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strong light    
相关语句
  强光
    Effects of Strong Light and Exogenous Active Oxygen Species on Chlorophyll Fluorescence in Lettuce
    强光及外源活性氧对莴苣叶绿素荧光的影响
短句来源
    Effects of Strong light Stress at Low Temperature on Structure and Function of Photosystem Ⅰ from Wheat ( Triticum aestivum L.) Leaves
    低温下强光胁迫对小麦叶片光系统Ⅰ结构与功能的影响
短句来源
    2. The effects of strong light on the structure and function of CP43 and CP47Strong light (1000 mol E./m2.s) was found to bring about considerable bleaching of chlorophyll a and degradation of protein, but they were inhibited obviously by sodium thiosulfate.
    2.强光照射对CP43结构和功能的影响强光(10001及蛋白质的降解,pmol E./m“.5)可以引起eP43中ehl这种作用明显地被连二亚硫酸钠抑制。a的漂白同样条件下,p一Car的光吸收几乎不受光破坏的影响。
短句来源
    Besides, ABS/RC and DIq/RC increased significantly after strong light treatment and the increasing extent of samples with Na+ addition was lower than those without Na+ addition.
    此外,强光处理过程中Synechocystis sp.898的F_v/F_m和ET_o/RC值急剧下降,加有Na~+的样品的下降幅度低于不加Na~+的样品:而强光处理使ABS/RC和DI_o/RC的值显著升高,加有Na~+的样品的上升幅度低于不加Na~+的样品。
短句来源
    The results showed that there are certain differences of sensibility in response to natural strong light or photooxidation between C3 and C4 plants.
    结果表明C_3和C_4植物对自然强光或光氧化作用响应的敏感性存在一定的差别.
短句来源
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  强光下
    20mg/L rutin treatment served as protection by increasing the maximal quantum yield of photosystemⅡ(Fv/Fm) and actual quantum yield of photosystemⅡ(ΦPSⅡ) of shade plants (Spathiphyllum floribundum and Aglaonema modestum),relieving photoinhibition under strong light.
    20mg/L芦丁(rutin)处理提高了阴生植物白掌(Spathiphyllumfloribundum)和万年青(Aglaonemamodestum)的PSⅡ最大光化学量子产量(Fv/Fm)、PSⅡ光化学能量转换的有效量子产量(ΦPSⅡ),减轻了它们在强光下的光抑制,起到了一定的光保护作用。
短句来源
    In strong light, the inhibition of nitrogenase activity in response to NH_4~+ was delayed.
    被氨抑制了的固氮活性在强光下较在弱光下提前解抑。
短句来源
    The antioxidants DABCO, mannitol, ascorbate and histidine protected the leaves, but weakly, from strong light.
    抗氧化剂DABCO、甘露醇、抗坏血酸和组氨酸对强光下的大豆叶片有保护作用,但这种保护作用不强。
短句来源
    The results suggested that photoinhibition did take place in soybean leaves under strong light, and it was related to active oxygen in vivo .
    据此推测,在强光下大豆发生了光抑制,光抑制的发生与活性氧的存在有一定的关系
短句来源
    The results showed that the diurnal variation of apparent photosynthetic quantum efficiency (AQY) and the photochemical efficiency (Fv/Fm) of photosystem Ⅱ (PSⅡ) of the same plant or the different plant leaves in noon in Qinghai and Shanghai were lower than morning on bright days under strong light,the diurnal variation of AQY and Fv/Fm of PS Ⅱ measured the declining extent in Shanghai were bigger than Qinghai.
    结果表明,两地在晴天强光下,中午植物叶片光系统Ⅱ(PSⅡ)的光化学效率(Fv/Fm)和表观光合量子效率(AQY)的日变化比早晨低; 上海测定PSⅡ的Fv/Fm和AQY的日变化比青海的下降幅度大。
短句来源
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  强光照
    Under 12h weak light and 12h strong light illuminance the callus produced early and grown well.
    12h弱光照和12h强光照条件下的剑麻愈伤组织启动快,生长好,24h光照和黑暗处理不利于剑麻愈伤组织的诱导和生长。
短句来源
    The inhibition of co_2 assimination rate could return if the time of strong light shining is less than four hours.
    4小时以内的强光照对西洋参光合CO_2同化率的抑制是可以恢复的。
短句来源
    Using Dullaliella Salina under different light conditions and determinating the quantity of chloroplast matrix protein,the authors find that the quantity of chloroplast matrix protein is 26.40g/L in weak light while 11.50g/L in strong light.
    以不同光照条件下生长的盐生杜氏藻为材料,通过测定叶绿体基质蛋白的含量发现,在低光照下叶绿体基质蛋白的含量为26.40g/L,而在强光照下叶绿体基质蛋白为11.50g/L。
短句来源
    The results showed that the rutin treatment could alleviate photoinhibition under strong light and protect photosynthetic apparatus from strong light impairment.
    结果表明,在长时间的强光照环境下,20 mg/L芦丁溶液培养可以减轻白掌所受到的强光抑制,同时也减轻了强光照对植物体的伤害.
短句来源
  强光
    Effects of Strong Light and Exogenous Active Oxygen Species on Chlorophyll Fluorescence in Lettuce
    强光及外源活性氧对莴苣叶绿素荧光的影响
短句来源
    Effects of Strong light Stress at Low Temperature on Structure and Function of Photosystem Ⅰ from Wheat ( Triticum aestivum L.) Leaves
    低温下强光胁迫对小麦叶片光系统Ⅰ结构与功能的影响
短句来源
    2. The effects of strong light on the structure and function of CP43 and CP47Strong light (1000 mol E./m2.s) was found to bring about considerable bleaching of chlorophyll a and degradation of protein, but they were inhibited obviously by sodium thiosulfate.
    2.强光照射对CP43结构和功能的影响强光(10001及蛋白质的降解,pmol E./m“.5)可以引起eP43中ehl这种作用明显地被连二亚硫酸钠抑制。a的漂白同样条件下,p一Car的光吸收几乎不受光破坏的影响。
短句来源
    Besides, ABS/RC and DIq/RC increased significantly after strong light treatment and the increasing extent of samples with Na+ addition was lower than those without Na+ addition.
    此外,强光处理过程中Synechocystis sp.898的F_v/F_m和ET_o/RC值急剧下降,加有Na~+的样品的下降幅度低于不加Na~+的样品:而强光处理使ABS/RC和DI_o/RC的值显著升高,加有Na~+的样品的上升幅度低于不加Na~+的样品。
短句来源
    The results showed that there are certain differences of sensibility in response to natural strong light or photooxidation between C3 and C4 plants.
    结果表明C_3和C_4植物对自然强光或光氧化作用响应的敏感性存在一定的差别.
短句来源
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  strong light
Low temperature cathodoluminescence spectrum measured in response to spot excitation of wire region showed a strong light emission whose analysis indicated that it originates from InGaAs ridge quantum wire itself.
      
Self-modulation and nonlinear diffraction of strong light fields in dispersive media
      
The parametric striction excitation of acoustic oscillations in droplets under the influence of a strong light wave is examined.
      
This Y-junction device, unlike other adiabatic Y-junctions, has the advantage that it may be directly written into a planar medium with homogeneous saturable nonlinearity by a strong light beam.
      
In this range, strong light scattering is observed, which shows that the helium density fluctuates on a microscopic scale.
      
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The city of Lanehow lies in the central part of China in latitude approximate 36°03′north, longitude 103°57'east, at elevation 1,508.53 M. Kowlanshan, the area surveyed, being one of the many loess plateau hills surrounding Lanchow, situates on the southeastern suburb of the city. Physiographically, the area is a part of the dissected loess plateau with an altitude of 1,508-2100 M. Owing to the influences of the geographical condition and high elevation, the climate of this area is of continental climatic type....

The city of Lanehow lies in the central part of China in latitude approximate 36°03′north, longitude 103°57'east, at elevation 1,508.53 M. Kowlanshan, the area surveyed, being one of the many loess plateau hills surrounding Lanchow, situates on the southeastern suburb of the city. Physiographically, the area is a part of the dissected loess plateau with an altitude of 1,508-2100 M. Owing to the influences of the geographical condition and high elevation, the climate of this area is of continental climatic type. The mean annual precipitation is 338.6mm. with 61.1% of it falling in June, July and August, annual mean temperature, 6.9℃., relative humidity, 58%, annual total evaporation, 3,571mm. and annual mean wind velocity 5.8m/sec. The upper portion of the hill is entirely covered with a thick layer of loess and underneath lies the red earth of the tertiary period. As a result of that, soils in the area surveyed, which has been developed from the loess, is high in calcium content. It belongs to the chestnut soil type with a PH value between 7.6 and 8.1. The vegetation of this area shows the following ecological characteristics: 1) The specific composition of the plant is rather scanty with about. 124 speeies belonging to 93 genera and 41 families; 2) The vegetation bears a simple physiognomy. No natural growth arbor been found in the whole area during the period of investigation, though a few species of cultivated trees are found and the vegetation is mainly composed of semi-frutexes and herbages; 3) Most of the essential species distributing here express distinct xeromorphic structures and many of them are typical components of the vegetation of the steppe and semi-dessect, such as Caragana spp., Hololachne soongarica Ehrenb., Artemisia spp., Chrysanthemum neofruticulosum Ledeb., Stipa spp. Achnatherum splendens Ohwi. and so on. Four plant associations are found in this area. Three of them distribute on the Dorthern slope and one on the southern slope of the hill. They are described as follow: Ⅰ. Chenupodium album+Artemisia annua+Elymus dasystachys Association. The distribution of this association is limited to the erosion valleys situating on the piedmont belt of the northern slope at an elevation between 1, 510 and 1, 560 M., where the edaphic condition is marked by high soil moisture content. The climatic features are of low light intencity with short duration of daily sunshine, high relative humidity and low wind velocity. Three hygrophilous and shade-loving species are the main constituents of this association. They are chenopodium album L., Artemisia annua L., and Elymus dasystachys Trin. Other herbaceous plants are Chenopodium glaucum L.. Sonchus aler- aceus L., Xanthium strumarium L., Polygonum amphibium L., P. aviculare L. etc. A few shrubs are present in the association. They are Lycium chinensis Mill., Lonicera heteroloba Batal. and Lonicera ferdinandi Fr. Ⅱ. Artemisia pectinata Association. The Artemisia pectinata Association occurs on the piedmont belt of the northern slope at an elevation varying from 1510 to 1580 M. It occupies the open slope with gradients under 15°. The climatic conditions, in speaking of the northern slope, are rather high in temperature, strong light intencity, low relative humidity and low wind velocity. The projective total cover-degree is about 50% and Artemisia pectinata Pall. appears to be the dominant species in the association. Besides, there are species of thermophilous and heliophilous plants such as Salsola kali L., S. arachnoides‘Moq’. Kung, Cymbaria mongolica Maxim., Artemisia capillaris Thumb., Aster altaicus willd., chrysanthemum neofruticulosum Ledeb., which are frequently scattered among the dominant plants. Plants growing in this association, are all below 10 cm. in height. They give an appearence of open association. Ⅲ. Chrysanthemum neofruticulosum+Artemisia sacrorum var. latiloba—Polytrichum sp. Association. This association, being the largest one in the surveyed area, appears on the northern slope, where it occupies the space ranging from altitude 1,580M. to the top of the hill,2,100M, above the sea level. Soil is of chestnut soil type with a PH value of 8. 0—8. 1.The soil moisture content varies between 6.0 and 7.4%(layer above 60 cm.). In vertical structure, the association consists of two strata. They are described below: Stratum Ⅰ: This stratum includes all shrubs, semi-frutexes and herbages which are taller than 10 cm. in height. Among the plants found in this stratum, chrysanthemum neofruticulosum Ledeb. and Artemisia sacrorum var. latiloba Ledeb. are dominant species and Stipa Bungeana Trin. is the subdominant one. Other species one may frequently meet with are Allium subangulatum Rag., Saussurea nigrescens Maxim., Peganumharmala L., Astragalus dahuricus Dc., Potentilla multifida L., Linum perenne L., Car-agana frutex K. Koch. etc. They spread widely in almost all over the association. Stratum Ⅱ: This stratum is composed of those species less than 10 cm. in height, forming the ground flora of the association. Polytrichum sp. and Lichens are the essential plants in the stratum. One may occasionlly find species of Plantago Lessingii and Gentiana squarrosa Ledeb. growing among those main constituents. The underground stratification of the association has also been studied during the time of surveying. IV. Stipa Bungeana+Aster altaicus+Chrysanthemum neofruticulosum Association. This association distributes on the entire southern slope except the portions tilled for agriculture purposes. The striking local ecological conditions of this association are strong light intensity with long duration of daily sunshine, high temperature, low relative humidity and extremely low in soil moisture content which ranges between 2. 7 and 4. 0% (the layer above 60cm.). On account of the severe destruction of natural vegetation by man and cattle in the past years, the degree of soil erosion is serious throughout the slope where the association locates. The PH value of the soils is 7.4-76. The polydominant plants in this association are Stipa Bungeana Trin., Aster altaicus Willd. and Chrysanthemum neofruticulosum Ledeb. They are quite adaptable to the drought condition of the environment and distribute widely in the association. Besides, other xerophilous or drought resistant plants are frequently met, such as Hololachne soongarica Ehrenb., Linum perenne L., Astranalus dahuricus Dc., Peganum harmala L., Artemisia sacrorum var. latiloba Ledeb., Artemisia capillaris Thumb., Incarvillea Iutea Bur.&Franch., Kochia scoparia Schred. etc. They dispersely grow in the association. In addition to the frequent species mentioned above, Salsola ruthenica Iljin. and S. arachnoides‘Moq’. Kung form seperately micro-associations lying scatterly on the slope. No ground flora stratum may be found and the association shows no above ground stratification. The projective total cover-degree of this association is only about 25-30%. Owing to the difference in the aspects of the northern and sourthern slopes, the climatic and edaphic conditions vary remarkable. Therefore, the vegetation of the surveyed area shows distinctions in distribution, floristic composition, physiognomy, structure, condition in growth and development of plants in the association of different slopes. Taking the floristic composition for example, the following species are entirely absent in the association of the northern slope, yet they are main components on the southern one: Pappophorum brachystachyum Taub. et Spach, Thermopsis lanceolata R. Br., Caragana spinosa Dc., Stellera chamaejasme L., Hololachne soongarica Ehrenb., Nitraria schoberi L., Pennisetum flaccidum Griseb. Differences in elevation also induce striking changes in climatic and edaphic con-ditions especially in aspects of air temperature, relative humidity and soil moisture content. All these gives great influence to the alterations either in quantity or in quality of each species distributing along the northern slope of the area. Following the seasonal change, the physiognomy of the associations expresses sucession of seasonal aspect. Vernal, aestival and autumnal aspects have been observed and recorded.

兰州位于我国的中心,约占北纬36度03分,东经103度57分,拔海1508.53米。皋兰山是兰州四周环山中的最高峰,位居兰州市东南郊。在地形上,皋兰山属于分割黄土高原山岭的一部分,拔海高度约为2100米。由于地理位置及海拔的影响,兰州的气候属大陆性气候类型。年平均温度为6.9℃,年平均雨量为338.6毫米,而61.61%集中在6、7、8、三个月,全年各月平均相对湿度为58%,年蒸发量则达3,571毫米,风力为5.8米/秒。皋兰山山岭的顶部均为厚层的黄土所掩盖,其下则为第三纪红土层。因此,调查区的土壤,全由黄土母质发育而来,含多量钙质,属栗钙土类,PH值为7.6—8.1。调查区的植被,有如下的生志特点:(1)植物种属比较贫乏:全区植物只有41科,93属,124种;(2)群落外貌单纯:调查区内缺乏自然生长的乔木,植被主要由半灌木与草本植物所构成,属干燥草原区的灌木草本群落型;(3)植物具明显旱生形态:群落主要成分,很多是干燥草原区的代表种属,如锦鸡儿属、蒿属、菊属的小黄菊(Chrysanthemum neofruticulosum Ledeb.)、羽茅属、芨芨草等。它们都具有各种适应干旱环境的形态特征。调查区植物...

兰州位于我国的中心,约占北纬36度03分,东经103度57分,拔海1508.53米。皋兰山是兰州四周环山中的最高峰,位居兰州市东南郊。在地形上,皋兰山属于分割黄土高原山岭的一部分,拔海高度约为2100米。由于地理位置及海拔的影响,兰州的气候属大陆性气候类型。年平均温度为6.9℃,年平均雨量为338.6毫米,而61.61%集中在6、7、8、三个月,全年各月平均相对湿度为58%,年蒸发量则达3,571毫米,风力为5.8米/秒。皋兰山山岭的顶部均为厚层的黄土所掩盖,其下则为第三纪红土层。因此,调查区的土壤,全由黄土母质发育而来,含多量钙质,属栗钙土类,PH值为7.6—8.1。调查区的植被,有如下的生志特点:(1)植物种属比较贫乏:全区植物只有41科,93属,124种;(2)群落外貌单纯:调查区内缺乏自然生长的乔木,植被主要由半灌木与草本植物所构成,属干燥草原区的灌木草本群落型;(3)植物具明显旱生形态:群落主要成分,很多是干燥草原区的代表种属,如锦鸡儿属、蒿属、菊属的小黄菊(Chrysanthemum neofruticulosum Ledeb.)、羽茅属、芨芨草等。它们都具有各种适应干旱环境的形态特征。调查区植物群落,可区分为下列的四个群丛: 1.白药+黄花蒿+厚穗滨草群丛(Chenopodium album+Artemisia annus+Elymus dasystachys Association) 本群丛分布于皋兰山山麓的侵蚀沟谷内,约占海拔1510至1560米的地段。所在地气候与土壤特点是光线弱、日照时间短、风力小、大气相对湿度大与土壤潮湿。群丛优势种有白藜、黄花蒿和厚穂滨草三种喜湿耐阴植物。此外,伴生有灰绿藜、苦苣菜、苍耳、两栖蓼、扁蓄等草本植物。灌木则可见枸杞(Lycuim chinensis Mill)、紫金银花(Lonicera heteroloba Batal.)、裴氏金银花(L.ferdinandi.Fr.)三种。 2.篦叶蒿群丛(Artemisia pectinata Association) 这一群丛占据皋兰山北坡山麓海拔1510—1580米,坡度在15°以下的开旷地段。其环境条件,在北坡来说,主要表现于阳光充沛,温度高,大气相对湿度低与土壤干燥。群丛总夏盖度约为50%,而以篦叶蒿最占优势。常见植物有钾猪毛菜、灰蓬(Salsola arachnoides‘moq’Kung)、蒙古芯芭(Cymbaria mongolica Maxim.)、茵陈蒿、阿尔泰紫菀、小黄菊等喜光喜温种类。 3.小黄菊+供蒿-藓群丛(Chrysanthemum neofruticulosum+Artemisia sacrorum var latiloba-Polytrichum sp. Association) 本群丛包括皋兰山北坡自海拔1580米以上一直至山顶(海拔2100米)的全部地段,为调查区内分布面积最广的群丛。其生态环境是阳光弱、日照时间短、蒸发量小、气温低;土镶为栗钙土,PH值在8.0—8.1左右,土壤风干含水量为5.2—5.6%。群丛在垂直结构上,可分为两层:第一层包括高度在10厘米以上的灌木、半灌木与草本植物,而以小黄菊和供蒿最占优势。本氏羽茅则为本属中的亚优势种。常见植物尚有野葱、青木香(Saussurea nigrescens Maxim.)、骆驼蓬、达乌里紫云英,多裂委陵菜、宿根亚麻、木锦鸡儿(Caragana frutex K. Koch.)等。第二层为地被层,主要由藓类和地衣所组成。此外,偶尔出现细叶车前(Plantago Lessingii)与鳞叶龙胆(Gentiana squarrosa Ledeb.)铺地生长。群丛总复盖度约为67%。 4.本氏羽茅+阿尔泰紫菀+小黄菊群丛(Stipa Bungeana+Aster altaicus+Chrysanthemum neofruticulosum Association) 这一群丛占皋兰山南坡除农田以外的全部地区。其气候与土壤条件,可归纳为下:日晒强烈、日照时间长、气温高;人为对自然植被破坏强烈,表土冲刷现象异常严重。土壤水分含量甚低,仅占风干重的1.88—3.41%,pH值为7.4—7.6。本氏羽茅、阿尔泰紫菀与小黄菊为群丛中的主要种类。它们对于干旱的环境均具有强大的适应力。其他常见植物有红砂、宿根亚麻、达乌里紫云英、骆驼蓬、供蒿、茵陈蒿、黄角蒿(Incarvillea lutea Bur.&Franch.)地肤等抗旱或耐旱种类。苏联猪毛菜(Salsola rutheniea Iljin)和灰蓬,常各成单纯小群丛,出现于山坡间。本群丛中缺地被层,无地上成层现象。群丛总复盖度仅为25—30%。由于南北坡取向不同所引起气候与土壤因子的变化,调查区植物群落,在分布、结构、外貌、种类成分及生长发育状况上,也随着发生很大的差异。海拔高度的改变,对气温、相对湿度,土温及土壤水分状况的影晌,也明显地反映在群落中各个种间的数量比例关系上。随着季节的更换,群落中的种类成分,表现出比较显著的季相演替关系。作者等曾作北坡群丛春、夏和秋三季季相的观察与纪录。

In chloroplasts illuminated in strong light for a few seconds, some high energy intermediates are accumulated, which can transform ADP and Pi into ATP in darkness. This phenomenon, preliminarily reported in a previous paper, has been further studied, and the results obtained are as follows:(1)It is shown that the high energy substances accumulated in the light is neither the result of irrelevant side reactions(Tab. 1), nor that of ATP-Pi exchange reaction(Tab. 2, 3), but is connected with the intermediate...

In chloroplasts illuminated in strong light for a few seconds, some high energy intermediates are accumulated, which can transform ADP and Pi into ATP in darkness. This phenomenon, preliminarily reported in a previous paper, has been further studied, and the results obtained are as follows:(1)It is shown that the high energy substances accumulated in the light is neither the result of irrelevant side reactions(Tab. 1), nor that of ATP-Pi exchange reaction(Tab. 2, 3), but is connected with the intermediate steps of photophosphorylation. Further experiment indicate that the step concerned with the accumulation of intermediates is located in the phosphorylation mechanism(Tab. 7)and before the velocity limiting reaction of the PMS mediated photophosphorylation process(Tab. 6).(2)By comparing the effects of the various conditions, it is found that the accumulation and transformation of the intermediate and the process of photophosphorylation, are closely related. Many experimental results, such as the light intensity curve(Fig. 1), the influence of the coexisting photophosphorylation on the accumulation of intermediate(Tab. 6), the requirement of cofactors or hydrogen acceptors(Tab. 7)et al., indicate that the accumulated high energy substance behaves like an intermediate of photophosphorylation. But, there are also some clues that certain behaviours of the high energy substance cannot be simply treated as a simple intermediate of photophosphorylation, for example, the velocities of its accumulation and transformation being several times slower than the process of photophosphorylation; the severe hindrance of its transformation into ATP at low temperatures(Fig. 5), etc.(3)The accumulation of the high energy product in the chloroplasts may amount to 1/10 of the chlorophyll content on molar basis, and some times even more. Investigations on the properties of the product show that it is fat soluble(Fig. 6, 7, 8)and is easily destroyed by ultraviolet light(Tab. 12).(4)Possible reasons for the discrepancy in the velocities of the accumulation and transformation of the intermediates compared with that of the process of photophosphorylation are suggested and the similarities of the accumulated intermediates to plastoquinone are discussed.

当叶綠体在強光下預照光数秒钟后,其中有高能物貭积聚,它可在暗中使ADP和Pi轉化成ATP。这个現象,在前文已有初步报导,現在更作了进一步的研究,所得結果如下: (1)肯定这光下积聚的高能物貭不是旁杂反应的产物或ATP—Pi交換反应的产物,而是与光合磷酸化中間步驟有关的。有些实驗表明,与此积聚高能物貭有关的中間步驟处于磷酸化部分并且位于PMS促进的光合磷酸化的速度限制反应之前。(2)比較了一些条件对高能物貭的积聚与轉化及对进行光合磷酸化的影响,看到高能物貭的积聚与轉化同光合磷酸化有密切的关系,諸如光強的影响、有光合磷酸化进行时高能物貭的积聚情况、对輔助因子或氫受体的要求等实驗結果,都符合于表明光下所积聚的高能物貭是光合磷酸化的中間产物。但是,也有不少迹象显示出来,这光下积聚的高能物貭有許多行为不能簡单地把它当作光合磷酸化过程中的中間产物来解释,例如,它的积聚速度与轉化速度比光合磷酸化过程要慢好多倍,并且低温显著地不利于光下积聚中間产物轉化成ATP(这現象在光合磷酸化过程中是沒有的)等。(3)光下积聚中間产物量最高时可达叶綠素含量的1/10;甚至更多些。初步研究此中間产物的性貭,說明它很可能是一个脂溶性物貭,并且...

当叶綠体在強光下預照光数秒钟后,其中有高能物貭积聚,它可在暗中使ADP和Pi轉化成ATP。这个現象,在前文已有初步报导,現在更作了进一步的研究,所得結果如下: (1)肯定这光下积聚的高能物貭不是旁杂反应的产物或ATP—Pi交換反应的产物,而是与光合磷酸化中間步驟有关的。有些实驗表明,与此积聚高能物貭有关的中間步驟处于磷酸化部分并且位于PMS促进的光合磷酸化的速度限制反应之前。(2)比較了一些条件对高能物貭的积聚与轉化及对进行光合磷酸化的影响,看到高能物貭的积聚与轉化同光合磷酸化有密切的关系,諸如光強的影响、有光合磷酸化进行时高能物貭的积聚情况、对輔助因子或氫受体的要求等实驗結果,都符合于表明光下所积聚的高能物貭是光合磷酸化的中間产物。但是,也有不少迹象显示出来,这光下积聚的高能物貭有許多行为不能簡单地把它当作光合磷酸化过程中的中間产物来解释,例如,它的积聚速度与轉化速度比光合磷酸化过程要慢好多倍,并且低温显著地不利于光下积聚中間产物轉化成ATP(这現象在光合磷酸化过程中是沒有的)等。(3)光下积聚中間产物量最高时可达叶綠素含量的1/10;甚至更多些。初步研究此中間产物的性貭,說明它很可能是一个脂溶性物貭,并且易受紫外光破坏。(4)文中对此中間产物积聚与轉化速度較光合磷酸化过程为慢的現象分析了它可能的原因,并且将此中間产物与叶綠醌的一些性貭的类似之处作了討論。

(1)When etiolated wheat seedlings were illuminated, chlorophyll appeared immediately, but no photophosphorylation activity could be found. After about 3 hrs. of greening, photophosphorylation activity began to appear and its rate, calculated on chlorophyll basis, increased up to 7—8 hrs., after which it became more or less constant, while the chlorophyll content of the chloroplasts continued to rise.(2)The capacity of ATP formation(per nag. chlorophyll)by cyclic photophosphorylation was much higher than that...

(1)When etiolated wheat seedlings were illuminated, chlorophyll appeared immediately, but no photophosphorylation activity could be found. After about 3 hrs. of greening, photophosphorylation activity began to appear and its rate, calculated on chlorophyll basis, increased up to 7—8 hrs., after which it became more or less constant, while the chlorophyll content of the chloroplasts continued to rise.(2)The capacity of ATP formation(per nag. chlorophyll)by cyclic photophosphorylation was much higher than that by noncyclic photophosphorylation at the early stages of greening, but their difference became smaller as the greening goes on.When the capacity of ATP formation by cyclic photophosphorylation was compared with the O_2 evolving power by noncyclic photophosphorylation, no such difference in ratio during greening was observed. This fact indicates, that the low capacity of noncyclic photophosphorylation is mainly due to its lower degree of coupling, and not to the involvement of a O_2 evolving step which might develop slower. The development of the ATP formation capacity of the oxidative photophosphorylation with DCPIPH_2 as hydrogen donor during greening behaved similarly to that of noncyclic photophosphorylation, and also lagged behind that of cyclic photophosphorylation. This fact further confirms the conclusion that the cause of delayed development of ATP formation capacity by noncyclic photophosphorylation is not connected with the O_2 evolving step.(3)The light intensity required to saturate the photophosphorylation and Hillreaction activities of the greening wheat-seedling chloroplasts was found to be similar to that of fully green control. At the beginning of the development of the photophosphorylation capacity, it had a strong"light intensity effect", i.e. the slowing down of the rate of electron transport at low light intensity resulted in an uncoupling of the phosphorylating mechanism. This phenomenon may have some relation to the extraordinarily low capacity of ATP formation of noncyclic photophosphorylation at the early stage of greening.(4)During greening of etiolated wheat seedlings, the appearance of CO_2 assimilation was approximately simultaneous to that of the photophosphorylation capacity, but the activity calculated on chlorophyll basis, seemed to reach a maximum much earlier.

(1)黄化小麦幼苗初变绿时,光合磷酸化活力之发生远较叶绿素的生成为迟。在实验条件下,照光变绿3小时后,才可测得光合磷酸化活力,且其按叶绿素为基础计算的活力随照光变绿时间的增加而增加,至照光变绿7—8小时后,叶绿体上叶绿素含量尚在继续增加,但光合磷酸化活力则趋向恒定。(2)在黄化幼苗变绿初期,测得的循环光合磷酸化ATP形成能力较非循环光合磷酸化ATP形成能力高得多,以后较接近;但将循环光合磷酸化之ATP形成能力与非循环光合磷酸化之放氧能力相比较,则其比例在不同时期相差不大。这说明,在变绿初期非循环光合磷酸化之ATP形成能力特别小的原因,主要是由于当时它的偶联程度特别低,并不是因为它较循环光合磷酸化多牵涉到放氧等步骤,而这些步骤可能发生得较晚所致。以DCPIPH_2作氢供体的氧化光合磷酸化活力的最初增长情况与以Fe(CN)_6~≡作氢受体的非循环光合磷酸化ATP形成能力的增长情况一样,均比以PMS促进的循环光合磷酸化活力增长时间为晚,这结果也有助于证明非循环光合磷酸化ATP形成能力增长较晚的原因与它牵涉到放氧步骤无关。(3)使黄化变绿幼苗光合磷酸化、希尔反应活力达到饱和所需的光强度与绿苗所需的相仿。变绿初期的叶绿...

(1)黄化小麦幼苗初变绿时,光合磷酸化活力之发生远较叶绿素的生成为迟。在实验条件下,照光变绿3小时后,才可测得光合磷酸化活力,且其按叶绿素为基础计算的活力随照光变绿时间的增加而增加,至照光变绿7—8小时后,叶绿体上叶绿素含量尚在继续增加,但光合磷酸化活力则趋向恒定。(2)在黄化幼苗变绿初期,测得的循环光合磷酸化ATP形成能力较非循环光合磷酸化ATP形成能力高得多,以后较接近;但将循环光合磷酸化之ATP形成能力与非循环光合磷酸化之放氧能力相比较,则其比例在不同时期相差不大。这说明,在变绿初期非循环光合磷酸化之ATP形成能力特别小的原因,主要是由于当时它的偶联程度特别低,并不是因为它较循环光合磷酸化多牵涉到放氧等步骤,而这些步骤可能发生得较晚所致。以DCPIPH_2作氢供体的氧化光合磷酸化活力的最初增长情况与以Fe(CN)_6~≡作氢受体的非循环光合磷酸化ATP形成能力的增长情况一样,均比以PMS促进的循环光合磷酸化活力增长时间为晚,这结果也有助于证明非循环光合磷酸化ATP形成能力增长较晚的原因与它牵涉到放氧步骤无关。(3)使黄化变绿幼苗光合磷酸化、希尔反应活力达到饱和所需的光强度与绿苗所需的相仿。变绿初期的叶绿体,其光合磷酸化作用有很强的“光强效应”,卽弱光下电子传递速度慢、PSP活力低时,与磷酸化的偶联程度会急剧下降。这现象可能是造成变绿初期测得的非循环光合磷酸化ATP形成能力特别低的原因。(4)黄化幼苗变绿时,同化CO_2能力之发生时间与光合磷酸化活力之发生时间差别不大,但以叶绿素为基础计算,前者的活力较早达到恒定。

 
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