Comparative Analyses on the Bioactive Compounds and in Vitro Antioxidant Capacity of Tea Infusions Prepared from Selected Medicinal Fruits

This study was conducted to analyze the bioactive compounds and in vitro antioxidant capacity of tea infusions prepared from whole and ground medicinal fruits, including gardenia, jujube, magnolia, quince, and wolfberries. The dried medicinal fruit samples were ground, and then passed through a 60‐mesh sieve (pore size, 250 μm). Hot water (80 °C) infusions of whole and ground fruits were examined. In average of both whole and ground tea infusions, the maximum bioactive compounds were found in gardenia (β‐carotene, lycopene, and vitamin C), magnolia (total chlorophyll and anthocyanin), quince (flavonoid), and wolfberries (phenolic), and the maximum antioxidant capacity was found in quince (ABTS and DPPH) and wolfberries (NSA). Whole fruit tea infusions showed a higher brightness than the ground fruit tea infusions. The total chlorophyll, anthocyanin, β‐carotene, lycopene, phenolic, flavonoid, and vitamin C contents were found to be significantly (p≤0.001) higher in the ground fruit tea infusions than in the whole fruit tea infusions; additionally, the ground fruit tea infusions had a higher antioxidant capacity especially ABTS, DPPH and NSA. Therefore, the ground fruit tea infusions appeared to be more powerful with regard to the contents of bioactive compounds and antioxidant capacities than the whole fruit tea infusions.     

Thermal Acclimation of Respiration and Photosynthesis in the Marine Macroalga Gracilaria lemaneiformis (Gracilariales,Rhodophyta)

The responses of respiration and photosynthesis to temperature fluctuations in marine macroalgae have the potential to significantly affect coastal carbon fluxes and sequestration. In this study, the marine red macroalga Gracilaria lemaneiformis was cultured at three different temperatures (12, 19, and 26°C) and at high‐ and low‐nitrogen (N) availability, to investigate the acclimation potential of respiration and photosynthesis to temperature change. Measurements of respiratory and photosynthetic rates were made at five temperatures (7°C–33°C). An instantaneous change in temperature resulted in a change in the rates of respiration and photosynthesis, and the temperature sensitivities (i.e., the Q₁₀ value) for both the metabolic processes were lower in 26°C‐grown algae than 12°C‐ or 19°C‐grown algae. Both respiration and photosynthesis acclimated to long‐term changes in temperature, irrespective of the N availability under which the algae were grown; respiration displayed strong acclimation, whereas photosynthesis only exhibited a partial acclimation response to changing growth temperatures. The ratio of respiration to gross photosynthesis was higher in 12°C‐grown algae, but displayed little difference between the algae grown at 19°C and 26°C. We propose that it is unlikely that respiration in G. lemaneiformis would increase significantly with global warming, although photosynthesis would increase at moderately elevated temperatures.     

Karyology and cytophotometric estimation of nuclear DNA content variation in Gracilaria,Gracilariopsis and Hydropuntia (Gracilariales,Rhodophyta)

Chromosome numbers of 1 N=24 were determined for three species of Gracilaria (G. flabelliforme P. Crouan et H. Grouan ex Schramm et Maze, G. mammillaris Montagne and G. tikvahiae McLachlan) and 1 N=32 for two species of Gracilariopsis (G. lemaneiformis (Bory) Dawson, Acleto et Folvik and G. tenuifrons (Bird et Oliveira) Fredericq et Hommersand). Karyotypes for these species exhibit a characteristic size difference between largest and smallest chromosomes. Polyvalents were a common feature of meiotic nuclei. Microspectrophotometry with the DNA-localising fluorochrome DAPI was used to quantify nuclear genome sizes. A 2 C genome size of 0·37–0·40 pg was determined for five species of Gracilaria (G. chilensis Bird, McLachlan et Oliveira, G. flabelliforme, G. mammillaris, G. pacifica Abbott, G. tikvahiae) and 0·33 pg for an isolate of G. verrucosa (Hudson) Papenfuss from Pas de Calais, France. Species of Hydropuntia (H. cornea (J. Agardh) Wynne and H. dentata (J. Agardh) Wynne) and Gracilariopsis (G. lemaneiformis and G. tenuifrons) were found to have slightly larger 2 C genome contents of 0·42–0·47 pg. No intraspecific variation in 2 C genome sizes was found in regional populations of Gracilaria tikvahiae and Gracilariopsis tenuifrons.     

Effects of UVB Radiation on the Initial Stages of Growth of Gigartina Skottsbergii, Sarcothalia Crispata and Mazzaella Laminarioides (Gigartinales, Rhodophyta)

The effects of UVB radiation on the growth of macroalgal thalli were evaluated using tetrasporophytic fronds of the Rhodophytes Gigartina skottsbergii, Sarcothalia crispata and Mazzaella laminarioides. The tetrasporophytic fronds were collected from nature and the tetrasporophyte sporelings grown in a temperature regulated chamber at 8 ± 2 ^∘C with a 12L:12D (Light: Dark) photoperiod, Photosynthetically Active Radiation (PAR) of 55 μmol photons m⁻² s⁻¹ and seawater enriched with 20 mL L⁻¹ of Provasoli medium. We exposed the thalli of these macroalgae to PAR (55 μmol photons m⁻² s⁻¹) and three treatments using a combination of PAR with three different levels of UVB radiation (0.10, 0.15 and 0.23 W m⁻² for G. skottsbergii and S. crispata and 0.02, 0.05 and 0.10 W m⁻² for M. laminarioides) during a period of 71 days. Growth of thalli was quantified by measuring their length using digitized photographs of samples.Important differences were detected in the growth of individuals cultured under the effects of UVB radiation, when compared to the control (i.e. plants exposed to PAR only). In the case of G. skottsbergii and S. crispata higher levels of UVB radiation resulted in slower growth of thalli. In nearly all measurements for the first two species, UVB radiation levels of 0.1 W m⁻² induced differences in thallus growth, while for M. laminarioides levels of UVB radiation of 0.1 W m⁻² were effective only after a prolonged period of exposure.Differential effects of UVB radiation on G. skottsbergii, S. crispata and M. laminarioides could interfere with the natural populations of these economically important macroalgal species in southern Chile, where they occur under the annual influence of the Antarctic Ozone Hole and the general thinning of the ozone layer.     

Photosynthesis and respiration of a deep-water periphyton community (Macclesfield Bank,South China Sea)

The production parameters of the deep-water periphyton were investigated on the Macclesfield Bank (South China Sea) at depths down to 240 m. At 70–90 m depths the substrate is composed of the remains of dead corals and fragments of porous calcareous material overgrown with red coralline and articulated thalline algae Halimeda sp. At 220–240 m depths the substrate consists of rhodolites, which are individual unattached nodules encrusted mainly with red calcareous coralline algae Lithophyllum sp., Porolithon sp. and red lamellar alga Hypoglossum sp. At all depths the substrate is pierced with green filiform algae Ostreobium sp. and covered with benthic diatom algae. The zooperiphyton in the studied area is comprised of bryozoans, sponges, foraminifers and drilling mollusks. Respiration (R) and the gross (Pg) and net (Pn) primary production of the deepwater periphyton community were determined using the oxygen technique (polarographic electrode) at values of photosynthetically active radiation (PAR) close to natural levels. At 70–90 m depths the Pg of the photoperiphyton was 23.3 mg O₂/(m² h), and the Pn of the community had negative values due to respiration of phytoand mainly zooperiphyton and bacteria. At 220–240 m depths, where less than 0.001% of the surface PAR penetrates, the Pg of the phytoperiphyton decreased to 9.6 mg O₂/(m² h), and the R of the community was 25.9 mg O₂/(m² h). A high efficiency of light energy utilization by the phytoperiphyton was found. The apparent quantum yield (Fa) for algae collected at 70–90 m depths was close to the maximum level of 0.097. The values of Fn that we obtained for 220–240 m depths and calculated from identical data [27], were much higher than theoretical values, which cannot be explained based on modern views on the mechanisms of photosynthesis. Possible sources of errors are discussed. It is proposed that we observed additional evolution of oxygen as the result of H₂O₂ degradation.     

三类重要真菌生物活性物质及其研究方法概述

对高等真菌、内生真菌和海洋真菌活性物质的研究现状进行了概述,并对活性物质的筛选和分离方法等进行了介绍。     

增强UV-B辐射和干旱对春小麦光合作用及其生长的影响

在室外盆栽条件下研究了UV-B辐射和土壤干旱对春小麦 '和尚头'生长和光合作用的影响.结果显示:(1)干旱、UV-B辐射、干旱+UV-B(复合)处理均可使叶片类黄酮含量增加,且干旱+UV-B处理增加显著高于其他处理(P<0.05).UV-B辐射和干旱单独处理均能显著降低叶片光合色素含量,但UV-B辐射的副作用大于干旱,复合处理对光合色素的影响介于UV-B和干旱之间.(2)各处理间的光合速率日均值大小次序为:对照>UV-B+干旱>UV-B>干旱;增强UV-B对净光合速率的抑制作用大于干旱,而UV-B+干旱处理的抑制作用较二者单独处理有所减轻.(3)UV-B辐射和干旱单独处理后总生物量比对照减少15%,且抑制作用为:干旱>UV-B>复合处理; UV-B辐射和干旱胁迫不但影响春小麦的生物量,而且影响小穗特征和产量.研究表明,UV-B辐射和干旱之间存在交互作用,说明一种胁迫可以减缓(轻)另外一种胁迫对春小麦的抑制作用.     

钴在蚕豆中的积累分布及其对叶片光合作用和抗氧化酶活性的影响

以6叶期蚕豆(Vicia faba L.)幼苗为材料,用不同浓度钴(0、20、40、80、120mg·kg-1)土培处理14d,研究不同浓度钴处理对蚕豆体内钴的富集和分布特征,以及叶片光合色素含量、叶绿素荧光参数、光合作用参数、生长指标和POD、SOD、CAT活性的影响。结果显示:(1)蚕豆的根、茎、叶均能吸收一定量的钴,但不同器官间积累量有显著差异,并表现为根叶茎,且在不同钴浓度处理下根吸收量也存在显著差异。(2)不同浓度钴处理下,蚕豆叶片叶绿素(a、b)含量、气孔导度(Gs)、最大光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/F0)等参数与对照组相比表现出0~40mg·kg-1浓度下促进,40~120mg·kg-1浓度下抑制,而净光合速率(Pn)、胞间CO2浓度(Ci)以及光系统Ⅱ最小荧光(F0)、最大荧光(Fm)表现为在0~80mg·kg-1浓度下促进,80~120mg·kg-1浓度下抑制,蒸腾速率(Tr)和类胡萝卜素含量则在各浓度下一直表现为促进,并且以上光合作用相关参数与对照组相比都在40mg·kg-1浓度下促进作用达到最大。(3)蚕豆幼苗的根长、株高、生物量以及抗氧化酶POD、SOD和CAT活性均随着钴浓度增加表现出先升高后降低的趋势。研究表明,蚕豆的根、茎、叶均能积累钴,且吸收量有随土壤钴浓度增加而增加的趋势,但以根部的富集能力最强、积累量最大;低浓度钴可以诱导蚕豆中抗氧化酶活性增强,促进其叶片光合色素含量、光合作用效率提高和植株生长发育,而高浓度钴则表现出相反趋势,抑制蚕豆的光合效率和生长发育。     

Identification of Bioactive Compounds against Aedes aegypti (Diptera: Culicidae) by Bioassays and in Silico Assays

Most of the hematophagous insects act as disease vectors, including Aedes aegypti, responsible for transmitting some of the most critical arboviruses globally, such as Dengue. The use of repellents based on natural products is a promising alternative for personal protection compared to industrial chemical repellents. In this study, the repellent effect of essential oils extracted from Lippia thymoides, Lippia alba, Cymbopogon winterianus, and Eucalyptus globulus leaves was evaluated. Essential oils used showed repellent activity against Ae. aegypti in laboratory bioassays, obtaining protection rates above 70 % from 3.75 mg/mL and higher concentration for all analyzed oils. GC/MS identified 57 constituents, which were used in the ligand-based pharmacophore model to expose compounds with requirements for repellents that modulate mosquitoes behavior through odorant-binding protein 1 Ae. aegypti. Ligand-based pharmacophore model approach results suggested that repellent activity from C. winterianus, L. alba, and L. thymoides essential oils’ metabolites is related to Citronelal (QFIT=26.77), Citronelol (QFIT=11.29), Citronelol acetate (QFIT=52.22) and Geranil acetate (QFIT=10.28) with synergistic or individual activity. E. globulus essential oil's repellent activity is associated with Ledol (0.94 %; QFIT=41.95). Molecular docking was applied to understand the binding mode and affinity of the essential oils’ data set at the protein binding site. According to molecular docking, Citronelol (ChemPLP=60.98) and geranyl acetate (ChemPLP=60.55) were the best-classified compounds compared to the others and they can be explored to develop new repellents.     

Photosynthesis,pigment composition and antioxidant defences in the red alga Gracilariopsis tenuifrons (Gracilariales,Rhodophyta) under environmental stress

Gracilariopsis tenuifrons is a red alga living in the upper intertidal zone of Playa de Carmen (Quintana Roo, Mexico), where abiotic stressors occur over the year. A high antioxidant capacity has been previously demonstrated for G. tenuifrons from the Mexican Caribbean. In this study, we evaluated the photosynthetic activity, pigment composition and antioxidant activity of G. tenuifrons under different culture conditions. G. tenuifrons was submitted to different irradiance intensities (100 and 1,000 μmol photons m^?2 s^?1), UV-B radiation and two nitrogen treatments (enriched and non-enriched). An effective defence system against oxidative stress in G. tenuifrons was induced by UV-B radiation coupled with high photosynthetically active radiation (PAR) with an increase in chlorophyll a, carotenoids content and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH) and Folin-Ciocalteu antioxidant assays). Our study has confirmed the hypothesis that G. tenuifrons is a stress-tolerant tropical species, and its tolerance strongly depends on nitrogen availability in the medium.     

Combined effects of ocean acidification and solar UV radiation on photosynthesis,growth, pigmentation and calcification of the coralline alga Corallina sessilis (Rhodophyta)

Previous studies have shown that increasing atmospheric CO₂ concentrations affect calcification in some planktonic and macroalgal calcifiers due to the changed carbonate chemistry of seawater. However, little is known regarding how calcifying algae respond to solar UV radiation (UVR, UVA+UVB, 280–400 nm). UVR may act synergistically, antagonistically or independently with ocean acidification (high CO₂/low pH of seawater) to affect their calcification processes. We cultured the articulated coralline alga Corallina sessilis Yendo at 380 ppmv (low) and 1000 ppmv (high) CO₂ levels while exposing the alga to solar radiation treatments with or without UVR. The presence of UVR inhibited the growth, photosynthetic O₂ evolution and calcification rates by13%, 6% and 3% in the low and by 47%, 20% and 8% in the high CO₂ concentrations, respectively, reflecting a synergistic effect of CO₂ enrichment with UVR. UVR induced significant decline of pH in the CO₂‐enriched cultures. The contents of key photosynthetic pigments, chlorophyll a and phycobiliproteins decreased, while UV‐absorptivity increased under the high pCO₂/low pH condition. Nevertheless, UV‐induced inhibition of photosynthesis increased when the ratio of particulate inorganic carbon/particulate organic carbon decreased under the influence of CO₂‐acidified seawater, suggesting that the calcified layer played a UV‐protective role. Both UVA and UVB negatively impacted photosynthesis and calcification, but the inhibition caused by UVB was about 2.5–2.6 times that caused by UVA. The results imply that coralline algae suffer from more damage caused by UVB as they calcify less and less with progressing ocean acidification.     

Effects of Short-term Red Radiation and Choline Compounds on Cytokinin Content, Chlorophyll Accumulation and Photomorphogenesis in Wheat Seedlings

Effects of choline compounds (2-chloroethyltrimethylammonium chloride and 2-ethyltrimethylammonium chloride) as well as red radiation (R) pulse on the dynamics of cytokinin changes, growth and chlorophyll (a + b) accumulation were studied during the growth and greening of etiolated wheat seedlings (Triticum aestivum L., var. Mironovskaya-808). The seedlings were grown for 120 h in the dark and then exposed for 72 h to white light. Pre-treatment of caryopses with cholines and pre-irradiation of etiolated seedlings with R inhibited elongation of both coleoptile and first leaf; but the same factors accelerated these growth responses when seedlings were exposed to white light. Chlorophyll (Chl) accumulation and the first leaf appearance from coleoptile were accelerated by the pre-treatments as well. Far-red radiation (FR) reversed all effects of R but choline pre-treatment eliminated partly R/FR photoreversibility. Two compounds with high cytokinin activity (tested on a fresh weight basis by the bioassay with Amaranthus caudatus L.) were found in shoots and first leaves. One of them had R_f, UV absorbance spectrum and the biological activity similar to N⁶-(Δ²-isopentenyl)adenosine. Another cytokinin-like substance was not identified with the used standards. Stimulation of greening by R pulse and cholines was accompanied with accelerated accumulation of both cytokinin-like substances. We conclude that the influence of R and cholines on the concentration of substances with cytokinin activities detected in the leaves might be involved in the stimulation of Chl accumulation.     

Photosynthesis and calcification in the articulated coralline alga Ellisolandia elongata (Corallinales,Rhodophyta) from intertidal rock pools

Calcifying coralline algae are functionally important in many ecosystems but their existence is now threatened by global climate change. The aim of this study is to improve our understanding of coralline algal metabolic functions and their interactions by assessing the respiration, photosynthesis and calcification rates in an articulated (geniculate) coralline alga, Ellisolandia elongata. Algal samples selected for this case study were collected from an intertidal rock-pool on the coast of Brittany (France). Physiological rates were assessed in summer and winter by measuring the concentration of oxygen, dissolved inorganic carbon and total alkalinity fluxes at five irradiance levels and in the dark using incubation chambers.

Respiration, photosynthetic and calcification rates were strongly affected by seasonal changes. Respiration increased with temperature, being ten-fold higher in summer than in winter. Photosynthetic parameters of the photosynthesis-irradiance (P-E) curve, P_g^max, P_n^max and E_k, were two- to three-fold higher in summer relative to winter. Photoinhibition was observed under high irradiance indicating an acclimation of E. elongata to low irradiance levels. Parameters of the calcification-irradiance (G-E) curve, G^max and E_k, were approximately two-fold higher in summer compared with winter. In summer, calcification rates were more strongly inhibited under high irradiance than photosynthetic rates, suggesting a dynamic relationship between these metabolic processes. By inhabiting intertidal rock pools, E. elongata exhibits tolerance to a dynamic physico-chemical environment. Information on respiration, photosynthesis and calcification rates in a calcifying coralline alga inhabiting such dynamic environments in terms of pH and temperature is important in order to better understand how ocean acidification and warming will affect coralline algae in the future.     

Photosynthesis and growth rates of Laurencia brongniartii J. Agardh (Rhodophyta, Ceramiales) in preparation for cultivation

Laurencia brongniartii is usually found at depths below 4 m, but can be found in shallow subtidal areas in crevices and on the walls of a coral reef in Amami Oshima Island, Kagoshima Prefecture, Japan, where irradiances were significantly lower than those at similar depths in open water. In preparation for the possible cultivation of this species for its antibiotic compounds, the effects of temperature and irradiance on photosynthesis and growth were measured. Photosynthesis and growth rates of L. brongniartii explants were highest at 26 and 28 °C, which closely corresponded to temperatures found during August to late December when it was most abundant. The estimated maximum photosynthesis rate (P _max) was 4.41 mol photon m^–2 s^–1 at 26 °C and 4.07 mol photon m^–2 s^–1 at 28 °C. Saturating irradiance occurred at 95 mol photon m^–2 s^–1 at 26 °C and 65 mol photon m^–2 s^–1 at 28 °C. In contrast, growth experiments at 41.7 mol photon m^–2 s^–1 caused bleaching of explants and the maximum growth rate observed during the study was 3.02 ± 0.75% day^–1 at 28 °C and 25 mol photon m^–2 s^–1. The difference in the saturating irradiance for photosynthesis and the irradiance that caused bleaching in growth experiments suggests that long-term exposure to high irradiance was detrimental and should be addressed before the initiation of large scale cultivation.     

钴在油菜中的积累分布及其对光合作用的影响

以甘蓝型油菜(Brassica napus L.)幼苗为材料,分别采用不同浓度的钴(0、10、25、50、100mg.kg-1)土培处理7d,研究钴在油菜体内的分布规律及钴对叶片光合色素含量、光合气体交换参数和叶绿素荧光参数的影响。结果表明:(1)油菜的根、茎、叶均可以吸收积累一定量的钴,油菜对钴的富集量与土壤中的钴含量呈显著正相关,不同器官对钴的积累量存在显著差异,表现为:根>茎>叶,且老叶>嫩叶。(2)土壤中钴浓度为10mg.kg-1时,油菜叶片的色素含量和净光合速率、气孔导度、胞间CO2浓度、蒸腾速率等光合气体交换参数比对照均显著增加,此后随着钴浓度的增加各参数均显著下降,即钴对油菜光合作用的影响表现出低浓度促进高浓度显著抑制的效应。(3)叶绿素荧光分析表明,钴处理显著影响了油菜叶片光系统Ⅱ(PSⅡ)的结构和功能,高浓度钴处理显著抑制了PSⅡ反应中心的活性。     

Temperature response of photosynthetic light‐ and carbon‐use characteristics in the red seaweed Gracilariopsis lemaneiformis (Gracilariales,Rhodophyta)

The red seaweed Gracilariopsis is an important crop extensively cultivated in China for high‐quality raw agar. In the cultivation site at Nanao Island, Shantou, China, G. lemaneiformis experiences high variability in environmental conditions like seawater temperature. In this study, G. lemaneiformis was cultured at 12, 19, or 26°C for 3 weeks, to examine its photosynthetic acclimation to changing temperature. Growth rates were highest in G. lemaneiformis thalli grown at 19°C, and were reduced with either decreased or increased temperature. The irradiance‐saturated rate of photosynthesis (P_max) decreased with decreasing temperature, but increased significantly with prolonged cultivation at lower temperatures, indicating the potential for photosynthesis acclimation to lower temperature. Moreover, P_max increased with increasing temperature (~30 μmol O₂ · g^?1FW · h^?1 at 12°C to 70 μmol O₂ · g^?1FW · h^?1 at 26°C). The irradiance compensation point for photosynthesis (I_c) decreased significantly with increasing temperature (28 μmol photons · m^?2 · s^?1 at high temperature vs. 38 μmol photons · m^?2 · s^?1 at low temperature). Both the photosynthetic light‐ and carbon‐use efficiencies increased with increasing growth or temperatures (from 12°C to 26°C). The results suggested that the thermal acclimation of photosynthetic performance of G. lemaneiformis would have important ecophysiological implications in sea cultivation for improving photosynthesis at low temperature and maintaining high standing biomass during summer. Ongoing climate change (increasing atmospheric CO₂ and global warming) may enhance biomass production in G. lemaneiformis mariculture through the improved photosynthetic performances in response to increasing temperature.     

Elevated Temperature Affects Phenotypic Plasticity in the Bull Kelp (Nereocystis luetkeana,Phaeophyceae)

The sensitivity of kelps to elevated temperatures has been linked to recent declines in some kelp populations, with cascading impacts on marine communities. However, it remains unclear how thermal stress affects the ability of kelps to respond to other environmental factors, which could influence their vulnerability to climate change. We investigated the effect of thermal stress on the ability of the bull kelp Nereocystis luetkeana to acclimate to its surrounding hydrodynamic environment through tension-regulated plasticity in blade morphology. We first determined optimal and stressful temperatures for N. luetkeana by measuring growth over nine temperatures from 5°C to 22°C. We then exposed N. luetkeana blades to a factorial combination of temperature (13°C and 20°C) and tension (0.5 N and 2.0 N) simulating different flow conditions, and measured changes in blade length and width after 7 days. The temperature at which N. luetkeana exhibited maximum growth was estimated to be ~11.9°C, though growth was high over a relatively wide temperature range. When thermally stressed, N. luetkeana maintained morphological responses to simulated high flow, but were inhibited from acclimating to low flow, indicated by an inability of blades to widen. Our results suggest that N. luetkeana in sheltered habitats may be particularly vulnerable to climate warming, where an inability to adjust blade morphology to local hydrodynamic conditions could drive declines at sublethal levels of warming. As ecologically important foundation species, declines in sheltered kelp populations could result in major biodiversity loss and disrupt ecosystem function.     

Effect of visible light on superoxide dismutase (SOD) activity in the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)

Superoxide dismutase (SOD) was studied in the agarophyte Gracilariopsis tenuifrons. Similar SOD activity (130 ± 9U mg^-1) was observed in material from different regions of SouthAmerica, from different phases of the life cycle (gametophytes andtetrasporophytes), and from apical and basal sections of the thallus.In alga grown under a light-dark cycle, SOD activity in samples takenat different times exhibited a diurnal rhythm. The activity measured duringthe day phase was twice as much as during the night phase. This rhythm didnot persist under constant light, indicating light regulation of SOD activity.SOD activity was tested in algae submitted to different light intensities anddifferent wavelengths. It increased with the light intensity. The blue lightwavelength exerted a greater induction of SOD activity than other specificwavelengths.     

光合菌对黄瓜光合及抗氧化同工酶的影响

以2种基因型的黄瓜（Cucumis sativus）为材料,研究光合菌（PSB）的喷施对植物生物量、净光合速率（Pn）、叶片PSII的最大光化学效率（Fv／Fm）及抗氧化同工酶代谢的影响。结果表明,喷施PSB均能诱导2种基因型黄瓜的生物量显著增加,并伴随Pn的显著提高。但是,2种基因型黄瓜的Fv/Fm并不受PSB喷施的影响：PSB能使总过氧化物歧化酶（soo）和抗坏血酸过氧化酶（APX）活性提高,并使它们的多数同工酶的活性上调,这些同工酶活性的增加在叶绿体中表现更为明显（如Cu／Zn-SOD、Fe-SOD和sAPX）。研究结果表明,PSB能通过增强黄瓜抗氧化酶体系的活性改善植株的抗氧化能力,从而在植株的生长和光合作用方面起到促进作用。