金属离子在液相氧化中的催化作用——Ⅷ.在丙酸氧化反应中Mn(Ⅲ)-Co(Ⅲ)催化体系不同离子的功能

本文仔细地研究了Mn(Ⅲ)-Co(Ⅲ)催化体系中不同离子在丙酸氧化中的功能:Mn(Ⅲ)离子首先与丙酸作用并被还原成Mn(Ⅱ)离子;Co(Ⅲ)离子可在反应体系中将Mn(Ⅱ)再氧化,而还原了的Co(Ⅱ)离子可为氧再生.这样建立起的氧化还原体系形成了催化循环.

Characterization of amphioxus GDF8/11 gene, an archetype of vertebrate MSTN and GDF11

MSTN, also known as growth and differentiation factor 8 (GDF8), and GDF11 are members of the transforming growth factor-beta (TGF-beta) subfamily. They have been thought to be derived from one ancestral gene. In the present study, we report the isolation and characterization of an invertebrate GDF8/11 homolog from the amphioxus (Branchiostoma belcheri tsingtauense). The amphioxus GDF8/11 gene consists of five exons flanked by four introns, which have two more exons and introns than that of other species. In intron III, a possible transposable element was identified. This suggested that this intron might be derived from transposon. The amphioxus GDF8/11 cDNA encodes a polypeptide of 419 amino acid residues. Phologenetic analysis shows that the GDF8/11 is at the base of vertebrate MSTNs and GDF11s. This result might prove that the GDF8/11 derived from one ancestral gene and the amphioxus GDF8/11 may be the common ancestral gene, and also the gene duplication event generating MSTN and GDF11 occurred before the divergence of vertebrates and after or at the divergence of amphioxus from vertebrates. Reverse transcriptase polymerase chain reaction results showed that the GDF8/11 gene was expressed in new fertilized cell, early gastrulation, and knife-shaped embryo, which was different from that in mammals. It suggested that the GDF8/11 gene might possess additional functions other than regulating muscle growth in amphioxus.

cDNA cloning and mRNA expression of a selenium-dependent glutathione peroxidase from Zhikong scallop Chlamys farreri

The glutathione peroxidases are essential enzymes of the cellular antioxidant defence system. In the present study, the full-length cDNA sequence encoding an extracellular glutathione peroxidase (designated CfGPx3) was isolated from Zhikong scallop Chlamys farreri. The complete cDNA was of 1194 bp, containing a 5' untranslated region (UTR) of 50 bp, a 3' UTR of 490 bp and an open reading frame (ORF) of 654 bp encoding a polypeptide of 217 amino acids. CfGPx3 possessed all the conserved features critical for the fundamental structure and function of glutathione peroxidase, such as the selenocysteine encoded by stop codon UGA, the GPx signature motif ((96)LGVPCNQFI(103)) and the active site motif ((WNFEKF184)-W-179). The high similarity of CfGPx3 with GPx from other organisms indicated that CfGPx3 should be a new member of the glutathione peroxidase family. By fluorescent quantitative real-time PCR, the CfGPx3 mRNA was universally detected in the tissues of haemocytes, gill, gonad, muscle and hepatopancreas with the highest expression in hepatopancreas. After scallops were challenged by Listonella anguillarum, the expression level of CfGPx3 transcript in haemocytes was significantly up-regulated (P<0.05) at 8 h post challenge. These results suggested that CfGPx3 was potentially involved in the immune response of scallops and perhaps contributed to the protective effects against oxidative stress. (C) 2010 Elsevier Inc. All rights reserved.

Dominant chloramphenicol-resistant bacteria and resistance genes in coastal marine waters of Jiaozhou Bay, China

Studies of abundance, diversity and distribution of antibiotic-resistant bacteria and their resistance determinants are necessary for effective prevention and control of antibiotic resistance and its dissemination, critically important for public health and environment management. In order to gain an understanding of the persistence of resistance in the absence of a specific antibiotic selective pressure, microbiological surveys were carried out to investigate chloramphenicol-resistant bacteria and the chloramphenicol acetyltransferase resistance genes in Jiaozhou Bay after chloramphenicol was banned since 1999 in China. About 0.15-6.70% cultivable bacteria were chloramphenicol resistant, and the highest abundances occurred mainly in the areas near river mouths or sewage processing plants. For the dominant resistant isolates, 14 genera and 25 species were identified, mostly being indigenous estuarine or marine bacteria. Antibiotic-resistant potential human or marine animal pathogens, such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Shewanella algae, were also identified. For the molecular resistance determinants, the cat I and cat III genes could be detected in some of the resistant strains, and they might have the same origins as those from clinical strains as determined via gene sequence analysis. Further investigation about the biological, environmental and anthropogenic mechanisms and their interactions that may contribute to the persistence of antibiotic-resistance in coastal marine waters in the absence of specific antibiotic selective pressure is necessary for tackling this complicated environmental issue.

六种重组别藻蓝蛋白的抗氧化活性研究

藻胆蛋白（ phycobiliprotein ）是某些藻类中一类重要的捕光色素蛋白，由脱辅基蛋白（ apoprotein ）和四吡咯结构的藻胆素（ phycocyanobilin ）共价结合组成，具有抗氧化和抗肿瘤等多种生物活性。本实验室利用两种载体pMAL-p2X和pET28a对APC及其亚基分别进行重组表达，产生了MBP-APC、MBP-αAPC（Mα）、MBP-βAPC（Mβ）、6×His-αAPC（Hα）、6×His-βAPC（Hβ）和6×His-APC（HAPC）六种重组别藻蓝蛋白。本研究将表达产物和天然APC一起进行抗氧化活性研究，以期筛选出分子量更小、活性更强的组分。 本研究通过以下模型比较了六种重组别藻蓝蛋白和天然别藻蓝蛋白在体外不同抗氧化模型中的活性氧清除作用： 1. 通过比较对体外纯化学体系产生的羟自由基的清除作用，发现MBP系列的重组别藻蓝蛋白组分对体外化学体系产生的羟自由基均有一定的清除能力，清除活性大小依次为：MαAPC、rAPC、MβAPC、HβAPC、HαAPC、HAPC、Native APC。 2. 通过比较对体外纯化学体系产生的氢过氧自由基的清除作用，发现带有MBP标签的重组别藻蓝蛋白组分除MβAPC 有很低的抗氧化活性外，MαAPC和rAPC均无明显的抗氧化活性；而带有His标签的HβAPC和HAPC均高于天然APC，且随着浓度的提高，清除能力随之提高，呈现良好的量效关系。 3. 通过比较对体外纯化学体系产生的超氧阴离子自由基的清除作用，发现除MβAPC和MαAPC外，不同浓度的天然及重组别藻蓝蛋白组分对超氧阴离子自由基均有一定程度的清除作用，且随着浓度的增加清除率随之增加。其中，rAPC和HβAPC对超氧阴离子自由基的清除效果最强，IC50值分别达到36.98和42.27μg/mL。 4. 通过比较对O2-损伤红细胞膜的保护作用发现，天然及6种重组别藻蓝蛋白及其亚基对O2-损伤红细胞膜的作用均无显著的抑制作用。 5. 通过比较对•OH诱导的脂质过氧化的保护作用发现，，在100~500μg/mL的剂量范围内， rAPC和HβAPC有显著的抑制脂质过氧化的作用，IC50值分别为230.50和217.35μg/mL；HAPC 和Native APC有弱抑制作用；而MαAPC、MβAPC和HαAPC则无明显抑制脂质过氧化的作用。 我们又对其中各组分在不同体系中的抗氧化效果进行比较后发现：不同的抗氧化体系中，各种重组别藻蓝蛋白组分的抗氧化活性虽然各不相同，但带有His标签的重组别藻蓝蛋白组分明显高于带有MBP标签的重组别藻蓝蛋白组分；其中，HβAPC对体外羟自由基、氢过氧自由基、超氧阴离子自由基以及生物互作产生的•OH均有较强的清除作用，有望开发成为新一代抗氧化剂。 本研究筛选出了具有高效抗氧化活性的新型重组别藻蓝蛋白HβAPC（海普克），分子量小，且抗氧化活性比雷普克显著，这为进一步探讨雷普克和海普克的抗肿瘤作用机理提供了资料。

四种海藻热休克蛋白70（HSP70）基因的克隆与表达分析

热休克蛋白70是热休克蛋白家族中重要的成员，参与新生蛋白的折叠、转运、重折叠变性蛋白、协助降解变性蛋白和抗逆环境胁迫等功能。海带和裙带菜是浅海潮下带典型的褐藻，孔石莼和浒苔是潮间带典型的绿藻，四种大型海藻均有重要的经济价值和生态价值。随着潮汐变化固着藻类生境理化因素变化剧烈，藻类面临着严重的环境胁迫，因此研究藻类抗逆机理有着重要的意义。 本研究采用同源克隆法配合RACE-PCR，克隆了海带、孔石莼、裙带菜和浒苔HSP70基因的全序列（分别命名为LJHSP70、UPHSP70、QDHSP70和EPHSP70）。利用生物信息学方法分析了四种藻类HSP70结构特征、同源性关系和进化地位。获得的海带HSP70基因全序列长为2918 bp，5’非翻译区为248 bp，3’非翻译区为696 bp，开放阅读框为1974 bp，编码657个氨基酸，预测的分子量为72.03 kDa，等电点为4.97。获得的裙带菜HSP70基因全序列长为3243 bp，5’非翻译区为248 bp，3’非翻译区为1021 bp，开放阅读框为1974 bp，编码657个氨基酸，预测的分子量为72.03 kDa，等电点为4.96。获得的孔石莼HSP70基因全序列长为2283 bp，5’非翻译区为65 bp，3’非翻译区为247 bp，开放阅读框为1971 bp，编码656个氨基酸，预测的分子量为71.13 kDa，等电点为5.04。获得的浒苔HSP70基因全序列长为2265 bp，5’非翻译区为65 bp，3’非翻译区为217 bp，开放阅读框为1983 bp，编码660个氨基酸，预测的分子量为71.39 kDa，等电点为5.03。四种海藻HSP70氨基酸序列均含有四肽重复序列GGMP，具有三个典型的HSP70签名基序。细胞质定位的HSP70 C-末端特征基序为EEID或EEVD，并且N-端氨基酸序列保守性高于C-端。海带和裙带菜HSP70蛋白同源性为98%，孔石莼和浒苔HSP70蛋白同源性为96%，四种海藻HSP70蛋白序列与陆地植物和其他藻类HSP70蛋白序列同源性为70-80%。 利用荧光定量RT-PCR技术对不同胁迫条件处理的海带和孔石莼HSP70 mRNA的表达水平进行定量分析。不同热激温度（5-40 ℃）处理组中，30 ℃处理组的海带HSP70 mRNA表达量最高是10 ℃处理组的海带HSP70 mRNA表达量的3倍，而35 ℃或40 ℃处理组的海带HSP70表达量却低于25 ℃或30 ℃处理组的海带HSP70 mRNA表达量。25 ℃不同热激时间（0-12 h）处理组中，海带HSP70 mRNA表达量呈先上升后下降趋势。热激1 h后海带HSP70 mRNA表达量迅速上升，热激7 h后mRNA表达量达到最大，是对照组表达量的4倍。不同盐度（0‰-45‰）胁迫处理组中，0‰或5‰盐度处理组的海带HSP70 mRNA表达量是30‰盐度处理组海带HSP70 mRNA表达量的3倍。35‰、40‰和45‰盐度处理组之间HSP70 mRNA表达量较低且无显著差异。 不同热激温度（5-40℃）处理组中，20 ℃或25 ℃处理的孔石莼HSP70 mRNA表达量较低，而5 ℃、35 ℃、或40 ℃处理组的孔石莼HSP70 mRNA的表达量是25 ℃处理组孔石莼HSP70 mRNA表达量的2倍以上。30 ℃不同热激时间（0-12 h）处理组中，孔石莼HSP70 mRNA表达量也呈先上升后下降趋势。热激5 h后孔石莼HSP70 mRNA表达量达到最大，是对照组的3.5倍。不同盐度（0‰-45‰）胁迫处理组中，0‰或5‰盐度处理组的孔石莼HSP70 mRNA表达量是30‰盐度处理组孔石莼HSP70表达量的3倍。30‰、40‰和45‰盐度处理组孔石莼HSP70 mRNA表达量较低，且无显著差异。不同紫外线照射时间（0-4.0 h）和不同干燥时间（0-4.0 h）处理组中，孔石莼HSP70 mRNA表达量都在3 h后达到最高值，之后表达量维持在较高水平。 为进一步研究藻类HSP70的生物学功能，将海带HSP70基因的开放阅读框区域克隆到表达载体pEASY-E2中，并转化到大肠杆菌BL21(DE3)pLysS。将阳性重组子培养于含有AMP（100 U/mL）的LB培养基，IPTG诱导表达，SDS-PAGE电泳鉴定。经5 h诱导，其表达量达到平台期，继续培养HSP70表达量并不显著增高。5 mM IPTG诱导海带HSP70蛋白表达量高于1 mM IPTG诱导蛋白表达量。

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.

Behavioral responses of tilapia (Oreochromis niloticus) to acute fluctuations in dissolved oxygen levels as monitored by computer vision

Behavioral and ventilatory parameters have the possibility of predicting the stress state of fish in vivo and in situ. This paper presents a new image-processing algorithm for quantifying the average swimming speed of a fish school in an aquarium. This method is based on the alteration in projected area caused by the movement of individual fish during frame sequences captured at given time intervals. The image enhancement method increases the contrast between fish and background, and is thus suitable for use in turbid aquaculture water. Behavioral parameters (swimming activity and distribution parameters) and changes in ventilation frequency (VF) of tilapia (Oreochromis niloticus) responded to acute fluctuations in dissolved oxygen (DO) which were monitored continuously in the course of normoxia, falling DO level, maintenance of hypoxia (three levels of 1.5, 0.8 and 0.3 mg l(-1)) and subsequent recovery to normoxia. These parameters responded sensitively to acute variations in DO level; they displayed significant changes (P < 0.05) during severe hypoxia (0.8 and 0.3 mg l(-1) level) compared with normoxic condition, but there was no significant difference under conditions of mild hypoxia (1.5 mg l(-1) level). There was no significant difference in VF between two levels of severe hypoxia 0.8 and 0.3 mg l(-1) level during the low DO condition. The activity and distribution parameters displayed distinguishable differences between the 0.8 and 0.3 mg l(-1) levels. The behavioral parameters are thus capable of distinguishing between different degrees of severe hypoxia, though there were relatively large fluctuations. (c) 2006 Elsevier B.V. All rights reserved.

Divergent selection and realized heritability for growth in the Japanese scallop, Patinopecten yessoensis Jay

In order to improve the production and accurately estimate response to selection, divergent selection for growth in shell height was conducted in a cultured population of the Japanese scallop Patinopecten yessoensis. Applying the same selection intensity +/- 1.756 in upward and downward directions, three groups including two selected groups of Fast and Slow and one non-selected Control group were created, which were reared under the same environmental conditions at any stage. Differences always significantly existed among the three groups (P < 0.05), except for larvae at day 1 and at day 5, and in the order of Fast > Control > Slow. The average standardized response to selection (SR), realized heritability (h(R)2) and genetic gain (GG) was 0.473%, 0.269% and 7.85% for the Fast group and 0.381%, 0.217% and 6.60% for the Slow group respectively. Moreover, significant differences (P < 0.05) were detected between the fast and the slow lines in both SR and h(R)2, providing evidence for an asymmetric response in two directions. Performance in shell height is improved by 7.85% in the fast line after one generation selection, suggesting that mass selection for faster growth in a cultured population of the Japanese scallop is effective.

The influence of the cationic of quaternized chitosan on antifungal activity

Quatemized chitosan: N-(2-hydroxyl-phenyl)-NN-dimethyl chitosan (NHPDCS), N-(5-chloro-2-hydroxyl-phenyl)-NN-dimethyl chitosan (NCHPDCS), N-(2-hydroxyl-5-nitro-phenyl)-NN-dimethyl chitosan (NHNPDCS) and N-(5-bromic-2-hydroxyl-phenyl)-NN-dimethyI chitosan (NBHPDCS) were synthesized and their antifungal activities against Botrytis cinerea Pers. (B. cinerea Pers.) and Colletotrichum lagenarium (Pass) Ell.et halst (C. lagenarium (Pass) Ellet halst) were investigated. The results indicated that the quaternized chitosan derivatives had better inhibitory effects than chitosan, and the antifungal activities should be affected by the cation in these compounds. (C) 2007 Elsevier B.V. All rights reserved.

青海湖区东部沙地植被及其特征研究

根据野外样地调查资料,对青海湖区东部沙地植被从区系特征及其物种多样性进行了研究,结果表明:①青海湖东部沙地植被种类组成简单,共有27科58属71种.其中禾本科比重最高为22.535%,其次为菊科占12.676%;再次为豆科占9.8592%;桔梗科等14科比重较小均占1.4085%.②地理成分上,湖东沙地植物区系以世界分布为主,共有16科,湖区植物区系中的优势科均为世界广布科;其次是温带成分10科;热带亚热带成分仅有1科.③生活型以多年生地面芽植物和地下芽植物为主,两者种类系数之和达到76.06%,一年生植物所占种类比重最小.④湖东沙地植被群丛多以单一优势种为主,物种多样性指数H、丰富度指数R1和均匀度指数Jsw三者的变化趋势大致是一致的,即随物种的增多,他们的指数趋向增大;生态优势度C的变化趋势则正好相反.⑤湖东沙地群丛物种相似性差异较大.固定沙地之间植被群丛相似性较高,流动半流动沙地与流动沙地之间则较低.

土地利用变化对高寒草甸土壤有机质更新的影响

对青藏高原海北站区的自然土壤和扰动土壤进行高分辨率采样,测定土壤根系、有机碳及其~(14)C含量;用~(14)C示踪技术探讨土地利用变化对高寒草甸土壤有机质更新的影响.研究表明,土地利用变化对高寒草甸土壤碳循环影响显著. 耕作活动导致扰动土壤有机碳储量比自然土壤增加29.35%;扰动土壤剖面10～50 cm深土壤有机质的14C含量相对富集;自然土壤大多数有机碳储存在土壤表层,更新时间＜50 a,同一深度扰动土壤有机碳储量显著少,更新时间长(171～294 a);自然土壤10 cm以下有机碳主要为更新时间＞1 000 a的稳定碳所控制,扰动土壤的相应值出现在40 cm以下;自然土壤有机质更新产生的CO2通量为114 gC•m~(-2)•a~(-1),扰动土壤为48.7 gC•m~(-2)•a~(-1).

三种高寒草甸植被分布及与湍流交换通量关系的比较

对海北定位站分布的金露梅灌丛草甸、矮嵩草草甸、藏嵩草沼泽化草甸3种高寒植被类型群落结构、感热(H)和潜热(LE)通量比较观测表明,3种植被类型年地上净初级生产力表现出矮嵩草草甸(318.600 g/m~2)＞藏嵩草沼泽化草甸(258.341 g/m~2)＞金露梅灌丛草甸(217.6 g/m~2).植物种类组成有矮嵩草草甸(54种)＞金露梅灌丛草甸(47种)＞沼泽草甸(24种).3种植被类型区近地表大气能量交换过程中,LE和H的月际变化明显,而且随植被类型的不同月际变化差异显著.3种不同植被类型在年内均表现出H+L E＞0,表明在青海海北高寒草甸地区,太阳辐射强烈,近地层湍流输送明显,地表为-热源.3类型高寒草甸植被的年地上净生产量基本与波文比(β)呈现正效应,与LE+H呈现明显的反效应.植物种类组成基本与LE+H有反效应,与β呈明显的正效应.

柴达木盆地唐古特白刺籽油的安全性与降血脂作用

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