A novel membrane based process to isolate photosystem-I membrane complex from spinach

The isolation of photosystem-I (PS-I) from spinach has been conducted using ultrafiltration with 300 kDa molecular weight cut-off polyethersulfone membranes. The effects of ultrafiltration operating conditions on PS-I activity were optimized using parameter scanning ultrafiltration. These conditions included solution pH, ionic strength, stirring speed, and permeate flux. The effects of detergent (Triton X-100 and n-dodecyl-beta-D-maltoside) concentration on time dependent activity of PS-I were also studied using an O₂ electrode. Under optimized conditions, the PS-I purity obtained in the retentate was about 84% and the activity recovery was greater than 94% after ultrafiltration. To our knowledge, this is the first report of the isolation of a membrane protein using ultrafiltration alone.     

Mouse-rabbit germinal vesicle transfer reveals that factors regulating oocyte meiotic progression are not species-specific in mammals

A series of experiments were designed to evaluate the meiotic competence of mouse oocyte germinal vesicle (GV) in rabbit ooplasm. In experiment 1, an isolated mouse GV was transferred into rabbit GV-stage cytoplast by electrofusion. It was shown that 71.8% and 63.3% of the reconstructed oocytes completed the first meiosis as indicated by the first polar body (PB1) emission when cultured in M199 and M199 + PMSG, respectively. Chromosomal analysis showed that 75% of matured oocytes contained the normal 20 mouse chromosomes. When mouse spermatozoa were microinjected into the cytoplasm of oocytes matured in M199 + PMSG and M199, as many as 59.4% and 48% finished the second meiosis as revealed by the second polar body (PB2) emission and a few fertilized eggs developed to the eight-cell stage. In experiment 2, a mouse GV was transferred into rabbit MII-stage cytoplast. Only 13.0-14.3% of the reconstructed oocytes underwent germinal vesicle breakdown (GVBD) and none proceeded past the MI stage. When two mouse GVs were transferred into an enucleated rabbit oocyte, only 8.7% went through GVBD. In experiment 3, a whole zona-free mouse GV oocyte was fused with a rabbit MII cytoplast. The GVBD rates were increased to 51.2% and 49.4% when cultured in M199 + PMSG and M199, respectively, but none reached the MII stage. In experiment 4, a mouse GV was transferred into a partial cytoplasm-removed rabbit MII oocyte in which the second meiotic apparatus was still present. GVBD occurred in nearly all the reconstructed oocytes when one or two GVs were transferred and two or three metaphase plates were observed in ooplasm after culturing in M199 + PMSG for 8 hr. These data suggest that cytoplasmic factors regulating the progression of the first and the second meioses are not species-specific in mammalian oocytes and that these factors are located in the meiotic apparatus and/or its surrounding cytoplasm at MII stage.     

西南桦人工林与山地雨林的群落学特征比较

人类活动对生态系统的影响是当今生态学的研究热点之一,但对在退化生态系统上进行人工造林对地带性植被群落学特征的影响研究尚较欠缺。本文根据组成群落的植物生态学特征能对其生态环境做出准确的反应这一规则,通过样地调查法分析了林龄为12年的西南桦（Betula alnoides）人工群落的区系组成和基本的群落学特征,并与当地的地带性植被——山地雨林的区系组成和群落学特征进行了比较,从而探讨人工造林对当地天然生态系统的影响。结果发现,与天然群落相比,人类活动（人工种植西南桦林）对生态系统的植物物种的生活型谱、物种叶型谱、区系成分、物种多样性等方面的群落学特征影响不大;即使在这些方面有或多或少的差异,可能也是小环境的异质性造成的。但是人工种植西南桦林对群落的季相外貌、群落的结构、物种组成、物种丰富度以及生物量等方面有较大的影响。进行综合分析后得出结论：虽然人工造林可以缩短植被自然恢复的时间以及具有显著的经济价值,但与地带性植被相比,还是有较大的生态学差异。建议为了当地经济的发展,有必要适当发展一定面积的人工林,但规模应适度。     

Serum miR-128-2 Serves as a Prognostic Marker for Patients with Hepatocellular Carcinoma

Circulating miRNAs are promising biomarkers for predicting the aggressiveness of hepatocellular carcinoma (HCC). We aimed to identify differentially expressed miRNAs in the serum of HCC patients with different Barcelona Clinic Liver Cancer (BCLC) stage, and to investigate the potential of serum miRNAs as biomarkers for patient outcomes. In the discovery stage, TaqMan Low-Density Array was used to test the difference in levels of serum miRNAs between 20 patients with portal vein tumor thrombosis (PVTT) and 20 patients without PVTT. The detected serum miRNAs then were validated in 182 patients. Fifteen serum miRNAs showed more than two-fold higher expression in patients with PVTT, and miR-128-2 was found to be significantly up-regulated and was selected for further validation. In the validation stage, patients were divided into two groups with low or high serum miR-128-2 using the median expression level of all 182 cases as the cut-off point. Kaplan-Meier analysis revealed that patients with low level of serum miR-128-2 had favorable trends of survival (log rank = 13.031, p < 0.001). The median survivals for patients with a low and high level of serum miR-128-2 were 625 (95% CI, 527–722) days and 426 (95% CI, 362–491) days, respectively. MiR-128-2 was also an independent factor of overall survival (p = 0.001, HR 2.793, 95%CI 1.550, 5.033). Serum levels of the ubiquitously expressed miR-128-2 showed no significant correlation with parameters of liver damage or liver function. In addition, expressions of miR-128-2 in HCC tissues were up-regulated in comparison with adjacent non-tumor tissues. In conclusion, serum level of miR-128-2 serves as a noninvasive biomarker for the overall survival of patients with hepatocellular carcinoma.     

体外模拟人体细胞癌变的进展

癌症的发生是一个多基因决定和多阶段演进的过程 ,首先是某些基因发生突变并不断积累 ,引起细胞分化生长失控。然而这些突变必须克服机体设置的细胞增殖障碍、应激产生的染色体基因修补机制以及多种抑癌基因的作用。在染色体受到损伤时 ,这些抑癌因子会激活表达 ,调控基因转录以抑制肿瘤生长 ,所以只有当排除了抑癌因子的多重作用后 ,一个正常细胞才能逐渐突破防线而转化成为一个肿瘤细胞[1] 。经过多年研究 ,科学家虽已搞清了主导肿瘤转化的相关基因及其在转化过程中所起的作用 ,但能否根据这些已经了解的细胞转化机制 ,在体外模拟肿瘤的发…     

高剂量热休克蛋白gp96通过激活调节性T细胞预防1型糖尿病

旨在以非肥胖糖尿病(Non-obese diabetic,NOD)小鼠为动物模型,研究高剂量昆虫细胞表达的重组热休克蛋白gp96(Recombinant gp96,rgp96)对1型糖尿病(Type 1 diabetes,T1D)的预防作用。以高剂量rgp96免疫NOD小鼠,用血糖仪监测小鼠血糖值,用流式细胞术检测小鼠脾脏CD4~+CD25~+Foxp3~+调节性T细胞(Regulatory T cells,Tregs)亚群频率,然后用一系列体外实验探究高剂量rgp96对Tregs的影响。结果显示高剂量rgp96免疫有效地预防或延缓小鼠T1D发病,免疫诱导Tregs数量明显增加。体外实验发现rgp96蛋白促进Tregs增殖,诱导Foxp3表达上调和IL-10分泌增加。研究结果为开发基于rgp96的新型T1D预防和治疗性疫苗提供了依据。     

渗透胁迫对杜氏盐藻胞内甘油含量及相关酶活性影响

杜氏盐藻(Dunaliella salina)是一种抗渗透能力强的单细胞绿藻, 甘油在其渗透调节过程中发挥重要作用。本实验对5种不同NaCl浓度条件下, 盐藻的生长、细胞内甘油含量及甘油代谢相关酶的活性变化进行了测定。结果表明, NaCl浓度过高或过低均影响盐藻的生长; 高渗胁迫条件下甘油含量迅速增加,3-磷酸甘油磷酸酶的活性和二羟丙酮还原酶催化二羟丙酮转化为甘油的活性明显增加; 而低渗胁迫条件下的甘油含量会迅速降低, 3-磷酸甘油磷酸酶的活性丧失, 二羟丙酮还原酶催化甘油转化为二羟丙酮的活性增加。基于此实验结果, 我们对盐藻渗透胁迫条件下细胞内的甘油代谢过程与其抗渗透胁迫能力的相关性进行了探讨。     

NF-κB激活gp96转录从而促进肝细胞生长、细胞周期进展和细胞转化

【目的】探讨乙肝感染中gp96上调的机制及其可能发挥的病理学机制。【方法】首先通过生物信息学、Real-time PCR、荧光报告基因和Western blot研究NF-κB激活gp96表达的机制。进一步通过在肝细胞中过表达或敲低gp96的水平,运用CCK-8法和流式检测分析gp96对肝细胞增殖、凋亡,和细胞周期的影响,通过检测肝细胞EMT发生和细胞集落形成实验,分析gp96对于HCC发生的作用。【结果】NF-κB与gp96启动子上NF-κB结合位点结合,激活gp96的表达。实验结果显示,gp96能够促进肝细胞增殖、抑制凋亡,促进细胞周期从静息期向分裂期的转化,同时促进肝细胞EMT发生和细胞集落的形成。【结论】NF-κB通过活化gp96启动子上调其表达,为HBV慢性感染上调gp96的机制提供了线索,同时提示gp96在慢性炎症引发HCC过程中发挥重要作用。     

LncRNA MEG3 inhibits the progression of prostate cancer by modulating miR‐9‐5p/QKI‐5 axis

This study was designed to detecting the influences of lncRNA MEG3 in prostate cancer. Aberrant lncRNAs expression profiles of prostate cancer were screened by microarray analysis. The qRT‐PCR and Western blot were employed to investigating the expression levels of lncRNA MEG3, miR‐9‐5p and QKI‐5. The luciferase reporter assay was utilized to testifying the interactions relationship among these molecules. Applying CCK‐8 assay, wound healing assay, transwell assay and flow cytometry in turn, the cell proliferation, migration and invasion abilities as well as apoptosis were measured respectively. LncRNA MEG3 was a down‐regulated lncRNA in prostate cancer tissues and cells and could inhibit the expression of miR‐9‐5p, whereas miR‐9‐5p down‐regulated QKI‐5 expression. Overexpressed MEG3 and QKI‐5 could decrease the abilities of proliferation, migration and invasion in prostate cancer cells effectively and increased the apoptosis rate. On the contrary, miR‐9‐5p mimics presented an opposite tendency in prostate cancer cells. Furthermore, MEG3 inhibited tumour growth and up‐regulated expression of QKI‐5 in vivo. LncRNA MEG3 was a down‐regulated lncRNA in prostate cancer and impacted the abilities of cell proliferation, migration and invasion, and cell apoptosis rate, this regulation relied on regulating miR‐9‐5p and its targeting gene QKI‐5.     

海洋抑菌放线菌Y15的筛选、鉴定及其代谢产物理化性质

【目的】筛选产广谱、高效抑菌活性物质的海洋放线菌,为新型抗生素的开发奠定基础。【方法】采用琼脂块法初筛,打孔扩散法复筛,以金黄色葡萄球菌、大肠埃希氏菌、枯草芽孢杆菌和单核细胞增生李斯特菌为指示菌从海泥样品中筛选目标菌株;利用20种指示菌株考查Y10、Y11、Y15、Y16和Y21的抑菌谱;通过形态观察和16S r RNA基因序列分析确定菌株分类地位;以单核细胞增生李斯特菌的OD600值为指标探讨Y15抑菌活性物质对该菌的作用方式;以抑菌活性为指标研究Y15抑菌活性物质的理化性质。【结果】共分离12株具抑菌活性的海洋放线菌,其中Y15抑菌谱最广,对20种指示菌株中的18种具有抑菌活性,并且在4种培养基中均能产生抑菌活性物质。16S r RNA基因序列分析表明Y15属于小单孢菌属,并与Micromonospora endolithica亲缘关系最近。Y15抑菌活性物质在144 h达到最高值为480 AU/m L,在168-216 h保持平衡为320 AU/m L。Y15抑菌活性物质对单核细胞李斯特菌作用方式为杀菌。Y15抑菌活性物质在-20-60°C抑菌活性保持稳定,在80-120°C活性逐渐下降,但在120°C处理30 min仍保留37.5%的活性;在p H 7.0-10.0抑菌活性稳定,在p H 2.0-6.0和p H 11.0-12.0抑菌活性均有所损失;Y15抑菌活性物质对紫外和4种酶(蛋白酶K、胰蛋白酶、木瓜蛋白酶和α-淀粉酶)处理均保持稳定,表明活性物质为非蛋白和非多肽类的抑菌物质。【结论】Y15产生的活性物质具有良好的抑菌谱和抑菌活性,且较为稳定,具有较高的应用价值。