顶青霉D_(15)木聚糖酶性质研究

本文对项青霉D_(1(?))的四个木聚糖酶组分的特性进行了研究。木聚糖酶组分D_(x1)、D_(x4)的最佳反应pH为4.8,最适温度分别为40℃和50℃,D_(x2)和D_(x3)的最适pH和温度都分别为pH4.2和50℃。Ag~(++)、Hg~(++),Cu~(++)对四个组分的活性均有强烈的抑制作用,SDS也能产生明显的抑制效果。Mn~(++)对D_(x1)具有促进作用。D_(x1)、D_(x4)在以燕麦木聚糖为底物时活性最高,其Km值分别为11.7(mg/ml)和8.3(mg/ml),D_(x2)和D_(x3)则分别在水解红麻杆木聚糖和落叶松木聚糖时活性最强,Km值分别为8.4(mg/ml)和6.3(mg/ml)。水解燕麦木聚糖,D_(x1)的产物主要为木糖,同时带有少量的低聚木糖。D_(x2)、D_(x3)和D_(x4)的产物则包括木糖和较多的低聚木糖。D_(x4)与D_(x2)及D_(x3)之间在水解燕麦木聚糖时存在协同作用关系。     

人胸腺上皮细胞培养及其分泌产物

本文通过降低培养基中血清含量,向RPMI 1640培养基中补加三碘甲腺原氨酸而获得一种人胸腺网状上皮细胞占优势生长的培养物。在此培养基中细胞经传代培养长达90天,仍维持正常形态特征。胸腺组织在培养14天后,新生细胞的突起形成网状结构,细胞化学检查和电镜观察表明具有丰富的分泌颗粒,囊泡及张力原纤维束和桥粒等上皮细胞特征。收集合并细胞培养液,经部分纯化后检查其生物活性,表现出具有促进玫瑰花结形成和降低胸腺细胞TdT活性的作用,说明培养细胞的分泌产物具有胸腺激素活性。根据形态学,细胞化学和生物活性检测结果,我们倾向于认为该培养物主要为网状上皮细胞。     

Involvement of Annexin A2 in p53 induced apoptosis in lung cancer

Tumor suppressor p53 plays important roles in cell cycle regulation, apoptosis and DNA repair in different cell types including lung cancer. There are different p53 apoptotic pathways in high and low metastatic ability lung cancer cells. However, the exactly mechanism in the pathway is still unclear. Here we found that Annexin A2, a Ca²⁺-dependent phospholipid-binding protein, is involved in p53-mediated apoptosis. First, by using mRNA differential display technique, down-regulated Annexin A2 expression was found in all cell lines transfected of Ad-p53 (adenoviral expression construct encoding wild type p53 gene) especially in highly metastatic Anip973 lung cancer cells. Then, decreased expression of Annexin A2 was further confirmed by Northern blot and Western blot analysis. At last, knock down of Annexin A2 by siRNA inhibited cellular proliferation in BE1 cell line with highly metastatic ability. Taken together, our results suggested that Annexin A2 may play roles in p53 induced apoptosis and it is also involved in regulation of cell proliferation. The authors Yun Huang, Yan Jin and Cheng-hui Yan contributed equally to this work.     

Choline Transporters in Human Lung Adenocarcinoma： Expression and Functional Implications

Choline is an essential nutrient for cell survival and proliferation, however, the expression and function of choline transporters have not been well identified in cancer. In this study, we detected the mRNA and protein expression of organic cation transporter OCT3, carnitine/cation transporters OCTN 1 and OCTN2, and choline transporter-like protein CTL1 in human lung adenocarcinoma cell lines A549, H 1299 and SPC-A-1. Their expression pattern was further confirmed in 25 human primary adenocarcinoma tissues. The choline uptake in these cell lines was significantly blocked by CTL1 inhibitor, but only partially inhibited by OCT or OCTN inhibitors. The efficacy of these inhibitors on cell proliferation is closely correlated with their abilities to block choline transport. Under the native expression of these transporters, the total choline uptake was notably blocked by specific PI3K/AKT inhibitors. These results describe the expression of choline transporters and their relevant function in cell proliferation of human lung adenocarcinoma, thus providing a potential ＂choline-starvation＂ strategy of cancer interference through targeting choline transporters, especially CTL1.     

鱼类多样性监测的理论方法及中国内陆 水体鱼类多样性监测

近年来, 生物多样性监测网络的建设得到广泛重视, 全球、地区或国家生物多样性观测网不断组建。生物多样性观测的理论框架得到发展, 提出了生物多样性核心监测指标(Essential Biodiversity Variables, EBV)。鱼类多样性监测的理论框架包含于生物多样性核心监测指标之内, 在遗传、物种、生态系统等多层次进行。基于鱼类监测提出的生物完整性指数(index of biotic integrity, IBI)强调不同物种的生态功能, 可以综合反映群落结构和功能的变化, 得到广泛应用。鱼类多样性的监测方法是传统网具和现代水声学等方法的结合。监测结果的分析可以进行简单的指数比较, 也可以进行长期的趋势分析, 寻找关键节点, 探讨宏观生态格局的变化。中国内陆水体鱼类多样性监测网隶属于中国生物多样性监测与研究网络, 拟选取长江、黄河、黑龙江、珠江、澜沧江、怒江、塔里木河及青海湖8大流域, 对25个重要区域和24个重点物种(类群)进行监测, 从重要区域鱼类群落结构、重点物种(类群)种群动态和个体生物学特征、遗传多样性、早期资源等不同层次, 全面监测我国内陆水体鱼类生物多样性状况。     

中华蟾蜍消化道6种酶的组织化学定位

目的研究中华蟾蜍消化道酸性磷酸酶(ACP)、碱性磷酸酶(ALP)、腺苷三磷酸酶(ATPase)、非特异性酯酶(NSE)、过氧化物酶(POX)和琥珀酸脱氢酶(SDH)等6种酶的分布。方法在消化道的8个部位取材,采用冰冻切片技术、石蜡切片技术、酶的组织化学方法和光密度定量分析。结果 ACP主要分布于胃贲门中贲门腺部,十二指肠和回肠中酶反应呈弱阳性。ALP主要分布于食管、十二指肠至回肠的粘膜上皮,十二指肠酶活性最高。ATPase在消化道各部位均有分布,胃中胃腺部和回肠粘膜上皮酶活性显著较高(P0.05)。NSE和POX在整个消化道粘膜上皮和粘膜固有层均有分布,胃各部位酶活性显著较低(P0.05)。SDH除在食管和直肠酶活性显著较低外,其它部位均有大量分布,十二指肠和回肠酶活性显著较高(P0.05)。结论中华蟾蜍消化道粘膜6种酶的分布同其它动物有相似之处,也有其自身特点。6种酶在消化道中的分布与消化道各部位的生理机能密切相关。     

Synthesis and characterization of thermosensitive graft copolymer of N-isopropylacrylamide with biodegradable carboxymethylchitosan

A novel thermosensitive and hydrogel was designed and synthesized by graft copolymerization of N-isopropylacrylamide (NIPAAm) with biodegradable carboxymethylchitosan (CMCS). The influence of the content of CMCS grafted on the properties of the resulted hydrogels was examined. The morphology of the hydrogels was observed by scanning electron microscopy (SEM), their thermal property was characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and deswelling/swelling kinetics upon external temperature changes. In comparison with the conventional PNIPAAm hydrogels, the resulted hydrogels have improved thermosensitive properties, including enlarged water content at room temperature and faster deswelling/swelling rate upon heating. The strategy described here presents a potential alternative to the traditional synthesis techniques for thermosensitive hydrogels.     

Removal of selectable marker gene from fibroblast cells in transgenic cloned cattle by transient expression of Cre recombinase and subsequent effects on recloned embryo development

Introduction of selectable marker genes to transgenic animals could create an inconvenience to further research and may exaggerate public concerns regarding biological safety. The objective of the current study was to excise loxP flanked neo^R in transgenic cloned cattle by transient expression of Cre recombinase. Green fluorescent protein gene (GFP) was incorporated to monitor Cre expression; therefore, Cre-expressed cells could be selected indirectly by fluorescence-activated cell sorting (FACS). The neo^R was removed and Cre expressed transiently in GFP-positive colonies; excision of neo^R was confirmed by single-blastocyst PCR in recloned blastocysts, with neo^R-free fibroblast cells as donors. There was no difference (P > 0.05) in rates of cleavage (76.0% vs. 68.8%) or blastocyst formation (56.6% vs. 52.9%) between recloned embryos with neo^R-free or neo^R-included donors. The differential staining of recloned blastocysts were similar (P >0.05) in terms of total cell number (124 vs. 122) and the ratio of ICM (Inner Cell Mass) to the total cell number (38.1% vs. 38.2%). Furthermore, pregnancy and calving rates were not different (P > 0.05) from those of the control. In conclusion, we successfully excised neo^R from transgenic cloned cattle; the manipulation did not affect the developmental competence of recloned preimplantation embryos. This approach should benefit bioreactor and transgenic research in livestock.     

桂林小花苣苔离体快速繁殖技术

对抗结核植物桂林小花苣苔(Chiritopsis repanda var. guilinensis)进行离体培养与快速繁殖技术研究。结果表明: 桂林小花苣苔叶片外植体的最适初代诱导培养基为MS+0.5 mg·L^–16-BA+0.05 mg·L^–1IBA, pH8.0; 最适继代增殖培养基为 MS+0.1 mg·L^–16-BA+0.05 mg·L^–1IBA, pH6.0, 繁殖系数7.0/35天; 最适生根培养基为1/2MS+0.2 mg·L^–1NAA, pH6.0, 生根率为93.6%。模拟桂林小花苣苔自然生境, 在春季对生根试管苗进行大棚移栽, 成活率达90%。根据上述快繁技术, 理论上每株试管苗每年可繁殖桂林小花苣苔种苗46万株。