酸脱蛋白-石墨炉原子吸收法快速检测全血中铊

目的建立一种石墨炉原子吸收光谱法快速检测全血中铊的方法。方法血样用基体改进剂稀释后,加入100μl硝酸脱去蛋白,离心分离后取上清液测定血中铊。结果在优化条件下,采用1 g/L Ni(NO3)2-0.2%TritonX-100作为混合基体改进剂,有效消除了基体干扰。用工作曲线法定量,方法线性范围0μg/L^50μg/L(r=0.9999),当进样量20μl时,方法最低检出限为0.64μg/L。在加标水平为10μg/L、20μg/L、40μg/L时,加标平均回收率为97.8%~107.3%,相对标准偏差为1.0%~6.8%。结论血样经酸脱蛋白后可直接用于石墨炉原子吸收光谱法测定,方法简便快速,准确度和精密度好,可以满足急慢性铊中毒者血中铊含量的快速检测,为临床诊断治疗提供参考依据。

酸脱蛋白-混合基体改进剂测定血中镍

建立以酸脱蛋白处理全血,以氯化钯与抗坏血酸为混合基体改进剂,有效消除干扰石墨炉原子吸收光谱法测定血中镍的方法。采用5%硝酸溶液脱去血样中蛋白,离心后取上清液,用二磁场可调塞曼原子吸收光谱仪直接进样测定。分别以氯化钯、磷酸二氢铵、硝酸镁、抗坏血酸作为基体改进剂进行血样分析,优化组合混合基体改进剂。结果显示,利用2 g/L氯化钯与5 g/L抗坏血酸作为混合基体改进剂,使用横向加热平台石墨管能够有效消除血样中背景干扰,线性范围较宽,检出限低,精密度和准确性等方面效果满意。提示,该方法测定简单、实用,用5%硝酸脱去血样中蛋白后直接进样测定,吸收信号不会出现双峰,峰形较为光滑无锯齿状峰形,且石墨管不易积碳。适用于职业性接触和非职业性接触镍的群体测定。

酸脱蛋白法测定血铅标准方法的改进

目的 改进酸脱蛋白法测定血铅的校准方法.方法 以标准曲线法代替工作曲线法进行校准,石墨炉原子吸收光谱法测定全血中的铅含量.结果 该方法改进了校准方法,方法检出限为2μg/L,相对标准偏差为0.66％～4.45％,测定的标准物质误差都在允许范围之内.结论 该校准方法操作简单,免去了复杂的血样处理步骤,且精密度和准确度较好,值得推广.

组蛋白赖氨酸的脱甲基化

组蛋白甲基化修饰调节染色质结构与基因转录,影响细胞分化与个体发育。2004年Shi等鉴定了第一个组蛋白脱甲基酶:赖氨酸特异性脱甲基酶1(lysinespecificdemethylase1,LSD1)。这个发现是“组蛋白密码”学说的重要进展,标志着组蛋白脱甲基化研究的开始。

组蛋白赖氨酸特异性脱甲基酶在大肠杆菌中的重组表达及酶学性质研究

为了探究组蛋白赖氨酸特异性脱甲基酶的酶学性质,克隆并在大肠杆菌BL21(DE3)异源表达了斑马鱼来源的组蛋白赖氨酸脱甲基酶1(histone lysine specific demethylase 1,Lsd1)和咖啡来源的组蛋白赖氨酸脱甲基酶(jumonji C,Jmjc)基因,进一步优化了发酵产酶条件。利用镍柱亲和层析纯化表达产物,考察了重组酶的酶学性质。结果表明,成功构建2个来源的重组大肠杆菌菌株BL21(DE3)/pET28a-lsD1和BL21(DE3)/pET28a-jmjC,在发酵温度25℃、诱导剂异丙基-β-D-硫代半乳糖苷浓度0.1 mmol/L条件下获得了可溶性目的蛋白,并在咪唑浓度分别为100、200 mmol/L的条件下纯化洗脱得到纯酶。纯化的Lsd1、Jmjc最适反应温度分别为35、20℃,最适反应pH分别为7.0、8.0,Lsd1的温度稳定性相对较高,Jmjc的酸碱耐受力更强;在金属离子影响方面,Mn^(2+)对Lsd1和Jmjc的酶活力都有明显的促进作用,Co^(2+)、Mg^(2+)、Ca^(2+)、Zn^(2+)、Ni^(2+)对两者有不同程度的抑制作用;动力学研究发现,需要较长时间才能与底物反应,Lsd1和Jmjc的催化效率较低,k_(cat)/K_(m)分别为8.23×10^(-6)、1.06×10^(-5) L/(mol·s)。研究结果为组蛋白赖氨酸脱甲基酶在非组蛋白的N—CH_(3)类化合物降解和体外抑制剂中的研究提供了基础。

蛋白质精氨酸脱亚胺酶2与4在恶性间皮瘤中的表达及其临床意义

目的探讨恶性间皮瘤(MM)组织中蛋白质精氨酸脱亚胺酶(PAD2和PAD4)的表达及其与瓜氨酸化蛋白的相关性和临床意义。方法回顾性收集2014年至2021年浙江省45例MM病理组织样本,制成组织芯片,利用免疫组织化学法检测癌组织和配对癌旁组织中PAD2与PAD4的表达及其与瓜氨酸化蛋白的相关性,结合生物信息库数据分析其临床意义。结果PAD2和PAD4在癌组织中的表达显著高于癌旁组织(P<0.05)。PAD2和PAD4的蛋白表达在上皮型恶性间皮瘤、腹膜和胸膜部位的MM中呈正相关(P<0.05)。PAD2与PAD4的mRNA转录水平呈正相关(P<0.05)。PAD2、PAD4的表达与瓜氨酸化蛋白分别呈正相关(P<0.05)。PAD2和PAD4高表达组的总生存期(OS)均较低表达组更短,PAD4高表达组的无进展间隔期(PFI)相对于低表达组更长(P<0.05)。结论PAD2和PAD4可能与MM进展和预后有关,具有作为生物标志物或治疗靶点的潜在价值。

NDUFS6蛋白生物信息学分析及过表达质粒的构建与鉴定

目的 应用生物信息学方法分析线粒体呼吸链复合体Ⅰ结构亚基烟酰胺腺嘌呤二核苷酸脱氢酶(泛素)铁硫蛋白6(NDUFS6)的理化性质,构建pCV702-NDUFS6过表达质粒并进行鉴定,为进一步研究NDUFS6蛋白功能奠定基础。方法 利用Expasy、UniProtKB、NCBI、SOPMA等生物信息学工具分析NDUFS6蛋白的理化性质、二级结构等;根据NDUFS6 cDNA序列构建携带NDUFS6基因的过表达质粒pCV702-NDUFS6,转染大鼠心肌细胞H9C2,并设置阴性对照(NC)组和相应空载体CON520作为阳性对照(PC)组,经嘌呤霉素筛选后,采用RT-qPCR和Western blot检测NDUFS6 mRNA和蛋白表达水平。结果 NDUFS6蛋白由116个氨基酸组成,理论等电点pI为9.37。蛋白二级结构以无规则卷曲(占50%)为主。酶切鉴定和基因测序结果显示,pCV702-NDUFS6表达质粒构建成功。RT-qPCR和Western blot结果显示,相较于NC组和PC组,过表达组NDUFS6表达水平均上调(P均<0.05)。结论 成功构建了能在心肌细胞H9C2中有效过表达NDUFS6基因的过表达质粒。

鼻咽癌血清比较蛋白质组学研究

目的采用双向电泳-质谱技术优化肿瘤抗原筛选方法,筛选鼻咽癌肿瘤抗原。方法鼻咽癌转移组、鼻咽癌未转移组和正常对照组血清先采用高丰度蛋白去除、脱盐预处理等以优化双向电泳,图像分析3组血清图谱寻找差异蛋白质点,基质辅助激光解吸电离飞行时间质谱对差异蛋白质点进行鉴定。结果通过调整、优化各个阶段的实验条件,实验结果比较稳定,重复性也比较好,分辨率得到一定的提高。图谱比较所得29个差异蛋白质点,成功鉴定了23种蛋白质。与正常组比较,转铁蛋白、锌指蛋白544、甲状腺激素结合蛋白、NM23-H1蛋白和FAD合成酶在两组鼻咽癌患者中低表达,12-脂氧合酶、血清淀粉样蛋白A1前体、细胞色素P450、sICAM-1、组织蛋白酶G和组蛋白赖氨酸特异性脱甲基酶1等在两组鼻咽癌中均高表达,其中12-脂氧合酶、sICAM-1、组织蛋白酶G和组蛋白赖氨酸特异性脱甲基酶1在鼻咽癌转移组中比未转移组中表达增高,而热休克蛋白70则只在鼻咽癌转移组表达。结论双向电泳-质谱技术可发现鼻咽癌发生发展过程中血清蛋白表达谱质或量的变化,从而为鼻咽癌的早期诊断和治疗奠定基础。

侧链二氧酸脱氢酶复合体E2蛋白关键性氨基酸在原发性胆汁性胆管炎诊断中的意义

目的探究与自身抗体抗线粒体抗体Ⅱ型(AMA-M2)发生反应的侧链二氧酸脱氢酶复合体E2蛋白(BCOADC-E2)关键性氨基酸在原发性胆汁性胆管炎(PBC)诊断中的价值。方法克隆能够表达BCOADC-E2蛋白抗原表位同源目的基因序列BCKD, 与工程质粒pGEX-4T1进行DNA重组, 通过PCR获得15个点突变质粒, 转入原核表达菌株中进行蛋白表达与纯化;ELISA法、蛋白质印迹法鉴定其与PBC患者血清AMA-M2特异性反应程度并进行分析比较, 定位出对BCOADC-E2蛋白和AMA-M2特异性反应有关键影响的氨基酸, 探讨其在PBC诊断中的价值。统计学处理采用单因素方差分析、两两比较采用LSD-t检验。结果共获得14个突变型蛋白、1个野生型蛋白。突变型蛋白pGEX-BCKD-S1A和pGEX-BCKD-C3A与PBC患者血清AMA-M2特异性反应程度均高于野生型蛋白pGEX-BCKD与AMA-M2特异性反应程度;突变型蛋白pGEX-BCKD-S1A(1.634±0.328)和pGEX-BCKD-C3A(1.744±0.345)与PBC患者血清AMA-M2特异性反应程度均高于野生型蛋白pGEX-BCKD(1.000±0.000)与AMA-M2特异性反应程度;突变型蛋白pGEX-BCKD-E4A(0.157±0.067)、pGEX-BCKD-V5A(0.057±0.029)、pGEX-BCKD-Q6A(0.580±0.166)、pGEX-BCKD-S7A(0.744±0.125)、pGEX-BCKD-D8A(0.351±0.135)、pGEX-BCKD-S10A(0.496±0.158)、pGEX-BCKD-V11A(0.149±0.089)、pGEX-BCKD-T12A(0.061±0.043)、pGEX-BCKD-I13A(0.007±0.017)、pGEX-BCKD-T14A(0.198±0.101)、pGEX-BCKD-S15A(0.156±0.087)、pGEX-BCKD-R16A(0.884±0.099)与AMA-M2特异性反应程度均低于野生型蛋白pGEX-BCKD(1.000±0.000)与AMA-M2特异性反应蛋白。结论 BCOADC-E2蛋白的1号和3号位半胱氨酸是提高蛋白BCOADC-E2与PBC患者血清AMA-M2特异性反应关键性氨基酸;4、5、6、7、8、10、11、12、13、14、15、16号位氨基酸被丙氨酸代替后形成突变型蛋白会降低其与AMA-M2特异性反应程度;5号位和13号位氨基酸是影响蛋白BCOADC-E2与AMA-M2特异性反应关键性氨基酸, 对BCOADC-E2蛋白功能有着重要影响, 对BCOADC-E2关键性氨基酸进行深入研究对PBC诊治有重要意义。

石墨炉原子吸收法测定全血标本铅含量的3种前处理方法

目的比较石墨炉原子吸收法测定全血标本中铅的3种前处理方法优劣,从中筛选一种更简便、准确、灵敏的方法,从而达到提高检测质量,降低工作强度的目的。方法采用酸脱蛋白法、混合基体改进剂法、微波消解法对无铅接触史的健康成年人全血标本进行前处理,分别用石墨炉原子吸收法检测,对检测结果进行统计分析,比较标准曲线线性、相关系数（r）、相对标准偏差（RSD%）、准确度等指标。结果 3种方法标准曲线r分别为0.996 5、0.994 2、0.999 5;检出限分别为5.4、3.6、2.7μg/L;RSD%分别为4.1、4.5、2.8;回收率分别为95.7%～103.3%、98.7%～104.5%、98.3%～102.3%。结论微波消解处理全血标本各项指标均令人满意,是测量血铅较好的前处理方法。

In Vivo Tissue-dependent Abscisic Acid Specific-binding Proteins with High Affinity in Cytosol of Developing Apple Fruits

The in vivo highly tissue-dependent abscisic acid (ABA) specific-binding sites localized in cytosol were identified and characterized in the flesh of developing apple ( Malus pumila L. cv. Starkrimon) fruits. ABA binding activity was scarcely detectable in the microsomes and the cytosolic fraction isolated from the freshly harvested fruits via an in vitro ABA binding incubation of the subcellular fractions. If, however, instead that the subcellular fractions were in vitro incubated in H-3-ABA binding medium, the flesh tissue discs were directly in vivo incubated in H-3-ABA binding medium, a high ABA binding activity to the cytosolic fraction isolated from these tissue discs was detected. The in vivo ABA binding capacity of the cytosolic fraction was lost if the tissue discs had been pretreated with boiling water, indicating that the ABA binding needs a living state of tissue. The in vivo tissue-dependent binding sites were shown to possess protein nature with both active serine residua and thiol-group of cysteine residua in their functional binding center. The ABA binding of the in vivo tissue-dependent ABA binding sites to the cytosolic fraction was shown to be saturable, reversible, and of high affinity. The scatchard plotting gave evidence of two different classes of ABA binding proteins, one with a higher affinity ( Kd = 2.9 nmol/L) and the other with lower affinity ( Kd = 71.4 nmol/L). Phaseic acid, 2-trans-4-trans-ABA or cis-trans-(-)-ABA had substantially no affinity to the binding proteins, indicating their stereo-specificity to bind physiologically active ABA. The time course, pH- and temperature-dependence of the in vivo tissue-dependent binding proteins were determined. It is hypothesized that the detected ABA-binding proteins may be putative ABA-receptors that mediate ABA signals during fruit development.

氧化苦参碱对缺氧缺血性脑损伤新生大鼠脑组织Casepase-3、Bcl-2及Bax表达的影响

目的观察氧化苦参碱(OMT)对缺氧缺血性脑损伤(HIBD)新生大鼠的保护作用及对Caspase-3、Bax、Bcl-2蛋白表达的影响。方法清洁级新生7 d龄SD大鼠72只,随机分为假手术组、模型组、OMT 120 mg/kg治疗组。后2组采用经典Rice法制作HIBD动物模型,假手术组未给予缺氧处理及左侧颈总动脉结扎。模型组和假手术组在造模完成后,即刻开始腹腔注射无菌注射用水,剂量为10 m L/kg,每12 h 1次。OMT治疗组在造模完成后,即刻开始腹腔注射OMT 120 mg/kg,每12 h 1次,共注射4次。末次注射后12 h断头取材,用HE染色方法观察脑组织病理变化,采用免疫荧光及Western blot检测损伤侧脑组织内凋亡相关基因Caspase-3、Bax、Bcl-2蛋白表达情况。结果 HE染色结果表明假手术组大鼠皮层及海马CA3区锥体神经元结构完整、排列紧凑;与假手术组比较,模型组神经元边界不清、排列紊乱、组织疏松、基质不完整,OMT治疗组可以改善HIBD新生大鼠脑组织神经元的异常形态变化。免疫荧光显示假手术组脑组织中Caspase-3、Bax荧光细胞数目少、荧光强度低,Bcl-2阳性细胞较多、荧光明显;模型组Caspase-3、Bax阳性细胞数增加、荧光增强,Bcl-2阳性细胞数减少、荧光减弱,OMT治疗组显著逆转上述改变。Western blot显示模型组脑组织中Caspase-3、Bax蛋白表达增强(P<0.05),Bcl-2蛋白表达减少(P<0.05);与模型组比较,OMT治疗组Caspase-3、Bax蛋白表达减少(P<0.05),Bcl-2蛋白表达增加(P<0.05)。结论 OMT可能是通过上调Bcl-2表达,抑制Caspase-3、Bax表达,减轻缺氧缺血引起的神经元凋亡,从而对HIBD新生大鼠发挥保护作用。

Effects of Used Battery on Key Enzyme Activity during the Germination of Wheat Seeds

[Objective] This study aimed to explore the effects of used battery lixivium on wheat germination. [Method] The wheat seeds were treated with used battery lix- ivium at different concentrations to detect the change of activities of amylase, pro- tease, pyruvate dehydrogenase （PDH） and polyphenol oxidase （PPO） during the ger- mination period. [Result] The results showed that the used battery affected enzyme activity. With the increase of concentration of used battery lixivium, trends of the changes of amylase and protease activities were not different. The activities were en- hanced at low concentrations of lixivium, while were inhibited at high concentrations. The tends of changes of pyruvate dehydrogenase （PDH） and polyphenol oxidase （PPO） activities were not consistent with that of either amylase or protease, which showed continuous downward trends with the increasing concentration of used battery lixivium. [Conclusion] This study is of great practical significance for understanding the effects of used battery lixivium on the germination of wheat seeds.

Ornithine decarboxylase, mitogen-activated protein kinase and matrix metalloproteinase-2 expressions in human colon tumors

AIM: To investigate the expressions of omithine decarboxylase (ODC), MMP-2, and Erk, and their relationship in human colon tumors.METHODS: ODC activity, MMP-2 expression, and mitogenactivated protein (MAP) kinase activity (Erk phosphorylation) were determined in 58 surgically removed human colon tumors and their adjacent normal tissues, using [1-14C]-ornithine as a substrate, ELISA assay, and Western blotting, respectively.RESULTS: ODC activity, MMP-2 expression, and Erk phosphorylation were significantly elevated in colon tumors, compared to those in adjacent normal tissues. A significant correlation was observed between ODC activities and MMP-2 levels.CONCLUSION: This is the first report showing a significant correlation between ODC activities and MMP-2 levels in human colon tumors. As MMP-2 is involved in cancer invasion and metastasis, and colon cancer overexpresses ODC, suppression of ODC expression may be a rational approach to treat colon cancer which overexpresses ODC.

DIETARY PHOSPHORUS REQUIREMENT OF YOUNG ABALONE, HALIOTIS DISCUS HANNAI INO.

An experiment was performed to determine the dietary phosphorus requirement of the young abalone, Haliotis discus hannai. Five semi-purified diets were formulated to provide a series of graded levels of dietary total phosphorus (0.23%-1.98) from monobasic potassium phosphate (KH2PO4). The brown alga, Laminaria japonica, was used as a control diet. Similar size abalone were distributed in a single-pass, flow-through system using a completely randomized design with six treatments and three replicates each treatment. The abalone were hand-fed to satiation with appropriate diets in excess, once daily at 17:00. The feeding trial was run for 120-d. Survival rate and soft-body to shell ratio (SB/S) were constantly maintained regardless of dietary treatment. However, the weight gain rate (WGR), daily increment in shell length (DISL), muscle RNA to DNA ratio (RNA/DNA), carcass levels of lipid and protein, soft-body alkaline phosphatase (SBAKP), and phosphorus concentrations of whole body (WB) and soft body (SB) were significantly (ANOVA, P<0.05) affected by the dietary phosphorus level. The dietary phosphorus requirements of the abalone were evaluated from the WGR, DISL, and RNA/DNA ratio respectively, by using second-order polynomial regression analysis. Based on these criteria, about 1.0%-1.2% total dietary phosphorus, i.e. 0.9%-1.1% dietary available phosphorus is recommended for the maximum growth of the abalone.

Elicitation of strong immune responses by a DNA vaccine expressing a secreted form of hepatitis C virus envelope protein E2 in murine and porcine animal models

AIM： To characterize the immunogenicity of a hepatitis C virus （HCV） E2 DNA vaccine alone or with a protein vaccine boost in murine and porcine animal models. METHODS： A DNA vaccine expressing a secreted form of HCV E2 protein was constructed and used to vaccinate mice and piglets with or without boosting with a recombinant E2 protein vaccine formulated with CpG ODN and 10% Emulsigen. The immunogenicity of HCV E2 vaccines was analyzed by ELISA for antibody responses, MTT assay for lymphocyte proliferation, ELISPOT for the number of interferon-γ secreting cells, and cytotoxic T lymphocyte assays. RESULTS： Intradermal injection of E2 DNA vaccine induced strong Th1-1ike immune responses in mice. In piglets, E2 DNA vaccine elicited moderate and more balanced immune responses. A DNA vaccine prime and protein boost vaccination strategy induced significantly higher E2-specific antibody levels and shifted the immune response towards Th2-1ike ones in piglets. CONCLUSION： A DNA vaccine expressing a secreted form of HCV E2 protein elicited E2-specific immune responses in mice and piglets. Recombinant E2 protein vaccination following DNA immunization significantly increased the antibody response in piglets. These HCV E2 vaccines may represent promising hepatitis C vaccine candidates for further investigations.

Low temperature stress on the hematological parameters and HSP gene expression in the turbot Scophthalmus maximus

To study the effect of low temperature stress on hematological parameters and HSP gene expression in the turbot （Seophthalmus maximus）, water temperature was lowered rapidly from 18 to 1℃. During the cooling process, three individuals were removed from culture tanks at 18, 13, 8, 5, 3, and 1℃. Blood samples and tissues were taken from each individual, hematological indices and HSP gene expression in tissues were measured. The red blood cell count, white blood cell count, and hemoglobin concentration decreased significantly （P〈0.05） as temperature decreased. Enzyme activities of plasma alanine transaminase and creatine kinase increased as temperature decreased, whereas aspartic transaminase and γ-glutamyl transpeptidase activities displayed no obvious changes above 1℃ and lactate dehydrogenase activity increased first and then decreased. Blood urea nitrogen and uric acid levels were highest at 8℃, and creatinine concentration was highest at 3℃. The concentrations of plasma cortisol, cholesterol, and triglyceride all increased significantly （P〈0.05） as temperature decreased. The serum glucose concentration increased first and then decreased to the initial level. The HSP70 mRNA expression showed various patterns in different tissues, whereas HSP90 mRNA expression showed the same tendency in all tissues. Overall, these results indicate that temperature decreases in the range of 8 to 5℃ may induce a stress response in S. maximus and that temperature should be kept above 8℃ in the aquaculture setting to avoid damage to the fish.

A novel protein-DNA interaction involved with the CpG dinucleotide at -30 upstream is linked to the DNA methylation mediated transcription silencing of the MAGE-A1 gene

To understand the DNA-methylation mediated gene silencing mechanisms, we analyzed in cell culture of the promoter function of the MAGE-A1 gene, which is frequently demethylated and over-expressed in human hepatocellular carcinoma. We have established the correlation of the DNA methylation of the promoter CpG island with expression status of this gene in a panel of the established liver cancer cell lines. The crucial CpG dinucleotide(s) within the minimal promoter subjected to the control mediated by DNA methylation with profound biological functions was also delineated.Furthermore, a novel sequence-specific DNA-protein interaction at the -30 CpG dinucleotide upstream of the gene was found having a vital part to play in the DNA methylation mediated transcription silencing of the MAGE-A1 gene. Our results would not only provide new insights into the DNA methylation mediated mechanisms over transcription of the MAGE-A1 gene, but also pave the way for further defining the cross-talk among DNA methylation, histone modification and chromatin remodeling in detail.

Glutamate dehydrogenase and Na^+-K^+ ATPase expression and growth response of Litopenaeus vannamei to different salinities and dietary protein levels

Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture.The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp(L.vannamei) were investigated.This involved an examination of growth performance,glutamate dehydrogenase(GDH) and Na+-K+ ATPase mRNA expression,,and GDH activity in muscles and gills.Three experimental diets were formulated,containing 25%,40%,and 50% dietary protein,and fed to the shrimp at a salinity of 25.After 20 days,no significant difference was observed in weight gain,though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels.Subsequently,shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5,respectively,and sampled at weeks 1 and 2.Shrimp fed with 40% protein at 25 in salinity(optimal conditions) were used as a control.Regardless of the salinities,shrimp fed with 50% dietary protein had significantly higher growth performance than other diets;no significant differences were found in comparison with the control.Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks.Ambient salinity change also stimulated the hepatosomatic index,which increased in the first week and then recovered to a relatively normal level,as in the control,after 2 weeks.These findings indicate that in white shrimp,the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism.Increased dietary protein level could improve the osmoregulation capacity of L.vannamei with more energy resources allocated to GDH activity and expression.

Kinetics of Desolvation of the Glycation of Hemoglobin Catalyzed by Buffer Phosphate and Arsenate

The glycation of hemoglobin is catalyzed by buffer phosphate and arsenate. The catalytic constant （kB） for aqueous arsenate is two-fold larger than for aqueous phosphate. The catalytic constant （ks） of phosphate in sorbitol mixtures increase from （1.67 ± 0.11） × 10-10 s-1·M-1 to （5.78 ± 0.39） × 10-10 s-1·M-1 and the catalytic constant is enhanced 3.5 times, relative to that in water; the catalytic constant （kB） of arsenate in sorbitol mixtures increase from （2.98±0.07）× 10-10 s-1·M-1 to （6.62 ± 0.53） × 10-10 s-1·M-1 and the catalytic constant is enhanced 2 times, relative to that in water. The spontaneous rate constants are independent of sorbitol concentration for phosphate and arsenate. The catalytic power of phosphate and arsenate in sorbitol are the same. Desolvation of strongly hydrated species such as HPO42 and HAsO42 should make a contribution to the energy cost of the formation of anion-hemoglobin complexes and can be a possible explanation for higher catalytic potential of HAsO42 in water. The same catalytic constant （ksB） for phosphate and arsenate in sorbitol indicates that the same catalyst base group on the hemoglobin molecule may be involved in the abstraction of proton in the Amadori rearrangement.