小珊瑚藻对赤潮异弯藻的化感效应

研究了不同浓度的小珊瑚藻组织4种不同极性有机溶剂(甲醇、丙酮、乙醚、氯仿)提取物对赤潮异弯藻的生长抑制作用.结果表明：小珊瑚藻组织甲醇提取物对赤潮异弯藻的生长抑制活性最强,并且在较高浓度下能使赤潮异弯藻完全死亡,其他3种有机溶剂提取物对赤潮异弯藻的生长无明显影响.表明小珊瑚藻组织中含有的对赤潮异弯藻有抑制作用的活性物质具有较高的极性.对小珊瑚藻的甲醇提取物进行液液萃取,将其分离为石油醚相、乙酸乙酯相、正丁醇相和蒸馏水相, 并对赤潮异弯藻进行生物活性检测.结果发现石油醚相和乙酸乙酯相具有较强的杀藻活性,表明脂肪酸可能是小珊瑚藻组织内抑制赤潮异弯藻生长的化感物质的重要组成成分之一.     

小珊瑚藻对赤潮异弯藻的克生效应及其 对UV-B辐射增强的响应

通过共培养方法,以细胞密度为主要测定指标,研究了小珊瑚藻对赤潮异弯藻的克生效应及其对UV-B辐射增强的响应.结果表明：小珊瑚藻的新鲜组织和水溶性抽提液对赤潮异弯藻的生长表现出显著的抑制作用(P＜0.05),说明小珊瑚藻对赤潮异弯藻具有克生效应;而小珊瑚藻干粉末和培养水过滤液对赤潮异弯藻生长则无明显影响(P>0.05).将小珊瑚藻用不同剂量的UV-B辐射预处理后,再与赤潮异弯藻共培养,除培养水过滤液外,其新鲜组织、干粉末和水溶性抽提液对赤潮异弯藻生长的作用效果均有所改变,高剂量(3.0 J·m^-2)UV-B辐射使小珊瑚藻对赤潮异弯藻的抑制作用减弱(P＜0.05),而低剂量(0.9 J·m^-2) UV-B辐射则使抑制作用增强(P＜0.05).     

缘管浒苔对赤潮异弯藻的克生效应

利用共存培养系统研究了缘管浒苔(E nterom orpha linza)新鲜组织和干粉末对赤潮异弯藻(H eterosigm a akash iw o)生长的克生效应。共存实验结果表明,缘管浒苔新鲜组织和干粉末对赤潮异弯藻生长均有强烈的克生效应。同时,研究了缘管浒苔培养水过滤液对赤潮异弯藻的克生作用。赤潮异弯藻在缘管浒苔培养水过滤液的半连续添加方式下生长受到明显的克制作用,但在一次性培养方式下生长未受到明显的抑制作用,说明克生物质的连续分泌是有效克制赤潮异弯藻生长的关键;煮沸的大藻培养水过滤液对微藻的生长无抑制作用,表明克生物质在高温下不稳定和易分解。     

鼠尾藻对赤潮异弯藻和中肋骨条藻的抑制作用

通过共培养的方法,研究了鼠尾藻（Surgassum thunbergii）培养水的过滤液、新鲜组织、干粉末、水溶性抽提液对赤潮异弯藻（Heterosigma akashiwo）和中肋骨条藻（Skeletonema costatum）生长的抑制效应,建立了分隔共培养系统并证明了抑制物质的存在,排除了细胞直接接触抑制的可能性.结果表明,在共培养实验中,鼠尾藻新鲜组织、干粉末及水溶性抽提液对赤潮异弯藻和中肋骨条藻的生长具有显著的抑制作用,且在较高浓度下对两种赤潮微藻的生长具有致死效应.在一次性及半连续培养方式下,鼠尾藻培养水过滤液对赤潮异弯藻的生长无抑制效应,而对中肋骨条藻的生长具有显著的抑制效应.     

氮磷营养因子对赤潮异弯藻生长的影响

研究了N、P营养浓度对赤潮异弯藻(Heterosigma akashiwo)生长的影响.结果表明,该藻的生长速率与N、P营养因子浓度的关系符合Monod公式.在NO₃^--N浓度达到7.5 mg·L^-1时,赤潮异弯藻开始生长;浓度为3.75～75 mg·L^-1时,赤潮异弯藻的比生长速率与NO₃^--N浓度成正比关系.N营养充足时,赤潮异弯藻的最大生长速率μ_m-n=0.3475·d^-1,K_s-n=18.91 mg·L^-1.PO₄^--P浓度为0～1.0 mg·L^-1时,赤潮异弯藻的比生长速率与P浓度成正比关系;P营养充足时,赤潮异弯藻的最大生长速率μ_m-p=0.3024·d^-1,K_s-p=0.4086 mg·L^-1.N/P达到25后藻细胞浓度达到最大,表明N/P为25时最适合赤潮异弯藻生长.赤潮异弯藻最适合在N 37.5～225.0 mg·L^-1、P 5.0～50.0 mg·L^-1、N/P=25条件下生长.     

有机磷农药草甘膦异丙胺盐对赤潮异弯藻的毒物干扰效应

以我国典型赤潮藻赤潮异弯藻(Heterosigma akashiwo)为研究对象,设置了6个浓度梯度(0 mg·L^-1、0.001mg·L^-1、0.01 mg·L^-1、0.1 mg·L^-1、1 mg·L^-1和10 mg·L^-1)的草甘膦异丙胺盐处理,研究了草甘膦异丙胺盐暴露对赤潮异弯藻的生长、叶绿素a含量和可溶性蛋白含量等指标的影响.结果表明,草甘膦异丙胺盐对赤潮异弯藻具有明显的毒性效应,10 mg·L^-1浓度处理下,赤潮异弯藻细胞大量死亡,藻细胞密度以及叶绿素a、可溶性蛋白的含量显著降低(p<0.05);当草甘膦异丙胺盐浓度在0.001～1 mg·L^-1范围内,在培养的第3 d草甘膦异丙胺盐能够显著促进赤潮异弯藻的细胞密度增加,叶绿素a含量也明显高于对照组(p<0.05),表现出毒物刺激效应;在暴露实验的中后期(第7 d、第9 d和第11 d),赤潮异弯藻的各生长指标均与对照无显著差异,可能是随着培养时间的延长,农药的降解、生物体对农药的适应、进入细胞的农药减少等原因,藻细胞生理状态逐渐恢复到正常水平.     

赤潮水体中胶体物质对赤潮异弯藻(Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)生长的影响

2004年2月9～10日在胶州湾发生的柔弱几内亚藻(Guinardia delicatula)赤潮期间分别在3个典型赤潮站位采集表层水样,利用过滤(0.7μm)和切向超滤(1000 Daltons)分离赤潮暴发水体中的胶体物质,分析了不同滤液及截留液的有机碳含量,并将赤潮异弯藻 (Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)在<1000 Daltons的超滤液及具有不同含量胶体物质(1000 Daltons～0.7μm)的截留液中进行培养.结果发现在发生柔弱几内亚藻赤潮期间水体中的溶解有机碳浓度会增加,特别是胶体有机碳浓度会成倍增长;在不同胶体含量海水中培养的赤潮异弯藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量的增加而显著增大,而中肋骨条藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量增加而显著降低,表明柔弱几内亚藻赤潮水体中的胶体物质对赤潮异弯藻的生长起促进作用,而对中肋骨条藻的生长起抑制作用.这说明柔弱几内亚藻在增殖过程中所产生的胶体物质具有他感作用,会影响其它微藻的生长,从而可能对柔弱几内亚藻赤潮的形成起重要作用.     

3种海洋赤潮微藻蛋白质和核酸合成对UV-B辐射增强的响应

应用同位素标志法, 研究了赤潮异弯藻 (Heterosigmaakashiwo) 、亚历山大藻 (Alexandriumtamarense ) 和中肋骨条藻 (Skeletonemacostatum) 核酸和蛋白质合成对紫外线B波段 (UV_B, 2 80~ 32 0nm) 辐射增强的响应变化。结果表明 :1) 按照由高到低的顺序, 3种海洋赤潮微藻对UV_B辐射增强的敏感性依次是赤潮异弯藻、亚历山大藻和中肋骨条藻。 2 ) UV_B辐射增强抑制赤潮异弯藻的生长和脱氧核糖核酸 (DNA) 的合成, 而低剂量的UV_B辐射对中肋骨条藻和亚历山大藻的生长与DNA的合成表现出刺激作用, 高剂量则表现出抑制作用。 3) 随着UV_B辐射的增强, 3种海洋赤潮微藻核糖核酸 (RNA) 和蛋白质的合成速度下降, 其中赤潮异弯藻合成速度的下降幅度明显大于中肋骨条藻和亚历山大藻, 表明赤潮异弯藻RNA和蛋白质的合成对UV_B辐射增强的敏感性高于中肋骨条藻和亚历山大藻。     

不同起始密度对3种赤潮微藻种间竞争的影响

通过共培养的方法,研究了不同起始密度对赤潮异弯藻和中肋骨条藻、塔玛亚历山大藻和赤潮异弯藻、塔玛亚历山大藻和中肋骨条藻之间种间竞争的影响。结果表明1赤潮异弯藻对中肋骨条藻的生长有一定的抑制作用,随着初始接种时赤潮异弯藻细胞密度的提高,这种抑制作用愈加明显。2塔玛亚历山大藻和中肋骨条藻与塔玛亚历山大藻和赤潮异弯藻之间的种间竞争结果相类似,即起始密度比例为A∶S(H)=1∶4时,中肋骨条藻和赤潮异弯藻分别在竞争中占优势;当起始密度比例为A∶S(H)=1∶1和A∶S(H)=4∶1,塔玛亚历山大藻在竞争中占优势。     

厚游仆虫(Euplotes crassus)对有毒赤潮藻的清除效应研究

原生动物是水生食物网中主要的植食性生物, 在自然水体中能够有效控制浮游植物的生物量, 具有预防及延缓赤潮发生的潜在应用价值。在福建沿岸分离筛选出一种常见的原生动物—厚游仆虫(Euplotes crassus), 通过研究其对三种常见有毒赤潮藻类的毒素耐受性、抑藻率及自身在赤潮压力下的生长速率, 评测厚游仆虫对常见有毒赤潮藻类的抑制作用, 挖掘其作为控藻生物的应用潜力。将厚游仆虫分别接种于不同浓度的剧毒卡尔藻(Karlodinium veneficum)、赤潮异弯藻(Heterosigma akashiwo)及米氏凯伦藻(Karenia mikimotoi)中, 在温度20 ℃、光照度100 μmol·M–2 ·s–1和光暗比12 h: 12 h 的条件下进行共培养。结果显示, 厚游仆虫对剧毒卡尔藻和赤潮异弯藻具有明显的抑制作用, 持续抑藻时间可达72 h以上, 且未见藻细胞数量的明显反弹, 而对于米氏凯伦藻则没有明显的抑制能力。说明厚游仆虫在一定条件下可作为一种有效可行的控藻生物, 但其对赤潮藻类的抑制作用具有一定的种类特异性。结果证明, 在赤潮形成初期厚游仆虫对赤潮藻类的摄食压力可能有助于抑制或延缓剧毒卡尔藻及赤潮异弯藻赤潮的发生与发展, 其在赤潮治理中的实际应用还需结合野外水体做进一步研究。     

Isolation and structure determination of algicidal compounds from Ulva fasciata

Thirty-seven species of seaweeds including 10 Chlorophyta, 13 Phaeophyta, and 14 Rhodophyta collected from the coast of Nagasaki Prefecture, Japan, were screened for algicidal activity against the red-tide phytoplankton Heterosigma akashiwo. The green alga Ulva fasciata (Ulvaceae, Chlorophyta) showed the strongest algicidal activity among the seaweeds tested. Bioassay-guided fractionation of the methanol extract of U. fasciata led to isolation of three algicidal compounds whose structures were determined to be hexadeca-4,7,10,13-tetraenoic acid (HDTA), octadeca-6,9,12,15-tetraenoic acid (ODTA), and alpha-linolenic acid on the basis of spectroscopic information. These polyunsaturated fatty acids (PUFAs) showed potent algicidal activity against H. akashiwo (LC(50) 1.35 microg/ml, 0.83 microg/ml, and 1.13 microg/ml for HDTA, ODTA, and alpha-linolenic acid, respectively), and the result demonstrated the potential of these PUFAs for practical harmful algal bloom control.     

Selective toxic effects of polyunsaturated fatty acids derived from Ulva fasciata on red tide phyotoplankter species

Alpha-linolenic acid and linoleic acid isolated from Ulva fasciata showed toxic effects on red tide phytoplankters in a concentration-dependent manner. Among six species tested, raphidophycean flagellate Heterosigma akashiwo was the most susceptible to these fatty acids, and 50% lethal concentrations (LC50) of alpha-linolenic acid and linoleic acid were estimated to be 0.58 and 1.91 microg/ml respectively, whereas dinoflagellate Gymnodinium impudicum and Heterocapsa circularisquama were highly resistant and no significant toxic effects were observed up to 1,000 microg/ml. Both fatty acids were less toxic to fish (devil stinger), zooplankters (brine shrimp and rotifer), and mammalian cell lines (U937, HeLa, Vero, and CHO cells) than H. akashiwo.     

不同叶色矢竹叶绿体结构和光系统特性差异

以矢竹(Pseudosasa japonica)、花叶矢竹(P. japonica f. akebonosuji)和曙筋矢竹(P. japonica f. akebono)为研究对象, 借助叶绿体超微结构和荧光动力学曲线的变化揭示不同叶色矢竹的光系统活性及光合特性差异。结果表明: 3个竹种的光合色素含量差异明显, 除花叶矢竹条纹叶白色部分叶绿体内无完整类囊体片层结构外, 花叶矢竹绿条纹和曙筋矢竹的基粒数明显少于矢竹, 叶绿体发育成熟度不一致; OJIP曲线及参数表明, 花叶矢竹条纹绿叶和曙筋矢竹光系统II (PSII)反应中心开放降低程度低于矢竹, 捕获能量用于电子传递的份额变小, PSII活性变弱; 而曙筋矢竹叶片P700至初级电子受体(Q_A)的电子传递链氧化还原平衡偏向于还原侧, 推测其光系统I (PSI)反应中心P700至PSII Q_A电子传递链受损。因此, PSII活性变化导致叶绿体发育不成熟, 可能是引起矢竹类叶色差异的直接原因。     

间伐改形对陇东高原密闭富士苹果园冠层微域环境及叶片生理特性的影响

为了研究间伐改形对成龄乔化密闭红富士苹果园冠层微域环境、叶片显微结构、叶片生理特性和光合能力的影响,以16年生密闭红富士苹果园为研究对象,对果园冠层相对光照强度、温度、相对湿度、叶片叶绿素含量、显微结构、叶片光合和荧光等参数进行了测定。结果表明: 间伐改形后树体冠层相对光照强度、温度得到显著改善,分布更均衡,>30%的有效光强是对照(未间伐改形,CK)的1.57倍,温度比CK平均高1.1 ℃;间伐树体叶片叶绿素、叶片厚度、栅栏组织厚度显著提高,分别比CK提高了8.7%、5.4%、9.2%;叶片净光合速率、蒸腾速率、气孔导度也显著提高,分别比CK提高了12.6%、17.1%和7.3%。间伐果园和密闭果园叶片光合作用均受非气孔因素限制,间伐树体叶片的PSⅡ最大荧光产量和非光化学猝灭系数比CK提高了1.5%和2.1%。间伐改形后,叶片并未发生强光抑制,叶片单位反应中心吸收的光能、捕获的用于电子传递的能量和用于还原Q_A的能量得到显著提高。叶片生理特性与所处的光照、温度环境密切相关,密闭果园间伐改形后,果园冠层光照、温度得到改善,促进了叶片生长发育,改善了叶片显微结构,提高了叶片光合效能,是适宜陇东高原苹果产区密闭红富士果园调整和优化的关键措施。     

Depletion of Vipp1 in Synechocystis sp. PCC 6803 affects photosynthetic activity before the loss of thylakoid membranes

A vipp1 mutant of Synechocystis sp. PCC 6803 could not be completely segregated under either mixotrophic or heterotrophic conditions. A vipp1 gene with a copper-regulated promoter (P _petE -vipp1 ) was integrated into a neutral platform in the genome of the merodiploid mutant. The copper-induced expression of P _petE -vipp1 allowed a complete segregation of the vipp1 mutant and observation of the phenotype of Synechocystis 6803 with different levels of vesicle-inducing protein in plastids 1 (Vipp1). When P _petE -vipp1 was turned off by copper deprivation, Synechocystis lost Vipp1 and photosynthetic activity almost simultaneously, and at a later stage, thylakoid membranes and cell viability. The photosystem II (PSII)-mediated electron transfer was much more rapidly reduced than the PSI-mediated electron transfer. By testing a series of concentrations, we found that P _petE -vipp1 cells grown in medium with 0.025 μM Cu²⁺ showed no reduction of thylakoid membranes, but greatly reduced photosynthetic activity and viability. These results suggested that in contrast to a previous report, the loss of photosynthetic activity may not have been due to the loss of thylakoid membranes, but may have been caused more directly by the loss of Vipp1 in Synechocystis 6803.     

Evidence for slow turnover in a fraction of Photosystem II complexes in thylakoid membranes

We used two different techniques to measure the recovery time of Photosystem II following the transfer of a single electron from P-680 to Q_A in thylakoid membranes isolated from spinach. Electron transfer in Photosystem II reaction centers was probed first by spectroscopic measurements of the electrochromic shift at 518 nm due to charge separation within the reaction centers. Using two short actinic flashes separated by a variable time interval we determined the time required after the first flash for the electrochromic shift at 518 nm to recover to the full extent on the second flash. In the second technique the redox state of Q_A at variable times after a saturating flash was monitored by measurement of the fluorescence induction in the absence of an inhibitor and in the presence of ferricyanide. The objective was to determine the time required after the actinic flash for the fluorescence induction to recover to the value observed after a 60 s dark period. Measurements were done under conditions in which (1) the electron donor for Photosystem II was water and the acceptor was the endogenous plastoquinone pool, and (2) Q₄₀₀, the Fe²⁺ near Q_A, remained reduced and therefore was not a participant in the flash-induced electron-transfer reactions. The electrochromic shift at 518 nm and the fluorescence induction revealed a prominent biphasic recovery time for Photosystem II reaction centers. The majority of the Photosystem II reaction centers recovered in less than 50 ms. However, approx. one-third of the Photosystem II reaction centers required a half-time of 2–3 s to recover. Our interpretation of these data is that Photosystem II reaction centers consist of at least two distinct populations. One population, typically 68% of the total amount of Photosystem II as determined by the electrochromic shift, has a steady-state turnover rate for the electron-transfer reaction from water to the plastoquinone pool of approx. 250 e⁻ / s, sufficiently rapid to account for measured rates of steady-state electron transport. The other population, typically 32%, has a turnover rate of approx. 0.2 e⁻ / s. Since this turnover rate is over 1000-times slower than normally active Photosystem II complexes, we conclude that the slowly turning over Photosystem II complexes are inconsequential in contributing to energy transduction. The slowly turning over Photosystem II complexes are able to transfer an electron from P-680 to Q_A rapidly, but the reoxidation of Q⁻_A is slow (t1/2 = 2 s). The fluorescence induction measurements lead us to conclude that there is significant overlap between the slowly turning over fraction of Photosystem II complexes and PS II_β reaction centers. One corollary of this conclusion is that electron transfer from P-680 to Q_A in PS II_β reaction centers results in charge separation across the membrane and gives rise to an electrochromic shift.     

大米草对赤潮藻的抑制作用及其抑藻物质的分离鉴定

以赤潮异弯藻和海洋原甲藻为研究对象,研究了海洋滩涂植物大米草对两种赤潮微藻的抑制作用及抑藻物质.结果表明：大米草对赤潮异弯藻的影响表现为高浓度抑制生长,低浓度则有一定的促进作用,大米草新鲜组织、干粉末和提取物浓度分别为4.8、0.8和0.5 mg·ml^-1以上时对赤潮异弯藻有致死作用;大米草对海洋原甲藻则表现出明显的抑制作用,且大米草新鲜组织、干粉末和提取物浓度分别为9.6、1.6和1.25 mg·ml^-1以上时对海洋原甲藻有致死作用.对大米草提取物进行抑藻活性物质的分离纯化,从中分离鉴定了2个具有抑藻活性的黄酮糖苷类化合物：异鼠李素-3-O-槐二糖-7-O-鼠李糖苷和丁香亭-3-O-半乳糖苷.     

Properties of mutant reaction centers of Rhodobacter sphaeroides with substitutions of histidine L153, the axial Mg2+ ligand of bacteriochlorophyll BA

Mutant reaction centers (RC) from Rhodobacter sphaeroides have been studied in which histidine L153, the axial ligand of the central Mg atom of bacteriochlorophyll B_A molecule, was substituted by cysteine, methionine, tyrosine, or leucine. None of the mutations resulted in conversion of the bacteriochlorophyll B_A to a bacteriopheophytin molecule. Isolated H(L153)C and H(L153)M RCs demonstrated spectral properties similar to those of the wild-type RC, indicating the ability of cysteine and methionine to serve as stable axial ligands of the Mg atom of bacteriochlorophyll B_A. Because of instability of mutant H(L153)L and H(L153)Y RCs, their properties were studied without isolation of these complexes from the photosynthetic membranes. The most prominent effect of the mutations was observed with substitution of histidine by tyrosine. According to the spectral data and the results of pigment analysis, the B_A molecule is missing in the H(L153)Y RC. Nevertheless, being associated with the photosynthetic membrane, this RC can accomplish photochemical charge separation with quantum yield of approximately 7% of that characteristic of the wild-type RC. Possible pathways of the primary electron transport in the H(L153)Y RC in absence of photochemically active chromophore are discussed.     

The long-term responses of the photosynthetic proton circuit to drought

Proton motive force (pmf) across thylakoid membranes is not only for harnessing solar energy for photosynthetic CO₂ fixation, but also for triggering feedback regulation of photosystem II antenna. The mechanisms for balancing these two roles of the proton circuit under the long-term environmental stress, such as prolonged drought, have been poorly understood. In this study, we report on the response of wild watermelon thylakoid 'proton circuit' to drought stress using both in vivo spectroscopy and molecular analyses of the representative photosynthetic components. Although drought stress led to enhanced proton flux via a ∼34% increase in cyclic electron flow around photosystem I (PS I), an observed ∼fivefold decrease in proton conductivity, g_H⁺, across thylakoid membranes suggested that decreased ATP synthase activity was the major factor for sustaining elevated q_E. Western blotting analyses revealed that ATP synthase content decreased significantly, suggesting that quantitative control of the complex plays a pivotal role in down-regulation of g_H⁺. The expression level of cytochrome b ₆ f complex – another key control point in photosynthesis – also declined, probably to prevent excess-reduction of PS I electron acceptors. We conclude that plant acclimation to long-term environmental stress involves global changes in the photosynthetic proton circuit, in which ATP synthase represents the key control point for regulating the relationship between electron transfer and pmf.     

东海原甲藻对羊栖菜合子生长及光合活性的化感作用研究

为评估东海原甲藻(Prorocentrum donghaiense)赤潮发生对羊栖菜(Sargassum fusiformis)幼苗产量的影响并探讨其化感机理,在实验室条件下分别利用浓度为1.00×10⁵cells/mL东海原甲藻活细胞悬浮液(LC)、细胞破碎液(RC)和无细胞滤液(FC)培养羊栖菜合子,并对其生长发育及光合活性进行测定。结果显示,LC、RC和FC均会抑制羊栖菜合子的生长、叶绿素a合成和光合活性,其中FC及LC对合子的抑制程度相似且均大于RC。JIP-test分析表明,FC及LC对合子的最大量子产率(φP_o)、性能指数(PI)及PSⅡ反应中心密度(RCs/ABS)的抑制作用显著大于RC。表明东海原甲藻主要通过向细胞外释放化感物质产生抑制作用,这些化感物质抑制了羊栖菜合子PSⅡ的电子传递,使PSⅡ部分光化学反应中心(RCs)失活,进而使大量激发能转化为热能被耗散掉。而RC中可能含有某些能够刺激羊栖菜合子生长的物质,从而在一定程度上抵消了化感物质的抑制作用。结果表明东海原甲藻对羊栖菜合子的抑制作用主要是由化感物质引起的,东海原甲藻赤潮可以抑制羊栖菜合子的发育和光合活性,减少羊栖菜种苗产量,并最终阻碍了羊栖菜产业的发展。