城市遮阴环境变化对大叶黄杨光合过程的影响

城市遮阴与自然生态系统遮阴环境不同,它由城市中的建筑、基础设施等人工构筑物所产生,并对植物光合过程产生影响。采用Li-6400便携式光合作用测定系统对北京市不同建筑遮阴环境下的生态因子特征及大叶黄杨光合参数特性进行了现场实验对比观测与分析。研究显示:(1)城市建筑或基础设施布局或格局变化导致建筑遮阴环境光、温等生态因子的差异性变化,主要体现在光合有效辐射(PAR)在时间分布及强度上的显著差异。(2)遮阴改变大叶黄杨的光合参数,日净光合速率曲线为不规则单峰型,由遮阴进入太阳直射时,净光合速率(Pn)明显升高,随遮阴程度加重峰值时间有后延现象,完全遮阴时净光合速率最低。(3)大叶黄杨叶片在有一定时间太阳直射的中度遮阴(2.3h和5.5h)下适应性良好,日均净光合速率、光补偿点(LCP)、光合能力(P_nmax)、叶面积(LA)、比叶重(LMA)没有显著差异,植物主要通过光合色素含量及组成的改变来适应太阳直射时间变短(2.3h)的遮阴环境。(4)遮阴改变植物的光暗适应策略,没有阳光直射的重度遮阴下,大叶黄杨通过其光合、形态、光合色素等多方面的改变来适应遮阴环境,建筑重度遮阴严重影响植物光合过程。探讨了不同程度建筑遮阴对植物光合作用的影响及植物的适应机制,为基于提高其生态服务功能的树种配置和城市规划提供科学依据。     

广东南岭天然常绿阔叶林林下光环境对林下幼树功能性状的影响

光环境与幼树功能性状的关系对天然林的更新与演替具有重要的生态学意义。以广东南岭区域天然常绿阔叶林下不同林龄(幼龄林,中龄林,老龄林)的森林群落为研究对象,通过监测冠层结构、林下光照数据和林下幼树功能性状等指标,研究林龄梯度下其冠层结构与林下光环境之间的关系,以及林下幼树功能性状对光环境的响应。结果表明:(1)中龄林叶面积指数显著高于幼龄林和老龄林(P0.05),随着林龄的增长,林冠开度和透光率逐渐下降,林龄梯度下透光率、R/FR(红光/远红光比值)、Bw/Rw(宽带蓝光/宽带红光比值)差异极显著(P0.001);(2)天然常绿阔叶林中透光率与光质之间极显著相关(P0.001),R/FR随着透光率的增加而增加,Bw/Rw随着透光率的增加而减少。(3)林下幼树功能性状在光环境之间差异显著(P0.05),老龄林林下幼树叶片氮含量显著高于幼龄林,而叶片重叠率显著低于幼龄林;(4)在本试验地中,R/FR和Bw/Rw的变化对林下幼树的高径比和光合作用并无显著影响,光强对同种植物不同光环境下最大净光合速率的影响较大。总体而言,林龄梯度冠层结构和光环境的差异能在一定程度上解释幼树功能性状的差异,这将有助于我们理解光环境对林下幼树更新的影响机制,同时为天然植被恢复和森林经营提供指导。     

新型光源LED辐射的不同光质配比光对菊花组培苗生长的影响

采用新型光源LED辐射的红光[R,(658±20)nm]、远红光[Fr.(715±20)nm]和蓝光[B,(460±20)nm],观测不同红光/远红光(R/Fr)和红光/蓝光(R/B)配比光对菊花组培苗生长的影响.试验结果表明:红光处理的植株最高,根较长.远红光和蓝光处理的植株矮小,根短细.类胡萝卜素含量与R/Fr比率呈负相关,叶绿素a、叶绿素b、叶绿素(a b)、类胡萝卜素含量与R/B比率也呈负相关.叶绿素a/b比值与R/Fr和R/B比率呈正相关.红光有利于可溶性糖和淀粉的积累,降低色素含量.而蓝光能够逆转此效应,可促进色素和可溶性蛋白的合成.红光和蓝光组合处理的叶中可溶性糖和淀粉含量以及根系活力均高于白光处理的,尤以高R/B配比光处理的组培苗生长健壮,移栽成活率最高.     

不同比例红蓝光对番茄幼苗生长和光合作用的影响

为了探索番茄幼苗生长发育对红蓝组合光的响应机制,本试验采用发光二极管(LED)精量调制光源,以番茄品种‘SV0313TG’为试材,设红光(R)、蓝光(B)和红蓝组合光(9R1B、6R1B、3R1B、1R1B、1R3B)7个处理,以白光为对照,研究不同比例红蓝光质对番茄幼苗生长、光合色素含量、光合特性、叶绿素荧光参数及根系活力的影响.结果表明:不同比例红蓝光质处理对番茄幼苗生长的影响具有明显差异.红光显著促进幼苗株高增加,比叶面积增大,胞间CO₂浓度提高,但PSⅡ最大光化学效率(F_v/F_m)、PSⅡ实际光化学效率(Ф_PSⅡ)降低,根系生长受阻,根系活力下降,壮苗指数降低;蓝光下幼苗生长受到明显抑制,叶绿素含量降低,但叶绿素a/b 值升高;红蓝组合光有利于番茄幼苗的生长发育,3R1B处理下植株干物质量、叶绿素含量和光合性能均显著提高,幼苗生长健壮,壮苗指数最大.综上,红蓝组合光能够增加番茄幼苗叶片光合色素含量,提高光合效率,促进植株生长,尤以3R1B处理最佳.     

藤本植物Potentilla reptans叶对风和遮阴的响应

生长在一个密集植物群中的植株由于相互遮蔽而不可能对风的影响做出反应,因为这样的环境条件(有限的光资源)对由风导致的矮小表型植株的生长是不利的。为弄清在密集植物群体中生长的植株对风的响应,利用藤本植物Potentilla reptans的10种基因型做实验材料,在温室条件下(光照强度为日光照的50%,红光/远红光=1.2)模拟冠层遮阴(相当于15%的日光照,红光/远红光=0.3),研究了藤本植物叶对风的响应。结果表明,Potentilla reptans的10种基因型植株在冠层遮阴下(低的红光/远红光)都表现出典型的避阴生长响应:较少的叶(叶生物量少),长而细但硬度系数高(higher Young's modulus)的叶柄;而受风影响的植株,无论遮阴或不遮阴,其植株的叶相对较多,叶柄短、粗且柔韧性强(lower Young's modulus),说明Potentilla reptans叶对风的响应并未因遮阴而被压抑,其可塑性变化不过是对复杂生境做出的一种生长权衡:尽可能增强抗风能力(矮壮)和获取最大光能(足够高而避免被遮光),即保证在存活下去的前提下获取最大的生长效率。     

钝顶螺旋藻形态、生长及光合作用对不同波段太阳辐射的响应

为探讨中不同波段的光合有效辐射对钝顶螺旋藻(Arthrospira platensis)形态、生长及光合作用的影响,实验将钝顶螺旋藻D-0083藻液转入带塞的石英管中, 石英管水平置于阳光下并在其上覆盖不同的截止型和带通型滤光片, 以使藻丝接受不同波段的太阳辐射; 并检测其生长、形态与光合活动的变化。结果发现: 所有波段 (320500、395700、510700和610700 nm) 光合有效辐射下的藻丝均螺旋变紧且生物量增加。其中以包含少量紫外辐射A (Ultraviolet-A)的蓝光波段 (320500 nm)和红光波段(600700 nm) 对藻丝形态变化、生长及光合速率的诱发效率较高。在320500、395700、510700和 610700 nm波段上的单位能量光照引起钝顶螺旋藻螺距变化的效率分别为0.070、0.015、0.021、0.045 m/(Wm2)。 波段320500 nm虽然会轻微抑制钝顶螺旋藻D-0083的有效光化学效率(Fv'/Fm')、电子传递速率(ETR)和藻蓝蛋白的荧光发射, 但是却能够有效诱导其藻丝变紧促进生长。此外, 钝顶螺旋藻D-0083的藻丝变紧程度、比生长速率变化与不同波段太阳辐射下藻丝体的光合性能相一致。该研究表明任何波段的光合有效辐射都能使螺旋藻藻丝螺旋变紧并引发生长和光合作用, 其中以蓝光和红光的效率最高。     

不同光质对桑树幼苗生长和光合特性的影响

光质可影响植物光合特性、形态以及生理过程。本试验研究了不同光质(白光W、红光R、红蓝混合光RB、蓝光B)对桑树植株生长、形态和光合作用的影响。结果表明:与白光对照相比,红光、蓝光和红蓝混合光处理下植株的生长、干物质积累受到抑制;红光处理下植株的株高、叶面积显著高于白光、红蓝混合光、蓝光处理;而白光、红蓝混合光、蓝光处理下植株的LMA、叶绿素a/b比值、可溶性蛋白含量、蔗糖、淀粉含量和叶片总N含量显著高于红光处理;红蓝混合光处理下植株的Pn、Gs、ΦPSⅡ与白光处理相近,红光、蓝光处理下植株的Pn、ΦPSⅡ低于白光、红蓝混合光处理,同时红光、红蓝混合光、蓝光处理下植株的抗氧化酶活性高于白光处理,而MDA含量低于白光处理;红光处理下植株的叶片厚度、栅栏组织和海绵组织厚度显著小于白光处理。因此,一定比例的红蓝混合光可以使桑树植株的生长、光合特性、生理特征和叶片解剖结构与白光下生长植株相近,并减少单质红光、单质蓝光对植株生长发育的不利影响。     

红光与远红光比值对切花菊‘神马’发育和外观品质的影响

为了探讨不同R/FR值对温室切花菊发育进程和品质的影响,以切花菊品种‘神马’(Chrysanthemum morifoliumcv.‘Jingba’)为试材,设计不同红光(R:660nm!10nm)与远红光(FR:730nm!10nm)比值(R/FR)为0.5、2.5、4.5、6.5的LED灯照射处理试验,以自然光为对照(CK),观测不同处理的菊花发育阶段和品质指标。结果表明:与CK相比,R/FR=2.5处理显著加快菊花的发育进程(P<0.05),R/FR=2.5处理下短日照处理到现蕾、现蕾到破蕾及破蕾到收获3个发育阶段分别比CK提前4d、8d和5d,R/FR=0.5处理发育速度最慢,3个阶段分别比CK晚4d、2d和2d;不同R/FR值处理下菊花株高、单株叶龄、单株叶面积、茎粗、花径和花梗长度均随温光效应的增加呈增加的趋势,并在R/FR=2.5时取得最大值;收获时切花菊达到A级和B级产品等级的比例分别以R/FR=2.5和4.5处理最高。本研究发现,R/FR为2.5能够显著促进菊花发育进程和提高菊花的外观品质和A级切花的比例。     

光照与葡萄品质

众所周知,光能是地球上生命活动所需的最终能源,因此,光对葡萄植株的生长发育十分重要。太阳的光能都能通过辐射吸收来影响葡萄植株的光合作用和温度以及浆果的温度。不同光质(如紫外线、红光和远红光)对葡萄植株的生长发育也有较大的作用,尤其是红光(R)(660nm)和远红光(FR)(730nm)能调控植物的光敏素反应。那么光的调控机制是什么呢?归纳起来大体有以下几方面:光合效应、热量效应和光敏素效应。     

采用不同光谱波段宽度的归一化植被指数估算水稻叶面积指数

通过大田试验,测量了水稻不同生育期的冠层光谱,并通过在TM红光波段和近红外波段范围内不断扩展波段宽度,计算了各个波段宽度对应的归一化植被指数(NDVI)及其与叶面积指数(LAI)的最大相关系数,再根据NDVI与LAI最佳拟合方程的最大R2值随波段宽度的变化特征确定了最佳波段宽度.结果表明:NDVI与LAI的相关系数和最佳拟合方程的最大R2值具有相同的变化趋势,在小于红光波段宽度60nm范围内,均随波段宽度的增大而减小,即窄波段NDVI比宽波段NDVI对LAI的估算效果好;在超过60nm后,由于受近红外波段宽度的影响而略有波动.对R2规律的分析表明,使用NDVI估算水稻LAI的最佳波段宽度为15nm.     

Responses of insectivorous bats and nocturnal insects to local changes in street light technology

Artificial light at night is a pervasive anthropogenic stressor for biodiversity. Many fast‐flying insectivorous bat species feed on insects that are attracted to light‐emitting ultraviolet radiation (10–400 nm). Several countries are currently focused on replacing mercury vapour lamps, which emit ultraviolet light, with more cost‐efficient light‐emitting diode (LED) lights, which emit less ultraviolet radiation. This reduction in ultraviolet light may cause declines in insect densities in cities, predatory fast‐flying bats, and some edge‐foraging and slow‐flying bats. Capitalising on a scheme to update streetlights from high ultraviolet mercury vapour to low ultraviolet LED in Sydney, Australia, we measured the activity of individual bat species, the activity of different functional groups and the bat and insect communities, before and after the change in technology. We also surveyed sites with already LED lights, sites with mercury vapour lights and unlit bushland remnants. Species adapted to foraging in cluttered vegetation, and some edge‐space foraging species, were more active in unlit bushland sites than in all lit sites and decreased in activity at lit sites after the change to LED lights. The change to LED streetlights caused a decrease in the fast‐flying Chalinolobus gouldii but not Miniopterus schreibersii oceanensis, the latter being more influenced by seasonal and environmental variables. Insect biomass was not affected by changing light types, but instead was negatively correlated with the moon's percentage illuminance. Changing streetlights to LEDs could result in a decline in some insectivorous bats in cities. This study confirms that unlit urban bushland remnants are important refuges for high bat diversity, particularly for more clutter‐adapted species and some edge‐space foraging species. Preventing light penetration into unlit bushland patches and corridors remains essential to protect the urban bat community.     

The effects of light and noise from urban development on biodiversity: Implications for protected areas in Australia

Global population growth and associated urban development are having profound effects on biodiversity. Two major outcomes of expanding development that affect wildlife are light and noise pollution. In this paper, we review literature reporting the effects of light and noise on biodiversity, and assess implications for conservation planning in Australia. Our results clearly indicate that light and noise pollution have the potential to affect the physiology, behaviour and reproduction of a range of animal taxa. Types of effects include changes in foraging and reproductive behaviours, reduction in animal fitness, increased risk of predation and reduced reproductive success. These could have flow‐on consequences at the population and ecosystem levels. We found a significant gap in knowledge of the impact of these pollutants on Australian fauna. To reduce the effect of light and noise pollution, there needs to be careful planning of urban areas in relation to protected areas, and for biodiversity more generally. Potential measures include strategically planning the types of development and associated human activities adjacent to protected areas, and the use of shields and barriers, such as covers for lights or the use of dense native vegetation screens, while still allowing movement of animals. Changes in government standards and regulations could also help to reduce the impacts of light and noise pollution.     

城市夜间灯光对香樟生长的影响

为了解常绿乔木对城市夜间灯光的生长响应,以华东地区典型常绿行道树种香樟为对象,研究南京市一条典型道路上近灯处(路灯正下方)和远灯处(两相邻路灯中间位置)生长区位的夜间光照强度差异性对香樟生长性状的影响.结果表明:近灯处香樟的平均胸径为16.8 cm,当年生小枝总生产力为309.4 g·m^-2,当年生叶片生产力为241.5 g·m^-2,叶片相对叶绿素含量为34.6 SPAD.远灯处香樟的平均胸径为15.5 cm,当年生小枝总生产力为273.4 g·m^-2,当年生叶片生产力为212.8 g·m^-2,叶片相对叶绿素含量为33.1 SPAD.近灯处香樟的平均胸径、当年生小枝总生产力、当年生叶片生产力及叶片相对叶绿素含量均显著高于远灯处.两处树木间比叶面积没有显著差异.夜间灯光的补充照明促进了近灯处香樟的生长,并改变了树冠生长对阳光的响应特征.     

High-fluence light emitting diode-red light inhibits cell cycle progression in human dermal fibroblasts

Skin fibrosis is a debilitating feature of several systemic and dermatologic diseases. While current treatment options carry significant risk of side effects and recurrence, high-fluence light emitting diode-generated red light (LED-RL) is an alternative therapeutic that is safe, non-invasive, and accessible. We previously demonstrated LED-RL decreases fibroblast proliferation, a key pathogenic component of fibrosis. However, the cellular mechanism by which high fluence LED-RL modulates fibroblast proliferation is unclear. Herein, we explored the effects of high fluence LED-RL on human dermal fibroblast cell cycle progression. We demonstrate that LED-RL at 640 J/cm² induced significant arrest of cells in G₀/G₁ compared to temperature-matched control. This was accompanied by a corresponding increase in expression of checkpoint regulator p53 in irradiated cells. These data demonstrate high fluence LED-RL may exert its anti-proliferative effect on fibroblasts by inducing G₀/G₁ arrest. Further, this study provides insight into the molecular mechanism underlying LED-RL as an anti-fibrotic therapeutic.     

基于夜间灯光数据的太湖流域城镇扩张对净初级生产力的影响研究

理解人类活动变化对生态环境的影响,识别生态环境变化区域及其成因,对制定差异化的区域生态保护政策具有重要意义。基于MODIS17A3和DMSP/OLS稳定夜间灯光数据,结合RS与GIS技术,构建城镇开发程度指数,采用一元线性趋势分析法对城镇开发程度进行分区,利用Pearson相关系数计算城镇开发程度与NPP的作用关系,并运用热点分析模型探讨土地利用转型对NPP变化的影响。结果表明:(1)2000—2010年,太湖流域年均NPP变化范围是388.79—452.54 gC m~(-2)a~(-1),NPP变化呈波动下降趋势;(2)城镇开发程度缓慢增加区对NPP变化影响较小,增加区与快速增加区对NPP变化影响较大;(3)太湖流域土地转型主要发生在耕地转建设用地、林地转建设用地和水域转建设用地,建设用地面积的快速扩张及由此导致的城镇开发程度的增加,是流域NPP降低的主要原因。     

Myosin light chain kinase and the role of myosin light chain phosphorylation in skeletal muscle

Skeletal muscle myosin light chain kinase (skMLCK) is a dedicated Ca²⁺/calmodulin-dependent serine–threonine protein kinase that phosphorylates the regulatory light chain (RLC) of sarcomeric myosin. It is expressed from the MYLK2 gene specifically in skeletal muscle fibers with most abundance in fast contracting muscles. Biochemically, activation occurs with Ca²⁺ binding to calmodulin forming a (Ca²⁺)₄•calmodulin complex sufficient for activation with a diffusion limited, stoichiometric binding and displacement of a regulatory segment from skMLCK catalytic core. The N-terminal sequence of RLC then extends through the exposed catalytic cleft for Ser15 phosphorylation. Removal of Ca²⁺ results in the slow dissociation of calmodulin and inactivation of skMLCK. Combined biochemical properties provide unique features for the physiological responsiveness of RLC phosphorylation, including (1) rapid activation of MLCK by Ca²⁺/calmodulin, (2) limiting kinase activity so phosphorylation is slower than contraction, (3) slow MLCK inactivation after relaxation and (4) much greater kinase activity relative to myosin light chain phosphatase (MLCP). SkMLCK phosphorylation of myosin RLC modulates mechanical aspects of vertebrate skeletal muscle function. In permeabilized skeletal muscle fibers, phosphorylation-mediated alterations in myosin structure increase the rate of force-generation by myosin cross bridges to increase Ca²⁺-sensitivity of the contractile apparatus. Stimulation-induced increases in RLC phosphorylation in intact muscle produces isometric and concentric force potentiation to enhance dynamic aspects of muscle work and power in unfatigued or fatigued muscle. Moreover, RLC phosphorylation-mediated enhancements may interact with neural strategies for human skeletal muscle activation to ameliorate either central or peripheral aspects of fatigue.     

Analysis of immunoglobulin light chain loci in sheep

A sheep kappa cDNA probe was isolated, characterized by sequence analysis and shown to have significant sequence identity to other kappa light chains. This probe and a sheep lambda light chain probe were used to estimate the extent of various sheep immunoglobulin light chain gene loci by Southern blot analysis of genomic DNA. The results showed that the sheep has a single hybridizing kappa constant gene and three to five kappa V segment bands. Segregation of three polymorphic bands at the lambda C locus indicated that they were products of separate C segments. Restriction fragment pattern variations were obtained using light chain probes on various sheep breeds, but no pattern or individual band was characteristic for a particular breed.     

Polarized light therapy: Shining a light on the mechanism underlying its immunomodulatory effects

This study investigates the immunomodulatory effects of polychromatic polarized light therapy (PLT) on human monocyte cells. While there is some evidence demonstrating a clinical effect in the treatment of certain conditions, there is little research into its mechanism of action. Herein, U937 monocyte cells were cultured and exposed to PLT. The cells were then analyzed for change in expression of genes and cell surface markers relating to inflammation. It was noted that 6 hours of PLT reduced the expression of the CD14, MHC I and CD11b receptors, and increased the expression of CD86. It was also shown that PLT caused downregulation of the genes IL1B, CCL2, NLRP3 and NOD1, and upregulation of NFKBIA and TLR9. These findings imply that PLT has the capacity for immunomodulation in human immune cells, possibly exerting an anti‐inflammatory effect.     

A laboratory experiment to determine the dispersal response of Atlantic salmon (Salmo salar) fry to street light intensity

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Studies on light absorption and photochemical activity changes in chloroplast suspensions and leaves due to light scattering and light filtration across chloroplast and vegetation layers

An experimental analysis is presented concerning the effect on relative light absorption by the two photosystems caused by (a) a highly light scattering environment (the detour effect) and (b) light filtration across successive chloroplast layers (the light attenuation effect). Both suspensions of isolated chloroplasts and leaves were employed.It is concluded that within a single spinach leaf these phenomena are likely to lead to only rather small increases in relative photosystem I absorption and activity with respect to photosystem II and will thus not exert a significant effect on non cyclic electron transport. On the contrary when light is filtrated across successive vegetation layers (shade light) significant increases in the relative PSI absorption and activity may be encountered.It is determined that the detour effect in mature leaves from a variety of plants increases overall photosynthetically useful light absorption by 35–40%.Abbreviations F_M maximal fluorescence - LHCP₂ light-harvesting chlorophyl a/b protein complex II - Q_A-primary quinone acceptor of photosystem II