塔玛亚历山大藻(Alexandrium tamarense)对鲈鱼(Lateolabrax japonicus) 的危害机制研究

本论文选择在我国分离得到的一株有毒赤潮甲藻-塔玛亚历山大藻（Alexandrium tamarense，ATHK株），研究了其对一种我国沿海常见和典型养殖鱼类鲈鱼（Lateolabrax japonicus）的危害机制。首先研究了塔玛亚历山大藻（ATHK）对鲈鱼鳃结构的影响及其溶血毒性； 然后采用腹腔注射的方法，研究了高剂量塔玛亚历山大藻毒素（ATHK毒素：约为1.6×105 细胞，相应PSP为0.886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.0118µg STX Equal）和低剂量塔玛亚历山大藻毒素（ATHK毒素： 约为0.16×105 细胞，相应PSP为0.0886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.00118µg STX Equal）在鲈鱼体内代谢过程中对鲈鱼肝脏、肾脏和鳃组织的超微结构、Na+K+-ATPase活性、肝脏功能和肾脏功能的影响、以及对抗氧化系统酶活性和异生物质代谢酶的影响，以期从不同方面了解塔玛亚历山大藻及其所产水溶性毒素（ATHK毒素）对鲈鱼的毒害效应及机制，为有毒赤潮的有效管理提供一定的科学依据。 塔玛亚历山大藻（ATHK）对鲈鱼鳃组织影响的实验结果表明，该藻使鲈鱼鳃组织出现水肿现象，细胞间隙变大；粘液细胞颗粒不规则，颜色加深，颗粒发生凝集，有板结状；氯细胞线粒体内部基质凝集。不产PSP的一种亚历山大藻（AT-6）也使鲈鱼鳃出现水肿，且使细胞出现一定的固缩现象。显微镜观察发现鲈鱼鳃丝间存在有这两种亚历山大藻细胞。由此推测塔玛亚历山大藻ATHK和AT-6的表面结构可能具有能导致鲈鱼鳃组织水肿的机械作用。对人血细胞溶血实验结果表明塔玛亚历山大藻（ATHK）具有较强的溶血毒性，大小与藻的生长阶段和细胞密度都有一定的关系：指数期的溶血毒性最大，随细胞数目的增多，活性逐渐加大；藻细胞、细胞碎片、细胞内容物都有一定的溶血毒性，其中细胞碎片的活性最大。通过11种（株）产PSP的亚历山大藻、不产PSP的亚历山大藻以及标准PSP的实验结果表明这种溶血毒性是由藻细胞的其它非PSP物质造成的，且这种溶血毒性在产PSP的亚历山大藻中具有一定的普遍性。 塔玛亚历山大藻（ATHK）对鲈鱼组织超微结构实验结果表明：ATHK毒素（约为1.6×105 细胞，相应PSP为0.886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.0118µg STX Equal）能导致鲈鱼组织细胞超微结构发生剧烈的变化，主要表现在：肝细胞细胞膜有肿胀现象，部分膜边缘溶解；细胞质糖原颗粒化；核糖体脱落，仅见滑面内质网；细胞质和线粒体内都出现空泡，且线粒体的嵴状结构也发生变化；核膜溶解比较严重，核质外溢，且异染色质边际化。前肾细胞超微结构的变化主要是淋巴细胞核质出现空泡，核膜有溶解迹象；Ⅰ型粒细胞颗粒膨大，伪足增多且变长；Ⅱ型颗粒细胞颗粒增多，内部出现空腔，细胞膜和核膜溶解，胞质、细胞器和核质外溢。鳃组织中氯细胞的核膜局部溶解，核仁弥散，线粒体膜溶解，微细小管膨大；粘液颗粒膜溶解，内部结构遭受破坏；扁平细胞核膜及线粒体膜几乎全部溶解。因此，我们的结果表明，ATHK毒素能作用于鲈鱼细胞的内膜和外膜系统，使膜发生溶解、脱落等变化；比较注射同样剂量大小ATHK毒素120h和240h时鲈鱼组织超微结构发现，细胞超微结构在一定程度上能够恢复。 ATHK毒素对Na+K+-ATPase活性、肝脏功能以及肾脏功能的影响结果表明，0.16×105―1.6×105细胞范围内的ATHK毒素可以显著影响肝脏和鳃组织中的Na+K+-ATPase，使这两种组织中的Na+K+-ATPase活性出现不同程度的下降； 而且还能够显著抑制肝脏中谷丙转氨酶的活性，最大抑制率为95%。但此范围内的ATHK毒素不能显著影响肾脏中的Na+K+-ATPase活性以及尿素氮含量。因此，ATHK毒素对Na+K+-ATPase活性的抑制则会导致细胞能量的缺失，使细胞进一步发生其它变化，而ATHK毒素对肝脏功能完整性的影响则可能会抑制对蛋白质的分解代谢。 ATHK毒素对鲈鱼肝脏、肾脏和鳃组织中的、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱肝肽过氧化物酶（GSH-Px）以及谷胱肝肽转硫酶（GST）活性变化影响的结果表明：高剂量（约为1.6×105 细胞，相应PSP为0.886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.0118µg STX Equal）ATHK毒素能显著诱导鲈鱼肝脏和鳃组织中SOD、GSH-Px以及GST酶活性，最大变化范围为正常状态下的3-4倍，对肝脏中CAT酶活性具有一定的抑制作用，对鳃中的CAT抑制效应则不显著；但此剂量的ATHK毒素仅对肾脏鳃中的GSH-Px活性有一定的诱导作用，对SOD、CAT以及GST的活性没有显著影响。低剂量（约为0.16×105 细胞，相应PSP为0.0886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.00118µg STX Equal）ATHK毒素也能诱导鲈鱼肝脏和鳃组织中SOD、GSH-Px以及GST酶活性，其在第一个24h内的诱导效果与临界致死毒素剂量相似； 且连续注射低剂量ATHK毒素则对肝脏和鳃中这三种酶活性具有累加的诱导作用，使这三种酶活性的变化范围为正常的5倍；低剂量ATHK毒素对肝脏中CAT酶活性也具有抑制作用，但对鳃中CAT酶活性的抑制作用并不显著。 同样，低剂量ATHK毒素除对肾脏中GSH-Px活性具有一定诱导效应外，对SOD、CAT以及GST都没有显著影响。 SOD、GSH-Px以及GST酶活性的显著升高表明ATHK毒素在鲈鱼体内代谢过程中能诱导鲈鱼产生活性氧自由基，且GST活性的升高则说明作为细胞色素P450依赖的异生物质代谢酶，GST在ATHK毒素代谢过程中可能可以加速ATHK毒素的代谢。推测鲈鱼可以通过这三种酶降低ATHK毒素以及次生毒物活性氧自由基对鲈鱼的危害。

改性粘土治理有害赤潮对生态环境的影响初探

本文以室内实验为基础，研究了改性粘土治理有害赤潮的方法对生态环境的影响。研究结果表明：有机和无机改性粘土对溶解氧（DO）、化学耗氧量（COD）、pH等主要水质因子均有改善作用；对营养盐，尤其是磷酸盐有一定的吸附作用，在外加磷酸盐为0-0.3μmol/ml范围内，吸附量随水体中磷酸盐浓度的增加而增大，有机改性粘土对海水中磷酸盐的吸附能力为：有机改性粘土Ⅰ>有机改性粘土Ⅱ>有机改性粘土Ⅲ。通过有机改性粘土对磷酸盐的吸附－再释放情况，进一步探讨了其磷酸盐的释放对赤潮异弯藻（Heterosigma akashiwo）、东海原甲藻（Prorocentrum donghaiense）等赤潮生物生长的影响。实验结果显示，经过有机改性的粘土有利于提高其对磷酸盐的吸附能力，降低对磷酸盐的解吸率，利用有机改性粘土治理赤潮可以缓解海水富营养化程度，即使被吸附的部分磷酸盐能缓慢释放，但仍不足以维持赤潮生物的正常生长。无机改性粘土对磷酸盐和硝酸盐与有机改性粘土有相似的吸附性能。其添加剂PAC的重金属含量符合沉积物排放要求，不会对环境造成压力。 其次，以太平洋牡蛎(Crassostrea gigas)幼贝为对象，研究了有机改性粘土Ⅱ和无机改性粘土在对海洋底栖生物的影响。急性毒性试验中二者对牡蛎幼贝的半致死浓度（LC50）分别为4.62 g/L和2.67 g/L，均远远大于改性粘土去除赤潮藻的浓度。在能够有效去除赤潮微藻的粘土浓度条件下，经慢性毒性试验发现改性粘土对牡蛎幼贝成活率、生长和摄食略有降低，但无明显影响，在牡蛎幼贝鳃组织和消化道组织的超微结构中未发现机械损伤。 最后，研究了改性粘土在对去除有毒赤潮藻过程中对底栖生物的影响。以能产生麻痹性贝毒（PSP）的塔玛亚历山大藻（A. tamarense，ATHK）为例，研究了PSP在水体中和粘土沉积层中的分布，发现改性粘土去除塔玛亚历山大藻能有效降低水体中藻细胞浓度及其所携带的PSP毒素。由于藻细胞破裂, 虽然沉积层中藻细胞体内部分PSP毒素溢出，但通过塔玛亚历山大藻细胞不同组分对牡蛎的影响发现，细胞内容物和细胞碎片对牡蛎没有明显毒副作用，由此推断改性粘土对藻细胞絮凝沉降后,能降低对生物的不良影响。此外，室内实验模拟了去除赤潮生物塔玛亚历山大藻（A. tamarense，ATHK）、东海原甲藻 (P. donghaiense )、赤潮异弯藻 (H. akashiwo)过程中，比较改性粘土和赤潮微藻对生物体的影响发现改性粘土在去除赤潮藻过程中能提高牡蛎的存活率，进一步证明改性粘土在赤潮生物防控中，是一种有效的应急措施。

亚历山大藻对海产贝类胚胎和蒙古裸腹溞的影响及致毒机制研究

本文研究了典型有毒赤潮藻——亚历山大藻(Alexandrium)对海湾扇贝(Argopecten irradians Lamarck)、文蛤(Meretrix meretrix Linnaeus)和太平洋牡蛎(Ostrea gigas Thunberg)受精卵孵化的影响和致毒机制以及对蒙古裸腹溞(Moina mongolica Daday)生命活动的影响。此外，还针对我国赤潮发生特点，模拟研究了我国东海大规模赤潮对菲律宾蛤仔（Ruditapes philippinarum (Adams et Reeve)）受精卵孵化和蒙古裸腹溞种群数量的影响。 结果发现：8株产PSP毒素的亚历山大藻：塔玛亚历山大藻( ATHK, AT5-1, AT5-3, ATCI02, ATCI03)，链状亚历山大藻, A. lusitanicum、微小亚历山大藻和2株不产PSP毒素的相关亚历山藻(AC-1, AS-1)对海湾扇贝受精卵的孵化均有显著抑制作用，说明在亚历山大藻属中，这种抑制作用具有一定的普遍性，并与PSP毒素的产生无直接关系，表明存在非PSP毒素的其它毒性物质。一种PSP标准毒素STX也没有这种抑制作用，进一步证明该抑制作用与PSP毒素不直接相关。 相关亚历山大藻AC-1对海湾扇贝、文蛤和太平洋牡蛎受精卵孵化的有显著的毒害作用，其藻液、重悬液、去藻液和内容物均显著影响受精卵的孵化。相关亚历山大藻AC-1对海湾扇贝、文蛤和太平洋牡蛎担轮幼虫细胞的超微结构有显著破坏作用，破坏膜结构和胞内结构，影响细胞内的功能器官如溶酶体的稳定性，使卵黄颗粒萎缩变形；对文蛤和太平洋牡蛎的受精卵显示出极强的毒害作用： 3000cells•ml-1时，使二者胚胎完全溶掉消失；在2000cells•ml-1的藻液中培养2h后，担轮幼虫的外膜发生溶解，整个幼体呈葡萄串样。相关亚历山大藻AC-1产生的这种毒性物质可能对贝类胚胎细胞的结构和功能有影响。 亚历山大藻对蒙古裸腹溞的毒性效应与不同藻种/藻株密切有关：塔玛亚历山大藻（AT-6, ATCI02）、链状亚历山大藻、A. lusitanicum和微小亚历山大藻不影响蒙古裸腹溞的存活，而塔玛亚历山大藻（ATHK、ATCI03和AT5-1）和相关亚历山大藻(AC-1, AS-1)有显著影响。蒙古裸腹溞能摄食塔玛亚历山大藻(AT-6, ATHK, ATCI02, ATCI03, AT5-1)，链状亚历山大藻, A. lusitanicum和微小亚历山大藻，很少或基本不摄食相关亚历山大藻。亚历山大藻影响蒙古裸腹溞的RNA/DNA比值和蛋白质含量以及Na+,K+-ATP酶活性。相关亚历山大藻AC-1对蒙古裸腹溞的存活有极强的毒性作用，藻液、重悬液、内容物和碎片均有显著影响；即使与3×106cells•ml-1小球藻混合，10和50cells•ml-1的相关亚历山大藻AC-1仍能使蒙古裸腹溞的产幼数和存活时间显著下降。亚历山大藻对蒙古裸腹溞生命活动的影响不仅与PSP毒素有关，还与非PSP毒素有关；蒙古裸腹溞可能也是研究有害藻急性和慢性毒性的一种理想生物。 应用菲律宾蛤仔胚胎和蒙古裸腹溞评价我国东海特大规模赤潮对海洋生物资源的潜在危害时发现：单种链状亚历山大藻对菲律宾蛤仔受精卵的孵化和蒙古裸腹溞的种群增长均有显著不利影响；单种东海原甲藻（1~10×104cells•ml-1）对菲律宾蛤仔受精卵的孵化没有影响；较低密度的东海原甲藻能维持蒙古裸腹溞（2~5×104cells•ml-1）的种群增长；较高密度的东海原甲藻对蒙古裸腹溞（10×104cells•ml-1）种群有显著的抑制作用。两种藻以赤潮密度混合后，适当密度的东海原甲藻能在一定程度上减轻链状亚历山大藻对菲律宾蛤仔受精卵和蒙古裸腹溞的毒性。可见，东海连年爆发的大规模赤潮不仅对浮游生态系统有不利影响，若同时爆发亚历山大藻赤潮，则对海洋浮游生态系统和贝类资源的恢复产生更加不利的影响。

中国沿海典型区域织纹螺毒性及毒素成分研究

织纹螺（Nassarius spp.）味道鲜美，是中国及其它一些亚洲国家沿海地区居民习惯食用的一种水产品。但是，近几十年来，中国沿海频繁发生食用织纹螺中毒事件，严重威胁着人们的身体健康和生命安全。加之人们对织纹螺体内的毒素成分、来源及其毒性变化规律还没有清晰的认识，因此难以有效预防和控制食用织纹螺引起的中毒事件。本文根据文献报道，在中国沿海食用织纹螺中毒事件多发的典型区域，包括江苏省的连云港市和盐城市、浙江省的舟山市和宁波市、福建省的宁德市、厦门市和莆田市设立了监测点，于2006年和2007年间进行了连续采样，应用小鼠生物测试法调查了织纹螺毒性的消长情况，并利用高效液相色谱-质谱联用（Liquid Chromatography-Mass Spectrometry，LC-MS）和高效液相色谱技术（High Performance Liquid Chromatography，HPLC）对织纹螺体内的毒素成分进行了分析。 实验结果表明，2006年于江苏省盐城市射阳海域采集的织纹螺样品中，阳性样品检出率为56%，毒性在2-5 MU/g组织（湿重）之间变化，在2007年于同地采集的8个样品中，除一个样品毒性为3.14 MU/g组织（湿重）以外，其余样品均表现为阴性；而2007年采集自连云港市赣榆海域的织纹螺样品，在采样期间则呈现出极高的毒性，最高达到846.52 MU/g 组织（湿重），毒性在监测期间呈“M”状波动，在5月和7月下旬出现两个毒性高峰。2006年于浙江省宁波市象山港采集的织纹螺样品中，阳性样品检出率为25%，毒性均在2.5 MU/g组织（湿重）左右；而同年采集自舟山市定海的织纹螺样品中，阳性样品检出率为100%，最高毒性达18.40 MU/g组织（湿重），毒性在监测期间也呈“M”状波动，高峰期出现在6月初和7月底。2006年3-9月采集自福建省宁德霞浦、厦门同安和莆田涵江采集的织纹螺样品中，阳性样品检出率分别为20%、43%和14%，除7月中旬采集自宁德霞浦的一个样品毒性达到16.19 MU/g组织（湿重）之外，其余样品毒性均在2-5 MU/g组织（湿重）间波动。从阳性样品的时间分布规律来看，3月份和6、7月份是阳性样品集中出现的时期。根据以上调查结果可以看出，织纹螺的毒性消长呈现出较明显的地域性和季节性特征，不同地区的织纹螺毒性存在差异，而同一区域织纹螺毒性的消长则表现出明显的季节性集中趋势。除了2007年采集自连云港赣榆的织纹螺样品毒性与其平均个体组织重量有相似的变化趋势以外，其余地区的织纹螺样品毒性和个体大小无明显相关性。 利用LC-MS和HPLC技术对织纹螺样品中的毒素成分进行了分析，确定河豚毒素（tetrodotoxin, TTX）及其同系物（trideoxyTTX，4-epi-TTX，anhydroTTX，oxoTTX）是所采集织纹螺中的主要致毒成分，样品中没有检测到麻痹性贝毒毒素（Paralytic Shellfish Poison, PSP）。自不同地区采集的织纹螺中毒素成分基本一致，但组成存在一定差异。其中，采自江苏省连云港赣榆和浙江省舟山定海的织纹螺样品中，trideoxyTTX是主要的成分，其次是TTX；而从其它采样地点采集的织纹螺中，TTX都是主要的毒素成分，其次才是trideoxyTTX及其它同系物。对采集自江苏省连云港赣榆和浙江舟山定海的织纹螺体内毒素的解剖学分布进行了分析，结果表明肌肉、消化腺和剩余部分中的毒素组成基本一致，其中trideoxyTTX是主要的毒素成分，其次为TTX，但采自浙江舟山的织纹螺剩余部分中的TTX是主要的毒素成分。在监测期间，各组织中的毒素组成没有明显变化，但毒素含量随季节变化表现出了一定的差异。 综上所述，在中国沿海典型区域开展的织纹螺毒性调查结果表明其毒性消长具有一定的地域性和季节性特征。分析结果显示织纹螺体内的毒素成分是河豚毒素及其同系物，采自不同区域的织纹螺体内毒素成分基本一致，但毒素组成稍有差异。对织纹螺中毒素的解剖学分布研究显示，各组织中的毒素含量随季节变化而表现出一定差异，但毒素组成没有明显的季节性变化。这些结果显示中国沿海的织纹螺应具有相似的毒素来源，研究结果将为相关部门有效监测、预防和控制食用织纹螺中毒事件提供有力的科学依据。

麻痹性贝毒毒素的制备和活性研究

麻痹性贝毒（Paralytic Shellfish Poisons, PSP）毒素主要是由海洋甲藻产生的一类活性物质，在赤潮毒素监测、神经与分子生物学基础研究以及新型药物开发方面都有潜在的应用价值。然而，纯化毒素的缺乏在很大程度上限制了相关工作的开展。本文通过大量培养塔玛亚历山大藻（Alexandrium tamarense）来提取PSP毒素，完善了毒素的分离纯化过程，并对纯化毒素的活性进行了研究和探讨。在实验室进行了塔玛亚历山大藻的规模培养，对其生长和培养条件进行了优化，探讨了有毒藻大量培养的采收方式，并获取了一批用于纯化毒素的有毒藻细胞。将藻细胞破碎后离心分离，提取出含PSP的粗毒素，再用大孔径凝胶过滤去除粗毒素中的大部分杂质，然后用小孔径凝胶和离子交换树脂将不同毒素逐级分离、纯化。结果表明，大孔径凝胶能有效地去除粗毒素中的杂质，小孔径凝胶过滤能将膝沟藻毒素（GTX）和C毒素分开，应用离子交换树脂能将GTX2,3和GTX1,4分开，最终得到GTX2,3和GTX1,4的纯化产品。分离纯化过程始终以小鼠法和荧光法进行毒素在线监测。以提取的毒素对小鼠进行毒性测试，小鼠呈现典型的PSP毒素中毒死亡症状；电生理分析的结果表明PSP毒素能够有效地阻断小鼠运动神经末梢钠电流，并可逆地阻断NG108-15全细胞的钠电流，与PSP毒素的作用机理一致；高效液相色谱分析结果表明，纯化毒素与标准毒素的保留时间完全一致；经质谱分析，纯化毒素与标准毒素具有相同的分子离子峰和碎片离子峰。应用运动模型研究了纯化毒素的药理活性。分别采用家兔椎管麻醉法、小白鼠热板法、小白鼠攀网法研究了GTX2,3对家兔的局麻作用、对小鼠的镇痛和肌松作用。结果表明，GTX2,3按剂量0.4μg STX equivalent/kg给予家兔椎管注射时，具有显著的局麻作用。GTX2,3按剂量5.99μg STX equivalent/kg给予小鼠肌肉注射时，具有显著的镇痛作用。GTX2,3按剂量6.49μg STX equivalent/kg给予小鼠皮下注射时，具有显著的肌松作用。

塔玛亚历山大藻（Alexandrium tamarense）对双壳的影响研究

本文选取麻痹性贝毒产毒藻塔玛亚历山大（Alexandrium tamarense）以及双壳类为研究对象，进行了塔玛亚历山大藻对双壳类生命活动的影响，麻痹性贝毒在紫贻贝体内累积、转化与排出动力学过程的初步研究。实验证实，塔玛亚历山大藻能对栉孔扇贝受精卵至早期D型幼虫的整个发育阶段产生不利影响，抑制受精卵的孵化。经多方验证，我们推测这一抑制作用主要是由塔玛亚历山大藻藻细胞表面物质引起的。通过塔玛亚历大藻对栉孔扇贝和墨西哥湾贝早期发育的影响研究发现：产毒藻对其受精卵、早期D形幼虫、眼点幼虫、仔贝都有明显的影响。（1）两株塔玛亚历山大藻（ATHK、ATCI02）都能抑制栉孔扇贝受精卵的孵化，EC50分别是（1010、1580cells/mL）。指数生长期的藻作用最强，并发现毒性作用可能来源于细胞表面一种不同于PSP的毒性物质。（2）ATHK对D形幼虫有致死作用，死亡率随作用时间的延长和藻密度的增加而增加。栉孔扇贝的早期D形幼虫暴露于细胞密度为10，000/cells/mL的ATHK中14天，死亡就率达100％；在实验密度10，000cells/mL的48小时急性致毒实验中，墨西哥湾扇贝的早期D形幼虫的游泳能力受到了一定程度的抑制。（3）实验条件下未发现ATHK对墨西哥湾扇贝眼点幼虫的变态、存活产生明显影响，但变态后稚贝的个体大小与对照组相比有明显差异，表明有毒藻对变态过程幼体的生长有影响。（4）在1小时、5小时的急性致毒实验中ATHK对墨西哥湾扇贝仔贝（壳高：5mm）的爬升能力产生了明显的抑制（1hEC50 ＝ 1，000cells/mL）。作用5小时后仔贝的附着率与对照组相比显著降低。两次48小时急性实验的结果都显示高密度的塔玛亚历山大藻（ATHK）能抑制紫贻贝成体的滤水率，平均EC50为6000cells/mL。以（产麻痹性贝毒）的塔玛亚历山大藻（ATHK）投喂紫贻贝（Mytilus edulis），研究了麻痹性贝毒在紫贻贝体内的累积、转化与排出规律。结果表明，在八天的累积实验阶段，紫贻贝消化腺和肌肉组织中的毒素含量均随实验时间的延长而逐渐增加；累积实验结束时，平均每只贝体内的毒素量为13.40nmol，累积率为12.45％（以每只贝的总染毒量为107.67nmol计），毒性水平为12.24μgSTXeq／100g，还未达到国际上公认的贝类食用卫生标准（80μgSTXeq／100g）；贻贝消化腺的累积能力远远高于肌肉组织，累积实验结束时，消化腺中的毒素含量为13.07nmol，累积率为12.14％，而肌肉组织中的毒素量只有0.33nmol，累积率只有0.31％。消化腺中累积的毒素占贝体内毒素总量的97.5％。在八天的排出实验阶段贝体内的毒素总量有下降的趋势，只有进一步延长自净的时间，才能得到更明了的排出规律。

Application of rotifer Brachionus plicatilis in detecting the toxicity of harmful algae

The toxicity of seven major HAB (harmful algal bloom) species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense (AT-6, non-PSP producer), Alexandrium lusitanicum, Alexandrum tamarense (ATHK) and Heterosigma akashiwo were studied against rotifer Brachionus plicatilis under laboratory conditions. The results show that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6), or A. lusitanicum could maintain the individual survival and reproduction, as well as the population increase of the rotifer, but the individual reproduction would decrease when exposed to these five algae at higher densities for nine days; H. akashiwo could decrease the individual survival and reproduction, as well as population increase of the rotifer, which is similar to that of the starvation group, indicating that starvation might be its one lethal factor except for the algal toxins; A. tamarense (ATHK) has strong lethal effect on the rotifer with 48h LC50 at 800 cells/mL. The experiment on ingestion ability indicated by gut pigment change shows that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6) and A. lusitanicum can be taken by the rotifers as food, but A. tamarense (ATHK) or H. akashiwo can be ingested by the rotifers. The results indicate that all the indexes of individual survival and reproduction, population increase, gut pigment change of the rotifers are good and convenient to be used to reflect the toxicities of HAB species. Therefore, rotifer is suggested as one of the toxicity testing organisms in detecting the toxicity of harmful algae.

Experimental study on the impact of dinoflagellate Alexandrium species on populations of the rotifer Brachionus plicatilis

To investigate harmful effects of the dinoflagellate Alexandrium species on microzooplankton, the rotifer Brachionus plicatilis was chosen as an assay species, and tested with 10 strains of Alexandrium including one known non-PSP-producer (Alexandrium tamarense, AT-6). HPLC analysis confirmed the PSP-content of the various strains: Alexandrium lusitanicum, Alexandrium minutum and Alexandrium tamarense (ATHK, AT5-1, AT5-3, ATC102, ATC103) used in the experiment were PSP-producers. No PSP toxins were detected in the strains Alexandrium sp1, Alexandrium sp2. Exposing rotifer populations to the densities of 2000 cells ml(-1) of each of these 10 Alexandrium strains revealed that the (non-PSP) A. tarnarense (AT-6) and two other PSP-producing algae: A. lusitanicum, A. minutum, did not appear to adversely impact rotifer populations. Rotifers exposed to these three strains were able to maintain their population numbers, and in some cases, increase them. Although some increases in rotifer population growth following exposures to these three algal species were noted, the rate was less than for the non-exposed control rotifer groups. In contrast, the remaining seven algal strains (A. tamarense ATHK, AT5-1, AT5-3, ATC102, ATC103; also Alexandrium sp1 and Alexandrium sp2) all have adverse effects on the rotifers. Dosing rotifers with respective algal cell densities of 2000 cells ml-1 each, for Alexandrium spl, Alexandrium sp2, and A. tamarense strains ATHK and ATC103 showed mean lethal time (LT50) on rotifer populations of 21, 28, 29, and 36h, respectively. The remaining three species (A. tamarense strains AT5-1, AT5-3, ATC102) caused respective mean rotifer LT50S of 56, 56, and 71 h, compared to 160 h for the unexposed "starved control" rotifers. Experiments to determine ingestion rates for the rotifers, based on changes in their Chlorophyll a content, showed that the rotifers could feed on A. lusitanicum, A. minutum and A. tamarense strain AT-6, but could graze to little or no extent upon algal cells of the other seven strains. The effects on rotifers exposed to different cell densities, fractions, and growth phases of A. tamarense algal culture were respectively compared. It was found that only the whole algal cells had lethal effects, with strongest impact being shown by the early exponential growth phase of A. tamarense. The results indicate that some toxic mechanism(s), other than PSP and present in whole algal cells, might be responsible for the adverse effects on the exposed rotifers. (C) 2004 Elsevier B.V. All rights reserved.

Microbial modulation in the biomass and toxin production of a red-tide causing alga

The effect of S-10, a strain of marine bacteria isolated from sediment in the Western Xiamen Sea, on the growth and paralytic shellfish poison (PSP) production in the alga Alexandrium tamarense (A. tamarense) was studied under controlled experimental conditions. The results of these experiments have shown that the growth of A. tamarense is obviously inhibited by S-10 at high concentrations, however no evident effect on its growth was observed at low concentrations. Its PSP production was also inhibited by S 10 at different concentrations, especially at low concentrations. The toxicity of this strain of A. tamarense is about (0.9512.14) x 10(-6) MU/cell, a peak toxicity value of 12.14 x 10(-6) MU/cell appeared on the 14th day, after which levels decreased gradually. The alga grew well in conditions of pH 6-8 and salinities of 20-34 parts per thousand. The toxicity of the alga varied markedly at different pH and salinity levels. Toxicity decreased as pH increased, while it increased with salinity and reached a peak value at a salinity of 30 parts per thousand, after which it declined gradually. S-10 at a concentration of 1.02 x 10(9) cells/ml inhibited growth and the PSP production of A. tamarense at different pH and salinity levels. S-10 had the strongest inhibitory function on the growth of A. tamarense under conditions of pH 7 and a salinity of 34 parts per thousand. The best inhibitory effect on PSP production by A. tamarense was at pH 7, this inhibitory effect on PSP production did not relate to salinity. Interactions between marine bacteria and A. tamarense were also investigated using the flow cytometer technique (FCM) as well as direct microscope counting. S-10 was identitied as being a member of the genus Bacillus, the difference in 16S rDNA between S-10 and Bacillus halmapalus was only 2%. The mechanism involved in the inhibition of growth and PSP production of A. tamarense by this strain of marine bacteria, and the prospect of using it and other marine bacteria in the biocontrol of red-tides was discussed. (c) 2005 Elsevier Ltd. All rights reserved.

Environmental and health effects associated with Harmful Algal Bloom and marine algal toxins in China

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiological view.

Effects of the dinoflagellate Alexandrium tamarense on early development of the scallop Argopecten irradians concentricus

The effects of Alexandrium tamarense (strain ATHK) on early development of the bay scallop Argopecten irradians concentricus were studied under laboratory conditions. The algal culture was verified by HPLC to produce paralytic shellfish poisoning (PSP) at a level of 37.48 fmol/cell. Survival of the scallop larvae was not affected when they were grown with A. tamarense at concentrations of 500-10,000 cells/ml for 48 h. However, the activity of D-shape larvae was inhibited after 48-h exposure to A. tamarense at the algal cell density of 10,000 cells/ml. Scallop growth was inhibited significantly by A. tantarense during a 14-day exposure starting at the eye-spot larval stage. The size of juvenile scallops in the group of 10,000 cells/ml was only about 32% of that of the controls, although no obvious effect of A. tamarense was found on the rate of larval metamorphosis. All juvenile scallops survived in algal concentrations of 600-2400 cells/ml, however, attachment rates were significantly lower than control values after a 5-h exposure to A. tamarense at concentrations >600 cells/ml, while they were not obviously reduced after only 1 h of exposure. At concentrations >600 cells/ml, the climbing ability of juveniles was clearly reduced by exposure to A. tamarense after only 1 h. The climbing rate and height were only 55% and 45%, respectively, of those of the controls, when exposed to A. tantarense at a concentration of 600 cells/ml. The results indicated that A. tamarense blooms may have detrimental impacts on shellfish at early life stages, therefore, special attention should be paid to the toxic algal blooms in shellfish breeding area. (C) 2003 Elsevier Science B.V. All rights reserved.

Study on impact of dinoflagellate Alexandrium tamarense on life activities of marine bivalves

The effects of a PSP producing dinoflagellate Alexandrium tamarense on marine bivalves at their several important life,stages: egg, D - shape larva, eyespot larva, juvenile and adult, were studied! The results show that the hitching survival, activity, filtration and! growth were adversely affected by the alga and the impact was significantly increased with the increase of algal density. The inhibitory effect on egg hatching was most significant, which the hatching rate was only 30% of the control when exposed to the alga at 100 cell/cm(3) after 36 h. Further experiments show that the algal culture, re-suspended cells and cell fragments had the inhibitory effect, while no such effect was from the cell-free medium, cell contents and standard STX. The results indicate that the alga could produce unknown toxins, rather than PSP, associated with the cell surface.

A recent shellfish toxin investigation in China

A shellfish toxin investigation along the Chinese coast has recently been conducted using both HPLC and mouse assay methods. The results showed that DSP was widely distributed in different shellfish species in China. 26 out of 89 samples had DTX1 (dinophysistoxin-1) or OA (okadaic acid) but the DSP content in most shellfish samples did not reach the regulatory limit for human consumption adopted in many countries (20 mu g/100 g soft tissue). PSP was also found in 5 out of 96 samples along the coast. One sample, Chlamys nobilis from Hong Kong contained high levels of PSP (320 mu g STX equivalent/100 g soft tissue), compared to the regulatory limit (80 mu g STX equivalent/100 g soft tissue). After the recent outbreak of red tide in Hong Kong waters, three further shellfish samples were collected within 40 days to investigate the impacts of this event, It was shown that high levels of PSP continued to exist in Hong Kong waters. This report provides the first report of DSP and PSP distribution along the Chinese coast. (C) 1999 Elsevier Science Ltd, All rights reserved.

Real-Time and Data-Driven Operation Optimization and Knowledge Discovery for an Enterprise Information System

An enterprise information system (EIS) is an integrated data-applications platform characterized by diverse, heterogeneous, and distributed data sources. For many enterprises, a number of business processes still depend heavily on static rule-based methods and extensive human expertise. Enterprises are faced with the need for optimizing operation scheduling, improving resource utilization, discovering useful knowledge, and making data-driven decisions.

This thesis research is focused on real-time optimization and knowledge discovery that addresses workflow optimization, resource allocation, as well as data-driven predictions of process-execution times, order fulfillment, and enterprise service-level performance. In contrast to prior work on data analytics techniques for enterprise performance optimization, the emphasis here is on realizing scalable and real-time enterprise intelligence based on a combination of heterogeneous system simulation, combinatorial optimization, machine-learning algorithms, and statistical methods.

On-demand digital-print service is a representative enterprise requiring a powerful EIS.We use real-life data from Reischling Press, Inc. (RPI), a digit-print-service provider (PSP), to evaluate our optimization algorithms.

In order to handle the increase in volume and diversity of demands, we first present a high-performance, scalable, and real-time production scheduling algorithm for production automation based on an incremental genetic algorithm (IGA). The objective of this algorithm is to optimize the order dispatching sequence and balance resource utilization. Compared to prior work, this solution is scalable for a high volume of orders and it provides fast scheduling solutions for orders that require complex fulfillment procedures. Experimental results highlight its potential benefit in reducing production inefficiencies and enhancing the productivity of an enterprise.

We next discuss analysis and prediction of different attributes involved in hierarchical components of an enterprise. We start from a study of the fundamental processes related to real-time prediction. Our process-execution time and process status prediction models integrate statistical methods with machine-learning algorithms. In addition to improved prediction accuracy compared to stand-alone machine-learning algorithms, it also performs a probabilistic estimation of the predicted status. An order generally consists of multiple series and parallel processes. We next introduce an order-fulfillment prediction model that combines advantages of multiple classification models by incorporating flexible decision-integration mechanisms. Experimental results show that adopting due dates recommended by the model can significantly reduce enterprise late-delivery ratio. Finally, we investigate service-level attributes that reflect the overall performance of an enterprise. We analyze and decompose time-series data into different components according to their hierarchical periodic nature, perform correlation analysis,

and develop univariate prediction models for each component as well as multivariate models for correlated components. Predictions for the original time series are aggregated from the predictions of its components. In addition to a significant increase in mid-term prediction accuracy, this distributed modeling strategy also improves short-term time-series prediction accuracy.

In summary, this thesis research has led to a set of characterization, optimization, and prediction tools for an EIS to derive insightful knowledge from data and use them as guidance for production management. It is expected to provide solutions for enterprises to increase reconfigurability, accomplish more automated procedures, and obtain data-driven recommendations or effective decisions.

Design of Scheduling Algorithms Using Game Theoretic Ideas

Scheduling a set of jobs over a collection of machines to optimize a certain quality-of-service measure is one of the most important research topics in both computer science theory and practice. In this thesis, we design algorithms that optimize {\em flow-time} (or delay) of jobs for scheduling problems that arise in a wide range of applications. We consider the classical model of unrelated machine scheduling and resolve several long standing open problems; we introduce new models that capture the novel algorithmic challenges in scheduling jobs in data centers or large clusters; we study the effect of selfish behavior in distributed and decentralized environments; we design algorithms that strive to balance the energy consumption and performance.

The technically interesting aspect of our work is the surprising connections we establish between approximation and online algorithms, economics, game theory, and queuing theory. It is the interplay of ideas from these different areas that lies at the heart of most of the algorithms presented in this thesis.

The main contributions of the thesis can be placed in one of the following categories.

1. Classical Unrelated Machine Scheduling: We give the first polygorithmic approximation algorithms for minimizing the average flow-time and minimizing the maximum flow-time in the offline setting. In the online and non-clairvoyant setting, we design the first non-clairvoyant algorithm for minimizing the weighted flow-time in the resource augmentation model. Our work introduces iterated rounding technique for the offline flow-time optimization, and gives the first framework to analyze non-clairvoyant algorithms for unrelated machines.

2. Polytope Scheduling Problem: To capture the multidimensional nature of the scheduling problems that arise in practice, we introduce Polytope Scheduling Problem (\psp). The \psp problem generalizes almost all classical scheduling models, and also captures hitherto unstudied scheduling problems such as routing multi-commodity flows, routing multicast (video-on-demand) trees, and multi-dimensional resource allocation. We design several competitive algorithms for the \psp problem and its variants for the objectives of minimizing the flow-time and completion time. Our work establishes many interesting connections between scheduling and market equilibrium concepts, fairness and non-clairvoyant scheduling, and queuing theoretic notion of stability and resource augmentation analysis.

3. Energy Efficient Scheduling: We give the first non-clairvoyant algorithm for minimizing the total flow-time + energy in the online and resource augmentation model for the most general setting of unrelated machines.

4. Selfish Scheduling: We study the effect of selfish behavior in scheduling and routing problems. We define a fairness index for scheduling policies called {\em bounded stretch}, and show that for the objective of minimizing the average (weighted) completion time, policies with small stretch lead to equilibrium outcomes with small price of anarchy. Our work gives the first linear/ convex programming duality based framework to bound the price of anarchy for general equilibrium concepts such as coarse correlated equilibrium.