有害赤潮生物球形棕囊藻对卤虫的毒性研究

利用1997年10月和1998年6月分别在广东汕头饶平海域和香港海域分离到的球形棕囊藻,即球形棕囊藻香港株(Phaeocystis globosastrain HK)和球形棕囊藻汕头株(Phaeocystis globosastrain ST),在实验室条件下研究其对四日龄卤虫(Artemia sinica)的急性毒性。结果表明,对数生长期的HK株藻液24h对卤虫LC₅₀约为2.9×10⁵cell·mL^-1。对数期的ST株对卤虫的毒性难以达到半致死浓度,衰亡期的ST株24h对卤虫LC₅₀约为9.89×10⁶cell·mL^-1。在上述浓度下两者半致死时间分别为20.91h和26.62h,而对数生长期的HK株和衰亡期的ST株的培养物过滤液24h对卤虫LC₅₀则分别为7.1×10⁵cell·mL^-1和1.457×10⁷cell·mL^-1,且在该浓度下的半致死时间分别为26.56h和28.02h。实验表明,HK株藻液和滤液的毒性均大于ST株,且藻液的毒性均大于滤液。     

湛江棕囊藻对南美白对虾虾苗和多种鱼苗的毒性研究

测定了湛江棕囊藻赤潮海水和棕囊藻(Phaeocystis globosa)对南美白对虾(Penaeus vannamei Boone)虾苗、青石斑鱼(Epinephelus awoara)、鲻鱼(Mugil cephalus)和尖吻鲈鱼(Latescal carifer)鱼苗的毒性。结果表明,棕囊藻对虾苗有一定的毒性,24 h LC50为1.0×109 cells L-1,去除囊泡液后的棕囊藻碎片对虾苗毒性较弱,细胞密度为1.0×109 cells L-1时,24 h虾苗的死亡率仅为10%,赤潮海水对虾苗无毒性;棕囊藻囊泡液对青石斑鱼有一定毒性,24 h LC50为囊泡液占海水总体积的10.9%,赤潮海水对青石斑鱼苗无毒性;棕囊藻对尖吻鲈鱼和鲻鱼鱼苗无毒性。     

4种重金属离子对多刺裸腹溞的联合毒性效应

在研究了铜、铅、镉和锌4种单一因子对多刺裸腹溞（Moina macrocopa）急性毒性作用基础上,采用Marking 相加指数法研究了联合毒性效应.实验结果表明：4种重金属离子的毒性大小依次为Cd2＋＞Cu2＋＞Pb2＋＞Zn2＋,对多刺裸腹溞48h的LC50分别为0.0076mg/L,0.0306mg/L,0.0532mg/L,0.3568mg/L;Pb2＋-Cu2＋-Cd2＋、Pb2＋-Zn2＋-Cd2＋3种离子和Cu2＋-Pb2＋-cd2＋-Zn2＋4种离子共存时的毒性效应表现为拮抗作用;Cu2＋-Zn2＋-Cd2＋和Pb2＋-cu2＋-Zn2＋共存时的联合毒性较为复杂,三者浓度比1：1：1时表现为协同作用,而毒性比1∶1：1时在24h内表现为协同作用,至48h时为拮抗作用.     

实验室培养球形棕囊藻溶血毒素的提取、分离及其生成特征

研究从实验室培养的球形棕囊藻(Phaeocystis globosa)提取溶血毒素的条件,探讨不同生长期球形棕囊藻溶血毒素的生成特征,用薄层色谱法对溶血成份进行了初步分析。结果表明,球形棕囊藻细胞壁的超声波破碎最适条件为：功率600W,4℃下处理30min。对数生长期、平稳期和衰亡期藻细胞适宜处理量分别为每次3000、2000、1000ml;在球形棕囊藻生长的平稳期和衰亡期具有明显的溶血活性,对数生长期溶血活性很低,甚至检测不到。球形棕囊藻溶血毒素至少含有4种糖脂类化合物。     

二氧化氯对球形棕囊藻的抑制和杀灭作用

以海洋赤潮生物-球形棕囊藻汕头株(Phaeocystis globosa,ST strain)为材料,研究了ClO2对不同起始藻密度的棕囊藻的抑制和杀灭作用．结果表明,ClO2对球形棕囊藻有明显的抑制和杀灭作用．藻密度为2．35×10^9cells·L-1时,高于0．74×10-2mmol·L-1的ClO2对棕囊藻生长有一定的抑制作用。高于2．96×10-2mmol·L-1的ClO2对棕囊藻具有显著的杀灭作用．藻密度与ClO2浓度之间存在一定的剂量关系．藻密度为2．35×10^9、1．18×10^9、4．70×10^8、1．18×10^8 cells·L-1时。其96h的有效杀藻浓度分别为2．96×10^-2、2．22×10^-2、1．48×10^-2和0．59×10^-2mmol·L^-1．藻密度越高。杀灭单位藻细胞所需ClO2的浓度越低．ClO2作为杀藻剂在赤潮治理中具有很好的应用前景．     

Characterization of the Hemolytic Properties of an Extract from Phaeocystis globosa Scherffel

Phaeocystis globosa Scherffel, an organism that causes harmful algal blooms, is a genus of the family Prymnesiophyta (or Haptophyta) with eurythermal and euryhaline characteristics. P. globosa has been confirmed to produce hemolytic substances, which are a mixture of liposaccharides. In the present study, the hemolytic properties of extract ofP. globosa are analyzed further. The effects of temperature, pH,different divalent cations, and membrane lipids on extract-induced hemolysis are discussed, as is the possible hemolytic mechanism. The results of the present study showed that the hemolytic activity of the extract was approximately 127.1 hemolytic units (HU)/L. The hemolytic reaction became fastest and a 50% decrease in absorbance was induced at 30 min at 37 ℃, and at pH 7.0; Hg2 was the strongest inhibitor of the hemolysis compared with the other divalent cations and many membrane lipids, except for phosphatidic acid, inhibited the hemolytic activity to different degrees. These results suggest that the toxin may make pores in the surface of red blood cells and that Hg2 either combines with the hemolysin or closes the pores,hence inhibiting its further hemolytic reaction. The toxin probably has no specific membrane receptor in the red blood cell membrane.     

Characterization of the Hemolytic Properties of an Extract from Phaeocystis globosa Scherffel

Phaeocystis globosa Scherffel, an organism that causes harmful algal blooms, is a genus of the family Prymnesiophyta (or Haptophyta) with eurythermal and euryhaline characteristics. P. globosa has been confirmed to produce hemolytic substances, which are a mixture of liposaccharides. In the present study, the hemolytic properties of extract of P. globosa are analyzed further. The effects of temperature, pH,different divalent cations, and membrane lipids on extract-induced hemolysis are discussed, as is the possible hemolytic mechanism. The results of the present study showed that the hemolytic activity of the extract was approximately 127.1 hemolytic units (HU)/L. The hemolytic reaction became fastest and a 50% decrease in absorbance was induced at 30 min at 37℃, and at pH 7.0; Hg^2 was the strongest inhibitor of the hemolysis compared with the other divalent cations and many membrane lipids, except for phosphatidic acid, inhibited the hemolytic activity to different degrees. These results suggest that the toxin may make pores in the surface of red blood cells and that Hg^2 either combines with the hemolysin or closes the pores,hence inhibiting its further hemolytic reaction. The toxin probably has no specific membrane receptor in the red blood cell membrane.     

不同氮源对球形棕囊藻生长的影响

采用实验室培养的方法比较了6种不同氮源-硝态氮、尿素、甘氨酸、精氨酸、谷氨酸、腺嘌呤对典型赤潮藻球形棕囊藻(Phaeocystis globosa)生长的影响。结果表明,6种氮源均能不同程度地促进球形棕囊藻的生长,但比生长速率和光合作用效率具有显著差异性。将球形棕囊藻在不同浓度氮源下的最大比生长速率分别拟合Monod方程,得出球形棕囊藻在硝态氮、尿素、甘氨酸、精氨酸、谷氨酸和腺嘌呤等6种氮源下的最大比生长率分别为1.05,1.17,0.82,0.87,1.09,0.90d^-1,相应的半饱和常数分别为9.132,23.758,85.519,7.104,23.94,10.959μmol/L。其中,高氮浓度(8820μmol/L)下腺嘌呤对球型棕囊藻的生长具有显著抑制作用。相比较而言,球形棕囊藻对甘氨酸的亲和力最高。当硝态氮、尿素、甘氨酸、精氨酸、谷氨酸和腺嘌呤的浓度分别为8820,882,882,8820,882,0.441μmol/L时,球形棕囊藻的最大光合效率(Fv/Fm)分别为0.619,0.620,0.579,0.595,0.648,0.667。由此可见,氮源对球形棕囊藻的生长和光合作用具有显著影响;球形棕囊藻能够利用多种无机和有机氮源,与其它仅能利用无机氮源的浮游植物相比,更具有竞争优势。     

球形棕囊藻游离单细胞的密度与囊体形成的关系研究

球形棕囊藻(Phaeocystis globosa Scherffel)主要以囊体形态形成赤潮,由单细胞向囊体形态的转变是赤潮爆发的关键。本研究推测囊体形成的前提是游离单细胞达到一定密度阈值,当密度低于该阈值时,囊体无法形成。基于此,本文探究了不同条件(温度、营养充气搅动、摄食压力、初始密度)下囊体形成时游离单细胞的密度。结果显示:不同培养条件下,囊体形成所需的游离单细胞密度不一致,但都达到了104cells/mL的数量级;稀释试验表明,利用f/2培养基稀释使游离单细胞的密度小于104cells/mL时,囊体不能形成,而密度大于104cells/mL的游离单细胞对照组,在24 h内便有囊体形成。总的来说,游离单细胞在高密度情况下更容易形成囊体。     

充气和搅动对球形棕囊藻生长及囊体形成的影响

球形棕囊藻生活史中包含游离单细胞和球形囊体两种生活形态,但是实验室中培养的球形棕囊藻经常无法形成囊体。研究通过向培养基中泵入过滤空气,以及给培养基提供不同程度的搅动,研究了充气和搅动对球形棕囊藻生长及囊体形成的影响。充气和搅动均显著提高了囊体的数量,并且提高了囊体内细胞的生长速率。但是充气对于囊体直径及囊体内细胞密度并无显著影响。搅动则明显的提高了囊体直径和囊体内细胞数量。然而,尽管充气以及搅动有利于球形棕囊藻囊体的形成,但是培养的囊体直径依然小于自然海区中囊体的大小。     

二氧化氯对球形棕囊藻叶绿素a、蛋白质、DNA含量的影响

分析了二氧化氯(1.0、1.5、2.0、2.5mgL-1,作用96h;2.5、6.0、8.0、16.0mgL-1,作用60min)对球形棕囊藻叶绿素a、蛋白质含量、氨基酸组成、核酸含量的影响,用透视电镜对二氧化氯(0.5mgL-1,0.8mgL-1)作用24h后藻细胞形态的变化进行了观察,以探讨二氧化氯去除赤潮藻的机理。结果表明,二氧化氯对球形棕囊藻叶绿素a、蛋白质、DNA的含量均有影响。实验各组(1.0-2.5mgL-1,2.5-16.0mgL-1)球形棕囊藻的叶绿素a、蛋白质、DNA的含量均显著低于对照。二氧化氯浓度超过2mgL-1时,球形棕囊藻的叶绿素a、蛋白质、DNA的含量持续降低,氨基酸相对含量发生明显变化;半胱氨酸、酪氨酸和赖氨酸等的相对含量明显降低,而组氨酸、缬氨酸和苯丙氨酸则明显增加。当二氧化氯(2.5-16.0mgL-1)作用3min后,DNA漏出率在13%-18%之间;电镜观察发现,二氧化氯可使细胞膜破损,引起内容物外泄。这些结果显示,二氧化氯能以单分子形式进入细胞,引起叶绿素、蛋白质结构的变化,并破坏藻细胞膜系统,最终导致藻细胞死亡。