文蛤糖肽MGP0501的分离纯化及性质鉴定

文蛤粗提液经超滤、层析等纯化得到分子量为15.878×103、纯度为96.42%、糖和蛋白质含量各占约55.18%和44.82%的糖肽MGP0501。MTT法和流式细胞术检测证实MGP0501对A549细胞具有体外抗肿瘤活性,对小鼠移植瘤S180的体内抗肿瘤实验检测亦证实其对小鼠移植瘤S180具有体内抑制作用,表明MGP0501是一种具有抗肿瘤作用的糖肽。     

锌诱导金属硫蛋白在文蛤不同组织中的表达

采用体外暴露法对文蛤Meretrixmeretrix进行锌(0、1.5mg/L、3mg/L、6mg/L)染毒,研究不同染毒浓度的锌离子在不同染毒时间下,诱导金属硫蛋白(metallothionein,MT)在文蛤足、肝胰腺、鳃、外套膜组织中的表达差异。取经不同浓度的锌溶液在染毒2d及4d后的不同组织匀浆、离心后经Bio-GelP-10凝胶柱层析纯化,用TU-1810紫外可见分光光度计测定每个样品中金属硫蛋白的吸光值。实验结果显示:同一浓度锌离子染毒后,MT在文蛤4个不同组织中的表达量差异较显著,一般为足>肝胰腺>外套膜>鳃;不同染毒浓度的锌离子在不同染毒时间下诱导MT在不同组织中的表达也不同,具有一定的组织差异性和规律性。     

利用线粒体COI和微卫星标记分析文蛤7个地理群体的遗传变异

利用线粒体细胞色素氧化酶亚基I(COI)和微卫星标记分析了文蛤7个地理群体(朝鲜新义州,辽宁丹东、蛤蜊岗和盘山,山东东营,江苏如东和启东)的遗传多样性和群体分化。PCR扩增获得142条602 bp的COI核苷酸片段,比对到13个变异位点,包括11个转换和2个颠换,定义了22个单倍型,共享单倍型12个,新义州、丹东和启东群体分别拥有特有单倍型。单倍型多样性最高的是如东群体(h=0.900),最低的是东营群体(h=0.600);核苷酸多样性最高的是丹东群体(π=0.00350),最低的是蛤蜊岗群体(π=0.00115)。基于COI数据的Fu's Fs中性检验和核苷酸不配对分析揭示文蛤种群历史上曾经历过群体扩张事件。分子变异分析(AMOVA)表明,群体内遗传变异占71.64%,群体间遗传变异占28.36%,群体间发生显著的遗传分化(P0.05)。7个微卫星标记扩增280个个体共获得54个等位基因,平均等位基因数为7.7个,平均观测杂合度和期望杂合度分别为0.3878和0.7996。江苏群体具有较高的遗传多样性,但7个群体间遗传多样性不存在显著差异(Kruskal-Wallis检验,P0.05)。Hardy-Weinberg平衡检验结果显示49个群体-位点组合中有18个偏离平衡(P0.05),表现为杂合子缺失。单倍型邻接(NJ)树显示聚类未展示地域性特色,但某几个同一或者相近地理群体的单倍型具有聚类现象(如东和启东部分单倍型出现地理聚类)。依据群体间遗传距离以Kimura 2-parameter为模型建立UPGMA系统发育树,显示丹东群体和江苏的如东和启东群体聚为一支,暗示江苏苗种的异地养殖已经污染丹东文蛤的遗传背景。     

Purification and Partial Characterization of Hypocalcemic Factor from Human Saliva

This study reports the isolation and partial purification of a polypeptide from human saliva which causes a significant serum calcium lowering when administered to mice. Purification was achieved by preparative electrophoresis, dialysis, two gel filtration steps on Sephadex G-150, and ion exchange chromatography on DEAE-cellulose. Homogeneity was determined by poly-acrylamide electrophoresis. Blood sampling was carried out by puncture of the orbital venous plexus and serum analyzed for calcium. The most active preparations lower serum calcium from 10–27% of initial value, producing tetany and convulsions in some cases. The molecular weight of this polypeptide was estimated to be 4, 260 by the use of a calibrated Sephadex G-75 column. This is a much smaller molecular weight than that expected from its initial exclusion from Sephadex G-150, and suggests that this hypocalcemic factor is associated with larger molecules through most of the purification procedure up to and including DEAE-cellulose chromatography. A second gel filtration on Sephadex G-150 separates two minor salivary protein contaminants (IgA and IgG immunoglobulin) in the excluded fraction from the smaller, hypocalcemically active polypeptide.

No hypocalcemia activity could be detected or isolated in a preliminary investigation on the saliva of a dysgammaglobuli-nemic (IgA deficient) patient.

The hypocalcemia induced does not differ significantly from that observed after administration of calcitonin to mice in that: 2) minimum values are reached in 1.5–2 hours and return to normal in 5–6 hours, b) magnitude of hypocalcemia response is dose dependent. The salivary hypocalcemia factor isolated in this study has the properties of a protein, in that its activity is destroyed by the proteolytic enzyme trypsin, it yields amino acids upon acid hydrolysis and it behaves on electrophoresis, gel filtration and ion exchange chromatography as a typical protein.     

Targeting cellular apoptotic pathway with peptides from marine organisms

Apoptosis is a critical defense mechanism against the formation and progression of cancer and exhibits distinct morphological and biochemical traits. Targeting apoptotic pathways becomes an intriguing strategy for the development of chemotherapeutic agents. Peptides from marine organisms have become important sources in the discovery of antitumor drugs, especially when modern technology makes it more and more feasible to collect organisms from seas. This primer summarizes several marine peptides, based on their effects on apoptotic signaling pathways, although most of these peptides have not yet been studied in depth for their mechanisms of action. Novel peptides that induce an apoptosis signal pathway are presented in association with their pharmacological properties.