Physiological and ultralstructural changes of Chlorella sp. induced by UV-B radiation

In order to investigate the mechanisms of enhanced UV-B radiation on algae, the effects of UV-B radiation on the physiological and ultrastructural changes of Chlorella sp. were examined. The results showed that UV-B radiation could inhibit the growth and photosynthesis of microalgae. UV-B radiation at lower doses increased the photosynthetic pigment (chlorophyll a (Chla) and carotenoid (Car)) contents, while at higher doses of UV-B radiation Chla and Car contents were decreased. The ultrastructure of Chlorella sp. without exposure to UV-B showed that the thylakoid lamellae were clear and regular, the stroma of its chloroplast was apparent and clear. The globules with photosynthetic pigments and the cristae of mitochondria were clearly seen. After exposure to UV-B radiation at dose of 2.88 kJm2, the thylakoid lamellae of Chlorella sp. were lost and dissolved, the globules which contained photosynthetic pigments in chloroplast were bleached; some mitochondria cristae were dissolved; slight plasmolysis was found in some Chlorella sp. cells. After exposure to 5.76 kJm2 UV-B radiation, the thylakoid was in disarray and disintegration, plasmolysis was found in most cells, and the cell wall was broken and began to fall out. Many blank areas were observed in cells, mitochondria were seriously deformed and most of the mitochondria cristae were dissolved. Also, globules containing photosynthetic pigments in chloroplast were bleached and some empty globules were found in chloroplast. Therefore, UV-B radiation could damage cell structure of Chlorella sp., and this damage increased with the dose of UV-B radiation they exposed to.     

短期增补UV-B辐射处理对美丽风毛菊光合色素和紫外吸收物质的影响

以中国科学院海北高寒草甸生态系统定位研究站地区的美丽风毛菊为材料,通过短期增补UV-B辐射的模拟试验,研究了叶片光合色素和紫外吸收物质含量对增强UV-B的响应.不同处理天数的取样分析表明,与对照UV-A相比,增补UV-B＋UV-A处理时光合色素有增高的趋势,紫外吸收物质含量也略有增高.说明高山植物叶片中丰富的黄酮类物质能有效保护光合机构,短期内UV-B辐射强度的增加所加剧的色素光氧化现象并不严重,受叶片增厚的影响单位叶片面积的光合色素含量有增加趋势.     

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.     

增强UV-B辐射对水稻叶绿素荧光参数的影响

为探讨UV-B辐射对水稻光合作用的影响,本研究采用增强紫外线-B(UV-B,16 kJ/m2·d和40kJ/m2·d)辐照"两优培九"水稻幼苗,测定叶片的叶绿素含量、Ca/Cb以及反映植物光系统Ⅱ(PSⅡ)的荧光参数值,分析UV-B处理后水稻叶片中的叶绿素含量、Ca/Cb及荧光参数值变化情况以及对水稻叶绿体荧光参数及光合作用的影响.结果表明,经UV-B处理后,水稻叶片中的叶绿素含量、Ca/Cb及荧光参数值(除qN以外)低于对照组(CK),差异显著(P0.05).其中荧光参数Fv/Fm(PSⅡ最大光化学量子产量)是对环境胁迫反映最为敏感的一个指标.低剂量UV-B处理组原初光能转化指标差异不显著,高剂量UV-B处理组原初光能转化指标差异显著.说明高剂量的UV-B导致了水稻荧光特性减弱,光合作用受损.     

Cr~(6+)、As~(3+)污染对黑藻叶细胞伤害的超微结构研究

电镜观察发现 ,黑藻 (Hydrillaverticillata(L .F .)Royle)叶细胞遭受Cr6+ 、As3 + 毒害初期 ,高尔基体消失 ,内质网膨胀后解体 ,叶绿体中的类囊体和线粒体中的脊突膨胀 ,核中染色质凝集 .随着叶细胞毒害程度的加重 ,核仁消失 ,核膜破裂 ,叶绿体和线粒体解体 ,质壁分离使胞间连丝拉断 ,最后细胞死亡 .结果表明 :Cr6+ 、As3 + 对细胞的膜结构与非膜结构都产生毒害作用     

藻类对UV-B增强的响应及其分子基础(综述)

随着臭氧层破坏的日益严重,紫外线（ＵＶＲ）对环境的影响越来越引起人们的重视,本文探讨了ＵＶ－Ｂ增强对藻类的影响机制及藻类对ＵＶ－Ｂ的适应机制,ＵＶ－Ｂ对藻类有明显的伤害作用,损伤的主要目标是蛋白质、ＤＮＡ和光合色素等物质;同时,藻类对ＵＶ－Ｂ也有一定的适应能力,其适应的方式主要是逃避,屏障、损伤修复等,当损伤和修处于一种平衡状态时,不会显现受伤迹象,只有当损伤超出修复能力时,才会表现受伤症状。     

Z-QS01菌株对小球藻的生态学效应及对UV-B辐射的响应

利用生态毒理学方法研究了小球藻共栖Z-QS01菌株的生态学效应及对UV-B辐射的响应.结果表明:Z-QS01菌株通过分泌化学物质实现自我行为调节和对小球藻的抑制效应,Z-QS01菌株的密度和分泌到培养液中的化学物质的浓度是启动调节机制的必要条件;UV-B辐射增强显著影响Z-QS01菌株的群感效应,随UV-B辐射剂量的增加,Z-QS01菌株对小球藻的抑制效应降低.实验数据可为水产养殖业生态防病提供参考,并为揭示藻菌间相互作用机制提供有价值的参考资料.     

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.     

紫外辐射对3种叶色生菜生长及营养品质的影响

 在设施温室条件下,水培盆栽3 种叶色生菜,探究UV-B、UV-A 辐射对不同叶色生菜光谱吸收特性、生长和品质的影响。结果表明,不同UV 处理及对照下的3 种叶色生菜光合色素吸光曲线基本一致,330~500 nm 和640~690 nm 两个光谱区为峰值区域,吸光度较大且变化剧烈,在500~640 nm 和690~800 nm 两个光谱区吸光度很小且变化幅度小。绿叶生菜在不同UV 辐射下与对照无显著差异,红叶生菜在UV 照射下叶绿素a 和总光合色素含量显著提高,但紫叶生菜仅在UV-B 照射下比对照显著增加。绿叶生菜经UV 辐射处理后,地上部分鲜重显著降低,紫叶生菜相反。红叶生菜地上部分鲜重在不同UV 辐射处理下无显著差异。3 种生菜地上部分干重随UV 辐射处理变化规律相似,经UV 辐射处理后,地上部干重均显著降低。UV 辐射处理显著降低了绿叶生菜总酚含量,但对紫叶生菜无显著影响,红叶生菜仅在UV-B 处理下总酚含量显著提高。绿叶生菜在UV 辐射处理下,类黄酮含量比对照显著降低,而红叶生菜和紫叶生菜无显著差异。经UV 辐射处理的绿叶生菜花青素含量与对照无显著差异,红叶生菜和紫叶生菜则在UV-B 辐射处理下有显著提高。UV 辐射处理显著提高了绿叶生菜可溶性糖含量,紫叶生菜仅在UV-A照射下可溶性糖含量显著提高,而红叶生菜经UV 辐射处理后可溶性糖含量显著降低。     

田间条件下UV-B辐射增强对大豆叶片相关反射光谱指标的影响

本实验在室外大田条件下,模拟紫外线-B(UV-B)辐射增强条件,研究了两种不同辐射剂量对花期大豆叶片相关反射光谱指标的影响。结果发现,两种剂量的UV-B辐射处理导致叶绿素相对含量、光化学植被指数(PRI)和叶片相对水含量均显著降低,但未见剂量效应;导致花青素相对含量显著升高,且存在剂量效应;高剂量的UV-B处理导致类胡萝卜素相对含量显著升高,而低剂量UV-B处理下未见显著影响;对植物衰老反射指数(PSRI)则均无显著影响。实验表明不同剂量的UV-B辐射能诱导紫外防护色素花青素含量和类胡萝卜素含量增加,但均显著抑制了大豆叶片的叶绿素相对含量、PRI和叶片含水量,最终使得光合作用受到抑制。     

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.     

Effects of solar ultraviolet radiation on the photochemical efficiency, photosynthetic pigments and biomass production of Spirulina platensis

Effects of solar ultraviolet radiation (UVR) on Spirulina platensis were studied by investigating its photochemical efficiency, photosynthetic pigments and biomass production while exposed to full spectrum solar radiation or depleted of UVR for understanding how and to what extent UVR influences its photosynthe tic physiology and production. It was found that UVR brought about an extra inhibition of photochemical efficiency by 26%—30%. The greatest inhibition of pho tochemical efficiency in S. platensis was observed at noontime, and then recovered to some extent in late afternoon no matter which treatment they were exposed to. The contents of chlorophyll a, phycocyanin and carotenoids increased during initial stage of the exposure, but decreased with elongated exposure. UVR decre ased the biomass yield by about 6%. It indicated that filtering out UVR of solar radiation would raise the productivity of S. platensis, which is an important factor that should be considered in the production.     

He-Ne激光和增强UV-B辐射对小麦幼苗氮代谢的影响

为研究He-Ne激光对增强UV-B辐射后损伤的修复作用,采用5 mW.mm-2He-Ne激光辐照、10.08 kJ.m2.d1的UV-B辐射及二者组合对舜麦1718号小麦幼苗进行处理,测定各处理组小麦幼苗硝酸还原酶活性、一氧化氮合成酶含量和膜透性的变化.分析结果显示:He-Ne激光辐照可使UV-B辐射后小麦幼苗硝酸还原酶活力升高1.2倍,显著改善了增强UV-B辐射后硝酸还原酶活性降低的程度;而一氧化氮合成酶(NOS)含量B组和BL组分别高于CK组45.1%和17.8%,现促进作用.     

稻瘟病菌对水稻PS Ⅱ的影响研究

采用在分蘖期接种稻瘟病菌,研究稻瘟病菌不同生理小种对水稻叶片光合色素和叶绿素荧光参数的影响.结果表明水稻接种稻瘟病菌孢子后,叶片出现不同程度发病,光合色素含量下降,叶片的Fv/Fm,Fv/F0,F′v/F′m,ΦPS Ⅱ,qP,qN,ETR和α较对照均显著降低.不同水稻品种对稻瘟病菌的敏感程度不同,R725接种ZA5后,叶片细胞结构遭到破坏,光合色素含量大幅下降,叶瘟发生最重;R720接种ZC8后发病最重,叶绿素a(Chla)和类胡萝卜素(Car)含量大幅下降,Fv/F0和ΦPS Ⅱ等叶绿素荧光参数也显著低于对照;R727接种ZG1后发病最重,光合色素显著下降,叶绿素荧光参数Fv/Fm,qP,ΦPSⅡ,ETR,qN和α也显著低于对照.     

Effect of CO2 increase in atmosphere and UV-B intensification on Nostoc commune photosynthetic pigment and UV-B masking materials

Using Nostoc commune as experiment target,the effect of CO 2 with different concentrations in atmosphere and dosage of UV-B on photosynthetic pigment chlorophyll a (Chl a),carotenoids,phycoerythrin,phycocyanin,allophycocyanin and UV-B masking materials was studied.The results showed that high dosage of UV-B radiation inhibited the synthesis process of Chl a,phycoerythrin,phycocyanin and allophycocyanin,but promoted the synthesis of carotenoids,MAAs and scytonemin,thus the negative effect produced by UV-B radiation was reduced and the resistance of Nostoc commune against UV-B radiation was enhanced.     

金叶银杏叶色变化特性分析

【目的】金叶银杏为银杏(Ginkgo biloba L.)的1个芽变品种,具有独特的叶色性状及较高的观赏价值和药用价值。通过观察分析金叶银杏实生苗叶色变化特性,为选育更优良的品系及推广利用提供理论依据。【方法】以来自湖北安陆的1年生金叶银杏实生苗为材料,在对叶形、叶色观察的基础上,应用X-Rite色差仪测定叶色参数L ^*、a ^*和b ^*值,计算出反应色彩变化的彩度C ^*和色相角h,测定其色素含量及光合特征参数,并对各指标进行相关性分析。【结果】金叶银杏叶形主要为扇形,叶色4—5月为金黄色,6月开始转绿,先为浅黄绿色,直至深绿,10月底后再次变黄。色差参数L ^*维度方向上,大部分位点集中在中间位置(L ^*值为50~65),a ^*值主要集中在负值区域,b ^*维度方向位点整体呈现上移趋势。色素含量的年变化中, Chla(叶绿素a)、Chlb(叶绿素b)、ChlT(总叶绿素)的含量变化趋势相似,呈现“下降—上升—下降”的规律,且色素含量之间基本达到极显著差异(P<0.01)。Car(类胡萝卜素)含量变化呈现“下降—升高”趋势。ChlT/Car(总叶绿素与类胡萝卜素质量之比)与ChlT的变化趋势相似,Chla/b(叶绿素a与叶绿素b质量比)的变化呈现波动下降。Chla和Chlb均与色差参数L ^*、a ^*、b ^*和C ^*呈负相关,与h则为极显著正相关。Car与色差参数a ^*呈显著正相关,与b ^*呈极显著正相关。P_n(净光合速率)、G_s(气孔导度)的日变化均表现为明显的双峰,T_r(蒸腾强度)在13:00前处于较高水平,15:00后急剧下降。C_i(细胞间隙CO₂浓度)的日变化呈“W”形,即一天之内出现两个低谷,分别在11:00和15:00。P_n与Chla、Car含量呈显著负相关,与Chla/b呈显著正相关。其他光合特征值与色素含量的相关性不明显。【结论】1年生金叶银杏叶形主要为扇形,叶色在4—5月为金黄色,6月逐渐变绿色,10月时变黄。色差参数在4—5月,高亮度单株增加,各单株绿色变浅,随时间推移,黄色加深。相关性分析表明,色素含量与叶色密切相关。     

The photodamage process of pigments and proteins of PSI complexes fromSpinacia Oleracea L.

Purified PSI complexes fromSpinacia Oleracea L. were exposed to the strong light (PFD=2300 μmol m⁻²s⁻¹) for various period. Along with the illumination the photo-damage process of pigments and proteins of PSI complexes was investigated using absorption, fluorescence, circular dichroism (CD) spectroscopy and SDS-PAGE. It was found from the optical absorption spectra that the maximal absorbance of PSI complexes decreased and maximal peaks blue-shifted during the illumination, and the forth derivative spectra demonstrated that the absorbance decreasing at red region mainly resulted from the aborbance decreasing of the long wavelength Chla, implying that the long-wavelength Chla was readily to be bleached. The CD signals contributed by LHCI decreased more rapidly than other CD signals contributed by Chla and Carotenoid, indicating that the LHCI was more sensitive to light than core complexes. It was observed by SDS-PAGE that some small polypeptides of PSI complexes were damaged earlier than reaction center proteins PsaA and PsaB. Lhca3, Lhca2 and PsaD were the early degraded proteins during illumination. In addition, it is also observed that the insoluble-cohesive-denatured proteins appeared after prolonged illumination.     

唐古特虎耳草叶绿体和线粒体超微结构的研究

通过对生长在青藏高原东北部高海拔地区的唐古特虎耳草（Ｓａｘｉｆｒａｇａｔａｎｇｕｔｉｃａ）叶绿体和线粒体超微结构的分析表明：叶绿体长度缩短,厚度增加,局部有损伤,基粒垛叠程度小,类囊体有肿胀现象。线粒体的形态由棒状变为球状,被膜不整齐,局部有损伤,嵴的数目少而且有肿胀现象。这些特征的出现,是与青藏高原强辐射,低气压,高寒的生态环境密切相关。     

psbA genes indicate common ancestry of prochlorophytes and chloroplasts

It has long been suspected that chloroplasts evolved after an endosymbiotic event involving a photosynthetic prokaryote, presumably a cyanobacterium, and a eukaryotic organism. Recent studies have provided strong evidence about the cyanobacterial nature of chloroplasts. Since the discovery of prochlorophytes, oxygen-evolving photosynthetic prokaryotes containing chlorophyll a and chlorophyll b and lacking phycobiliproteins, there has been speculation that these represent evolutionary intermediates between cyanobacteria and chloroplasts. Prochloron sp., the first described prochlorophyte, proved difficult to work with because it is an obligate symbiont of marine ascidians. Prochlorothrix hollandica, a recently isolated, freshwater filamentous prochlorophyte, is easily maintained in the laboratory. Overall pigment composition and thylakoid membrane structure of P. hollandica suggest it has intermediate characteristics between cyanobacteria and the chloroplasts of higher plants. The P. hollandica psbA genes, which encode the photosystem II thylakoid protein D1, were cloned and sequenced and the sequences compared to those reported for cyanobacteria, a green alga, a liverwort, and several higher plants. The two psbA genes present in P. hollandica encode an identical amino-acid sequence. As in all chloroplast psbA genes, there is a seven amino-acid gap near the C terminus of the derived protein relative to the protein predicted by cyanobacterial genes, suggesting that P. hollandica is part of the lineage that led to chloroplasts after a divergence from cyanobacteria. This hypothesis is also supported by phylogenetic analysis of derived D1 amino-acid sequences from psbA genes of thirteen taxa on the basis of parsimony.     

Combined effects of solar UV radiation and CO2-induced seawater acidification on photosynthetic carbon fixation of phytoplankton assemblages in the South China Sea

We carried out short term pCO₂/pH perturbation experiments in the coastal waters of the South China Sea to evaluate the combined effects of seawater acidification (low pH/high pCO₂) and solar UV radiation (UVR, 280–400 nm) on photosynthetic carbon fixation of phytoplankton assemblages. Under photosynthetically active radiation (PAR) alone treatments, reduced pCO² (190 ppmv) with increased pH resulted in a significant decrease in the photosynthetic carbon fixation rate (about 23%), while enriched pCO₂ (700 ppmv) with lowered pH had no significant effect on the photosynthetic performance compared to the ambient level. The apparent photosynthetic efficiency decreased under the reduced pCO₂ level, probably due to C-limitation as well as energy being diverged for up-regulation of carbon concentrating mechanisms (CCMs). In the presence of UVR, both UV-A and UV-B caused photosynthetic inhibition, though UV-A appeared to enhance the photosynthetic efficiency under lower PAR levels. UV-B caused less inhibition of photosynthesis under the reduced pCO₂ level, probably because of its contribution to the inorganic carbon (Ci)-acquisition processes. Under the seawater acidification conditions (enriched pCO₂), both UV-A and UV-B reduced the photosynthetic carbon fixation to higher extents compared to the ambient pCO₂ conditions. We conclude that solar UV and seawater acidification could synergistically inhibit photosynthesis.