Arginine kinase from Litopenaeus vannamei: Cloning, expression and catalytic properties

Arginine kinase (AK) is a phosphotransferase that plays a critical role in energy metabolism in invertebrates. in this paper, the full-length cDNA of AI( was cloned from shrimp, Litopenaeus vannamei by using RT-PCR and RACE PCR. It was 1446 bp encoding 356 amino acids, and belongs to the conserved phosphagen kinase family. The quantitative real-time reverse transcription PCR analysis revealed a broad expression of AK with the highest expression in the muscle and the lowest in the skin. The expression of AK after challenge with LIPS was tested in hemocytes and muscle, which indicated that the two peak values were 6.2 times (at 3 h) and 10.14 times (at 24 h) in the hemocytes compared with the control values, respectively (P < 0.05), while the highest expression of AK was 41 times (at 24 h) in the muscle compared with the control (P < 0.05). In addition, AK was expressed in Eschetichia coli by prokaryotic expression plasmid pGEX-4T-2. The recombinant protein was expressed as glutathione s-transferase (GST) arginine kinase (GST-AK) fusion protein, which was purified by affinity chromatography using Glutathione Sepharose 4B. After cleavage from GST by using a site-specific protease, the recombinant protein was identified by ESI-MS and showed AK activity. After treatment with 10 mM ATP, the enzyme activity significantly increased. However, the enzyme activity was inhibited by 10 mM alpha-ketoglutarate, 50 mM glucose and 200 mM ATP. This research suggested that AK might play an important role in the coupling of energy production and utilization and the immune response in shrimps. (C) 2009 Elsevier Ltd. All rights reserved.

Molecular coordinated regulation of gene expression during ovarian development in the penaeid shrimp

To understand the molecular events of ovarian development in penaeid shrimp, RNA arbitrarily primed polymerase chain reaction (RAP-PCR) was used to identify differentially expressed genes during ovarian maturation in Metapenaeus ensis. From a screening of 700 clones in a cDNA library of the shrimp ovary by the products of RAP-PCR of different maturation stages, 91 fragments with differentially expressed pattern as revealed by dot-blot hybridization were isolated and sequenced. Forty-two of these fragments show significant sequence similarity to known gene products and the differentially expressed pattern of 10 putative genes were further characterized via Northern hybridization. Putative glyceraldehyde-3-phosphate dehydrogenase and arginine kinase are related to provision of energy for active cellular function in oocyte development. Translationally controlled tumor protein, actin, and keratin are related to the organization of cytoskeleton to accomplish growth and development of oocytes. High mobility group protein DSP1, heat shock protein 70, and nucleoside diphosphate kinase may act as repressors before the onset of ovarian maturation. Peptidyl-prolyl cis-trans isomerase and glutathione peroxidase are related to the stabilization of proteins and oocytes. This study provides new insights on the molecular events in the ovarian development in the shrimp.

栉孔扇贝抗氧化酶基因的克隆与表达分析

扇贝是我国海水养殖的重要品种，但自1994年以来，养殖扇贝陆续爆发的大规模死亡，不但造成了巨大的经济损失，而且直接威胁到现有产业的生存和发展。扇贝病害的不断爆发以及病因的多样性迫切要求制定新的疾病防治措施和开发新型的抗菌物质。因此，深入研究扇贝免疫防御机制，探讨提高机体抗病力的有效途径和方法，改良种质和培育抗病品系，无疑是解决目前困扰扇贝养殖业健康可持续发展的必经之路。 抗氧化酶可以清除活性氧，是维持机体内氧环境平衡，抵抗外界环境影响的重要免疫因子。本研究采用大规模 EST 测序方法和同源克隆的方法，结合 cDNA 末端快速扩增（RACE）技术，从栉孔扇贝中克隆到了超氧化物岐化酶(Superoxide dismutase，SOD)、过氧化氢酶(Catalase，CAT)、谷胱甘肽过氧化物酶（Glutathione peroxidase，GPX）等抗氧化酶基因的全长 cDNA序列，并对其基因结构进行了分析。同时，用实时定量PCR方法对这三个基因在健康扇贝血淋巴细胞、肾、鳃、肌肉、性腺等组织和在分别用鳗弧菌，溶壁微球菌和假丝酵母处理扇贝后不同时间段的表达差异情况进行了研究。 超氧化物歧化酶基因CfSOD的cDNA 全长为1022 bp，其中开放阅读框（Open Reading Frame, ORF）含有 459 bp，编码 153个氨基酸残基，无信号肽，为胞内蛋白。经BLASTP分析发现，CfSOD与其它动物具有较高的同源性。CfSOD中存在两个Cu/Zn-SOD的签名序列；另外Cu结合必须氨基酸(His-45，-47，-62 和-119)和Zn结合必须氨基酸(His-62，-70，-79和Asp-82)在CfSOD中保守。实时定量PCR 检测发现，CfSOD在鳃、血细胞和肾中有较高的表达。在鳗弧菌和溶壁微球菌刺激后，CfSOD的相对表达量逐渐下降，然后分别在32小时和16小时的时候恢复到刺激前的表达水平。在假丝酵母刺激后，CfSOD的mRNA表达没有显著差异。 栉孔扇贝过氧化氢酶基因CfCAT的cDNA全长为3146 bp，其中开放阅读框含有1521bp，编码507个氨基酸残基，无信号肽，为胞内蛋白。经BLASTP分析发现，CfCAT与其它动物具有较高的同源性。 CfCAT中存在过氧化氢酶近端活性位点和过氧化氢酶近端血红素配体签名序列，另外存在两个糖基化位点 NFS和 NFT，同时在CfCAT 的C末端存在过氧化物酶体定位信号AQL，为典型过氧化氢酶。实时定量PCR 检测发现，健康的扇贝中CfCAT在鳃和性腺中有较高的表达。CfCAT基因在鳗弧菌刺后表达升高，在4小时达到最高，约是刺激前表达量的6.8倍（P<0.05），后随着时间的变化而逐渐下降。在8小时表达量达到为刺激前表达量的1.3倍（P<0.05），在16和32小时略高于刺激前的水平。在溶壁微球菌刺激后CfCAT基因表达量也呈上升趋势，在刺激后4小时达到刺激前表达量的约2倍，然后有所下降，在16 小时又上升到刺激前表达量的2.9倍。CfCAT基因在假丝酵母刺激后的表达略有升高，4小时约是刺激前的1.2倍（P<0.05），在其他时间段变化不明显。 栉孔扇贝谷胱甘肽过氧化物酶基因CfGPX的cDNA 全长为1290 bp，其中开放阅读框含有705bp，编码235个氨基酸残基，有一个24核苷酸的信号肽序列。经BLASTP 分析发现，CfSOD与其它动物具有较高的同源性。CfGPX中发现谷胱甘肽过氧化物酶活性位点的签名序列， 另外发现硒半胱氨酸和硒半胱氨酸插入序列，为含硒型谷胱甘肽过氧化物酶。实时定量PCR 检测发现，未经处理的扇贝中CfGPX在性腺、肌肉、血和肾中有较高的表达。CfGPX基因在鳗弧菌刺后表达量快速上升，在6 小时的时候表达量达到最高，为刺激前的4.0倍（P>0.05），后随着时间的变化而逐渐下降。在溶壁微球菌刺激后CfGPX在前6小时表达略有降低，在6小时的时候表达量为刺激前的0.5倍（P<0.05），后随着时间的变化而逐渐升高。在16小时的时候表达量为刺激前的2.1倍（P<0.05）。在假丝酵母刺激后， CfGPX的表达量略有下降在8小时的时候表达量为刺激前的0.8倍（P<0.05）。 实验证明栉孔扇贝的超氧化物歧化酶基因CfSOD，过氧化氢酶基因CfCAT，谷胱甘肽过氧化物酶基因CfGPX基因在机体抵抗外界微生物刺激中起到了重要的作用。

Comparative researches on effects of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate upon Lateolabrax japonicus biomarker system

Fish Lateolabrax japonicus were exposed to anion surfactant sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS) at 1 mg/l, respectively, for 6, 12 and 18 d, with one control group. Liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH) and glutathione S-transferase (GST) were determined; brain acetylcholinesterase (AChE) and liver inducible nitric oxide synthase (NOS) activities were also measured. The results of the study indicated that these parameters made different, sometimes, adverse responses to SDBS and SDS exposure, such as the activity of NOS can be inhibited by SDBS and induced by SDS, the different physico-chemical characteristics of SDBS and SDS should be responsible for their effects on enzyme activities. (c) 2005 Elsevier B.V. All rights reserved.

Effect of alginic acid decomposing bacterium on the growth of Laminaria japonica (Phaeophyceae)

We collected the diseased blades of Laminaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identified as Alterornonas espejiana. This bacterium was applied as the causative pathogen to infect the blades of L. japonica under laboratory conditions. The aim of the present study was to identify the effects of the bacterium on the growth of L. japonica, and to find the possibly effective mechanism. Results showed that: (1) The blades of L. japonica exhibited symptoms of lesion, bleaching and deterioration when infected by the bacterium, and their growth and photosynthesis were dramatically suppressed. At the same time, the reactive oxygen species (ROS) generation enhanced obviously, and the relative membrane permeability increased significantly. The contents of malonaldehyde (MDA) and free fatty acid in the microsomol membrane greatly elevated, but the phospholipid content decreased. Result suggested an obvious peroxidation and deesterrification in the blades of L. japonica when infected by the bacterium. (2) The simultaneous assay on the antioxidant enzyme activities demonstrated that superoxide dismutase (SOD) and catalase (CAT) increased greatly when infected by the bacterium, but glutathione peroxidase (Gpx) and ascorbate peroxidase (APX) did not exhibit active responses to the bacterium throughout the experiment. (3) The histomorphological observations gave a distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population on the blades after infection. The bacterium firstly invaded into the endodermis of L. japonica and gathered around there, and then resulted in the membrane damage, cells corruption and ultimately, the death of L. japonica.

Response of integrated biomarkers of fish (Lateolabrax japonicus) exposed to benzo[a]pyrene and sodium dodecylbenzene sulfonate

Fish Lateolabrax japonicus were exposed to 0.1 and 1 mg/L of anion surfactant sodium dodecylbenzene sulfonate (SDBS) and to 2 and 20 mu g/L of benzo[a]pyrene (B[a]P) for 6, 12, and 18 days, with control and solvent control groups. Liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and glutathione S-transferase (GST), were determined; brain acetyleholinesterase (AChE) and liver inducible nitric oxide synthase (iNOS) activities were also measured. The results indicated that (1) L. japonicus avoided oxidative damage through antioxidant systems; (2) SOD, GPx, and GSH were induced, and GST was inhibited and then induced by B[a]P exposure; and (3) CAT, GPx, and AChE were induced while NOS was inhibited, and GST was induced and then inhibited by SDBS stress in experimental period. (c) 2005 Elsevier Inc. All rights reserved.

The structure of a sulfated galactan from Porphyra haitanensis and its in vivo antioxidant activity

The sulfated galactan fraction F1 isolated from the red seaweed, Porphyra haitanensis, showed typical porphyran structure. It has a linear backbone of alternating 3-linked beta-D-galactosyl units and 4-linked alpha-L-galactosyl 6-sulfate and 3,6-anhydro-alpha-L-galactosyl units. The L-residues are mainly composed of alpha-L-galactosyl 6-sulfate units, and the 3,6-anhydrogalactosyl units are minor. Partial methylation occurred at the C-6 position of the D-galactosyl units and at the C-2 position of the 3,6-anhydro-alpha-L-galactosyl units. Intraperitoneal administration of F1 significantly decreased the lipid peroxidation in aging mice. F1 treatment increased the total antioxidant capacity and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in aging mice. The results indicated that F1 had significant in vivo antioxidant activity. (C) 2003 Elsevier Ltd. All rights reserved.

In vivo antioxidant activity of polysaccharide fraction from Porphyra haitanesis (Rhodephyta) in aging mice

Sulfated polysaccharide fraction F2 from Porphyra haitanesis (Rhodephyta) showed inhibitory effect on the in vitro lipid peroxidation. In the present study, the age-related changes in the antioxidant enzyme activity, lipid peroxidation, and total antioxidant capacity (TAOC) in different organs in mice were investigated and the in vivo antioxidant effect of F2 in aging mice was checked. Increased endogenous lipid peroxidation and decreased TAOC were observed in aging mice. Intraperitoneal administration of F2 significantly decreased the lipid peroxidation in a dose-dependent manner. F2 treatment increased TAOC and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in all the organs tested in aging mice. It is concluded that the sulfated polysaccharide fraction F2 can be used in compensating the decline in TAOC and the activities of antioxidant enzymes and thereby reduces the risks of lipid peroxidation. (C) 2003 Elsevier Science Ltd. All rights reserved.

Purification and characterization of recombinant truncated human interleukin-11 expressed as fusion protein in Escherichia coli

Mature human interleukin-11 (HuIL-11) is a cytokine consisting of 178 amino acid residues that results from scission of the N-terminal signal peptide, consisting of 21 amino acid residaues, from the corresponding nascent polypeptide. A DNA fragment encoding a truncated HuIL-11 (trHuIL-11), with an additional 5 amino acid residues removed from the N-terminus, was cloned into vector pGEX-2T between the BamHI site and the EcoRI site. Upon transformation with Escherichia coli BL21, the construct over-produced a glutathione S-transferase (GST)-fused protein in a soluble form after IPTG induction. The fusion protein was initially fractionated with butyl-Sepharose 4 fast flow column and by affinity chromatography using a GSH-Sepharose 4B column. On-site enzymatic release with thrombin gave the target protein at 96% purity as judged by SDS-PAGE and HPLC. Expression of the interleukin as a GST-fused protein thus greatly improved downstream processing. Subsequent biological activity assay suggested that trHuIL-11 had similar activity profile to the naturally produced sample and may be a promising candidate for further development as biopharmaceutical.