紫外胁迫下NO对地木耳生理生化的影响

研究在紫外线B(UV-B,0.2 W/m2)辐射增强的情况下,硝普钠(SNP,一氧化氮供体)对地木耳的生长、抗氧化酶活性、蛋白质、色素和多糖含量的变化的影响.实验结果表明:UV-B辐射增强下,加入NO,能够提高藻类的生长速率,刺激过氧化氢酶(SOD)、超氧化物歧化酶(CAD)和过氧化物酶(POD)活性上升,提高蛋白质含量、叶绿素a和类胡萝卜素含量、多糖含量.     

田间增加UV-B辐射对丝瓜光合作用日变化及水分利用效率的影响

在自然条件下，增加不同强度的UV—B辐射，对攀援植物丝瓜叶片光合速率日变化和水分利用效率进行了研究，发现经增加R1强度UV—B辐射处理的丝瓜的净光合速率和蒸腾速率比对照上升了28％和33％，水分利用效率则下降了3．4％，而经增加R2强度UV—B辐射处理的丝瓜的净光合速率和蒸腾速率比对照上升了47％和13％，水分利用效率也上升了28％，且其光合作用不受午间强光的抑制，光合午休现象消失了．这表明，在该实验的UV—B强度下，丝瓜的光合作用不但未受抑制，反而还增强了，说明适当增加UV—B辐射对丝瓜的生长有利．     

不同演替阶段树种的光合和生长对增强UV-B辐射的响应

利用野外盆栽实验方法,模拟南亚热带地区地面增强UV-B辐射20%(L)和30%(H)的条件下(L和H分别为4.83和7.24 kJ.m-2.d-1),研究南亚热带植被恢复先锋树种马占相思(Acacia mangium)、演替前期树种荷木(Schima superba)、演替中后期树种华润楠(Machilus chinensis)和黄果厚壳桂(Cryptocarya concin-na)等4种乔木树种对增强UV-B辐射的响应。结果表明,增强UV-B辐射处理引起马占相思和荷木的最大光合速率(Pm ax)明显下降,高剂量(7.24 kJ.m-2.d-1)和延长处理时间(160 d)的效应更加明显;它们的光合速率下降幅度依次为:马占相思>荷木>华润楠>黄果厚壳桂,先锋树种光合作用对增强UV-B辐射的响应明显大于演替中后期树种。增强UV-B辐射处理,马占相思的株高生长和茎生物量以及荷木的株高有较明显减小,它们的地径、总生物量和冠根比有减小的趋势;同时马占相思的叶宽度明显地增大。结果表明,马占相思和荷木属UV-B辐射敏感种,而华润楠和黄果厚壳桂则属低敏感种。当前臭氧层的减薄趋势没有得到有效遏制的情况下,马占相思和荷木因个体生长发育过程中对增强UV-B辐射的敏感性,可能会导致南亚热带地区群落的先锋种和演替前期树种加速衰退,而演替中后期树种由于较能忍耐UV-B辐射而能竞争到更多的资源以利其在群落竞争中占优势,从而保持更稳定的状态。     

The Heck reaction of aryl bromides: a green protocol for synthesis of 2-ethylhexyl-4-methoxy cinnamate

Abstract

Deactivated aryl halide 4-bromoanisole and electron poor olefin 2-ethylhexyl acrylate were shown to undergo palladium catalyzed Heck reaction with the utilization of a cost-effective, thermally robust and unexplored morpholine-based ionic liquid. The developed protocol gives an environmentally friendly process for the synthesis of 2-ethylhexyl-4-methoxy cinnamate, an important UV-B sunscreen agent.     

外源一氧化氮供体SNP对UV-B辐射下红芸豆叶片中SOD,CAT和POD同工酶的影响

以对UV-B敏感的红芸豆为材料,采用一氧化氮的供体硝普钠(SNP)研究15μmol/(m<'2>·S)的UV-B辐射下SNP对植物抗氧化酶的影响.结果表明:红芸豆叶片超氧化物歧化酶、过氧化氢酶和过氧化物酶等抗氧化酶活性的增加,同工酶电泳也显示100 μmolSNP促进SOD,CAT,POD同工酶的表达,特别是诱导一些同工酶条带提前出现,还出现一些单独UV-B处理所没有的条带.说明100μmolSNP可以提高UV-B作用下抗氧化酶的活性,在一定程度上减轻植物遭受UV-B伤害.     

紫外线(UV)-B辐射增强对植物影响的研究进展

紫外线—B辐射增强时生物和生态系统的影响是目前科学研究的热点之一，本文从植物的生理活动、蛋白质和DNA分子、防御反应等几个方面对植物受到紫外线—B辐射增强的影响进行了综述，并论述了在紫外线—B辐射下植物产生的一些防御反应。     

铜绿微囊藻对UV-B的适应及其种内差异

 在人工UV-B辐照下培养铜绿微囊藻的3个单细胞纯种株系(FACHB905,FACHB85,FACHB69),结果发现:UV-B辐射下藻细胞数目和叶绿素a含量下降,而细胞干重和胞内外多糖含量上升,水溶性和脂溶性色素的吸收光谱改变;铜绿微囊藻对UV-B的适应存在种内差异.     

Effects of solar and artificial UV irradiation on pigments and assimilation of N ammonium and N nitrate by macroalgae

Three macroalgal species, Fucus vesiculosus, Laminaria saccharina and Ulva lactuca were exposed to natural daylight in UV-transparent and UV-non-transparent Plexiglas vessels at different water depths. Uptake of ¹⁵NH₄⁺ and ¹⁵NO₃⁻ was measured at different light intensities. In general, uptake rates in August surpassed those in May 1987 and Ulva assimilated significantly more nitrogen than Fucus and Laminaria. A negative influence of ambient solar UV radiation on nitrogen uptake was dound in Fucus and Ulva. Additionally, the impact of UV of different wave bands, using cut-off filters (WG 295, WG 305 and WG 320) and special UV-A and UV-B lamps, on pigments and ¹⁵N ammonium assimilation by several macroalgae was studied under controlled laboratory conditions. UV-B irradiation of shorter wave bands led to a reduction in the main pigments of Fucus except antheraxanthin and those of Ulva except lutein and violaxanthin. Uptake of ¹⁵N-ammonium by Fucus and Ulva was reduced after UV-B radiation whereas an increase was observed after UV-A irradiance in Ulva. Ammonia utilization by Halidrys was more damaged by UV-A than UV-B. The impact of UV radiation on the labelling of free amino acids and the pattern of pool sizes varied with the species and the UV wave bands. A marked reduction in ¹⁵N incorporation into the amino acids of Plocamium was found after UV-B exposure. The ¹⁵N labelling of the amino acids of Halidrys and Rhodomela was less affected. Results are discussed with reference to photoinhibitory effects on the enzymes of the nitrogen metabolism.     

不同氮素水平对铁皮石斛UV-B辐射缓解作用研究

研究了高、中、低3种氮素营养水平(2.208 4,0.552 1和0.138 0g/L)对UV-B辐射(5.1,15.6μW/cm~2)下铁皮石斛的光合色素、类黄酮质量分数、苯丙氨酸解氨酶(PAL酶)活性及主要药用成分总多糖质量分数的动态变化情况,探讨了缓解铁皮石斛UV-B辐射伤害的适宜氮素营养条件.结果表明:低氮素营养条件下,铁皮石斛光合色素质量分数较低,但PAL酶活性强、类黄酮及多糖质量分数明显高,其类黄酮质量分数变化与PAL酶活性变化存在明显的正相关性.分析表明,低氮素营养条件虽然不利于铁皮石斛光合色素的形成,但促进类黄酮及药用成分多糖的积累,有助于缓解UV-B辐射带来的损伤.     

3种多环芳烃和UV-B辐射对3种赤潮微藻生长的作用

通过实验生态学的方法，研究了3种多环芳烃（菲、芘和蒽）对3种赤潮微藻（赤潮异弯藻、亚历山大藻和中肋骨条藻）生长的影响．结果表明：低浓度的菲、芘和蒽处理对3种赤潮微藻的生长都有刺激作用，而高浓度处理则显示出抑制作用．菲、芘和蒽处理对赤潮异弯藻生长96hEC50分别为0．059、0．071、0．078mg／L，对中肋骨条藻的96hEC50分别为0．079、0．097、0．112mg／L，对亚历山大藻的96hEC50分别为0．089、0．107、0．119mg／L．在菲、芘和蒽处理的同时，附加辐射剂量为0．3J／m^2的UV—B辐射处理，3种多环芳烃对3种赤潮微藻的生长抑制作用更加明显．