreased with increasing exposure time, which relates to the amounts of absorbed light energy. The decreases of CDOM absorption and normalized fluorescence corresponded to first order kinetics reactions. Different decreases of CDOM absorption and fluorescence at different wavelengths suggested that the composition of CDOM changed when it absorbed ultraviolet radiation. Photochemical degradation increased the spectral slope during 275–295 nm region (S _275–295) but decreased the spectral slope during 275–295 nm region (S _350–400). The slope ratio S _R (S _275–295:S _350–400) increased in the photochemical process, which could be used as an indicator of photobleaching and composition change of CDOM. Our results show that photochemical degradation is important in the cycling of CDOM, which indicated change in the composition of CDOM. Handling editor: Luigi Naselli-Flores     

EPO/EPO-R、Bcl-2、Bax在皮肤血管瘤组织的表达及意义

目的研究促红细胞生成素(erythropoietin,EPO)和促红细胞生成素受体(erythropoietin-receptor,EPO-R)、B细胞淋巴瘤/白血病-2(B-cell lymphoma/Leukemia-2,bcl-2)、促凋亡基因在血管瘤不同时期的表达,探讨其意义及相互关联。方法采用免疫组织化学方法检测人皮肤血管瘤增生期、退化期及正常皮肤组织中EPO/EPO-R、Bcl-2、Bax的表达水平,利用计算机图像分析技术测量不同时期血管瘤组织和正常皮肤组织EPO/EPO-R、Bcl-2、Bax表达的平均光密度和平均阳性面积率。结果 1.EPO/EPO-R在增生期血管瘤内皮细胞的表达明显高于退化期血管瘤内皮细胞和正常皮肤组织血管内皮细胞(P0.01);EPO/EPO-R在退化期血管瘤内皮细胞的表达与正常皮肤组织血管内皮细胞相比,差异无显著性(P0.05)。2.Bcl-2在增生期血管瘤的表达明显高于退化期血管瘤和正常皮肤组织(P0.01);Bcl-2在退化期血管瘤的表达与正常皮肤组织相比,差异无显著性(P0.05)。3.Bax在退化期毛细血管瘤中表达高于增殖期和正常皮肤组织(P0.01),Bax在增殖期中表达高于正常皮肤组织(P0.05)。结论 Bcl-2可能是通过抑制内皮细胞的凋亡,使其增殖;Bax可能通过促进内皮细胞凋亡而抑制血管瘤的增生;EPO/EPO-R可能上调Bcl-2及下调Bax,改变Bcl-2与Bax比值,促进了内皮细胞的增殖。     

Physical Localization and DNA Methylation of 45S rRNA Gene Loci in Jatropha curcas L.

In eukaryotes, 45S rRNA genes are arranged in tandem arrays of repeat units, and not all copies are transcribed during mitosis. DNA methylation is considered to be an epigenetic marker for rDNA activation. Here, we established a clear and accurate karyogram for Jatropha curcas L. The chromosomal formula was found to be 2n = 2x = 22 = 12m+10sm. We found that the 45S rDNA loci were located at the termini of chromosomes 7 and 9 in J. curcas. The distribution of 45S rDNA has no significant difference in J. curcas from different sources. Based on the hybridization signal patterns, there were two forms of rDNA - dispersed and condensed. The dispersed type of signals appeared during interphase and prophase, while the condensed types appeared during different stages of mitosis. DNA methylation analysis showed that when 45S rDNA stronger signals were dispersed and connected to the nucleolus, DNA methylation levels were lower at interphase and prophase. However, when the 45S rDNA loci were condensed, especially during metaphase, they showed different forms of DNA methylation.     

Multifunctional organic–inorganic composite luminescent nanospheres

A simple general strategy was successfully developed for the preparation of magnetic–luminescent multifunctional nanocomposites by incorporating fluorescent (pyrene) and magnetic (Fe₃O₄) components simultaneously into a poly(styrene‐co‐methacrylic acid) [poly(St‐co‐MAA)] copolymer matrix. The nanospheres so prepared were characterized using scanning electron microscopy (SEM), powder X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The prepared magnetic–fluorescent inorganic–organic nanocomposites have excellent magnetic and photoluminescent properties. They can be used in magnetic separation of trace amounts of sample, fluorescence detection and imaging applications, including magnetic resonance imaging (MRI) and fluorescence imaging. The fluorescence quenching of the nanospheres in the presence of different amounts of Cu²⁺ ions was also investigated. Under optimal experimental conditions, the relative fluorescence intensity of the composite nanosphere colloidal solution is proportional to the concentration of Cu²⁺ ions, which indicates that these multifunctional nanocomposites can be used for the magnetic separation and fluorescence detection of Cu²⁺ ions. Copyright © 2011 John Wiley & Sons, Ltd.     

基于叶面积指数估算植被总初级生产力

长时间序列的陆地碳通量数据在全球生态环境变化研究中具有重要意义。采用MODIS GPP(Gross Primary Productivity)算法,基于GIMMS LAI3g,MODIS15和Improved-MODIS15三种叶面积指数(LAI),估算了全球2000至2010年的植被总初级生产力(GPP)。该估算的GPP数值经过全球20个通量站点的验证,并结合MODIS17分析了它们在时空变化上的异同。结果表明:(1)4种GPP精度如下:GPP_(MOD17)GPP_(impro_MOD15)GPP_(LAI3g)GPP_(MOD15)。(2)4种GPP整体上具有一致的季节波动,冬季和夏季整体好于春季和秋季。GPP_(LAI3g)的4个季节精度较相近,而GPP_(MOD17)除了春秋季外其它季节都较好。(3)GPP_(LAI3g)在中等GPP值分布区的估值相对较高,其全球总GPP大体为(117±1.5)Pg C/a,GPP_(MOD17)和GPP_(impro_MOD15)相近且都低于该值。(4)GPP_(LAI3g)和GPP_(impro_MOD15)在大约63.29%的陆面上呈显著(P0.05)的正相关关系,它们和GPP_(MOD17)在LAI不确定性小的地区呈显著的正相关关系。GPP_(LAI3g)和GPP_(MOD15)正相关分布面积占比为40.61%。     

Growth and loss of mariculture kelp Saccharina japonica in Sungo Bay, China

The aim of this study was to understand the growth dynamics of Saccharina japonica (previously known as Laminaria japonica), particularly the portion lost during its growth cycle and the key factors that control loss rate in Sungo Bay, China. Growth and loss of S. japonica were investigated between January and July 2010 in Sungo Bay. Losses of the seaweed are typically the result of three factors: removal of the entire individual from mariculture ropes (falloff), breakage in sections of the thalli (breakoff), and erosion of distal tissue. Results showed that individual growth rates in wet weight ranged between 2.4 and 32.7 g day^?1. The total falloff rate was approximately 16% and took place during January and February. Breakoff rate showed a significant positive correlation with kelp length and took place during June and July. The erosion rate increased significantly from January to the end of April, reaching a maximum value of 20.4 g day^?1 on 25 April, and maintained a relatively higher value following the peak value (approximately 10–15 g day^?1). Erosion rates were positively correlated with temperature (r?=?0.787, n?=?23, p?<?0.01) before May; however, they were not significantly correlated with temperature from May to July (p?=?>0.05). There was no significant relationship between erosion and transparency. At the end of this experiment, the ratio of total loss of carbon and nitrogen to gross production was 61% and 54%, respectively. Loss from distal erosion, falloff, and breakoff in carbon was 91.5, 4.2, and 4.3%, respectively. In Sungo Bay, the annual gross production and total loss in carbon and nitrogen were estimated to be 58,652 t C and 3,506 t N, and 36,150 t C and 1,920 t N. This is expected to have a significant impact on the detritus available in the food chain.