增强UVB辐射对菜豆蛋白质代谢的影响

模拟研究了温室条件下兰州地区臭氧层减薄２５ ％ 时增强的ＵＶＢ（２８０ ～３２０ ｎｍ） 辐射对菜豆（ Ｐｈａｓｅｏｌｕｓｖｕｌｇａｒｉｓ Ｌ．） 蛋白质代谢的影响。菜豆幼苗期，ＵＶＢ辐射（ＵＶＢＢＥ：１６ ｋＪ·ｍ －２·ｄ－１） 促进菜豆叶片中蛋白质的合成；菜豆生长后期，ＵＶＢ辐射则抑制蛋白质的合成，降低叶片中可溶性蛋白质的含量，促进蛋白水解酶活性的上升和总游离氨基酸的积累。ＳＤＳＰＡＧＥ分析表明，ＵＶＢ辐射使幼苗期菜豆叶片中８８ ｋＤ、７６ ｋＤ、４２ ｋＤ、３５ ｋＤ、３３ ｋＤ 多肽的含量上升；而在菜豆生长后期，ＵＶＢ辐射使大分子量多肽（７６ ｋＤ 以上） 的含量迅速下降，１０～１４ ｋＤ、２９ ｋＤ、３３ ｋＤ、３５ｋＤ的多肽含量上升。

Influences of Different UV-B Radiation Treatments in Short Time on Some Physiological Characteristics of Winter Wheat Seedlings

[Objective] studying the influences of different UV-B radiation treatments in short time on some physiological characteristics of winter wheat seedlings was to provide reference for the mechanism of plant response to ultraviolet irradiation in short time. [Method] The winter wheat taken as materials were treated with 15 and 30 pW/cm^2 UV-B radiation, then the physiological indexes such as pigment content and photosynthetic rate were determined. [ Results] The UV-B treatment caused the declines of chlorophyll content, soluble protein content and water content of leaves, besides, dose-effect was existed. The decline of 30 pW/cm^2 treatment was bigger than that of 15 μW/cm^2 treatment. The influences of UV-B radiation on carotenoid content and anthocyanidin content were similar; the change trends were declined firstly then increased. The UVB treatment with two doses restrained the electron transport of PSⅡ, particularly; the inhibitory effect was biggest after treated 2 h, and then this effect was declined in 4, 6 and 8 h, so the dose-effect was existed. The UV-B radiation with two doses restricted photosynthetic rate and the inhibitory effect increased with the increase of treatment time. The high dose treatment caused huge damage to membrane system, while the result of low dose treatment was not obvious. [ Conclusion] UV-B radiation treatment had dose-effect on winter wheat seedlings in short time and the influence of high dose was bigger than that of low dose. With the increase of treatment time, the damage was alleviated; besides, the result was not similar to that of UV-B radiation in long time.

Responses of Membrane Lipid Peroxidation and Endogenous Hormones of Soybean Seedlings to UV-B Radiation and Rare Earth

[ Objective] The aim was to provide strategies for development of rare earth and control of environmental pollution. [ Method] Responses of membrane lipid peroxidation and endogenous hormones of soybean seedlings to UV-B radiation and rare earth were studied through hydroponics in laboratory. [ Result] The results showed that under irradiation of UV-B（ T1-0.15 W/m^2 and T2-0.45 W/m^2）, chlorophyll and indole-3-acetic acid（IAA） contents firstly decreased during the stress phase （1 -5 d） and then increased during the restoration phase （6 -9 d） while contents of malonadialdehyde（MDA） and abscisic acid（ABA） gradually increased during the imposition of UV-B radiation （1 -5 d） and subsequently decreased during recovery from UV-B stress （6 -9 d） . With adding of La （III） with the concentration of 20 mg · L^-1 , the decline/dse trend of chlorophyll, IAA, MDA and ABA contents was slowed down during the stress period while the rise/decline speed was accelerated during the recovery period. [ Conclusion] It suggests that the regulation of La （ III ） on membrane lipid peroxidation and endogenous hormones could increase chlorophyll and IAA contents, improve the metabolism of reactive oxygen species （ ROS）, inhibit membrane lipid peroxidation, decrease the accumulation amount of ABA and alleviate injury of UV-B radiation to soybean seedlings. Further, the protective potential of La （ III ） was better under low UV-B radiation than under high one.

The Effects of UV-B Radiation on Maize at the Seedling Stage

In this study, maize plant seedlings were grown in soilless cultures, with and without ^-B radiation at a close of 5.4 kJt（m2-d）. Three clays later, it was found that the treatment of UV-B radiation significantly reduced such characteristics as biomass, plant height, leaf area, and so on. Also, the photosynthesis of the maize was inhabited, the anti-oxid activity decreased, and the MDA concentration increased with the UV-B radiation exposure. The maize presented visible hybrid vigor under the control condition, while the hybrid vigor under UV-B radiation barely emerged in biomass, plant height, leaf area, and physiological metabolic index.

Effect of Enhanced UV-B Radiation on Seed Setting Rate and 1 000-grain Weight of Indica Hybrid Rice Restorer Lines

[Objective] This study was to investigate the effect of enhanced UV-B radiation on seed setting rate and 1 000-grain weight of hybrid rice combinations. [Method] The seed setting rate and 1 000-grain weight of 10 new sterile indica restorer lines planted in pots under enhanced UV-B radiation and fluorescent lamps （control） were respectively measured, and the differences were compared. [Result] The enhanced UV-B radiation significantly reduced the seed setting rate of indica restorer lines, and the differences between that UV-B radiation treatment and control all reached extremely significant level. In addition, the enhanced UV-B radiation reduced the 1 000-grain weight of most indica restorer lines, and compared with that of control the difference achieved significant or very significant level. However, the effect of enhanced UV-B radiation on seed setting rate and 1 000-grain weight differed to different indica restorer lines, and the differences among restorer lines tested were significant or very significant, which indicated the possibility to screen antiUV-B radiation rice materials and combinations. Finally, the indica restorer lines 09R-14, Luhui 37 and 10R-7703 which were strongly resistant to UV-B radiation were screened out. [Conclusion] This study laid foundation for breeding hybrid rice varieties resistance to UV-B radiation.

Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm(Rhodophyta),and effects of red and blue light on repair of UV-B-induced damage

We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels(0,36,72,108,144 and 180 J/m2),and thereafter subjected to PAR,darkness,or red or blue light during a 2-h repair stage,each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers(CPDs),chlorophyll a(Chl a),phycoerythrin,and UV-B-absorbing mycosporinelike amino acids(MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation(36 and 72 J/m 2) promoted the growth of C. ocellatus; however,increased UV-B radiation gradually reduced the C. ocellatus growth(greater than 72 J/m2). The MAAs(palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition,photorepair was inhibited by red light,so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase,greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore,PAR,red light,and blue light play different roles during the repair processes for damage induced by UV-B radiation.

Effects of UV-B irradiation on isoforms of antioxidant enzymes and their activities in red alga Grateloupia filicina(Rhodophyta)

Macroalgae in a littoral zone are inevitably exposed to UV-B irradiance. We analyzed the effects of UV-B on isoenzyme patterns and activities of superoxide dismutase （SOD）, peroxidase （POX）, catalase （CAT）, and ascorbate peroxidase （APX） of red algae Grateloupia filicina （Lamour.） C. Agardh. The activities of SOD, CAT, and APX changed in response to UV-B in a time- and dose-dependent manner. POX activity increased significantly under all three UV-B treatments. The enzymatic assay showed three distinct bands of SODI （Mn-SOD）, SODII （Fe-SOD）, and SODIII （CuZn-SOD） under a low （Luv） and medium （Muv） dose of UV-B irradiation, while SODI and SODIII activities decreased significantly when exposed to a high dose of UV-B irradiation （Huv）. The activity of POX isoenzymes increased significantly after exposure to UV-B, which is consistent with the total activity. In addition, a clear decrease in activity of CATIV was detected in response to all the three doses of UV treatments. Some bands ofAPX isoenzyme were also clearly influenced by UV-B irradiation. Correspondingly, the daily growth rate declined under all the three exposure doses, and was especially significant under Muv and Huv treatments. These data suggest that, although the protection mechanisms of antioxidant defense system are partly inducible by UV-B to prevent the damage, G.filicina has incomplete tolerance to higher UV-B irradiation stress.

Physiological responses of macroalga Gracilaria lemaneiformis(Rhodophyta) to UV-B radiation exposure

This paper aims to evaluate the effects of ultraviolet-Bradiation(UVBR) on Gracilaria lemaneiformis,a commercial red macroalga and an important source of agar. To study the in-vitro effect of UVBR on G. lemaneiformis,this plant was cultivated and exposed to photosynthetically active radiation(PAR) at 40 μmol photons/(m2 ·s) and enhanced UVBR(0,0.36,0.72,1.08,1.44,and 1.80 k J/(m 2 ·d)) for 13 days. The samples were processed for histochemical analysis,and the growth rate,photosynthetic pigment contents,photosynthetic performance,reactive oxygen species levels,membrane permeability,malonyl dialdehyde contents and antioxidant capacity of G. lemaneiformis were investigated. After 13 days of exposure to PAR+UVBR,G. lemaneiformis showed photodamage and photoinhibition of photosynthetic pigments(chlorophylla and phycoerythrin),leading to a decreased photosynthetic efficiency. Further,there was a corresponding decrease in the relative growth rates and depigmentation and partial necrosis of the apical segments were noted after exposure to PAR+UVBR. Additionally,UVBR induced excess production of superoxide radicals and hydrogen peroxide,eliciting a marked cellular membrane damage and antioxidative response.

Effects of Elevated Solar UV-B Radiation from Ozone Depletion on Terrestrial Ecosystems

In the last three decades much researchhas been carried out to investigate the biologicaleffects of a thinning stratospheric ozone layeraccompanied by an enhanced level of solarultraviolet-B radiation at the Earth’s surface.Enhanced UV-B radiation affects ecosystems in manyways directly and indirectly. The responses can bebiochemical, physiological, morphological oranatomical, and the direction of the response can varybetween different species, communities andecosystems. In this paper we firstly introduce generalconcepts, and methods for measuring the ecologicaleffects of UV-B radiation. Secondly, we provide anoverview interpretation of the effects of enhancedUV-B on terrestrial ecosystems from recent studies.These studies include effects of UV-B on growth andreproduction, composition of communities,competitive balance, decomposition of litter, andinteractions with other factors etc. Finally, werecommend future research directions to identify theeffects of elevated UV-B radiation on ecosystems inChina.

Effects of different light conditions on repair of UV-B-induced damage in carpospores of Chondrus ocellatus Holm

We evaluated the effects of ultraviolet-B （UV-B） radiation and different light conditions on the repair of UV-B-induced damage in carpospores of Chondrus ocellatus Holm （Rhodophyta） in laboratory experiments. Carpospores were treated daily with different doses of UV-B radiation for 48 days, when vertical branches had formed in all treatments; after each daily treatment, the carpospores were subjected to photosynthetically active radiation （PAR）, darkness, red light, or blue light during a 2-h repair stage. Carpospore diameters were measured every 4 days. We measured the growth and cellular contents of cyclobutane pyrimidine dimers （CPDs）, chlorophyll a, phycoerythrin, and UV-B-absorbing mycosporine-like amino acids （MAAs） in carpospores on Day 48. Low doses of UV-B radiation （36 and 72 J/m2） accelerated the growth of C. ocellatus. However, as the amount of UV-B radiation increased, the growth rate decreased and morphological changes occurred. UV-B radiation significant damaged DNA and photosynthetic pigments and induced three kind of MAAs, palythine, asterina-330, and shinorine. PAR conditions were best for repairing UV-B-induced damage. Darkness promoted the activity of the DNA dark- repair mechanism. Red light enhanced phycoerythrin synthesis but inhibited light repair of DNA. Although blue light, increased the activity of DNA photolyase, greatly improving remediation efficiency, the growth and development of C. ocellatus earpospores were slower than in other light treatments.

Effect of UV-B Radiation on Nitrate, Phosphate and Ammonium Uptake in Chlorella vulgaris

UV-B exposure （312 nm and 2.5 W.m^-2） caused 50 percent killing m Chlorella at lO mln and complete Killing at oo ram. Nitrate and phosphate uptakes were faster under UV-B irradiation than in fluorescent light. Short exposure of UV-B stimulated nitrate and phosphate uptakes but inhibited ammonium uptake. Ammonium uptake was inhibited upto 30 min and thereafter increased and become constant after 60 min UV-B exposure. UV-B stimulated the nitrate uptake in deficient cells. Interestingly, there was rapid stimulation of nitrate uptake in deficient medium after 30 min UV-B treatment. Darkness inhibited the uptake mechanism but the fluorescent light enhanced the rate of nitrate uptake stimulation in deficient cells of Chlorella vulgaris.

Effect of Enhanced Ultraviolet-B Radiation on Photosynthetic Pigments and Flavonoids in the Leaves of Grapevine

[Objective] The study aimed at investigating the influence of enhanced UV-B radiation on photosynthesis of grapevine.[Method] The seedlings of Cabernet sauvignon were treated with different intensities of UV-B radiation under outdoor conditions,and then the contents of photosynthetic pigments and flavonoids in leaves were determined by measuring the absorbance of leaves extracts at 663,645,470 and 300 nm,respectively.[Result] The content of photosynthetic pigments in the leaves of grapevine obviously increased with time under the treatments of different enhanced UV-B radiation.Compared with the control,the chlorophyll a,chlorophyll b,total chlorophyll and carotenoid were obviously increased by 5%,2%,4% and 3% in the enhanced UV-B radiation treatment of 10.8 μW/cm2（T1）,and in the treatment of 25.6 μW/cm2（T2） the corresponding levels were subsequently increased by 11%,9%,10% and 7% with a significant increase in the content of chlorophyll a.On the other hand,the flavonoids content in the leaves of grapevine were obviously increased by 13%,9% in T1 and T2.[Conclusion] The grapevine has strong adaptability to UV-B radiation,and appropriate enhanced UV-B radiation couldn＇t decrease the photosynthesis of grapevine leaves.