壶状臂尾轮虫(Brachionus urceus)培养滤液对斜生栅藻(Scenedesmus obliquus)形态和多聚糖含量的影响

分离自太湖的壶状臂尾轮虫(Brachionus urceus (Linnaeus))按1000 ind.L-1的密度置于斜生栅藻(Scenedesmus obliquus)中培养24h后,用孔径0.10μm的微孔滤膜抽滤,得到壶状臂尾轮虫培养滤液。将壶状臂尾轮虫培养滤液以20%的比例添加到纯培养的斜生栅藻中,进行为期7d的试验。结果表明壶状臂尾轮虫培养滤液能显著地影响斜生栅藻的形态,处理组中诱发性多细胞群体增加,导致处理组中斜生栅藻种群平均每个个体的细胞数量显著高于对照组。斜生栅藻在壶状臂尾轮虫诱发下形成群聚体可以解释为一种诱发性的反牧食防御,同时也进一步证实了栅藻对浮游动物牧食的响应是一种广泛存在的现象。壶状臂尾轮虫培养滤液处理后的斜生栅藻在生长率上与对照组没有显著性差异,说明诱发性防御群聚体形成的代价没有体现在对生长的影响上。在壶状臂尾轮虫培养滤液诱发下,较多栅藻细胞聚积在一起形成群聚体后,栅藻溶解性胞外多聚糖和固着性胞外多聚糖均有显著提高,而胞内多聚糖略有下降。但从总多聚糖含量看,处理组明显高于对照组,这也说明轮虫培养滤液刺激了栅藻多聚糖合成的额外增加,且被分泌到胞外,充当细胞之间的粘合物,促使细胞容易聚合形成群聚体,有效防御象轮虫这些小型浮游动物的进一步牧食,保持种群得以延续。

Effect of UV-B radiation on the feeding behavior of the rotifer Brachionus plicatilis

Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV - B radiation on five species of microalgae, i. e. , Chlorella sp. , Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV - B radiation when fed with five species of microalgae respectively （ P 〈 0.05 ） which indicates UV - B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp. , then C. muelleri, L galbana, N. clostertum and T. chuii in turn if without UV - B radiation. Under the highest dose of UV - B radiation treatment （2.70 kJ/m^2）, the rotifer preferred to feed C. muelleri, then Chlorella sp. , N. clostertum, L galbana and T. chuii in turn. Chlorella sp. , L galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV - B radiation will lead to the change in the structure of phytoplankton community.

Effect of UV-B Radiation on Ingesting and Nutritional Selecting Behavior of Rotifer Brachionus urceus

Effect of UV-B radiation on ingesting and nutritional selecting behavior of the roifer Brachionus urceus on 5 species of microlgae were studied under controlled laboratory conditions. Restdts showed that enhanced UV-B radiation significantly inhibited ingesting of the rotifer B. urceus when it was fed with 5 species of micro-algae （p〈0.05）. The ingesting selectivity rate varied with the UV-B radiation enhancement when it was fed with 5 species micro-algal mixture. Results indicated that the enhanced UV-B radiation could affect ingesting and nutritional selectivity of B. urceus.

The effect of the causative algae of large-scale HAB in the East China Sea on egg hatching of Argopecten irradians, and population growth of Brachionus plicatilis and Moina mongolica

The impacts of Prorocentrum donghaiense Lu and Alexandrium catenella Balech, causative species of the large-scale HAB in the East China Sea, were studied under laboratory conditions. According to bloom densities, the effects of monocuhure and mixture of the two species were examined on the egg-hatching success ofArgopecten irradiarts Lamarck, and the population growth of Brachionus plicatilis MUller and Moina mongolica Daday. The results showed that monocuhure of A. catenella had a significant inhibition on the egg hatching success of A. irradians, and the population growth of B. plicatilis and M. mongolica. The median effective densities （ED50） inhibiting the egg hatching success of A. irradhms for 24 h and the population growth of B. plicatilis and M. mongolica for 96 h were 800, 630, and 2 400 cells/cm^3 , respectively. Monoculture of P. dongha/ense has no such inhibitory effect on the egg hatching success of A. irradians; P. donghaiense at lower suitable densities could sustain the population growth of B. plicatilis （ 1 × 10^4 ～ 3 ×10^4 cells/cm^3 ） and M. mongolica （2 × 10^4～5 ×10^4 cells/cm^3 ） ; P. donghaiense at higher densities had significantly adverse effect on the population growth of B. plicatilis （4 × 10^4 ～ 10×10^4 cells/cm^3 ） and M. mongolica （ 10 ×10^4 cells/cm^3）. When the two algae were mixed according to bloom densities, P. donghaiense at suitable densities to some extent could decrease the toxicity of A. catenella to B. plicatilis and M. mongolica. The results indicated that the large-scale HAB in the East China Sea could have adverse effect on zooplankton, and might further influence the marine ecosystem, especially when there was also Alexandrium bloom.

Offspring of aged mothers of rotifer Brachionus calyciflorus shows lower sexual propensity than their elder siblings under crowded conditions

Maternal eff ects are one of the most interesting topics in evolutionary ecology as they can aff ect the rate of evolution and population dynamics by phenotypic manipulation of off spring related to fi tness. At present, studies examining the interaction between maternal environment eff ects and maternal age (birth order) eff ects are scarce. We designed an experiment to reveal whether environmentally induced maternal manipulation works equally on off spring across birth orders in rotifer Brachionus calycifl orus. In the experiment, newborn amictic mothers (F0) were cultured parallelly in low (LD) and high (HD) population density. Off spring (F1) of young (YF0) and old (OF0) mothers in both LD and HD groups were cultured under a crowded condition and the mixis ratios of both F1 and F2 were examined. Results show that F1 from HD-YF0 had a signifi cantly higher mixis ratio and those amictic ones produced daughters (F2 ) with higher mixis ratio in response to crowding than those from HD-OF0. In contrast, no such diff erences among F1 siblings were found in the LD-F0 group. Therefore, the eff ect of maternal age on the sexual propensity of the off spring can be aff ected independently by the maternal population density.

Effect of UV-B radiation on the population dynamics of the rotifer Brachionus urceus

The effect of UV-B radiation enhancement at experimental doses of 0.00,0.24,0.48,0.72,0.96,and 1.20 kJ/m 2 on the population dynamics of the rotifer Brachionus urceus feeding on the alga Chlorella sp.was studied under controlled laboratory conditions using clonal culture and life-table techniques.The results show that UV-B radiation treatment significantly shortened the survival time of the rotifer （P 0.05）： The longest survival time （336 h） occurred in the control （0.00 kJ/m 2 ） while the shortest （222 h） occurred when exposed to the highest UV-B radiation treatment （1.20 kJ/m 2 ）.The fecundity of the rotifer B.urceus was enhanced by the lower UV-B radiation treatment （0.24 and 0.48 kJ/m 2 ） but inhibited by the higher treatments （0.96 and 1.20 kJ/m 2 ）.Life expectancy also was obviously affected by UV-B radiation （P 0.05）.The highest life expectancy occurred in the control （0.00 kJ/m 2 ）,and it became shorter with increasing doses of UV-B radiation.The resutls in the present study indicate that the life expectancy of the rotifer B.urceus can be used as an indicator for UV-B radiation enhancement.

Studies on selection of low temperature tolerant strain of Brachionus plicatilis

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井盐水培育轮虫过程中碳酸钙浓度过饱和的危害及防控方法的研究

为探究自然海水、井盐水混合自然海水两种水体下轮虫产量差别,提高轮虫的单产水平,找到限制轮虫产量的环境影响因子,试验选择盘锦光合蟹业有限公司三角洲基地12排5个自然海水轮虫池塘和18排5个自然海水与井盐水混合的轮虫池塘进行调查,井盐水的量占总量的比例≥50%,连续监测15 d水温、pH值的变化,定期测定水体的理化指标,包括碱度、盐度、钙离子,计算晶型CaCO_(3)·H_(2)O临界突变的饱和度指数,并跟踪记录各池轮虫总产量。结果显示,对比自然海水池塘,井盐水混合池塘更易发生水质突变,且突变次数明显增多,平均自然海水为0.4±0.49次,井盐水混合池塘为2.6±0.49次。井盐水混合池塘碱度普遍较高,平均(4.18±0.10)mmol/L,自然海水为(2.63±0.22)mmol/L。添加井盐水的池塘,轮虫产量显著低于正常轮虫池(P<0.01),平均每亩产量低25万kg左右。研究结果显示,在轮虫池大量混合井盐水会使水体突变增多,最终导致轮虫大量减产。

Effects of two polybrominated diphenyl ethers(BDE-47,BDE-209) on the swimming behavior, population growth and reproduction of the rotifer Brachionus plicatilis

Polybrominated diphenyl ethers（PBDEs） are new kinds of persistent organic pollutants（POPs） and their potential threats to the equilibrium and sustainability of marine ecosystems have raised worldwide concerns. Here, two kinds of PBDEs, tetra-BDE（BDE-47）and deca-BDE（BDE-209） were applied, and their toxic effects on the swimming behavior,population growth and reproduction of Brachionus plicatilis were investigated. The results showed that：（1） The actual concentrations of BDE-47 and-209 in the seawater phase measured by GC–MS（Gas Chromatography-Mass Spectrometer） were much lower than their nominal concentrations.（2） In accordance with the 24-hr acute tests, BDE-209 did not show any obvious swimming inhibition to rotifers, but a good correlation did exist between the swimming inhibition rate and BDE-47 concentration suggesting that BDE-47 is more toxic than BDE-209.（3） Both BDE-47 and-209 had a significant influence on the population growth and reproduction parameters of B. plicatilis including the population growth rate, the ratio of ovigerous females/non-ovigerous females（OF/NOF）, the ratio of mictic females/amictic females（MF/AF）, resting egg production and the mictic rate, which indicate that these parameters in B. plicatilis population were suitable for monitoring and assessing PBDEs. Our results suggest that BDE-47 and-209 are not acute lethal toxicants and may pose a low risk to marine rotifers at environmental concentrations for short-term exposure. They also accumulate differently into rotifers. Further research data are needed to understand the mechanisms responsible for the effects caused by PBDEs and to assess their risks accurately.

乳酸菌联合小球藻对褶皱臂尾轮虫种群增长的影响

为研究乳酸菌联合小球藻(Chlorella vulgaris)对褶皱臂尾轮虫(Brachionus plicatilis)种群增长的影响,以盘锦光合蟹业有限公司轮虫池冬卵孵化的轮虫为试验对象,以小球藻为轮虫基础饵料并添加不同浓度的微生态制剂乳酸菌(Lactic acid bacteria,LAB),设置乳酸菌的浓度梯度为0(对照组)、1×10^(8) cells/mL、2×10^(8) cells/mL、5×10^(8) cells/mL、10×10^(8) cells/mL,连续观察4d,对轮虫种群密度、抱卵率和平均增长率等进行统计。结果表明,在轮虫种群密度起始相同的情况下,添加适宜浓度的乳酸菌处理组轮虫最大种群密度、抱卵率和平均增长率是同时期对照组的3倍、3倍和5倍(P<0.05),且能有效降低培养水体pH使其在轮虫生长适宜范围内。结果表明以小球藻为轮虫基础饵料,添加一定浓度的乳酸菌有利于褶皱臂尾轮虫的生长繁殖,可以提高轮虫的种群数量,促进种群增长。

4种重金属离子及其混合液对壶状臂尾轮虫的急性毒性试验

研究了铜、锌、镉、铅离子及其混合液对壶状臂尾轮虫(Brachionusurceus)的急性毒性影响,实验结果表明,Cu2+、Zn2+、Cd2+、Pb2+对壶状臂尾轮虫的24hLC50分别为83 .18μg/L、4 .27mg/L、7. 60mg/L、23 44mg/L,将4种离子按照质量比120∶20∶6∶1的比例配成混合金属溶液,其混合液对壶状臂尾轮虫的24hLC50为0 42mg/L。

UV-B辐射增强对壶状臂尾轮虫摄食的影响

研究了UV-B辐射条件下壶状臂尾轮虫(Brachionusurceus)对6株海洋微藻:小球藻(Chlorellasp.)、绿色巴夫藻(Pavlovauiridis)、扁藻(Tetraselmischuii)、球等鞭金藻8701(IsochrysisgalbanaPark8701)、牟氏角毛藻(Chaetocerosmuelleri)和小新月菱形藻(Nitzschiaclostertum)的室内摄食实验。结果表明,UV-B辐射增强对壶状臂尾轮虫的摄食有显著的抑制作用。与对照组相比,壶状臂尾轮虫对给定饵料单胞藻的滤水率和摄食率都随UV-B辐射剂量的增大而显著减小(P<0.05)。而且壶状臂尾轮虫对每一种饵料单胞藻的滤水率和摄食率是不相同的,这说明壶状臂尾轮虫对饵料单胞藻是有选择性的。

米氏凯伦藻对褶皱臂尾轮虫、卤虫和黑褐新糠虾存活的影响

初步研究了一株米氏凯伦藻对褶皱臂尾轮虫(Brachionus plicatilis)、卤虫(Artemia salina)幼体和黑褐新糠虾(Neomysis awatschensis)的毒性效应和机制。研究发现米氏凯伦藻(Karenia mikimotoi)在较低密度下就能明显减少轮虫的种群数量,24hEC50仅为20个/mL左右;该藻的各组分毒性比较结果显示,只有藻液和细胞重悬液有这种毒害作用,而去藻过滤液和藻细胞破碎液的影响不明显,表明这种毒害作用可能是由于活的藻细胞引起的;在米氏凯伦藻中卤虫和黑褐新糠虾的存活数量也明显下降。结果表明,米氏凯伦藻赤潮可能通过直接影响存活从而对浮游动物产生影响。

用富含DHA的裂殖壶菌对轮虫进行营养强化的研究

裂殖壶菌(Schizochytrium limanium)是一种高DHA含量的海洋真菌,本实验用裂殖壶菌对褶皱臂尾轮虫(Brachionus plicatilis)进行营养强化。结果表明:3个实验组强化后轮虫体内的DHA/FA值和DHA含量均显著提高,DHA/FA值分别为5.98%、10.21%和13.44%,轮虫体内的DHA质量比分别为4.42,7.85,8.14 mg/g,并于12 h后达到最大值,超过12h后轮虫体内的DHA质量比及DHA/FA值开始下降。对照组在实验过程中均未检出DHA。各实验组的其他指标,如轮虫密度也显著高于对照组,并且实验组的怀卵率分别为34.8%、46.5%和53.7%,而对照组仅为20.1%。

氟他胺对萼花臂尾轮虫的毒性影响

采用两天种群增长和生命表,研究了不同浓度氟他胺对萼花臂尾轮虫(Brachionus calyciflorus)的毒性影响。结果显示:轮虫种群增长率与氟他胺浓度对数负相关。氟他胺对萼花臂尾轮虫种群增长率的半效应浓度(EC50)、最低可见效应浓度(LOEC)和无可见效应浓度(NOEC)分别为4.31、3.17和1.59 mg/L。氟他胺对萼花臂尾轮虫的内禀增长率和世代时间有显著的影响(P<0.05);内禀增长率随氟他胺浓度升高而下降,其中1.59 mg/L和3.17 mg/L氟他胺浓度组内禀增长率分别比对照组降低了8.98%和17.95%(P<0.05),其无效应浓度为0.8 mg/L;而3.17 mg/L浓度组的世代时间显著延长(P<0.05)。实验结果表明内禀增长率是检测氟他胺对萼花臂尾轮虫毒性最敏感的指标。

壶状臂尾轮虫及其休眠卵的形态学研究

从乳山对虾养殖场池塘底泥中分离出数量较多的一种轮虫休眠卵,经孵化鉴定为壶状臂尾轮虫(Brachionus urceus),对该轮虫休眠卵及孵出的轮虫进行了形态学观察。扫描电镜观察发现,壶状臂尾轮虫休眠卵表面有明显的、不规则的褶皱突起,与已有报道略有差异,这可能是由生活水体盐度的不同引起的;该休眠卵表面附着一些污染物。透射电镜观察显示,壶状臂尾轮虫细胞内线粒体密集、分泌颗粒较多,这是与其代谢旺盛、运动活跃等机能相适应的。

药物杀除极大螺旋藻培养液中轮虫的初步研究

通过向极大螺旋藻(Spirulina maxima)培养液中添加"轮虫克星Ⅰ号",进行以杀除褶皱臂尾轮虫(Brachionus plicatilis)的试验。结果表明,该药物能有效杀灭藻液中的褶皱臂尾轮虫;褶皱臂尾轮虫的死亡时间、死亡率以及杀灭轮虫后螺旋藻的恢复情况与药物的浓度有关;在试验范围内既能杀灭轮虫、对螺旋藻生长的影响又较小的最佳药物质量分数为1.25%。

萼花臂尾轮虫非混交雌体SOX基因的克隆与分析

选用根据SOX基因蛋白序列设计的1对兼并引物,采用PCR技术扩增萼花壁尾轮虫(Brachionus calyciflorus)非混交雌体基因组DNA。结果显示:实验得到1个约220 bp的片段。经过克隆和测序分析,共获得2个有差异的DNA片段,其中一个DNA片段证明为萼花臂尾轮虫SOX2蛋白编码序列,与人和秀丽隐杆线虫(Cae-norhabditis elegans)DNA序列碱基组成相似性分别为68.98%和75.93%,其编码的氨基酸序列与人、秀丽隐杆线虫SOX2蛋白相似性分别为为84.72%和81.94%。另一个DNA片段长209 bp,用BLAST程序在GenBank数据库中搜索,没有找到相似性序列,用该序列推导氨基酸序列,发现两个终止密码子,推测该片段是受到自然选择作用失去功能的SOX基因。同时对多个物种的SOX2基因保守序列进行比对,发现萼花臂尾轮虫SOX2基因是一种古老的基因形式,具有高度的保守性。

秦皇岛海域“褐潮”海水对卤虫、轮虫存活和摄食的影响研究

为评价秦皇岛褐潮现场海水的毒性,作者利用HPLC技术及CHEMTAX,分析了2013年7月2日采自秦皇岛褐潮高峰期微型及微微型浮游植物的色素组成及群落结构;测定了卤虫(Artemia salina)、轮虫(Brachionus plicatilis)存活率和摄食量。研究表明,褐潮海水微型及微微型浮游植物中,海金藻(Pelagophyceae)占主要优势,其生物量占总生物量的72.6%。褐潮海水抑制卤虫存活,卤虫48 h存活率降至77%;对轮虫24 h存活没有显著效应。此外,褐潮海水抑制卤虫、轮虫的摄食,卤虫、轮虫8 h内摄食量分别由(5.5±0.4)ng/个降至(2.4±0.4)ng/个、由(1.5±0.2)ng/个下降至(0.9±0.1)ng/个。该结果与美国的3株褐潮藻的毒性进行了比较。CCMP 1507对卤虫存活有显著抑制作用,其他两株没有显著效应;3株褐潮藻对轮虫24 h存活都没有显著影响。暴露于3株褐潮藻中,卤虫的摄食量均显著较低;其中CCMP 1507在混合饵料中还抑制卤虫、轮虫对其他藻的摄食。对CCMP 1507各组分分析发现,该藻的毒性主要来源于藻细胞。结合现场试验与室内试验结果分析表明,秦皇岛褐潮对卤虫、轮虫有一定的毒性,其毒性与CCMP 1507的毒性相当。

UV辐射及化学诱变剂对褶皱臂尾轮虫的诱变选育

运用物理方法紫外线辐射(UV)和化学诱变剂秋水仙素、甲基磺酸乙酯(EMS)对褶皱臂尾轮虫Brachionus plicatilis进行诱变处理及小型化轮虫选育。结果表明,随着UV辐射剂量和化学诱变剂浓度的增加,轮虫的孵化率、挂卵率呈下降趋势。辐射剂量为4.8×104—6.0×104μW·s·cm-2时的孵化率、挂卵率指数减小;1.2×105—1.5×105μW·s·cm-2后减小趋势变缓。对照组轮虫平均体长250μm,UV辐射后轮虫平均体长200μm;秋水仙素20mg.L-1组的轮虫长、短轴、卵经相对对照组分别减少20%、14%、7.7%;甲基磺酸乙酯10%(体积分数)组减少30%、19%、12%。实验得到最佳UV辐射剂量和化学诱变剂浓度:辐射强度400μW.cm-2,辐射时间为2min,最终辐射剂量达到5.0×104μW·s·cm-2;秋水仙素浓度2mg·L-1、甲基磺酸乙酯浓度为0.6%(体积分数),浸渍时间为12h。