紫外线照射对黄曲霉菌产毒影响的研究

分别用照射强度373.8 mW/cm2的总紫外线,强度为60.6 mW/cm2、波长365 nm的UVA和强度7.8 mW/cm2、波长253.7 nm的UVC对黄曲霉进行照射处理,然后在避光和光照培养两种条件下继续培养,研究了不同波长紫外线照射对黄曲霉菌产毒的影响。试验结果表明:在一定条件下,各波长的最佳抑制率分别为:UVA:53%、UVC:91%、总紫外线:100%;而且在紫外照射强度相同的条件下,避光培养表现出的抑制作用强于光下培养,可能与光修复有关。     

银与光所产生的协同效应的微生物灭活现象观察

研究发现在使用紫外线(UV-A,395nm)进行照射时,银溶液对微生物的灭活作用得到增强,特别是对真核微生物的灭活作用得到显著增强。为解明这种银与光所产生的协同效应的微生物灭活机理,使用电子自旋共振仪(Electron Spin Resonance,ESR)对溶液进行检测,并采用扫描电子显微镜(SEM)以及测定线粒体酶活性等方法,推测出了其作用机理,即在光照下氧化银(Ag2O)被激活并与水分子发生反应产生羟基自由基(.OH)。羟基自由基破坏真核微生物的细胞壁,失活其细胞内线粒体酶活性,从而引起真核微生物细胞死灭。     

Skin color and nutrient photolysis: an evolutionary hypothesis

Human populations native to areas of intense sunlight tend to be heavily melanized. Previous explanations for this relationship have invoked only weak selective pressures. To test the hypothesis that dark pigmentation may protect against photolysis of crucial light-sensitive vitamins and metabolites by ultraviolet light, folate was used as a model. It was found that exposure of human plasma in vitro to simulated strong sunlight causes 30 to 50 percent loss of folate within 60 minutes. Furthermore, light-skinned patients exposed to ultraviolet light for dermatologic disorders have abnormally low serum folate concentrations, suggesting that photolysis may also occur in vivo. Deficiency of folate, which occurs in many marginally nourished populations, causes severe anemia, fetal wastage, frank infertility, and maternal mortality. Prevention of ultraviolet photolysis of folate and other light sensitive nutrients by dark skin may be sufficient explanation for the maintenance of this characteristic in human groups indigenous to regions of intense solar radiation.     

非均相UV/Fenton光催化降解土霉异味研究

[目的]探索非均相UV/Fenton光催化降解土霉异味的效果。[方法]利用离子交换方法将Fe2+负载在NaY分子筛载体上,制得催化剂FeY。在不同紫外波长照射下,利用Fenton反应降解2种土霉异味物质2-甲基异莰醇(MIB)和土腥素(Geosmin),优化pH和H2O2等降解条件,并将MIB和Geosmin添加到东湖本底湖水中进行降解。[结果]FeY的负载量为352.8 mg/g,Fe2+脱附率为5.7%。在FeY为28 mg/L,pH 6.5,H2O220 mg/L和反应60min的试验条件下,非均相UVB/Fenton体系对MIB和Geosmin的降解率分别为80.2%和84.9%。在UVA、UVB和UVC紫外光(波长分别为365、312和256 nm)条件下Photo-Fenton体系对MIB和Geosmin的降解率,随着紫外波长的降低而增大,且Geosmin降解速率常数高于MIB。湖泊水样中加入MIB和Geosmin降解表明,降解效率明显低于纯水样品。[结论]该研究制得的催化剂应用于非均相光催化体系,不仅可循环使用,而且还可扩大反应体系的pH应用范围。     

Stomatal Penetration of Wheat Seedlings by Stem and Leaf Rust: Effect of Light and Carbon Dioxide

Removal of atmospheric carbon dioxide enhanced penetration of seedling wheat by stem rust Puccinia graminis in light and dark but did not materially affect penetration by leaf rust P. recondita. A concentration of 5 percent CO(2) nearly suppressed penetration by P. graminis but not by P. recondita. Thus light may promote penetration by P. graminis through photosynthetic reduction of CO(2) within the leaf and P. recondita may penetrate independently of light because it is relatively insensitive to the effects of CO(2).     

Repair of damaged DNA in a eucaryotic cell: Tetrahymena pyriformis

Damage induced by ultraviolet light or x-rays to the DNA of a eucaryotic organism, Tetrahymena pyriformis, is repaired by a process similar to the repair system present in bacteria. This repair process, which involves defect excision and subsequent resynthesis of the damaged section of DNA, occurs in the dark. Photoreactivation of damage induced by ultraviolet light is also indicated by a reduction in observed repair synthesis. An improved method for detecting repair synthesis is described. Repair synthesis is measured in parental DNA strands isolated from cultures that have undergone normal DNA replication after the repair process.     

光照对小鼠下丘脑视上核及乳腺组织钟基因Clock表达的影响

分析光照对泌乳期小鼠下丘脑视上核(SCN)及乳腺组织内生物钟基因Clock表达的影响.采用荧光定量RT-PCR法测定不同光照条件下SCN和乳腺组织中Clock基因的昼夜表达规律.试验发现Clock基因的mRNA不但在SCN,而且在乳腺组织也具有昼夜节律性表达.在光照-黑暗交替光制下,SCN和乳腺组织Clock基因的mRNA表达的峰值相位存在约6 h的相位差;在全黑暗条件下,Clock基因的mRNA表达存在昼夜节律,SCN和乳腺组织Clock基因的mRNA表达的峰值相位基本同步.结果显示,Clock基因的昼夜节律表达具内源性特征;光照影响Clock基因mRNA的表达.     

低温、强光胁迫对螺旋藻光合速率的影响

以鄂尔多斯高原碱湖钝顶螺旋藻（S1）及非洲乍得湖钝顶螺旋藻（S2）为试验材料,采用生理学方法研究了低温、强光胁迫处理对螺旋藻光合速率的影响,及不同波长的光对胁迫处理后螺旋藻光合能力恢复的影响。结果表明：低温、强光胁迫下螺旋藻的光抑制现象十分显著,且随处理温度的降低、时间的延长,螺旋藻光合速率下降幅度加大,处理15 min 后净光合速率出现负值;处理后的样品在不同波长光下进行光合作用的恢复,蓝光的效果最显著,其次为红、黄、绿光,弱光的效果介于蓝光和红光之间,黑暗中的恢复效果最差。     

不同光照条件对斑马鱼趋光行为的影响

为探究斑马鱼(Danio rerio)在不同光照条件下的趋光行为差异,记录了6月龄的斑马鱼成鱼在紫外光(ultraviolet, UV)和可见光照射下的行为反应和在无光、紫光(420nm)、蓝光(460nm)、绿光(500nm)、黄光(585nm)和红光(620nm)6种光照条件下的趋光分布情况。结果表明,刺激光为UV时,斑马鱼优先游向黑暗环境一侧,刺激光为可见光时,斑马鱼优先游向可见光一侧;UV和可见光分别设置在试验区A和试验区B时,随着UV刺激强度增加,斑马鱼的偏好指数未呈现明显的增加趋势,UV和可见光同时设置在试验区B时,随着UV刺激强度增加,斑马鱼的偏好指数呈现出明显的下降趋势;5min和30min时斑马鱼的平均分布率均呈现红光区>紫光区>蓝光区>黄光区,绿光区的平均分布率在5min时高于红光区,在30min时介于紫光区和蓝光区之间。研究表明,斑马鱼趋向可见光而远离紫外光,表现出明显的避UV性和趋可见光性,且避UV性与趋可见光性之间存在显著的抑制作用,而无协同作用。此外,斑马鱼对红光、绿光和紫光的喜好程度较高,对黄光的喜好程度较低。研究结果可为斑马鱼视觉生态的...     

呋虫胺在有机溶剂和水中的手性稳定性

【目的】在人工氙灯光照、室内自然光照和避光培养条件下,探究呋虫胺外消旋体（Rac-呋虫胺）及其对映体（S-呋虫胺和R-呋虫胺）在甲醇、乙醇、异丙醇、乙酸乙酯、乙腈、二氯甲烷、超纯水以及β-环糊精水溶液中的手性稳定性,为大宗用量的手性新烟碱类杀虫剂呋虫胺的准确检测分析、药效和环境安全的正确评价提供依据。【方法】培养周期内分段取样,以直链淀粉-三（3, 5-二甲基苯基氨基甲酸酯）为手性固定相,正己烷/甲醇/乙醇（85/10/5, v/v/v）为流动相,柱温为30℃,流速为1.0 mL?min^-1,紫外检测波长为270 nm,进样量为20 µL,高效液相色谱/二极管阵列检测器（HPLC/DAD）进行分离分析,S-呋虫胺和R-呋虫胺的保留时间分别为8.3和9.7 min。外标法定量。【结果】人工氙灯光照、室内自然光照和避光培养条件下,S-呋虫胺和R-呋虫胺在甲醇、乙醇、异丙醇、乙酸乙酯、乙腈、二氯甲烷、超纯水以及β-环糊精水溶液中均不存在相互转化现象;配对样品t-test分析Rac-呋虫胺在每种溶剂中两个对映体的降解残留量,证实无对映体选择性降解。对映体浓度比值（EF值）为0.4746-0.5116。但在人工氙灯光照下,Rac-呋虫胺、S-呋虫胺和R-呋虫胺迅速降解,顺序为二氯甲烷＞乙腈＞乙酸乙酯≈异丙醇≈乙醇＞甲醇＞超纯水＞β-环糊精水溶液。相比水溶液,呋虫胺在有机溶剂中更容易降解,半衰期分别为3.3-3.6 h和1.2-2.3 h。光解动态符合一级动力学模型,相关系数为0.9550-0.9959。室内自然光照与避光培养条件下,Rac-呋虫胺、S-呋虫胺和R-呋虫胺在二氯甲烷、乙腈、乙酸乙酯、异丙醇、乙醇、甲醇、超纯水和β-环糊精水溶液中无明显降解,实测浓度和相对标准偏差分别为9.5-10.4 mg?L^-1,1.0%-3.2%和9.5-10.5 mg?L^-1,1.4%-2.8%。【结论】在（25±2）℃人工氙灯光照、室内自然光照和避光条件下,呋虫胺在甲醇、乙醇、异丙醇、乙酸乙酯、乙腈、二氯甲烷、超纯水以及β-环糊精水溶液中手性构型稳定,在此条件下进行定性定量分析、药效和环境安全评价是准确的。     

棉铃红粉病鉴定及气候条件对病菌生长和孢子萌发的影响

【目的】 研究新疆棉铃红粉病致病菌,分析不同温度、湿度和光照条件对该菌生长、产孢量及孢子萌发的影响。【方法】 通过对病菌的分离培养、致病性测定、形态学观察以及病原菌rDNA-ITS序列分析进行病原鉴定。设置不同温度、湿度和光照,对该菌菌落生长、产孢量及孢子萌发进行测定。【结果】 引起新疆棉铃红粉病的病原菌为Trichothecium roseum;该菌在10~35℃均可生长,生长最适温度为25℃左右,在5℃以下及40℃以上时不能生长;完全黑暗和光暗交替有利于产孢;最适孢子萌发温度为20~25℃,小于5℃或大于40℃均不能萌发;孢子在完全黑暗、完全光照和光暗交替的条件下均可萌发,完全黑暗最适萌发;80%以上的相对湿度萌发率最高。【结论】 棉铃红粉菌的致病菌是T. roseum。温度在25℃左右、完全黑暗和光暗交替有利生长和产孢;温度为20~25℃、完全黑暗、80%以上的相对湿度有利于孢子萌发。     

光周期对点带石斑鱼幼鱼生长及肝脏溶菌酶活性的影响

[目的]研究不同光周期对点带石斑鱼幼鱼生长、摄食及肝脏溶菌酶活性的影响。[方法]试验设计持续光照组、对照组、持续黑暗组,每组3个平行,计算生长率,测定肝脏溶菌酶活性,并作比较。[结果]持续光照组与其他2组相比,相对增重率与溶菌酶活性均最高,相对增重率为对照组的107.3%,溶菌酶活性为对照组的103.4%;对照组与持续光照组差异不显著;持续黑暗组显著低于对照组。[结论]点带石斑鱼幼鱼的生长、免疫及行为与光周期有紧密联系。     

Entrainment of the body temperature rhythm in rats: effect of color and intensity of environmental light

The daily rhythm in body temperature in rats was continuously monitored during exposure to low-intensity environmental illumination of various colors in the visible and near-ultraviolet spectrum. The ability of phase shifts in the lighting schedule to induce concomitant changes in the rhythm was used to determine the spectral sensitivity of the retinal photoreceptor systems mediating rhythm entrainment. Green light (lambda = 530 +/- 45 nanometers) was most potent, and red (lambda = 660 +/- 19 nanometers) and ultraviolet (lambda = 360 +/- 34 nanometers) were least potent in entraining the temperature rhythm.     

Self-trapping of dark incoherent light beams

"Dark beams" are nonuniform optical beams that contain either a one-dimensional (1D) dark stripe or a two-dimensional (2D) dark hole resulting from a phase singularity or an amplitude depression in their optical field. Thus far, self-trapped dark beams (dark solitons) have been observed using coherent light only. Here, self-trapped dark incoherent light beams (self-trapped dark incoherent wavepackets) were observed. Both dark stripes and dark holes nested in a broad partially spatially incoherent wavefront were self-trapped to form dark solitons in a host photorefractive medium. These self-trapped 1D and 2D dark beams induced refractive-index changes akin to planar and circular dielectric waveguides. The experiments introduce the possibility of controlling high-power coherent laser beams with low-power incoherent light sources such as light emitting diodes.     

EFFECT OF ULTRAVIOLET LIGHT ON POLYCYCLIC HYDROCARBONS IN STEROL SURFACE FILM SYSTEMS

Certain alkyl-1,2-benzanthracenes and other polycyclic hydrocarbons, when irradiated either in bulk aqueous suspensions or in the comparable excess phase under mixed surface films, were converted rapidly by ultraviolet light to photo-oxides. When held in two-dimensional solution or molecular association with sterols in mixed surface films at the air-water interface, the hydrocarbons were protected from such photodecomposition. In the one case where the comparison could be made photo-oxidation was accompanied by a loss of the ability of the hydrocarbon to interact with sterol films.     

光周期对白腰朱顶雀脱支酶活性的影响

将白腰朱顶雀(Carduelis flammea)分为长光组(16 h光照,8 h黑暗)、短光组(8 h光照,16 h黑暗)和对照组(12 h光照,12 h黑暗)分别驯化4周,探寻光周期对白腰朱顶雀体质量、器官质量、基础代谢率、体脂质量分数和脱支酶活性等生理生化指标的影响,结果显示:1)短光组白腰朱顶雀体质量随驯化时间的延长逐渐增加,驯化后比驯化前体质量增加了1.05 g,与对照组相比差异极显著(P0.01);长光组白腰朱顶雀体质量增加幅度不明显,驯化1~3周后涨幅较大。2)短光组白腰朱顶雀的基础代谢率在驯化2~4周的增加幅度最明显,增加量为0.38 m L/(g·h),驯化第3周至第4周结束时,短光组白腰朱顶雀基础代谢率与长光组的差异极显著(P0.01)。3)短光组白腰朱顶雀肌肉中脱支酶活性与对照组、长光组间的差异极显著(P0.01);长光组白腰朱顶雀肝脏中的脱支酶活性与对照组、短光组间的差异极显著(P0.01)。4)短光组白腰朱顶雀体脂质量分数较对照组高2.19%,长光组体脂质量分数较对照组低1.73%,短光组和长光组白腰朱顶雀体脂质量分数与对照组间的差异极显著(P0.01),短光组与长光组间的差异极显著(P0.01)。5)长光组白腰朱顶雀的消化能比短光组、对照组分别高22.71、24.69k J/g,长光组的消化能与对照组、短光组间的差异极显著(P0.01)。6)短光组和长光组白腰朱顶雀心脏、胃、肾脏、胰脏鲜质量与对照组间的差异无统计学意义(P0.05)。结果表明,光周期是影响白腰朱顶雀产热特征改变的主要环境因子之一,在短光照条件下,白腰朱顶雀通过增加体质量、提高代谢率、提高对食物的消化速率、提高肝脏和肌肉组织中脱支酶的活性来补偿能量消耗,以适应外界光周期的变化。     

中国梨木虱翅型变化及其影响因素初探

对中国梨木虱不同月份和不同光周期下的翅型变化进行研究.结果表明,梨木虱翅型随月份发生明显变化,5—9月为短翅型,10月至次年4月为长翅型.恒温20℃条件下,短光周期(9 h光/15 h暗、8 h光/16 h暗)可诱导产生长翅型,而长光周期(12 h光/12 h暗,10 h光/14 h暗)可诱导产生短翅型.短光周期下长翅...     

Ultraviolet irradiation of DNA in vitro and in vivo produces a 3d thymine-derived product

A new thymine-derived product was separated from DNA irradiated with utlraviolet light in vitro and in vivo. This compound was mistaken to be thymine homodiner (T=T) by other workers because it is chromatographically indistinguishable from T=T in most eluents. It has absorbancy maximums at 312, 312, and 300 millimicrons in neutral, pH 2, and pH 11 aqueous solutions, respectively. When it is irradiated in aqueous solution with wavelengths of 360 and 313 millimicrons its spectrum reverts to one similar to that of thymine. Therefore, at least three thymine-derived products can be detected in ultraviolet irradiated DNA, namely the homodimer, a material with absorbancy maximum at 312 millimicrons, and a "minor" product suggested by others to be a dimer of cytosine and thymine. In cells, the latter two are formed in aboult equal amounts. While these three products were shown to exist in the acid hydrolyzates of ultraviolet irradiated DNA, a material with absorbancy maximum at about 310 millimicrons was demonstrated to form in ultraviolet irradiated DNA without further treatment. The magnitude of this spectral increase varied directly with the incrcase in the adenine-thymine contents in the DNA as shlown by differential transmittance spectra of the irradiated Micrococcus lysodeikticus, calf thymus, Bacillus cereus, and Hemophilus influenzae DNA.     

Contribution of Ultraviolet Irradiance Variations to Changes in the Sun's Total Irradiance

The sun's total irradiance decreased from 1980 to mid-1985, remained approximately constant until mid-1987, and has recently begun to increase. This time interval covered the decrease in solar activity from the maximum of solar cycle 21 to solar minimum and the onset of cycle 22. The sun's ultraviolet irradiance also decreased during the descending phase of cycle 21 and, like the total irradiance, is now increasing concurrently with the increase in cycle 22 activity. Although only 1 percent of the sun's energy is emitted at ultraviolet wavelengths between 200 and 300 nanometers, the decrease in this radiation from 1 July 1981 to 30 June 1985 accounted for 19 percent of the decrease in the total irradiance over the same period.     

Vision in annelid worms

In a first electrophysiological study of worm vision, electroretinograms were measured in two alciopid worms: Torrea, taken at the surface, and deep-sea Vanadis. Both forms possess a primary retina in the focal plane of the lens, and accessory retinas lying beside the lens. Such accessory retinas occur also in deep sea fishes and cephalopods. In Torrea the primary retina peaks in sensitivity at 400 nanometers, the secondary retina at 560 nanometers. Both together could serve as a depth guage, since 560 nanometers attenuates much faster in seawater than 400 nanometers. The Vanadis eyes peaked in sensitivity at 460 to 480 nanometers, a property shared with deep-sea forms of other phyla; and appropriate, since these wavelengths penetrate seawater most deeply, and also are the wavelengths of maximum bioluminescence.