四列藻在光限制胁迫下的超补偿生长响应

采用海洋微藻四列藻为试验材料,试验前期微藻经光限制(500 LX)胁迫处理10 d,试验后期重新接种并恢复正常光照(5000 Lx)培养10 d,均以正常光照(5 000 Lx)培养作对照,测定四列藻的细胞密度、细胞内蛋白质含量、细胞内糖分含量等指标。结果表明,处理组在恢复工常光照的初期(1～2 d)细胞生长量超过对照(P<0.05),即藻细胞平均相对生长率提高,细胞数增多,叶绿素 a含量和生物量增加,细胞数净增率最高达31.6%,生物量净增率最高达34.8%。同时,四列藻在受到光限制胁迫后,藻细胞内蛋白质、细胞内糖和蛋白质/糖(P/C)的比值发生了变化,但是在恢复正常光照培养后,这几个指标均逐渐恢复至处理前的水平。四列藻的这种受到光胁迫后细胞生长量增加的特征表明微藻具有超补偿性能。     

三角褐指藻在磷营养限制胁迫下的补偿生长效应

以三角褐指藻(Phaeodactylum tricornutum)为研究材料,设置了5个磷营养限制处理:磷营养分量分别设为f/2培养基的1/20(P₁)、1/10(P₂)、1/8(P₃)、1/4(P₄)、1/2(P₅),以f/2为对照(P_ck),在磷限制胁迫下培养10d,然后均以相同密度(2.5×10⁵cells·mL^-1)接种在f/2条件下恢复培养16d,测定了三角褐指藻在磷限制胁迫下和恢复培养阶段的生长状况。结果表明,三角褐指藻在受到磷限制胁迫后,细胞密度、蛋白质和可溶性糖含量都显著低于对照(p<0.05);恢复阶段,P₁、P₂和P₃处理组的细胞密度、平均相对生长率及生物量在恢复培养的中前期显著高于对照(p<0.05),最高平均相对生长率分别为0.73、0.70、0.68d^-1,显著高于对照(0.55d^-1)(p<0.05);P₄处理组的细胞密度和生物量与对照无显著差异;P₅处理组的细胞密度和生物量在恢复培养的中前期显著低于对照(p<0.05);随着培养时间的推移,各处理组与对照之间的差异逐渐缩小,处理组和对照的细胞密度、生物量、蛋白质和可溶性糖含量等均无显著差异。     

海洋微藻四列藻对光周期改变的响应

以海洋微藻四列藻(Tetraselmis tetrathele)为试验材料,设置了短光周期(A)和长光周期(B)两组试验:A组分光周期1h、2h、4h、6h、8h和10h6个等级,B组分光周期14h、16h、18h、20h、22h和23h6个等级,均以光周期12h为对照,测定了四列藻的细胞密度、叶绿素a和蛋白质含量等指标.结果表明,在试验所设计的13个光周期等级中,光周期为6h、8h、10h、12h、14h、16h和18h等7个处理的藻细胞密度、叶绿素a和蛋白质含量等指标均达到较高水平.而光周期小于4h的3个处理和大于20h的3个处理,四列藻细胞的生长受到了明显抑制,细胞密度、叶绿素a和蛋白质含量均显著降低.     

绿色巴夫藻和四列藻种间竞争机制研究

种间竞争是生物普遍存在的一种生命现象 ,可以利用来调控生物的生长和数量变化 ,进行有害生物的防治。藻类植物间也存在明显的竞争现象。Ｈｏｌｍ[8] 报道了硅藻和微囊藻种间的相互作用。Ｈｅｇａｒｔｙ[9] 研究了光强和Ｎ、Ｐ比对棕囊藻和 5种硅藻间竞争的影响。Ｋｕｗａｔａ[10 ] 研究了铵盐对绿藻和蓝藻间竞争作用的影响。Ｄａｖｉｓ[11] 研究了海藻和海草间的竞争。Ｐｉａｚｚｉ[12 ] 研究了两种海洋绿藻生长的竞争情况。刘世枚[1] 研究了两种绿藻种群间的相互作用。陈德辉等[2 ] 对微囊藻和栅藻共培养进行了研究并计算了竞争参数。。绿…     

绿色巴夫藻在UV-B胁迫后的生长补偿效应

以绿色巴夫藻(Pavlova viridis)为试验材料,设置了4、6、8、10μW.cm-2和12μW.cm-25个UV-B辐射强度,以无紫外辐射为对照,UV-B分别胁迫处理10min(a组)和15min(b组)。解除胁迫后,处理组和对照组在相同接种密度和相同条件下培养12d,测定了生长过程中的吸光值、色素含量、可溶性蛋白质和胞内多糖含量。结果表明,P.viridis在UV-B胁迫下,藻细胞生长受到显著抑制,a组和b组辐射处理的细胞相对增长率分别比对照下降了17.70%~51.54%和26.16%~60.01%(p<0.05)。但是,当胁迫解除后,各处理的藻细胞生长速率,在恢复阶段前期(1~4d)与对照无显著差异,在恢复阶段的中后期(6~12d)则显著(p<0.05)或极显著(p<0.01)高于对照。证明P.viridis在胁迫后的恢复生长中表现超补偿生长现象,恢复培养第12d的最大光密度值比对照提高了26.55%,最大叶绿素a、类胡萝卜素、可溶性蛋白质和胞内多糖含量分别比对照提高了29.17%、29.93%、15.34%和34.37%。当然,在各处理中,随着辐射时间的延长和辐射强度的增大,超补偿生长发生的时间也相对滞后。     

蛋白核小球藻在光胁迫下的超补偿现象

2000.3-2000.7以蛋白核小球藻(Chlorella pyrenoidosa)为实验材料,测定了其在光胁迫条件下及胁迫解除后细胞的生长密度及生长率。结果表明:光照条件恢复后,遮光处理组较对照组在短期内有更高的产量及生长速率。藻类中存在的这种特性很可能也是形成赤潮爆发的一个生物内源性因素。     

棉粕对盐碱胁迫下棉花生理及生长补偿效应

为探究棉粕对盐碱胁迫下棉花(Gossypium hirsutum)的抗盐碱机理, 通过田间试验, 研究添加不同棉粕用量对8 g·kg ^-1盐碱胁迫下棉花生理及生长的补偿效应。结果表明, 添加棉粕能够增加盐碱胁迫下棉花不同器官对K ⁺的吸收, 降低对Na ⁺的吸收, 维持盐碱胁迫下细胞内K ⁺和Na ⁺的平衡, 显著促进棉花生长, 提高叶片叶绿素含量和光合作用效率, 有效缓解盐碱胁迫对棉花的伤害。其中, 以添加6 000 kg·hm ^-2棉粕处理的效果最显著, 且盐胁迫下棉粕的改良效果较好。主成分分析结果表明, 盐碱胁迫下棉花生长生理的主要影响因子为叶片K ⁺/Na ⁺比值、根长、鲜重、干重和胞间CO₂浓度(C_i)。     

蛋白核小球藻在光协迫下的超补偿现象

2000．3－2000．7以蛋白核小球藻（Chlorella pyrenoidosa）为实验材料,测定了其在光胁迫条件下及胁迫解除后细胞的生长密度及生长率。结果表明：光照条件恢复后,遮光处理组较对照组在短期内有更高的产量及生长速率。藻类中存在的这种特性很可能也是形成赤潮爆发的一个生物内源性因素。     

微囊藻和栅列藻光吸收特性的实验研究

在室内模拟槽中,以人工灯为光源,分别检测不同密度的微囊藻和栅列藻细胞悬液的光谱衰减,检测各样品的叶绿素含量和过滤后清液的溶解性有机碳(DOC)含量,并在紫外分光光度计上检测DOC光谱吸收,然后换算成吸收系数。再根据近似的线性加和关系计算出细胞悬液中各组分(藻细胞、水、DOC)的吸收系数。结果表明,微囊藻和栅列藻光衰减的波谱特征相似,在3个较高密度下的衰减系数的变化趋势相近,其衰减系数贡献率的平均值分别为84.95%和88.15%。将衰减系数除以各自的叶绿素浓度即可得到叶绿素的比吸收系数,两种藻3个较高密度的比吸收系数的平均值具有相似的波谱特征,在380～500、660～690nm两个波段有较明显的峰值,栅列藻和微囊藻在435nm的比吸收系数峰值分别为0.1118、0.0413(m2·mg-1chla),在670nm处的峰值分别为0.075、0.032(m2·mg-1chla)。但两者的比吸收系数差异较大,三个密度栅列藻在340～800nm的平均比吸收系数是0.0573(m2·mg-1chla),而微囊藻仅为0.0234(m2·mg-1chla),且微囊藻的所有波长的比吸收系数均小于栅列藻。根据这些参数来讨论两种藻类在分光衰减中的贡献率和光谱特征方面的差异及其生态学意义,以及在浮游植物的遥感监测方面的参考价值。     

不同营养条件对极端嗜盐杜氏藻生长的影响研究

探讨了不同浓度碳源、氮源(N/P)、无机磷源、脲及卤虫干粉(或发酵液)卤水培养基对极端嗜盐杜氏藻生长的影响, 以期为更好地开发杜氏藻资源提供全面、系统的资料。结果表明: 通过物理方式直接通入CO2 补充极端嗜盐杜氏藻培养基, 能有效的保障极端嗜盐杜氏藻生长所需的碳源; 采用尿素作为藻培养基氮源效果较好, 无机磷浓度应维持较低水平; 卤虫发酵液较卤虫干粉能有效延长藻细胞高密度生长期, 极端嗜盐杜氏藻适宜培育浓度范围: 尿素浓度为30.00 mg·L–1-90.00 mg·L–1, N/P 维持在25 左右, NaH2PO4 浓度为2.71 mg·L–1-12.00 mg·L–1, 3.50 mg·L–1 最优; 卤虫发酵液浓度应在250.00 mg·L–1 以上。     

THE CRYSTALLINE CELL WALL OF TETRASELMIS CONVOLUTAE (CHLOROPHYTA): A FREEZE FRACTURE ANALYSIS1

A freeze fracture analysis of the cell wall of Tetraselmis convolutae (Parke et Manton) revealed the existence of a crystalline median layer consisting of regular repeating subunits of 27 nm. These circular subunits lie in curved, interlocking, longitudinal rows with some irregular discontinuities appearing in the subunit pattern of the crystalline lattice. A comparison with the cell walls of other green algal flagellates is presented, revealing similarities and suggesting evolutionary patterns.     

我国沿海四爿藻的室内培养

在水产养殖中,四爿藻是一种重要的饵料资源,从我国沿海(包括广东、浙江、山东等省)采集到的海洋单细胞绿藻四爿藻,用毛细管法挑取进行单种培养,然后在固体培养基中稀释划线分离得到无菌纯培养物,利用改良的Guillard &; Ryther(Guillard F)培养基、海洋Ⅲ号培养基和改良的海洋Ⅲ号培养基对四爿藻进行了实验室培养。结果发现,改良的海洋Ⅲ号培养基中四爿藻的生长速率最快,最适pH范围为7．0～8．0,加入维生素B12(10μg·L^-1),也可以适当增加四爿藻的生长速率。这种改良的海洋Ⅲ号培养基配制简单,适合于水产养殖中四爿藻的规模生产。     

Precise identification of photosynthetic glycerolipids in microalga Tetraselmis chuii by UPLC-ESI-Q-TOF-MS

Precise structural identification of photosynthetic polar glycerolipids in microalga Tetraselmis chuii has been established using Ultra Performance Liquid Chromatography–Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF-MS) by direct analysis of the total lipids extract. The mass spectrometry was performed in reflective time-of-flight using electron spraying ionization in both positive and negative modes. The structural determination was based on the char-acteristic product ions yielded by different glycerolipids under ESI-MS/MS mode, and confirmed the molecular species by the carboxylate anions produced by glycerolipids in the negative mode. As a result, more than 40 lipid molecular species, including 11 monogalactosyldiacylglycerols (MGDG), 7 digalactosyldiacylglycerols (DGDG), 16 sulfoquinovosyldiacylglycerols (SQDG), and 9 phosphatidyl-glycerols (PG), were detected in Tetraselmis chuii, which had never been identified before in this mi-croalga. Furthermore, some intact lipid molecules with hydroxylated fatty acids that could not be de-tected by the traditional GC-MS method were found this time, providing novel information for the pho-tosynthetic lipidome of Tetraselmis chuii. Comparative studies on fatty acids at the sn-2 position showed that SQDG and MGDG are dominantly biosynthesized through the prokaryotic pathway, PG is a typically mixed biosynthetic pathway, while DGDG is somewhat peculiar with C14:0 and C16:0 at its sn-2 position. This method could provide a full structural profile of intact photosynthetic lipid molecular species, which may be applied to study the physiological and ecological functions of lipid by monitor-ing their individual changes.     

Growth Rate of the Microalga Tetraselmis suecica Changes the Biochemical Composition of Artemia Species

The impact of different microalgal semicontinuous cultures on growth and biochemical composition in the next link of the food chain was tested using the filter feeder Artemia species as a model. The marine microalga Tetraselmis suecica was cultured semicontinuously with renewal rates between 10% and 50% and used to feed Artemia. Microalgal cultures maintained with a low renewal rate that had biochemical composition similar to that of the stationary-phase cultures commonly used in aquaculture produced poor growth and survival and low food-conversion efficiency compared to cultures maintained with a high renewal rate. Changes in the renewal rate in microalgal cultures also resulted in important changes in the gross biochemical composition of the filter feeder. The gross biochemical composition of the Artemia resembled that of the microalgae used as food except for total lipid content. The percentage of protein in the organic fraction of Artemia increased from 45% to 65% of the organic weight with increasing renewal rates in the microalgal cultures, while the carbohydrate percentage decreased under the same conditions. Higher renewal rates resulted in higher lipid percentages in the microalga, but in Artemia the percentage of lipids decreased from 19% of the organic weight with a renewal rate of 10%, to 13% with a renewal rate of 50%. The percentage of all polyunsaturated fatty acids in Artemia, including 20:5n-3, increased slightly with increasing renewal rates in the microalgal cultures. Results emphasize the importance of controlling microalgal nutritional value for the success of aquaculture food chains in which filter feeders are involved. Received October 15, 2000; accepted December 29, 2000.     

Tetraselmis wettsteinii (Schiller) Throndsen comb. nov. and its occurrence in golfo di Napoli

Abstract

Carteria wettsteinii Schiller (1913) has been isolated from Golfo di Napoli and investigated by means of electron microscopy which revealed micro-anatomical features characteristic of the genus Tetraselmis. The species is commonly present in Golfo di Napoli during summer with cell numbers 10²–10⁶ cells-litre^?1, occasionally producing blooms of 10⁷ cells·litre^?1.     

EFFECTS OF CADMIUM ON GROWTH AND SUPEROXIDE DISMUTASE ACTIVITY OF THE MARINE MICROALGA TETRASELMIS GRACILIS (PRASINOPHYCEAE)1

Marine planktonic algae are frequently exposed to metallic contaminants. Because heavy metals can be assimilated and accumulated by algal cells, they can then be transferred to higher trophic levels of food chains. We studied the effects of cadmium on protein production and the growth of the marine prasinophyte Tetraselmis gracilis (Kylin) Butcher. By means of toxicological assays, we estimated the LC₅₀ of cadmium as 3.2 ppm and 1.8 ppm after 48 h and 96 h of exposure to this heavy metal, respectively. The growth curves and survival percentages of cell cultures in the presence of cadmium were determined, and a proportional reduction of both parameters with increasing metal concentrations was found. When chronically exposed to sublethal concentrations of cadmium, T. gracilis contained high levels of superoxide dismutase (SOD) activity, one of the main enzymes of the cell's antioxidant defense mechanism. Under these growth conditions, total SOD activity in crude extracts was increased by 41% (at 1.5 ppm) and 107% (at 3.0 ppm). Assays of SOD activity in nondenaturing polyacrylamide gels also showed a similar induction by cadmium. These results show that cadmium has potentially toxic properties since it significantly inhibited the growth of T. gracilis at low concentrations and promoted the induction of SOD activity, suggestive of an oxidative stress state. Besides being the first report of SOD in T. gracilis, this work describes experimental evidence of SOD induction by cadmium in this species.     

亚心形四爿藻氢酶的稳定性及初步纯化

亚心形四爿藻Tetraselmis subcordiformis是一种具有高产氢能力的海洋绿藻,在厌氧环境中经暗诱导调控,可进行一定时间的连续产氢。氢酶是亚心形四爿藻进行光合产氢的关键酶,本文研究了在厌氧环境中连二亚硫酸钠、β-巯基乙醇和丙三醇等试剂对氢酶的稳定性影响,考察了硫酸铵分级沉淀对氢酶的纯化效果及回收情况。结果表明,连二亚硫酸钠和丙三醇均能对氢酶起到较好的保护作用。60%～70%饱和度硫酸铵沉淀出的蛋白样品比酶活较高,且所含其他蛋白较少,可用于氢酶的进一步纯化。