中国茶对变形链球菌的抑菌作用

对３６只ｓｐｒａｑｕｅ－Ｄａｗｌｅｙ鼠分４组给予诱龋饲料（Ｄｉｅｔ２０００,ｋｅｙｓ）,并连续５天在口腔内接种变链菌６７１５菌株,分别给予我国主要产茶区的三种茶浸液：龙井绿茶（Ｂ组）,四川涪陵红茶（Ｃ组）,乌龙茶（Ｄ组）,先用０．５ｇ茶和５０ｍｌ双蒸馏水加热煮沸过滤后浸泡１０分钟以及对照组（Ａ组）用双蒸馏水为饮料喂养实验鼠。实验６０天后,杀鼠观察计算鼠磨牙面的菌落形成单位（ＣＦＵ）和菌斑指数（ｐｌａｑｕｅｓｃｏｒｅ）均显著下降。实验结果,实验组和对照组菌斑指数下降值顺序如下：Ｃ组＞Ｄ组＞Ｂ组＞Ａ组,并与实验组含氟量有相关性。很多研究表明变链菌是较为肯定的致龋菌、茶中氟化物对变链菌生长、粘附都有抑制作用。本研究选用茶来源广泛、价廉、无毒安全等优点,为开拓新的防龋方法进行探索。     

TLR4全长及其截断体重组腺病毒的制备和功能鉴定

制备脂多糖 (LPS)Toll样受体 4 (TLR4 )全长及其胞内段缺失的TLR4截断体 (ΔTLR4 )的绿色荧光蛋白重组腺病毒并鉴定其功能 .用PCR方法扩增TLR4及ΔTLR4基因片段 ,酶切后亚克隆至腺病毒穿梭质粒中 ,形成带有目的基因的穿梭载体pAdTrack TLR4和pAdTrack ΔTLR4 .用BJ5 1 83细菌同源重组法将目的基因重组于腺病毒骨架载体中 ;将重组腺病毒质粒用PacⅠ酶切线性化后 ,用脂质体法转染HEK 2 93细胞进行腺病毒的包装扩增 .将重组腺病毒感染CHO K1细胞 ,采用荧光毒酶报告基因方法检测其对LPS诱导NF κB激活的影响 .酶切及测序表明 ,TLR4全长及其截断体ΔTLR4的重组腺病毒载体构建正确 .荧光素酶报告基因检测结果表明 ,TLR4全长及其截断体的重组腺病毒感染细胞对LPS诱导的反应具有不同的影响 ,Ad ΔTLR4明显抑制了LPS引起的NF κB激活 (P <0 0 5 ) ,Ad TLR4则使LPS引起的NF κB活性增强 (P <0 0 5 ) .LPS对细胞的激活作用依赖于TLR4的结构完整性     

中心体蛋白Cenexin在大鼠精子发生过程中的表达特征

中心体蛋白Cenexin是成熟中心粒的唯一标志分子。为阐明中心粒在大鼠精子发生中的成熟以及功能,我们首先通过RT－PCR技术从大鼠睾丸组织中扩增出了Cenexin cDNA片段,原核表达重组蛋白后,用其免疫小鼠制备了高滴度的抗Cenexin的多克隆抗体,然后利用免疫荧光染色、Western Blot和半定量RT－PCR方法,研究了大鼠精子发生过程中Cenexin蛋白和基因的表达特征。结果显示Cenexin mRNA水平在精原细胞和精母细胞中较高,随后表达水平下降,而蛋白质分子在精原细胞到精子细胞中都定位于细胞的一个中心粒上,表示有成熟中心粒的存在,在长形精子细胞中该蛋白位于鞭毛的基体部。附睾的绝大多数成熟精子中Cenexin免疫染色消失。中心体蛋白Cenexin在精子变态期的表达变化可能与精子鞭毛形成的起始有关。     

长江中华鲟繁殖群体资源现状的初步研究

根据1994—1998年获得的246尾标本,对中华鲟繁殖群体的性比、性腺发育成熟个体比例、年龄结构、体长和体重特征等进行了研究。并结合历史资料,对其种群资源现状进行评价,提出了相应的资源保护措施建议。     

Distinct Promoters Affect Pyrroloquinoline Quinone Production in Recombinant Escherichia coli and Klebsiella pneumoniae

Pyrroloquinoline quinone (PQQ) is a versatile quinone cofactor participating in numerous biological processes. Klebsiella pneumoniae can naturally synthesize PQQ for harboring intact PQQ synthesis genes. Previous metabolic engineering of K. pneumoniae failed to overproduce PQQ due to the employment of strong promoter in expression vector. Here we report that a moderate rather than strong promoter is efficient for PQQ production. To screen an appropriate promoter, a total of four distinct promoters—lac promoter, pk promoter of glycerol dehydratase gene (dhaB1), promoter of kanamycin resistance gene, and T7 promoter (as the control)—were individually used for overexpressing the endogenous PQQ genes in K. pneumoniae along with heterologous expression in Escherichia coli. We found that all recombinant K. pneumoniae strains produced more PQQ than recombinant E. coli strains that carried corresponding vectors, indicating that K. pneumoniae is superior to E. coli for the production of PQQ. Particularly, the recombinant K. pneumoniae recruiting the promoter of kanamycin resistance gene produced the highest PQQ (1,700 nmol), revealing that a moderate rather than strong promoter is efficient for PQQ production. Furthermore, PQQ production was roughly proportional to glucose concentration increasing from 0.5 to 1.5 g/L, implying the synergism between PQQ biosynthesis and glucose utilization. This study not only provides a feasible strategy for production of PQQ in K. pneumoniae, but also reveals the exquisite synchronization among PQQ biosynthesis, glucose metabolism, and cell proliferation.     

Century-Scale Responses of Ecosystem Carbon Storage and Flux to Multiple Environmental Changes in the Southern United States

Terrestrial ecosystems in the southern United States (SUS) have experienced a complex set of changes in climate, atmospheric CO₂ concentration, tropospheric ozone (O₃), nitrogen (N) deposition, and land-use and land-cover change (LULCC) during the past century. Although each of these factors has received attention for its alterations on ecosystem carbon (C) dynamics, their combined effects and relative contributions are still not well understood. By using the Dynamic Land Ecosystem Model (DLEM) in combination with spatially explicit, long-term historical data series on multiple environmental factors, we examined the century-scale responses of ecosystem C storage and flux to multiple environmental changes in the SUS. The results indicated that multiple environmental changes shifted SUS ecosystems from a C source of 1.20?±?0.56?Pg (1?Pg?=?10¹⁵?g) during the period 1895 to 1950, to a C sink of 2.00?±?0.94?Pg during the period 1951 to 2007. Over the entire period spanning 1895–2007, SUS ecosystems were a net C sink of 0.80?±?0.38?Pg. The C sink was primarily due to an increase in the vegetation C pool, whereas the soil C pool decreased during the study period. The spatiotemporal changes of C storage were caused by changes in multiple environmental factors. Among the five factors examined (climate, LULCC, N deposition, atmospheric CO₂, and tropospheric O₃), elevated atmospheric CO₂ concentration was the largest contributor to C sequestration, followed by N deposition. LULCC, climate, and tropospheric O₃ concentration contributed to C losses during the study period. The SUS ecosystem C sink was largely the result of interactive effects among multiple environmental factors, particularly atmospheric N input and atmospheric CO_2.     

The inhibition of lung cancer cell growth by intracellular immunization with LC—1 ScFv

INTRODUCTIONLung cancer remains the leading cause of can-cer mortaIity in the world, accounting for more thanone sixth of cancer deaths in the world[1]. Antibod-ies have been proved to be a powerful tool fOr thestudy of 1ung cancer. A monoclonal IgM antibody,LC-1, was obtained in our laboratory. It can reactat a high rate with all four pathological types of lungcancers, including lung adenocarcinoma, 1ung squamous carcinoma, large cell lung cancer and smaIlcell lung cancert but not wit…     

表达流感病毒神经氨酸酶基因的重组腺病毒的构建

通过RT-PCR方法扩增流感病毒神经氨酸酶基因,将其克隆到腺病毒穿梭载体pTrackCMV,此重组质粒与腺病毒DNA共转化大肠杆菌BJ5183,通过细菌内同源重组获得重组腺病毒DNA,将其转染293细胞获得重组腺病毒.经PCR证实目的基因已整合至腺病毒基因组中,western blot检测到神经氨酸酶的表达.重组病毒经滴鼻和灌胃两种途径免疫小鼠,结果表明2次免疫后滴鼻组和灌胃组均产生明显的免疫应答反应,滴鼻组的免疫效果优于灌胃组.     

慢性胃炎肠化生CD_(44)、CD_(44V6)及Cyclin D_1、Cyclin E的表达和意义

目的探讨慢性胃炎胃粘膜肠化生CD44、CD44V6及cyclin D1、Cyclin E表达的意义。方法利用免疫细胞化学技术对39例伴有肠化生的慢性胃炎和5例正常人胃窦粘膜的活检组织进行检查。结果正常人胃窦粘膜上皮,腺上皮对CD44、CD44V6、Cyclin D1和Cyclin E均为阴性,但在有神经内分泌样细胞的粘膜,CD44V6和cyclin D1为阳性。慢性胃炎肠化生区和不典型增生区除CD44为阴性外,CD44V6、cyclin D1和cyclin E均呈现不同的阳性反应,但未见有阳性的神经内分泌样细胞。间质细胞大都呈阳性反应。结论CD44V6、cyclin D1和cyclin E可能是胃癌前状态的早期事件,而CD44可能为胃癌晚期的标志物。     

伯克霍尔德氏菌ZYB002脂肪酶lipC24基因的克隆、表达及其酶学性质

【目的】克隆伯克霍尔德菌ZYB002菌株中的新型脂肪酶lip C24基因,测定其基本酶学性质,为后续深入研究该基因在菌株中的生理功能奠定基础。【方法】根据洋葱伯克霍尔德菌JK321菌株的全基因组DNA信息,直接设计引物从伯克霍尔德菌ZYB002菌株基因组中扩增出lip C24基因,并对之进行原核表达、重组蛋白的纯化及酶学性质分析。【结果】lip C24基因全长1317 bp,编码438个氨基酸残基;多肽链中具有保守五肽-G-X1-S-X2-G-序列;重组蛋白Lip C24的分子量为45 k Da;能有效水解各种对硝基苯酯,对中链脂肪酸的对硝基苯酯表现出偏爱性;其催化水解反应的最适温度为40℃,最适p H7.5;40℃下的半衰期为15.72 min,在p H 7.0-8.0的条件下,具有较好的稳定性。【结论】lip C24的编码产物为一个45 k Da蛋白,具有明显的脂肪酶活性,为中温中性脂肪酶。