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1. chinaXiv:201901.00122 [pdf]

外泌体作为肿瘤标志物的研究进展

刘艳; 戴鹏; 朱运峰
Subjects: Biology >> Bioengineering

外泌体是细胞内源性囊泡样生物纳米级膜结构,直径大小在40-100 nm之间,可由各种类型的细胞分泌释放。外泌体具有许多功能,如蛋白质、mRNA、miRNA和脂类的细胞间运输和传递,以及抗原递呈,还可能具有致癌的能力。肿瘤细胞所分泌释放的外泌体在肿瘤的发生、发展以及迁移等生理和病理过程中发挥重要的作用。目前从肿瘤外泌体中寻找特异性标志物已成为肿瘤研究者重点关注的方向,对肿瘤早期诊断、疗效评价和预后分析具有重要的意义。本文作者就近年来外泌体在肿瘤研究和诊断中研究进展进行综述。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits1233Downloads194 Comment 0

2. chinaXiv:201901.00121 [pdf]

利用CRISPR/Cas9技术构建稳定表达人白蛋白基因的中国仓鼠卵巢细胞系

周松涛; 陈蕴; 龚笑海; 金坚; 李华钟
Subjects: Biology >> Bioengineering

通过目的基因的随机整合方式,构建得到的CHO表达细胞系,常会因为目的基因插入到染色体内不稳定区域,而在长期传代过程中出现表达不稳定的现象,这主要是由于位点效应所导致。为了解决这个问题,现利用CRISPR/Cas9技术介导的同源重组,将目的基因直接整合于CHO细胞染色体上稳定表达区域,以克服位点效应带来的CHO表达细胞系的长期表达不稳定。现总共利用该技术获得了2株外源基因(人白蛋白基因)定点整合细胞系;western blot结果显示,细胞上清液的产物具有人白蛋白抗原性;细胞在贴壁状态下,两株细胞系在第3、12、23、35、50代,细胞每日表达的HSA质量接近,且均维持在0.5 pg/cell/day;选取一株表达细胞系,经悬浮驯化后,在批次条件培养下,第1、25及50代的悬浮细胞,在摇瓶内的表达浓度均稳定在13-14 mg/L。本研究显示了将外源基因基因定点整合于CHO细胞基因组内的的可行性;且外源基因整合在稳定表达区域后,重组细胞系具有对外源基因长期表达的稳定性。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits2764Downloads208 Comment 0

3. chinaXiv:201901.00123 [pdf]

定点突变改善PvEH1对邻甲基苯基缩水甘油醚的催化特性

阚婷婷; 宗迅成; 苏永君; 王婷婷; 李闯; 胡蝶; 邬敏辰
Subjects: Biology >> Bioengineering

环氧化物水解酶能够对外消旋环氧化物进行动力学拆分保留单构型的环氧化物。测定了菜豆环氧化物水解酶 (PvEH1) 针对苯基缩水甘油醚及其甲基衍生物的催化特性,并基于分子对接及多序列比对分析确定7个突变位点,通过单点和组合突变对PvEH1进行改造,以期改善PvEH1对邻甲基苯基缩水甘油醚 (1a) 的催化特性。底物谱分析表明PvEH1对1a的催化活性 (157.2 U/g湿细胞) 和对映选择性 (E = 5.6) 最高。单点突变结果显示E. coli/pveh1L105I和E. coli/pveh1V106I对1a的催化活性和对映选择性均有明显提高;L105I和V106I位组合突变菌株E. coli/pveh1L105I/V106I的催化活性 (493.8 U/g湿细胞) 是E. coli/pveh1的3.1倍,对映选择性 (E = 8.3) 也提高至E. coli/pveh1的1.5倍。纯化后PvEH1L105I/V106I的催化活性为17.6 U/mg是PvEH1的1.5倍,对1a的催化效率提高至PvEH1的2.1倍。SDS-PAGE分析表明提高了蛋白的可溶性表达量。利用E. coli/pveh1L105I/V106I全细胞催化100 mmol/L 1a水解动力学拆分获得手性纯 (R)-1a (ee > 96%) 的产率和时空产率分别为31.2%和5.12 g/L/h,因此,在手性纯 (R)-1a的制备中,E. coli/pveh1L105I/V106I是一种颇具潜力的生物催化剂。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits1202Downloads155 Comment 0

4. chinaXiv:201901.00124 [pdf]

基于核酸适配体的肿瘤免疫治疗进展

吕海银; 王腾飞; 裴仁军
Subjects: Biology >> Bioengineering

肿瘤免疫治疗是通过调节机体的免疫功能来控制和杀伤肿瘤的一种治疗手段。针对免疫检查点的治疗等一系列临床突破使得肿瘤的免疫治疗受到了广泛重视。目前,抗体治疗和过继性细胞治疗是肿瘤免疫治疗的主要方式,但是这些方法仍具有副作用较强,实体瘤治疗难以实现,治疗费用高昂等缺点。因此改进和发展更加高效、安全、低成本的新技术仍十分必要。适配体是利用指数富集的配体系统进化技术筛选得到的单链寡核苷酸,有核酸“抗体”之称。适配体具有低免疫原性,组织穿透力强,易于化学合成与修饰等优势,且与其靶标的结合具有较好亲和力和特异性,可像抗体一样实现肿瘤的免疫治疗。本文对适配体在肿瘤免疫治疗相关技术中的新应用作一综述,主要包括基于免疫检查点的抗肿瘤作用、双特异性适配体的肿瘤免疫治疗、适配体靶向递送siRNA的肿瘤免疫治疗和适配体联合抗体的肿瘤免疫治疗几个方面。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits2050Downloads164 Comment 0

5. chinaXiv:201901.00125 [pdf]

甲醇周期诱导控制强化毕赤酵母生产猪干扰素

严建; 贾禄强; 丁健; 史仲平
Subjects: Biology >> Bioengineering

利用甲醇营养型毕赤酵母生产猪干扰素(pIFN-),诱导过程一般在高细胞密度、定值控制甲醇浓度于5-10 g/L下进行,此时、溶解氧浓度(DO)自然下降到接近于0的水平。如果高好氧的毕赤酵母长期处在高甲醇/低DO的诱导浓度环境会导致其代谢活性恶化;胞内甲醇积累严重;pIFN-表达生产效率低。为此,提出了一种甲醇周期诱导控制策略来强化pIFN-生产。先将甲醇控制于高浓度达7 h;再降低甲醇流加速率、将DO控制在~20%约4 h,一共重复6个循环。采用上述周期控制策略,毕赤酵母代谢活性可以长期维持在较高水平;胞内甲醇处于极低水平(≤ 0.003 g/g-DCW)、解除了甲醇毒性效应;pIFN-活性达到3.90×107 IU/mL的最高水平,是定值控制甲醇浓度时的1.86倍。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits2203Downloads184 Comment 0

6. chinaXiv:201901.00126 [pdf]

MOFs固定5-羟甲基糠醛氧化酶及其催化活性的研究

巩凤芹; 刘启顺; 谭海东; 金花; 谭成玉; 尹恒
Subjects: Biology >> Bioengineering

固定化酶作为一种绿色高效的生物催化剂,其性能远超游离酶。目前酶的固定化技术适用范围仍然较小,酶的研究范围多停留在模型酶阶段,扩大固定化酶的研究范围具有十分重要的意义。金属有机骨架材料(MOFs)作为酶固定化的载体在近些年得到了广泛的探索,但是具有生物功能的酶-MOFs复合材料的许多特性仍有待挖掘。本文采用仿生矿化的合成方法将5-羟甲基糠醛氧化酶(HMFO)固定到以沸石咪唑酯(ZIF-8)为代表的MOFs材料中,制备得到一种新的生物催化剂HMFO@ZIF-8,扫描电子显微镜表征其形态区别于经典的菱形十二面体。采用考马斯亮蓝法测定蛋白质浓度,计算得到酶的固定化效率达到89.0%。HMFO@ZIF-8催化5-羟甲基糠醛的转化率达到84.3%,收率和选择性均高于游离酶。本文拓展了MOFs固定化酶的研究范围,为研究其他生物大分子复合材料的生物催化剂提供一定的借鉴意义。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits1866Downloads173 Comment 0

7. chinaXiv:201901.00127 [pdf]

气相色谱法对狂犬病疫苗灭活工艺中β-丙内酯研究

高彦; 杜晶晶; 王斌; 刘琦; 申志强
Subjects: Biology >> Bioengineering

目的:基于GC-FID法,对狂犬病疫苗生产过程中采用的β-丙内酯灭活剂进行了含量及稳定性研究。方法:气相色谱条件:采用Agilent DB-624(30 m×0.530 mm×3.00 μm)毛细管柱;升温程序:初始温度为80 ℃,保持1 min,以20 ℃/min的速率升温至200 ℃,保持3 min;色谱柱流量:3 mL/min;检测器温度:250 ℃;进样口温度:150 ℃;载气:氮气,线速度:25 cm/sec;进样量:1 μL,分流比为2:1,进样方式:手动进样。结果:以乙腈作为稀释剂,BPL在1:100~1:32000范围内线性关系良好(R2≥0.999)。在1:200、1:1000、1:8000 三个浓度水平下,加标回收率在95.04%~116.86%之间,相对标准偏差(RSD)为2.6%~3.2%,检测限为0.112 μg/mL。结论:该方法简便、专属性强、稳定且在室温条件下操作,大大降低了对试验条件和技术操作的要求,能够满足灭活狂犬病病毒工艺中对BPL检测的需求。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits2131Downloads159 Comment 0

8. chinaXiv:201901.00128 [pdf]

细菌中D-氨基酸生物合成及调控作用研究进展

薛二淑; 吴昊; 宋倩倩; 田开仁; 乔建军; 财音青格乐
Subjects: Biology >> Bioengineering

细菌中普遍存在L/D型氨基酸,与L-氨基酸(L-AAs)不同,D-氨基酸(D-AAs)不参与蛋白质合成,而与细胞壁肽聚糖的合成有关,直接影响细菌细胞壁的形状、数量和强度。D-AAs在细菌表征、药物抑菌性、靶标确定等方面具有重要的作用。目前,外源添加D-AAs参与肽聚糖合成的机制已有一些研究进展,其荧光衍生物已应用于细菌可视化,特异性探测细胞壁形成/重塑、细菌生长和细胞形态。但D-AAs如何影响细菌生长及其抗逆性的机制尚未研究清楚。本文对D-AAs的研究现状进行了综述,重点介绍了D-AAs在细菌中的生物合成和参与细胞壁合成的机制,非典型D-AAs对细菌的调控以及在细菌可视化中的应用,并对D-AAs未来研究方向进行了展望。

submitted time 2019-01-17 From cooperative journals:《中国生物工程杂志》 Hits1884Downloads235 Comment 0

9. chinaXiv:201901.00105 [pdf]

Hydrological and economic feasibility of mitigating a stressed coastal aquifer using managed aquifer recharge: a case study of Jamma aquifer, Oman

Mustafa EL-RAWY; Ali AL-MAKTOUMI
Subjects: Geosciences >> Geography

This study explored the hydrological and economic feasibility of managed aquifer recharge (MAR) using tertiary treated wastewater (TWW) to mitigate salinity in the coastal aquifer of Jamma, Oman. A steady-state groundwater flow and transport model, using MODFLOW software, was developed and calibrated. Different managerial scenarios were simulated and the results reveal that the Jamma aquifer will be further deteriorated in the next 20 a if it remains unmanaged. The groundwater table will decline further by more than 3 m on average; and the iso-concentration salinity line of 1500 mg/L will advance 2.7 km inland, which will severely affect the farming activities in the area. However, MAR using TWW when integrated with the management of groundwater abstraction (e.g., using modern irrigation systems to reduce the abstraction rate) becomes hydrologically feasible to augment the aquifer storage and control seawater intrusion, and hence improves the farming activities. The results indicate that: (1) injecting TWW in the vicinity of irrigation wells (Scenario A2); (2) investing in smart water meters and online control of pumping from the wells to reduce the abstraction rate by 25% (Scenario B); and (3) a combination of both (Scenario B2) are feasible scenarios with positive net present values. Recharge in upstream areas is found not economically feasible because of the very high investment cost of the installation of pipes to transport the TWW over a distance of 12.5 km. Because of securing funds are challenging, Scenario B would be the best option and the second-best option is Scenario A2. Scenario B2 has the lowest net benefit investment ratio and is very attractive because it entails integrated demand and supply management of groundwater. It is required to reduce pumping and to invest in injecting TWW to improve groundwater quality in the vicinity of irrigation wells and to form a hydrological barrier to control seawater intrusion in the long run.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits4999Downloads261 Comment 0

10. chinaXiv:201901.00106 [pdf]

Arbuscular mycorrhizal fungi ameliorate the chemical properties and enzyme activities of rhizosphere soil in reclaimed mining subsidence in northwestern China

QIU Lang; BI Yinli
Subjects: Geosciences >> Geography

In semi-arid region of northwestern China, underground mining subsidence often results in decreased vegetation coverage, impoverishment of soil fertility and water stress. In addition, the physical-chemical and biological properties of soil also change, resulting in more susceptible to degradation. In particular, subsidence causes disturbance of the symbioses of plant and microbe that can play a beneficial role in the establishment of vegetation communities in degraded ecosystems. The objective of this study was to evaluate the effects of revegetation with exotic arbuscular mycorrhizal fungi (AMF) inoculum on the chemical and biological properties of soil over time in mining subsidence areas. Soils were sampled at a depth up to 30 cm in the adjacent rhizosphere of Amorpha fruticose Linn. from five reclaimed vegetation communities in northwestern China. In August 2015, a field trial was set up with five historical revegetation experiments established in 2008 (7-year), 2011 (4-year), 2012 (3-year), 2013 (2-year) and 2014 (1-year), respectively. Each reclamation experiment included two treatments, i.e., revegetation with exotic AMF inoculum (AMF) and non-AMF inoculum (the control). Root mycorrhizal colonization, glomalin-related soil protein (GRSP), soil organic carbon (SOC), soil nutrients, and enzyme activities were also assessed. The results showed that mycorrhizal colonization of inoculated plants increased by 33.3%–163.0% compared to that of non-inoculated plants (P<0.05). Revegetation with exotic AMF inoculum also significantly improved total GRSR (T-GRSP) and easily extracted GRSP (EE-GRSP) concentrations compared to control, besides the T-GRSP in 1-year experiment and the EE-GRSP in 2-year experiment. A significant increase in SOC content was only observed in 7-year AMF reclaimed soils compared to non-AMF reclaimed soils. Soil total N (TN), Olsen phosphorus (P) and available potassium (K) were significantly higher in inoculated soil after 1–7 years of reclamation (except for individual cases), and increased with reclamation time (besides soil Olsen P). The exotic AMF inoculum markedly increased the average soil invertase, catalase, urease and alkaline phosphatase by 23.8%, 21.3%, 18.8% and 8.6%, respectively (P<0.01), compared with the control. Root mycorrhizal colonization was positively correlated with soil parameters (SOC, TN and soil available K) and soil enzyme activities (soil invertase, catalase, urease and alkaline phosphatase) in both AMF and non-AMF reclaimed soils (P<0.05), excluding available K in non-AMF reclaimed soils. T-GRSP (P<0.01) and EE-GRSP (P<0.05) were significantly correlated with the majority of edaphic factors, except for soil Olsen P. The positive correlation between root mycorrhizal colonization and available K was observed in AMF reclaimed soils, indicating that the AMF reclaimed soil with a high root mycorrhizal colonization could potentially accumulate available K in soils. Our findings concluded that revegetation with exotic AMF inoculum influenced soil nutrient availability and enzyme activities in the semi-arid ecosystem, suggesting that inoculating AMF can be an effective method to improve soil fertility and support restoration of vegetation communities under poor conditions like soil nutrient deficiency and drought.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits4707Downloads283 Comment 0

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