光照-温度交互作用及不同氮源对拟柱孢藻生长的影响

为探讨不同环境因子对拟柱孢藻(Cylindrospermopsis raciborskii)生长的影响,对从广东省镇海水库分离的2株拟柱孢藻在不同的温度和光照组合,及不同氮源条件下的生长进行了研究。结果表明,在3种光强下,拟柱孢藻N1和N8藻株的生长随温度的上升而增加,均在28℃高光强下达到最大比生长速率,而N8藻株对低温的适应能力要高于N1藻株。拟柱孢藻N1和N8在各硝态氮浓度下均能正常生长,但仅能在中低浓度的铵态氮和尿素氮中生长,高浓度(128~247 mg L–1)的铵态氮和尿素氮会显著抑制藻细胞生长;在3种氮源下,N1藻株的比生长速率均显著大于N8藻株,这说明N1藻株对不同氮源的利用能力要高于N8藻株。因此,广东省的拟柱孢藻具株系多样性,喜好高温,适应较宽的光照范围,并可利用多种氮源用于生长,这可能是该地区拟柱孢藻水华频发的原因。     

The Discovery and Anti-Colorectal Cancer Activities of Cembranolides from the South China Sea Soft Coral Sinularia pendunculata

A new cembranolide, namely, sinupendunculide A ( 1 ), along with eight known related compounds ( 2–9 ), was isolated from the South China Sea Soft coral Sinularia pendunculata. The structure of sinupendunculide A ( 1 ) was established by extensive spectroscopic analysis and X-ray diffraction experiments. In a bioassay, anti-colorectal cancer (CRC) activity was performed, and the results showed that several compounds exhibited cytotoxicity against RKO cells, and a preliminary structure-activity relationship was analysed. Meanwhile, the most effective compound 7 was proven to increase reactive oxygen species levels, which promoted cell apoptosis and inhibited cell proliferation.     

盐度、温度和光照强度对针叶蕨藻的生长及光合活性的影响

为探究环境因子对针叶蕨藻（Caulerpa sertularioides）生长的影响,对不同盐度、温度和光照强度下针叶蕨藻的生长和叶绿素荧光参数进行了研究。结果表明：藻体日特定生长率（SGR）、最大光量子产量（F_v/F_m）、实际光合效率（Yield）、电子传递速率（ETR）和光化学淬灭（qP）随盐度升高呈先上升后下降的变化趋势,非光化学淬灭（qN）则呈相反的变化趋势,藻体光合活性和固碳效率在盐度27.5‰时达到最高,且与25‰和30‰盐度的差异显著（P<0.05,n=3）。藻体SGR、F_v/F_m、Yield、ETR和qP随温度升高而下降,qN则相反,藻体光合活性和固碳效率在26℃下达到最高,且与28℃和30℃的差异显著（P<0.05,n=3）。藻体的SGR、F_v/F_m、Yield、ETR和qP随光照强度升高呈先上升后下降的变化趋势,qN则相反,且在18.75 μmol/（m²·s）弱光照下出现轻微光抑制,藻体生长、光合活性及固碳效率在光照强度25.00 μmol/（m²·s）时达到最高,但与18.75和31.25 μmol/（m²·s）的差异不显著（P>0.05,n=3）。因此,针叶蕨藻在27.5‰盐度、26℃和25.00 μmol/（m²·s）光照强度下生长最快且光合作用能力最高。     

走马胎灰分对光的响应特征及其与生长指标的相关性

为探究光照强度和光质对走马胎(Ardisia giantifolia)灰分积累的影响，利用遮阳网和薄膜设定4个光照梯度(100%、60%、40%、20%全光照)和4种光质(绿、白、蓝、红)，分析了基径、株高以及生物量的响应特征，以及灰分与生长指标的关系。结果表明，走马胎灰分含量在绿光下随着光照强度的减弱而呈减少的趋势，在白光下随着光照强度的减弱呈现“低-高-低-高”的波动变化，在蓝光或红光下没有显著变化；在100%光照强度下，白光的灰分含量最低，与其余光照强度存在显著差异; 在60%、40%、20%光照强度下，光质对走马胎灰分含量的影响不显著。走马胎灰分含量与株高、基径和生物量间不存在明显的相关性；随着光照强度的减弱，走马胎的株高、基径以及生物量均呈现增加的趋势，且在白光下达到最大。因此，光照对走马胎灰分的积累和生长指标均有影响，种植走马胎时要选择适当遮荫强度或郁闭度较高的林型。     

Growth rate and control of development of the photosynthetic apparatus in Chloroflexus aurantiacus

Chloroflexus aurantiacus was grown photoheterotrophically in a chemostat in order to study the influence of growth rate on the formation of bacteriochlorophyll a (Bchl a) which represents the membrane-bound photosynthetic pigment complexes, and of Bchl c which represents the light harvesting pigment-proteins of the chlorosome. Steady state cell protein levels as well as specific Bchl a contents increased linearly and specific Bchl c contents exponentially when the dilution rate, representing growth rate, was decreased. In spite of differences in the light intensities, continuous cultures growing at comparable growth rates and densities exhibited comparable specific contents of both Bchls and largely identical molar ratios of Bchl c/Bchl a. The growth rate of constantly illuminated batch cultures was varied by changing the concentration of growth-limiting nutrients. Cultures growing at higher growth rates showed higher cell densities but lower specific Bchl levels as well as lower molar ratios of Bchl c/Bchl a than cultures growing at low growth rate. Determination of the light energy flux required for half-maximal saturation of photosynthetic activity (light dependent proton extrusion) by chemostat cultures showed a dependency of that activity by the content of cellular Bchl c. In summary, the results suggest that, growth rate or a factor regulating growth rate, rather than light affected specific Bchl levels and because of the increasing molar ratio of Bchl c to Bchl a, the light harvesting capacity and photosynthetic efficiency of the photosynthetic apparatus.     

Growth of the seaweed Ulva rigida C. Agardh in relation to biomass densities, internal nutrient pools and external nutrient supply in the Sacca di Goro lagoon (Northern Italy)

Growth of the seaweed Ulva rigida C. Agardh was investigated in relation to biomass densities, internal nutrient pools and external nutrient supply. Research was carried out from 23 March to 5 July 1994 in the Sacca di Goro (Po Delta, Northern Italy), whose south-eastern part was covered by extensive mats of Ulva rigida. Two types of field experiments were conducted by incubating Ulva thalli inside large cages. In the first experiment, beginning on 23 March, 100 g of wet thalli were placed into the cages, allowed to grow for two weeks, then collected and replaced. This procedure was repeated 8 times over the study period. In the second experiment, Ulva thalli were left inside the cages and collected at selected time intervals (14, 27, 41, 64 and 76 days) in order to simulate the effects of increased density on growth and nutrient storage.We recorded specific growth rates (NGR) ranging from 0.025 to 0.081 d^–1 for a period up to two months in the repeated short-term experiments performed at relatively low initial algal densities (300–500 g AFDW m^–3). These NGR resulted significantly related to dissolved inorganic nitrogen (DIN) in the water column. Tissue concentrations of total Kjeldahl nitrogen (TN) were almost constant, while extractable nitrate decreased in a similar manner to DIN in the water column. Total phosphorus showed considerable variation, probably linked to pulsed freshwater inflow.In the long-term incubation experiment, NGR of Ulva was inversely related to density. Internal concentrations of both total P and TN reached maximum values after one month; thereafter P concentration remained almost constant, while TN decreased below 2% w/w (by dry weight). The TN decrease was also accompanied by an abrupt decrease in nitrate tissue concentration. The biomass incubated over the two month period suffered a progressive N limitation as shown by a decreasing NY ratio (49.4 to 14.6). The reciprocal control of Ulva against biogeochemical environment and viceversa is a key factor in explaining both resource competition and successional stages in primary producer communities dominated by Ulva. However, when the biomass exceeds a critical threshold level, approximately 1 kg AFDW m^–3, the macroalgal community switches from active production to rapid decomposition, probably as a result of selfshading, biomass density and development of anaerobic conditions within the macroalgal beds.     

转录组和代谢组分析瘤菌根菌对铁皮石斛的促生机制

为筛选出促进铁皮石斛(Dendrobium officinale)生长的差异表达基因和差异代谢物,对瘤菌根菌与无菌盆栽铁皮石斛苗共生后形成的侧根根系进行转录组、代谢组和双组学联合分析。结果表明,转录组分析共找到262条差异表达基因富集到了35条通路中,其中内质网蛋白质加工通路途径的差异基因最多,其次为氨基糖和核苷酸糖代谢通路。代谢组分析共检测出194个差异代谢物富集到33个KEGG通路中,其中代谢途径的差异代谢物最多有133个,其次为不同环境的微生物代谢途径的差异代谢物有70个。通过联合分析,有9个差异基因的差异表达导致丝氨酸、谷氨酸、D-甘露糖和激素等代谢物的积累量发生变化,这可能是瘤菌根菌促进铁皮石斛生长的重要原因。因此,推测瘤菌根菌促进铁皮石斛生长与氨基酸、糖、植物激素的积累及相关基因的表达变化有关。     

不同光环境对海南龙血树幼苗表型可塑性及生存策略的影响

为了解光照对海南龙血树(Dracaena cambodiana)幼苗生长的影响,研究了不同光照环境下海南龙血树幼苗形态、生理特性和生物量分配的变化,并分析了其生态适应性。结果表明,海南龙血树幼苗的形态、生理和生物量分配指标在不同光照强度间存在显著差异,各指标的可塑性指数为0.08~0.86,其中根茎叶及总生物量的可塑性指数普遍较高(0.67~0.86),表明海南龙血树幼苗有较好的光照适应性,其策略主要是通过调整根茎叶生物量的分配来适应光照的变化。随着光照强度的降低,海南龙血树幼苗的比叶面积、叶根比呈现显著增大趋势,表明幼苗可通过增加单株叶面积比例,扩大光合作用面积,有效调节自身生物量配置。37.3%自然光照(L2)是海南龙血树幼苗生长的最佳光照强度。现存海南龙血树生境改变,生境缺少林荫以致光照强度过大,不利于幼苗根系生长,难以度过干旱季节,可能是海南龙血树自然更新失败的重要原因之一。     

不同光质及肥料浓度对小报春生长发育的影响

不同光质和肥料浓度对小报春(Primula forbesii)幼苗生长的影响进行了研究。结果表明:蓝光能促进小报春幼苗的光合速率和蒸腾速率,黄光能明显地促进小报春幼苗增高,红光则促进植株开花;肥料浓度EC 2.0 mS cm-1对促进小报春幼苗生长及叶面积增大的效果最佳;交互处理试验以红光/EC 2.0 mS cm-1的效果最明显,对小报春幼苗的营养生长和生殖生长均有促进作用。因此,选择合适的光质和肥料浓度有利于促进植物的生长发育。     

Phytochrome action in light-grown plants: the influence of light quality and fluence rate on extension growth in Sinapis alba L.

Using light-grown plants of Sinapis alba an analysis has been made of the effect on extension growth of adding far red light to a background photosynthetic source. It has been possible to distinguish between the increase in fluence rate and the reduction of the amount of phytochrome present as Pfr, which are both consequences of the addition of supplementary far red light, and to determine that the response of increased extension growth is due only to the latter. It is shown that the degree of fluence rate dependency varies with photoequilibrium and the significance of this interaction is discussed in terms of the mode of action of phytochrome and of its role in the natural light environment.Abbreviations PAR photosynthetically active radiation - SAN 9789 4-chloro-5-(methylamino)-2-(,,-trifluoro-m-tolyl)-3(2H) pyridazinone - Pfr far-red absorbing form of phytochrome - Pr red-absorbing form of phytochrome - LER logarithmic extension rate     

油茶砧和茶穗嫁接后苗期叶片形态和次级代谢物含量的变化

为了解茶/油茶嫁接苗叶片在形态和代谢产物上的变化,以茶‘舒茶早’品种（Camellia sinensis ‘Shuchazao’）为接穗,大别山野生油茶（C. oleifera）为砧木进行根颈嫁接,对嫁接体、茶树和油茶的叶片形态和次生代谢产物含量进行了研究。结果表明,茶/油茶嫁接体叶片在形态上更接近于茶,而嫁接体叶片形态学指标却受到了油茶的影响。嫁接体叶片中的氨基酸、嘌呤碱和多酚含量比油茶叶片高,其中茶氨酸含量比油茶显著提高。嫁接体叶片中含有酚酸,而在油茶中未被检出。嫁接体叶片中咖啡碱含量比茶树叶片显著下降。这对茶、油茶的栽培,茶树次级代谢及次级代谢物的转运机理研究具有一定的积极作用。     

Phototactic responses in Haematococcus lacustris and its modification by light intensity and the carotenoid biosynthesis inhibitor Norflurazon

At fluence rates below 45 W· m^-2 cells of the flagellate stage of Haematococcus lacustris react only positively phototactically with a rather high degree of orientation (indicated by r values up to 0.66 with the Rayleigh test). The directedness of orientation decreases with decreasing irradiance. The degree of directedness of the phototactic response depends on the intensity of preirradiation: Low light intensity applied after strong light application results in a dark reaction (low r values), low light given after darkness stimulates a rather high degree of directedness of positive phototaxis. Weak blue light (=483 nm; 0.4 W · m^-2) stimulates positive phototactic response, whereas comparable red light (=658 nm; 0.5 W · m^-2) does not.Cells which were grown in a medium containing 10^-4 M Norflurazon (effective in inhibition of carotenoid biosynthesis) although maintaining motility completely lose the ability to react positively phototactically. The possible role of carotenoids in the phototactic orientation is discussed.     

Life history and population dynamics of the Japanese Yam,Dioscorea japonica Thunb.

The adaptive significance of the emergence mode ofDioscorea japonica was studied with respect to initial plant size (seed, bulbil and tuber) and light intensity, using mathematical simulation based on Yokoi's (1976) model. Under 1.5% full sunlight conditions, plants emerging with only one leaf did not develop a shoot system throughout the growing period (Hori and Oshima, 1986). Simulation indicated that, for this species of plant under poor productive conditions, the optimal time for switch-over from the vegetative to reproductive growth phase to maximize the tuber weight at the end of the growing period, occurred immediately following the start of autotrophic growth. By means of shoot growth patterns, small and large size plants acquired the ability of shade tolerance and shade avoidance, respectively. Further, the life history ofD. japonica could be expressed as a flow chart based on plant size and light intensity data.     

Growth and Secondary Metabolite Production by Hairy Roots of Tagetes Patula in Aqueous Two-Phase Systems

Hairy roots of Tagetes patula have been grown in aqueous two-phase systems. After selecting suitable polymers from single-phase experiments (in which salt phases were unable to support growth in the desired concentrations) several two-phase systems were tested for their influence on cell growth and thiophene production. Cell growth occurred in all aqueous two-phase systems, but the highest growth rate was achieved in normal medium. There was no difference in thiophene production between medium and aqueous two-phase systems. The partition of thiophenes favoured slightly the more hydrophobic top phase in most cases, while the cells were confined to the bottom phase. One aqueous two-phase system (15% polyethyleneglycol 10,000 and 15% Reppal PES 200) was tested in a stirred tank reactor with normal medium as a control. The growth rate in medium was higher than in the aqueous two-phase system, while the thiophene production per unit cell weight was in the same range for both systems. The excretion of thiophenes in the reactor with the aqueous two-phase system was about ten times as high as in the control reactor. The amount excreted was however still not more than 3% of the total production.     

Key Amino Acid Residues Responsible for the Color of Green and Yellow Fluorescent Proteins from the Coral Polyp Zoanthus sp.

Site-directed mutagenesis was used to study the structural basis of color diversity of fluorescent proteins by the example of two closely related proteins from one organism (coral polyp Zoanthus sp.), one of which produces green and the other, yellow fluorescence. As a result, the following conversions of emission colors were performed: from yellow to green, from yellow to a dual color (yellow and green), and from green to yellow. The saltatory character of the spectral transitions and the manifestation of the dual-color fluorescence suggest that chemically different fluorophores are responsible for the green and yellow fluorescence. The simultaneous presence of three residues, Gly63, Lys65, and Asp68, is necessary for the efficient formation of the yellow rather than green fluorophore.     

Role of Light and Medium Composition on Growth and Valepotriate Contents in Valeriana glechomifolia Whole Plant Liquid Cultures

A system for growing in liquid medium whole plants of Valeriana glechomifolia, endemic to southern Brazil and capable of accumulating bioactive valepotriates, is described. Murashige and Skoog (MS) and Gamborg B5 (B5) media (1.0×, 0.3× and 0.1× strength) without phytohormones were evaluated after four weeks of culture in relation to growth and valepotriate yield. Plants grown in 1.0× MS displayed greatest growth and valepotriate yields and the study of the light condition showed that plants grown under light and dark had similar weight increase and maximum valepotriate yield, 27.2 mg/g DW and 25.0 mg/g DW, respectively. Valtrate was the most abundant valepotriate, followed by acevaltrate and didrovaltrate.     

Quantification of plasticity of plant traits in response to light intensity: comparing phenotypes at a common weight

Summary Plasticity of plant traits is commonly quantified by comparing different phenotypes at the same age. In this paper, we present a method in which the effect of resource conditions on plant weight is used as a basis for quantifying the plasticity of individual plant traits. Abutilon theophrasti individuals were grown in, and some transferred between, high and low intensity light conditions, resulting in four phenotypes. Plant traits were found to exhibit different degrees of plasticity, decreasing in this order: height; specific leaf area; allocation to branch roots; allocation to leaf area; number of nodes; allocation to tap roots; allocation to stem; allocation to leaf weight. Under these conditions, individuals of the four phenotypes had very similar heights when compared at the same age, but very different heights when compared at the same plant weight. The latter comparison indicates that light intensity influences height independently of its influence on plant weight. Individuals that were transferred from high to low light had greater allocation that had not been transferred, but individuals of all phenotypes had nearly the same leaf weight allocation when compared at the same plant weight. The latter comparison indicates that light intensity influeces leaf weight allocation mostly by influencing plant weight. In the phenotype resulting from the transfer of plants from low to high light, reproduction was stimulated much less than plant weight and axillary leaf growth, and reproductive allocation was delayed relative to the other three phenotypes. We conclude that when plasticity is measured by comparing phenotypes at the same plant weight, the effects of resources on plant size can be excluded from the quantification.     

Coral reef rehabilitation through transplantation of staghorn corals: effects of artificial stabilization and mechanical damages

In order to develop and test a low-cost method of coral reef rehabilitation, the staghorn corals Acropora muricata and A. vaughani were transplanted to a shallow site with unstable substrate. To avoid abrasion, dislodgement and transport due to water movement, the transplanted corals were tied to string sections, which were connected at the seabed to form a grid. This created stability and improved the survival of the corals. The average increase in weight of live coral over 1 year was 56%, eight times more than the control treatment with unattached coral branches. This difference was mainly due to a reduced partial mortality among smaller coral fragments in the stabilized treatment. Survival was positively related to initial size among the loosely placed coral branches, whereas the attached treatment showed a negative relation between size and relative increase in weight of the surviving parts of the coral branches. Coral fragments were not significantly affected by severe physical damage simulating the effects of handling.     

Response of cylindrospermopsin production and release in Aphanizomenon flos-aquae (Cyanobacteria) to varying light and temperature conditions

The influence of light and temperature on the cylindrospermopsin (CYN) production of two Aphanizomenon flos-aquae strains, isolated from North-eastern German lakes, was investigated with semi-continuously growing cultures. A light gradient from 10 to 60 μE m⁻² s⁻¹ in combination with temperatures of 16, 20, and 25 °C was tested.CYN concentrations varied by a maximum factor of 2.7 in strain 10E9 with a significant decrease with increasing temperature. Strain 22D11 showed less pronounced changes, i.e. by a factor of 1.6, and without clear relationship to temperature.Reaction patterns of CYN production to changing light intensities are different at different temperatures. In both strains CYN concentrations increase significantly at 20 °C between 10 and 60 μE m⁻² s⁻¹, whereas they decrease significantly at 25 °C in the same light gradient. The amount of synthesised CYN is not reflected by growth rates of the strains in a uniform manner. Nonetheless several temperature–light combinations which constitute physiological stress seem to trigger CYN production and particularly CYN release from cells. The lowest growth rate observed at 16 °C and 60 μE m⁻² s⁻¹ of strain 22D11 may reflect photoinhibition due to the lower temperature and related limited CO₂-fixation. Under these conditions, extracellular CYN concentrations increased to 58% of total CYN, while the share of extracellular CYN of all other light and temperature regimes was 11–26%. From the results and the experimental design we conclude an active release of the toxin into medium to be more likely than mere leakage from cells.