Photosynthetic performance of regenerated protoplasts from disintegrated cells of Bryopsis hypnoides (Chlorophyta)

The photosynthetic performances of regenerated protoplasts of Bryopsis hypnoides, which were incubated in seawater for 1, 6, 12, and 24 h, were studied using chlorophyll (Chl) fluorescence and oxygen measurements. Results showed that for the regenerated protoplasts, the pigment content, the ratios of photosynthetic rate to respiration rate, the maximal photosystem II (PSII) quantum yield (F-v/F-m), and the effective PSII quantum yield (I broken vertical bar(PSII)) decreased gradually along with the regeneration progress, indicated that during 24 h of regeneration there was a remarkable reduction in PSII activity of those newly formed protoplasts. We assumed that during the cultivation progress the regenerated protoplasts had different photosynthetic vigor, with only some of them able to germinate and develop into mature thalli. The above results only reflected the photosynthetic features of the regenerated protoplasts at each time point as a whole, rather than the actual photosynthetic activity of individual aggregations. Further investigation suggested a relationship between the size of regenerated protoplasts and their viability. The results showed that the middle-sized group (diameter 20-60 mu m) retained the largest number of protoplasts for 24 h of growth. The changes in F-v/F-m and I broken vertical bar(PSII) of the four groups of differently sized protoplasts (i.e. < 20, 20-60, 60-100, and > 100 mu m) revealed that the protoplasts 20-60 mu m in diameter had the highest potential activity of the photosynthetic light energy absorption and conversion for several hours.

Dioxopiperazine Alkaloids Produced by the Marine Mangrove Derived Endophytic Fungus Eurotium rubrum

Cultivation of the fungal strain Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus, resulted in the isolation of two new dioxopiperazine derivatives, namely, dehydrovariecolorin L (1) and dehydroechinulin (2), together with eight known dioxopiperazine compounds including variecolorin L (3), echinulin (4), isoechinulin A (5), dihydroxyisoechinulin A (6), preechinulin (7), neoechinulin A (8), neoechinulin E (9), and cryptoechinuline D (10). The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. Compounds 1, 2, 9, and 10 were investigated for their a,a-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity. In addition, the new compounds, 1 and 2, were evaluated for their cytotoxic activity against the P-388, HL-60, and A549 cell lines.

Distribution and mobility of metals in agricultural soils near a copper smelter in South China

The distribution and mobility of heavy metals in the paddy soils surrounding a copper smelting plant in south China was investigated. We assessed the degree of metal contamination using an index of geoaccumulation. The metals were divided into two groups: (1) Cu, Zn, Pb and Cd, whose concentrations were heavily affected by anthropogenic inputs, and (2) Ni, Co and Cr, which were mainly of geochemical origin. Concentrations of Cu, Cd, Zn, and Pb in the polluted soils were higher than the Chinese soil quality criteria. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the residual and NH2OH HCl extractable fractions. In contrast, Cd was predominantly associated with the MgCl2 extractable fraction. A large proportion of Cu was bound to the acidic H2O2 extractable fractions, while Zn was predominantly found in the residual phase. The fraction of mobile species, which potentially is the most harmful to the environment, was found to be elevated compared to unpolluted soils in which heavy metals are more strongly bound to the matrix. The mobility of the metals was studied by water extraction using a modification of Tessier's procedure, and the order of mobility was Zn > Cd > Cu > Ce > Pb.

中国明对虾免疫系统中抗氧化相关基因的克隆与表达分析

对虾病害在世界范围内的广泛传播，给水产养殖和沿海农村经济造成了重大损失。深入开展对虾免疫机制研究并在此基础上寻找对虾疾病防治的有效方法已成为当务之急。研究表明，当对虾等甲壳动物受到外界病原刺激时，其体内的吞噬细胞在吞噬活动中会激活磷酸己糖支路的代谢，引起呼吸爆发，产生多种活性氧分子。另外，受到病原侵染的对虾还会产生其他多种免疫反应，这些免疫反应将消耗大量的能量（ATP），产能的呼吸链会加速运转，由此也会引发大量活性氧的产生。这些活性氧分子可以杀灭入侵的病原微生物，但同时由于活性氧分子反应的非特异性，它们也会对宿主的细胞、组织和器官造成严重伤害，进而导致对虾生理机能的损伤和免疫系统的破坏。所以，消除对虾体内因过度免疫反应产生的过量氧自由基将能够增强其抵御病原侵染的能力，提高免疫力。本论文从中国明对虾体内克隆了线粒体型超氧化物歧化酶（mMnSOD）、胞质型超氧化物歧化酶（cMnSOD）、过氧化氢酶（Catalase）和过氧化物还原酶（Peroxiredoxin）等四种与免疫系统相关的抗氧化酶基因，分析了它们的分子结构特征，组织分布及应答不同病原刺激的表达变化模式，并对其中的mMnSOD基因和Peroxiredoxin基因进行了体外重组表达、分离纯化和酶活性分析。 采用RACE技术从中国明对虾血细胞中克隆了两个超氧化物歧化酶（SOD）基因，通过序列比对分析发现，其中一个为mMnSOD基因，另一个为cMnSOD基因。mMnSOD基因的cDNA全长为1185个碱基，其中开放阅读框为660个碱基，编码220个氨基酸，其中推测的信号肽为20个氨基酸。多序列比对结果显示中国明对虾mMnSOD基因的推导氨基酸序列与罗氏沼虾、蓝蟹的推导氨基酸序列同源性分别为88%和82%。Northern blot结果表明，该基因在对虾的肝胰脏、血细胞、淋巴器官、肠、卵巢、肌肉和鳃等组织中均有表达。半定量RT-PCR结果显示，对虾感染病毒3 h时，该基因在血细胞和肝胰脏中的转录水平显著升高。此外，通过构建原核表达载体，本研究对该基因进行了体外重组表达，并对纯化的重组蛋白进行了质谱鉴定和酶活分析。cMnSOD基因的cDNA全长为1284个碱基，其中开放阅读框为861个碱基，编码287个氨基酸。多序列比对结果显示中国明对虾cMnSOD基因的推导氨基酸序列与斑节对虾和凡纳滨对虾的同源性高达98%和94%。组织半定量结果显示，cMnSOD基因在对虾被检测的各个组织中均有表达。 另外，半定量RT-PCR结果表明，对虾感染病毒23h时，该基因在肝胰脏中的转录上升到正常水平的3.5倍；而感染后59 h时，该基因在血细胞中的转录上升到正常水平的2.5倍。 利用根据其他生物过氧化氢酶保守氨基酸序列设计的简并引物，结合RACE技术，从中国明对虾肝胰脏中克隆到了过氧化氢酶基因的部分片段，片段长1725个碱基。多序列比对结果发现目前所得中国明对虾Catalase基因部分片段的推导氨基酸序列与罗氏沼虾和皱纹盘鲍Catalase氨基酸序列的同源性分别达到95%和73%。通过实时荧光定量PCR技术对中国明对虾Catalase基因在各个组织中的分布情况及病毒感染后该基因在血细胞和肝胰脏中的转录变化进行了研究。结果发现，该基因在肝胰脏、鳃、肠和血细胞中表达水平较高，在卵巢、淋巴器官和肌肉中的表达水平相对较弱；感染病毒23 h和37 h时，对虾血细胞和肝胰脏中该基因mRNA的表达量分别出现显著性上升。 依据中国明对虾头胸部cDNA文库提供的部分片段信息，结合SMART-RACE技术，从中国明对虾肝胰脏中克隆到了过氧化物还原酶基因（Peroxiredoxin）， 该基因的cDNA全长为942个碱基，其中开放阅读框为594个碱基，编码198个氨基酸。中国明对虾Peroxiredoxin基因的推断氨基酸序列与伊蚊、文昌鱼和果蝇等Peroxiredoxin基因的推断氨基酸序列同源性分别为77%、76%和73%。其蛋白理论分子量为22041.17 Da，pI为5.17。Northern blot结果表明，Peroxiredoxin基因在对虾的肝胰脏、血细胞、淋巴器官、肠、卵巢、肌肉和鳃等组织中均有表达。实时荧光定量PCR结果显示，弧菌感染后，该基因在对虾血细胞和肝胰脏中的转录水平都有明显变化并且表达模式不同。另外，对该基因进行了体外重组表达，并对纯化的重组蛋白进行了质谱鉴定和酶活性分析。酶活性分析表明，复性后的重组蛋白能在DTT存在的条件下还原H2O2。

皱纹盘鲍的遗传育种与养殖技术研究

优良的种质是产业发展的重要保证，品种更新和养殖技术的发展已经给世界农业带来了令人瞩目的成就，然而我国水产生物的育种工作刚处于起步阶段，而育种技术的研究则更是滞后。借鉴陆生生物中发展起来的相对成熟的研究方法，可以帮助加快海洋生物遗传育种相关研究的进度。本研究以我国北方海区重要的海洋经济动物－皱纹盘鲍为研究对象，从表型遗传、数量性状遗传等2个方面开展了皱纹盘鲍的遗传育种研究，同时从幼鲍培育密度与分选效应等方面研究了皱纹盘鲍的中间培育技术。 主要结果如下： 1. 皱纹盘鲍的贝壳颜色遗传、食物对贝壳颜色表现型的影响，贝壳颜色与生长速度间的关系 将贝壳颜色为橘红色（O表型）的突变型皱纹盘鲍与贝壳颜色为绿色（G表型）的野生型皱纹盘鲍进行了连续2代的交配实验。结果表明：皱纹盘鲍橘红色的贝壳颜色相对于绿色的贝壳颜色为隐性性状，皱纹盘鲍的贝壳颜色表型受单位点、2个等位基因遗传控制，其中基因型为oo的个体，贝壳颜色的表现型为橘红色（O表型），而基因型为GG或Go的个体，贝壳颜色的表现型为野生型（G表型）。 为探讨食物类型对不同基因型皱纹盘鲍贝壳颜色表现型的影响，对不同贝壳颜色表型的个体投喂不同种类的食物，结果表明，除遗传因素外，皱纹盘鲍的贝壳颜色表现型显著地受食物类型的调控。其中oo基因型的个体，在摄食底栖硅藻（Navicula sp.）和红藻时，贝壳颜色的表型为橘红色；而在摄食褐藻、绿藻和以海带粉为唯一海藻源的人工配合饵料时，贝壳颜色的表型为黄色。GG和Go基因型的个体，在摄食底栖硅藻、红藻时，贝壳颜色的表型为褐红色；在摄食褐藻、绿藻和以海带粉为唯一海藻源的人工配合饵料时，贝壳颜色的表型为绿色。该结果表明，相同基因型的皱纹盘鲍在摄食不同类型的食物时，贝壳表现型不同，即不同类型的食物可以导致2种基因型皱纹盘鲍的贝壳颜色表现型在一定范围内发生转换：oo基因型的个体，贝壳的颜色可以表现为橘红色或者黄色，不会出现野生型皱纹盘鲍的褐红色或绿色；而GG与Go基因型的个体，相应的贝壳颜色表型只能是褐红色或者绿色，不会出现oo基因型可能表现的橘红色或黄色。特定基因型的皱纹盘鲍，在摄食特定类型的食物时贝壳的相应部位可表现出特定的颜色。皱纹盘鲍的这种“食物－贝壳颜色”的相关性可作为一种形态标记，用于标识皱纹盘鲍的个体和群体，该标记技术可用于皱纹盘鲍的养殖技术和遗传学研究。 此外，选用了贝壳颜色遗传学实验中建立的贝壳颜色发生分离的家系为实验材料，以壳长为指标，分析比较了来自相同家系的O表型与G表型个体之间的生长速度。结果表明，在幼鲍发育至412天止的3-5个统计时段内，没有在同一家系来源的2种贝壳颜色表型个体之间检验到生长速度的显著差异。 2. 皱纹盘鲍不同选育群体及杂交群体的贝壳形态参数分析 在皱纹盘鲍的7个群体中（包括已经对生长速度为指标进行了多代人工选育的群体4个、野生群体之间直接杂交繁育的杂交F1群体3个），测量了4-6龄成体样本的壳长（L）、壳宽（W）、壳高（H）和壳重（Sw），并计算了L/（L+W+H）、W/（L+W+H）、H/（L+W+H）和Sw/（L×W×H）等4个壳形态学参数。用方差分析方法（MANOVA、ANOVA）统计并比较了这些壳形态参数在皱纹盘鲍群体间的遗传变异。结果表明，4个壳形态参数在不同群体间变异系数分别为0.34、0.74、2.62和6.54，其中，H/（L+W+H）与Sw/（L×W×H）在各供试群体间均具有较高的多态性且差异达显著水平，表明这2个参数在不同群体间存在较高的遗传变异。由于在活体情况下无法测量壳重（Sw）性状，建议以参数H/（L+W+H）为指标对皱纹盘鲍贝壳形态（如壳型）等进行人工选择。 3. 皱纹盘鲍成体阶段生长性状的遗传参数估计 采用巢式设计，分析了成体阶段不同发育期皱纹盘鲍的壳长与生长速率的遗传力、不同发育期的壳长性状之间的遗传相关、以及不同发育期的生长速率之间的遗传相关，结果表明：（1）壳长遗传力在受精后第70 、130、320、320、380、490与550天的雄性组分估计值分别为0.161 ± 0.075、0.312 ± 0.131、0.326 ± 0.331、0.135 ± 0.228、0.153 ± 0.185和0.180 ± 0.106；雌亲组分估计分别为0.312 ± 0.172、0.699 ± 0.168、0.695 ± 0.168、0.977 ± 0.407、0.427 ± 0.195和0.449 ± 0.027。（2）生长速率遗传力在受精后第320~380天、490 ~ 550天，雄、雌组分估计值分别为0.080 ± 0.120（雄）、 0.210 ± 0.191（雌）以及0.299 ± 0.146（雄）、0.306± 0.148（雌）。雌亲组分的壳长遗传力和生长速率遗传力估计值较大且均达显著水平，表明皱纹盘鲍在成体阶段依然受母性效应的影响。成体阶段生长性状遗传力水平的估计对制定科学的皱纹盘鲍育种方案有指导意义。（3）雄亲组分估计的不同发育期（第390 ~ 550天）壳长间遗传相关为0.597 ~ 1.000，雌亲组分估计为0.589 ~ 1.177。由雄亲、雌亲组分估计，受精后第320~380天与第490 ~ 550天两个发育阶段生长速率间遗传相关均接近于0。雌亲组分估计不同发育期壳长间遗传相关均达显著水平（t0.05, d.f.=13 = 4.33 ~ 11.69，P<0.01），表明壳长性状早期选择有效，即在皱纹盘鲍早期阶段依据壳长性状对个体进行择优或去劣可在后期阶段获得壳长较大的个体。由于使用的雄亲数目少（8个父系半同胞），实验中以雄亲组分估计的遗传参数误差较大。 4. 皱纹盘鲍选育系间的群体杂交 进行了皱纹盘鲍4个人工选育系之间的完全双列杂交实验，以群体交配的方式共建立了16个组合；此外，以大连“98”选群与汕头“S”选群为亲本，以群体交配的方式建立了4个交配组合。对不同方向的杂交组合进行了中亲杂种优势、超亲杂种优势以及配合力等方面的评价。 （1）测量了4个选育群体（R、97、S和J）及其各杂交组合在受精后第9、20和30天时的壳长，统计分析了不同选育系间壳长性状的差异、评价了不同方向杂交组合的中亲与超亲杂种优势、以及配合力。结果如下： 选育系群体内交配繁育的4个组合，在受精后第9、20和30天的壳长均有显著差异，其中，97  97组合在早期发育各阶段均为最小，分别为0.462 ± 0.023mm、0.698 ± 0.057mm和1.476 ± 0.234mm；S  S组合的3次测量值均为最大，分别为0.522 ± 0.023mm、0.824 ± 0.084mm和1.798 ± 0.229mm。 两个方向杂交组合与选育系亲本群体内交配组合的平均值和高亲值比较，得到如下结果：（A）受精后第9天壳长表现正向中亲杂种优势的组合有6个、表现负向中亲杂种优势的组合6个，其中J  97组合的中亲优势率最高，为9.05%；R  S组合最低，为-6.61%。正向高亲杂种优势组合有4个、负向高亲杂种优势组合有8个，其中S  J组合的高亲优势率最高，为5.77%；R  S组合最低，为-7.96%。（B）受精后第20天壳长表现正向中亲杂种优势的组合有7个、表现负向中亲杂种优势的组合5个，其中J  97组合的中亲优势率最高，为12.60%；J  R组合最低，为-8.72%。正向高亲杂种优势组合有3个、负向高亲杂种优势组合有11个，其中J  97组合的高亲优势率最高，为12.20%；J  R组合最低，为-12.67%。（C）受精后第30天壳长表现正向中亲杂种优势的组合有7个、负向中亲杂种优势的组合5个，其中97  S组合的中亲优势率最高，为24.08%；S  97组合最低，为-12.69%。正向高亲杂种优势组合有6个、负向高亲杂种优势组合有6个，其中97  S组合的高亲优势率最高，为15.95%；S  J组合最低，为-19.44%。上述结果表明，皱纹盘鲍不同选育系之间的交配组合，杂种优势率差异很大，因此，通过组配实验，将杂种优势率高的交配组合选择出来应用于生产，可望显著提高目标性状的产量。 对早期发育阶段各生长期壳长性状，亲本一般配合力（GCA）、各杂交组合间特殊配合力（SCA）以及正反交（REC）效应值进行方差分析，结果表明：各亲本GCA差异显著，说明各选育群体存在显著的遗传差异，其中汕头选群“S”在测量的各个生长期均为正值且显著大于其它各亲本；特殊配合力（SCA）以及正反交（REC）效应值较大在各杂交组合间存在显著差异，说明在早期生长发育阶段非加性遗传效应（显性和上位效应）占主导地位。综合各个生长期亲本GCA和杂交组特殊配合力（SCA）以及正反交（REC）效应值，杂交组合97×S在早期生长阶段不仅有较高SCA值而且两个亲本也具有较大的GCA值，表明选育系97和S较适宜作为杂交亲本使用。 （2）大连“98”选群与汕头“S”选群进行2×2因子设计的群体杂交实验，比较了各交配组合早期存活相关性状如受精率、孵化率、变态率以及壳长性状，评价了两个方向杂交组合平均以及不同方向杂交组合的中亲杂种优势率。结果表明早期发育阶段各组合间的受精率无显著差异，而孵化率、变态率等两个杂交方向平均的中亲杂种优势率为5.49%与12.53%，高于壳长性状的优势率（0.936-1.534%）。方差分析结果表明不同方向的杂交组合在早期发育阶段存活相关性状以及壳长性状存在显著差异。孵化率、变态率性状，S×98的中亲杂种优势率分别为13.21%与21.10%，均高于98×S的-3.84%与3.85%；而第10和25d壳长性状，S×98的中亲杂种优势率为1.14%与-2.52%，低于98×S的1.93%与4.41%。 为进一步评价“98”选群与“S”选群不同交配组合在不同温度条件下的生长，进行了基因型与环境的互作研究。从“98”选群与“S”选群的4个交配组合中分别取5月龄幼鲍100头，各组合随机分成3组，每组1个重复，分别于12°C、16°C和 22°C温度条件下进行培育，比较各交配组合基因型与温度对幼鲍生长的影响。不同温度条件下，各组合壳长生长的方差分析结果表明，基因型和温度都能够对幼鲍生长以及最终壳长产生极显著的影响（P < 0. 01），它们的交互作用也达到显著水平（P < 0.05）。杂交子代的幼鲍壳长在12°C、16°C和 22°C温度条件下均表现出杂种优势，双向杂交的中亲杂种优势率分别为5.32%、5.55%和0.03%，表明低温条件（12°C），比高温条件（22°C）下有更强的杂种优势。汕头“S”选群的早期孵化率、变态率、生长性状以及低温条件下幼鲍生长性状的单亲杂种优势率分别为16.64%、42.49%、3.42~5.79%和5.73~9.15%，单亲杂种优势率较大，表明可通过杂交手段，显著地改良汕头“S”选群在早期发育阶段的生长速度、存活率以及幼鲍期的生长性状。本研究的结果支持了Lerner（1954）杂种优势的基因与环境互作学说。 5. 皱纹盘鲍幼鲍的中间培育技术研究 （1）对南方越冬方式的评价 目前，每年的11月前后，将6-7月龄幼鲍运往南方的闽东、闽中、闽南沿海越冬，翌年4月至6月再运回到北方（大连、山东半岛）的养殖模式已经普遍应用于皱纹盘鲍的实际生产，为评价南方越冬的幼鲍培育方式，本研究分别以不同幼鲍材料在闽东三都海湾进行了越冬培育实验。 选择生产上壳长分别为18.37 ± 1.28 mm、15.89 ± 1.10 mm、14.55 ± 1.10 mm与10.59 ± 0.84 mm的幼鲍进行了为期6.5个月的越冬培育，实验结束时，存活率分别为95.56 ± 2.21%、90.55 ± 1.96%、83.97 ± 1.63%与63.30 ± 2.79%。回归分析表明，供试幼鲍在实验起始时的壳长与越冬阶段的存活率成正相关（P = 0.018 < 0.05）。该结果表明，提高幼鲍的规格可显著提高皱纹盘鲍的越冬成活率，因此对于实际生产而言，采取适当措施提高皱纹盘鲍越冬苗种的规格将大幅增加生产的收益，而采用生长速率快的品种、品系或提早采苗均可实现该目标。综合各规格组幼鲍，幼鲍在南方开放性水域进行越冬培育的平均存活率较高，可达到91.38±0.01%，从幼鲍南方越冬的存活曲线可以看出，幼鲍的死亡主要集中在从大连运至福建某地后的15天内，出现死亡高峰的原因可能是由于运输过程的胁迫。此外，2月及4月中下旬水温出现显著降低或回升时也有较明显的死亡出现。该部分结果，对皱纹盘鲍幼鲍的养成管理有指导意义，可以通过合理安排越冬时间、避开死亡的敏感期等措施减少苗种越冬阶段的死亡量。 以中国大连野生群体繁育的子一代为亲本（10♀，10♂），以群体交配的方式繁育F2代个体为实验材料，分别于南方海区以及北方室内升温水方式下进行生长、存活比较，结果表明南方越冬培育方式下，幼鲍壳长的日增长率为81.37-108.89 µm•day-1，与北方室内升温培育条件相比，壳长生长提高了1.08 ~ 1.68倍；而存活率无显著差异。皱纹盘鲍幼鲍南方越冬方式的优势主要体现在鲍鱼幼鲍的生长速度加快，同时节约养殖场的能耗 （2）幼鲍培育过程中的养殖密度与分选效应评价 以3种规格皱纹盘鲍幼鲍为材料比较幼鲍在4个培育密度以及分选或混养条件下壳长的平均日生长及特定生长率。在南方越冬培育方式下实验进行106天，多因素方差分析结果表明实验初始幼鲍的壳长以及培育密度对壳长的生长有显著影响，而且密度效应在不同幼鲍起始规格组中有不同表现；分选没有能够提高不同规格组的生长。本研究的结果对皱纹盘鲍幼鲍的越冬培育有一定的指导作用。

趋磁细菌AMB-1培养条件优化及磁小体变化过程研究

趋磁细菌(Magnetotactic bacteria)的研究是国际微生物学研究热点之一。趋磁细菌体内含有纳米单磁畴的氧化铁/硫化铁(Fe3O4或Fe3S4)晶体，称为磁小体。由于趋磁细菌营养条件要求苛刻，在环境中需要微好氧条件，且营养类型属于化能自养，使得培养趋磁细菌时常遇到问题。 本研究首先通过正交试验优化趋磁细菌AMB-1菌株培养条件，在培养条件铁源为奎尼酸铁0.02 mmol/L，装瓶量75% ，pH值6.7，温度25 ℃时，AMB-1 OD600达到0.440(1.166×109 cells/ml)。同时运用磁收集传代法，使带有磁小体的AMB-1细胞比例占95％以上(Cmag值稳定在1.9-2.0)。 在AMB-1具有较好的生物量，同时又具有较好的含磁小体细胞比例后，研究磁小体的变化过程。通过透射电镜观察磁小体变化过程，发现培养24 h细菌体内已有较小晶体形成(平均27 nm，n=188)且沿长轴分布；48 h晶体长大(平均43 nm，n=203)且形成分段链沿长轴排列；72 h晶体进一步成熟(平均50 nm，n=191)仍以分段链沿长轴排列；随后细菌逐渐衰亡磁小体变小，168 h可见部分自溶细菌中仍有磁小体链(平均37 nm，n=186)；192 h细菌自溶磁小体链(平均33 nm，n=184)分散到环境中。 通过透射电镜在细胞水平上研究趋磁细菌细胞分裂时发现，磁小体在细菌分裂时采用两种分离方式：一种为磁小体分配到两个子细胞；另一种为磁小体只分配到一个子细胞。无磁小体的子细胞，在随后的生长过程又分为两种情况：一种为细胞逐渐产生磁小体，另一种为不再产生磁小体。这种现象的发现，解释了随着传代次数的增多，细菌磁性有所下降的原因(Cmag值降低)。 在对趋磁细菌磁小体合成机制的研究中，常使用基因敲除的办法获得缺陷型，并与野生型对比进行研究。但是，利用基因敲除获得缺陷型不仅操作繁琐并且所得缺陷型不稳定。本研究利用特殊的磁富集传代法，先将带有磁小体的菌体收集并连续传代，筛选获得了高磁菌株；利用这种方法，收集不含磁小体的菌体并连续传代，筛选获得了无磁菌株。 趋磁细菌磁小体在医疗、环保等领域具有广阔应用价值，但是目前由于趋磁细菌难以大规模培养，并且磁小体纯化存在成本高等原因，将磁小体真正实际应用尚有一段距离。通过研究磁小体在趋磁细菌中的变化过程发现，AMB-1菌株在培养192 h后自溶，并且磁小体随着细胞的破碎释放到环境中去。

Potential of the seaweed Gracilaria lemaneiformis for integrated multi-trophic aquaculture with scallop Chlamys farreri in North China

In this study the red alga, Gracilaria lemaneiformis, was cultivated with the scallop Chlamys farreri in an integrated multi-trophic aquaculture (IMTA) system for 3 weeks at the Marine Aquaculture Laboratory of the Institute of Oceanology, Chinese Academy of Sciences (IOCAS) in Qingdao, Shandong Province, North China. The nutrient uptake rate and nutrient reduction efficiency of ammonium and phosphorus from scallop excretion were determined. The experiment included four treatments each with three replicates, and three scallop monoculture systems served as the control. Scallop density (407.9 +/- 2.84 g m(-3)) remained the same in all treatments while seaweed density differed. The seaweed density was set at four levels (treatments 1, 2, 3, 4) with thallus wet weight of 69.3 +/- 3.21, 139.1 +/- 3.80, 263.5 +/- 6.83, and 347.6 +/- 6.30 g m(-3), respectively. There were no significant differences in the initial nitrogen and phosphorus concentration between each treatment and the control group (ANOVA, p > 0.05). The results showed that at the end of the experiment, the nitrogen concentration in the control group and treatment 1 was significantly higher than in the other treatments. There was also a significant difference in phosphorus concentration between the control group and the IMTA treatments (ANOVA, p < 0.05). Growth rate, C and N content of the thallus, and mortality of scallop was different between the IMTA treatments. The nutrient uptake rate and nutrient reduction efficiency of ammonium and phosphorus changed with different cultivation density and time. The maximum reduction efficiency of ammonium and phosphorus was 83.7% and 70.4%, respectively. The maximum uptake rate of ammonium and phosphorus was 6.3 and 3.3 A mu mol g(-1) DW h(-1). A bivalve/seaweed biomass ratio from 1:0.33 to 1:0.80 (treatments 2, 3, and 4) was preferable for efficient nutrient uptake and for maintaining lower nutrient levels. Results indicate that G. lemaneiformis can efficiently absorb the ammonium and phosphorus from scallop excretion and is a suitable candidate for IMTA.

Growth characters and photosynthetic capacity of Gracilaria lemaneiformis as a biofilter in a shellfish farming area in Sanggou Bay, China

Experiments on growth characters and ecological functions of the macroalgae Gracilaria lemaneiformis, collected from south China, were conducted in polyculture areas of kelp and filter-feeding bivalve in Sanggou Bay in Weihai City, Shandong, in north China from May 2002 to May 2003. The results of 116 days cultivation showed that the average wet weight of alga increased 89 times from 0.1 to 8.9 kg rope(-1), with an average specific growth rate ( based on wet weight) of 3.95% per day. The most favorable water layer for its growth was 1.0 - 1.8 m below the surface in July and August, with an average specific growth rate of 8.2% per day in 30-day experiments. Photosynthetic activity changed seasonally, with an average of 7.3 mg O-2 g dw(-1) h(-1). The maximum rate (14.4 mg O-2 g dw(-1) h(-1)) was recorded in July, or 19.3 mg CO2 g dw(-1) h(-1), while the minimum (0.40 mg CO2 g dw(-1) h(-1)) was in April. This study indicated that the culture of G. lemaneiformis is an effective way to improve water quality where scallops are cultivated intensively.

Phosphine in various matrixes

Matrix-bound phosphine was determined in the Jiaozhou Bay coastal sediment, in prawn-pond bottom soil, in the eutrophic lake Wulonglan, in the sewage sludge and in paddy soil as well. Results showed that matrix-bound phosphine levels in freshwater and coastal sediment, as well as in sewage sludge, are significantly higher than that in paddy soil. The correlation between matrix bound phosphine concentrations and organic phosphorus contents in sediment samples is discussed.

Matrix-bound phosphine: A new form of phosphorus found in sediment of Jiaozhou Bay

Matrix-bound phosphine (PH3), a new form of phosphorus, was found in sediment of Jiaozhou Bay in December 2001. Concentration and distribution of PH3 in different layers of sediment with different stations were analyzed. The results show that PH3 concentrations are various with different layers and different stations. PH3 concentrations in the bottom layer of sediment (20-30 cm) are usually higher than those in the surface layer (0-4 cm). The highest PH3 concentration in our investigation reaches 685 ng/kg (dry), which is much higher than those in terrestrial paddy soil, marsh and landfill that have been reported up to now. The correlation analysis indicates that there is no apparent correlation between the concentrations of PH3 and inorganic phosphorus in sediment. However, the correlation between the concentrations of phosphine and organic phosphorus in the bottom layer of sediment is remarkable (R-2=0.83). It is mainly considered that PH3 in sediment of Jiaozhou Bay is produced from the decomposition of organic phosphorus in the anaerobic condition, and so PH3 concentrations are related to organic phosphorus concentration and anaerobic environment in sediment. The discovery of PH3 in sediment will give people some new ideas on the mechanisms of phosphorus supplement and biogeochemical cycle in Jiaozhou Bay.

Seasonal variation in metabolism of cultured Pacific oyster, Crassostrea gigas, in Sanggou Bay, China

Rates of respiration and excretion of the Pacific oyster, Crassostrea gigas, were measured seasonally from June 2002 to July 2003 under ambient conditions of food, water temperature, pH, and salinity in Sanggou Bay, an important mariculture coast in north China. The aim of this study is to obtain fundamental data for further establishing an energy budget model and assessing the carrying capacity for cultivation of C. gigas in north China. Oysters were collected monthly or bimonthly from the integrated culture areas of bivalve and kelp in the bay. Oxygen consumption and ammonium and phosphorus excretion rates were measured, and ratios of O/N and NIP were calculated. One-way ANOVA was applied to determine differences among these parameters that act as a function of seasonal variation. All the physiological parameters yielded highly significant variations with season (P<0.01) The rate of respiration varied seasonally, with the highest oxygen consumption rate in July and the lowest rate in January, ranging from 0.07 to 2.13 mg O-2 h(-1) g(-1) dry tissue weight (DW). Maximum and minimum ammonium excretion rates were recorded in August and January, respectively, ranging from 0.51 to 5.40 mu mol NH4-N h(-1) g(-1) DW. Rates of phosphorus excretion varied from 0.11 (in January) to 0.64 (in July) mu mol PO4-P h(-1) g(-1) DW. The O/N and N/P ratios changed from 9.2 (in January) to 59.8 (in July) and from 4.6 (in January) to 10.9 (in August), respectively. For each season, the allometric relationship between the physiological response (e.g., rate of oxygen consumption, ammonium and phosphorus excretion) and DW of the animal was estimated using the formula: Y=a x DWb. (C) 2005 Elsevier B.V. All rights reserved.

The influence of diets containing dried bivalve feces and/or powdered algae on growth and energy distribution in sea cucumber Apostichopus japonicus (Selenka) (Echinodermata : Holothuroidea)

In recent years, bivalve feces and powdered algae have been used as the food sources of holothurians in China. In this study, growth and energy budget for sea cucumber Apostichopus japonicus (Selenka) with initial wet body,veights of 32.5 1.0 g (mean +/- SE, n=45) when fed with five different granule diets containing dried bivalve feces and/or powdered algae in water temperature 13.2-19.8 degrees C and salinity 30-32ppt were quantified in order to investigate how diets influence growth and energy distribution and to find out the proper diet for land-based intensive culture of this species. Results showed that diets affected the food ingestion, feces production, food conversion efficiency and apparent digestive ratios, hence the growth and energy budget. Sea cucumbers fed with dried feces of bivalve showed poorer energy absorption, assimilation and growth than individuals fed with other four diets; this could be because feces-drying process removed much of the benefits. Dried bivalve feces alone, therefore, were not a suitable diet for sea cucumbers in intensive cultivation. The mixed diets of feces and powered algae showed promising results for cultivation of sub-adult Apostichopus japonicus, while animals fed with powdered algae alone, could not obtain the best growth. According to SGR of tested animals, a formula of 75% feces and 25% powdered algae is the best diet for culture of this species. Extruded diets were used in the present experiment to overcome shortcomings of the traditional powdered feeds, however, it seems a conflict exists between drying bivalve feces to form extruded diets and feeding sea cucumbers with fresh feces which contain beneficial bacteria. Compared with other echinoderms, in holothurians the energy deposited in growth is lower and the energy loss in feces accounts for the majority of the ingested energy. Such detailed information could be helpful in further development of more appropriate diets for culture of holothurians. (c) 2006 Elsevier B.V. All rights reserved.

Bioremediation potential of the macroalga Gracilaria lemaneiformis (Rhodophyta) integrated into fed fish culture in coastal waters of north China

Fed fish farms produce large amounts of wastes, including dissolved inorganic nitrogen and phosphorus. In China, fish mariculture in coastal waters has been increasing since the last decade. However, there is no macroalgae commercially cultivated in north China in warm seasons. To exploit fish-farm nutrients as a resource input, and at the same time to reduce the risk of eutrophication, the high-temperature adapted red alga Gracilaria lemaneiformis (Bory) Dawson from south China was co-cultured with the fish Sebastodes fuscescens in north China in warm seasons. Growth and nutrient removal from fish culture water were investigated in laboratory conditions in order to evaluate the nutrient bioremediation capability of G. lemaneiformis. Feasibility of integrating the seaweed cultivation with the fed fish-cage aquaculture in coastal waters of north China was also investigated in field conditions. Laboratory seaweed/fish co-culture experiments showed that the seaweed was an efficient nutrient pump and could remove most nutrients from the system. Field cultivation trials showed that G. lemaneiformis grew very well in fish farming areas, at maximum growth rate of 11.03% day(-1). Mean C, N, and P contents in dry thalli cultured in Jiaozhou Bay were 28.9 +/- 1.1%, 4.17 +/- 0.11 % and 0.33 +/- 0.01 %, respectively. Mean N and P uptake rates of the thalli were estimated at 10.64 and 0.38 mu mol g(-1) dry weight h(-1), respectively. An extrapolation of the results showed that a 1-ha cultivation of the seaweed in coastal fish fanning waters would give an annual harvest of more than 70 t of fresh G. lemaneiformis, or 9 t dry materials; 2.5 t C would be produced, and simultaneously 0.22 t N and 0.03t P would be sequestered from the seawater by the seaweed. Results indicated that the seaweed is suitable as a good candidate for seaweed/fish integrated mariculture for bioremediation and economic diversification. The integration can benefit economy and environment in a sustainable manner in warm seasons in coastal waters of north China. (c) 2005 Elsevier B.V. All rights reserved.

Seed Germination of Swertia mussotii,an Important Application in Tibetan Folk Medicine

In this study,the effects of temperature,the growth regulator GA3 and storage conditions on seed germination of the biennial Swertia mussotii Franch were compared in seeds from a natural high altitude alpine site and after one-cycle of artificial cultivation at a low altitude.The untreated seeds from high altitude displayed higher germination than those from low altitude.Both GA3 and storage conditions enhanced germination from all sources.After treatment,the final germination of seeds from different sources shows no distinct difference.These results suggest that:(i) all seeds of this species,irrespective of their sources,have similar kinds of dormancy;(ii) the dormancy of this species can not been broken through one-cycle adaptation in ex situ cultivation and thus might be genetically controlled;(iii) both GA3 and 4℃ cold storage are effective for dormancy breaking in ex situ cultivation of this important medicinal species.

Variation of active constituents of an important Tibet folk medicine Swertia mussotii Franch. (Gentianaceae) between artificially cultivated and naturally distributed

Concentrations of seven phytochemical constituents (swertiamarin, mangiferin, swertisin, oleanolic acid, 1,5,8-trihydroxy-3methoxyxanthone, 1,8-dihydroxy-3,7-dimethoxyxanthone and 1,8-dihydroxy-3,5-dimethoxyxanthone) of "ZangYinChen" (Swertia mussotii, a herb used in Tibetan folk medicine) were determined and compared in plants collected from naturally distributed high-altitude populations and counterparts that had been artificially cultivated at low altitudes. Levels of mangiferin, the most abundant active compound in this herb, were significantly lower in cultivated samples and showed a negative correlation with altitude. The other constituents were neither positively nor negatively correlated with cultivation at low altitude. Concentrations of all of the constituents varied substantially with growth stage and were highest at the bud stage in the cultivars, but there were no distinct differences between flowering and fruiting stages in this respect. (c) 2005 Elsevier Ireland Ltd. All rights reserved.