纤维素衍生物在固定酶和药物中的应用

本文综述了纤维素衍生物在固定酶和药物中的应用。     

Comparative study of methodologies for obtaining β-glucosidase immobilized on dextran-modified silica

In this study, two procedures for the immobilization of β-glucosidase on silica are compared. The first approach comprises a preliminary stabilization of β-glucosidase by coupling with dextran dialdehyde and subsequent immobilization of the obtained β-glucosidase dextran dialdehyde with aminopropylsilica. In the second approach, β-glucosidase is immobilized on silica modified with a dextran-dialdehyde coating. Enzyme immobilized via coupling with dextran dialdehyde and subsequent attachment with aminopropylsilica show a remarkably enhanced thermostability. Enzyme immobilized by the alternative approach demonstrated an inferior thermoresistance. The difference in behavior of the immobilized enzyme obtained via these two methods can be explained considering the number of links between the enzyme and carrier. Enzyme immobilized on dextran dialdehydecoated silica is fixed via a limited number of links. On the other hand, with soluble β-glucosidase-dextran conjugates, the enzyme configuration is already stabilized via a high number of links with the dextran backbone. It is clear from this study that the sequence of reactions in immobilizing enzymes on silica support via a dextran-dialdehyde linker has a significant effect on the final properties.     

干细胞与再生医学技术发展态势研究

20世纪以来,干细胞与再生医学技术一直是国际生物医学领域的热点前沿之一,它为保障人类生命健康、改善人类生存质量和延长人类寿命发挥不可替代的巨大作用。因此,美国、欧洲国家、日本和中国等科技大国均将该领域纳入了国家科研与产业发展的重点战略中,并通过专项扶持、政策补贴、立法保障等方式激励该领域的创新发展。通过对近年来国际科技战略和科技研发态势的梳理分析,发现该领域的国际战略布局规律,揭示我国在该领域的领先优势与弱点,为我国未来干细胞与再生医学技术发展提出相关参考建议。     

关于周口店第15地点石器类型和加工技术的研究

在周口店第 15地点经过加工的石器中 ,刮削器占近 93%。其它石器类型包括砍砸器、尖刃器、石锥、凹缺器、雕刻器和薄刃斧。石器由锤击加工。绝大多数标本向一面加工。石片石器多为正向加工。大多数石器个体很小 ,形态不规则 ,修疤呈鳞状 ,深浅、大小不一。少数标本的修疤浅平、规则而平行。统计分析显示在各类器型之间存在着明显的大小与加工上的区别。单边刃刮削器的各亚型之间在大小、加工长度和深度以及刃角和刃形诸方面不存在明显的差异 ,说明这些刮削器在刃口形态 (直、凸与凹 )方面的的变异主要取决于毛坯的原始形态 ,而非代表类型与功能的不同。变量相关分析揭示石器的大小与加工程度和原坯的大小与形态紧密相关。     

不同林龄杉木氮素的获取策略

为了探讨不同林龄杉木人工林氮素获取策略,选择了江西千烟洲森林生态研究站红壤区的3种林龄杉木人工林(5年生幼龄林、13年生中龄林和30年生成熟林)作为研究对象,利用稳定性同位素~(15)N示踪技术研究了它们的氮素吸收策略。结果表明,杉木对硝态氮的吸收受林龄影响,成熟林的吸收速率最高,为(5.72±0.24)μg N g~(-1)干重h~(-1),而中龄林和幼龄林的吸收速率相当,分别为(1.57±0.13)μg N g~(-1)干重h~(-1)和(2.36±0.22)μg N g~(-1)干重h~(-1)。幼龄林((34.33±1.20)μg N g~(-1)干重h~(-1))和成熟林((34.18±2.32)μg N g~(-1)干重h~(-1))对铵态氮的吸收速率相似,均显著高于中龄林((23.33±1.39)μg N g~(-1)干重h~(-1))。杉木对甘氨酸的吸收不受林龄的影响。3种年龄的杉木均对铵态氮表现出强的获取能力,其中成熟林杉木对硝态氮的获取能力明显弱于对铵态氮的获取,但却强于对甘氨酸的获取。这样的结果反映了林龄能影响杉木人工林对无机氮的吸收,但未影响对有机氮的吸收;杉木偏好吸收铵态氮,对硝态氮和甘氨酸的吸收很少。如果能把氮素形态考虑进对杉木人工林的施肥管理当中,那么可能会极大地改善杉木的生产力。     

A practical approach in bioreactor scale‐up and process transfer using a combination of constant P/V and vvm as the criterion

Bioreactor scale‐up is a critical step in the production of therapeutic proteins such as monoclonal antibodies (MAbs). With the scale‐up criterion such as similar power input per volume or O₂ volumetric mass transfer coefficient ( ), adequate oxygen supply and cell growth can be largely achieved. However, CO₂ stripping in the growth phase is often inadequate. This could cascade down to increased base addition and osmolality, as well as residual lactate increase and compromised production and product quality. Here we describe a practical approach in bioreactor scale‐up and process transfer, where bioreactor information may be limited. We evaluated the sparger and (CO₂ volumetric mass transfer coefficient) from a range of bioreactor scales (3–2,000 L) with different spargers. Results demonstrated that for oxygen is not an issue when scaling from small‐scale to large‐scale bioreactors at the same gas flow rate per reactor volume (vvm). Results also showed that sparging CO₂ stripping, , is dominated by the gas throughput. As a result, a combination of a minimum constant vvm air or N₂ flow with a similar specific power was used as the general scale‐up criterion. An equation was developed to determine the minimum vvm required for removing CO₂ produced from cell respiration. We demonstrated the effectiveness of using such scale‐up criterion with five MAb projects exhibiting different cell growth and metabolic characteristics, scaled from 3 to 2,000 L bioreactors across four sites. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1146–1159, 2017     

A novel reactive perstraction system based on liquid-core microcapsules applied to lipase-catalyzed biotransformations

A novel reactive perstraction system has been developed based on liquid-core capsules, involving an enzyme-catalyzed reaction coupled with simultaneous in situ product recovery. Lipase-catalyzed reactions, hydrolysis of triprionin and nitrophenyl laurate, were selected to test the system and demonstrate the feasibility of immobilization of enzymes to the membranes of liquid-core capsules and the ability to extract hydrophobic products of the reaction within the capsule core. The lipase from Candida rugosa was immobilized to the microcapsules by adsorption and by covalent binding through activation with glutaraldehyde. In both cases improved temperature and operational stability were achieved. Both types of immobilization resulted in a basic shift of the pH optimum for activity, from 7.5 to 9.0. The presence of an organic phase within the capsule core allowed direct product separation and lead to a decrease in product inhibition of the lipase-catalyzed reaction.     

Ant fishing by wild chimpanzees is not lateralised

Right-dominant handedness is unique and universal in Homo sapiens, suggesting that it is a highly derived trait. Our nearest living relations, chimpanzees, show lateralised hand preference when using tools, but not when otherwise manipulating objects. We report the first contrary data, that is, non-lateralised tool-use, for ant fishing as done in the Mahale Mountains of Tanzania. Unlike nut cracking, termite fishing, and fruit pounding, as seen elsewhere, in which most individuals are either significantly or wholly left- or right-biassed, ant fishers are mostly ambilateral. The clue to this exception lies in arboreality; all other patterns of chimpanzee elementary technology are done on the ground. Arboreal tool use usually requires not only that one hand be used to hold the tool, but also that the other hand gives postural support. When the supporting hand is fatigued, then it must be relieved by the other. Terrestrial tool use entails no such trading off. To test the hypothesis, we compared frequency of hand changing with the incidence of major hand support, and found them to be significantly positively correlated. The evolutionary transition from arboreality to terrestriality may have been a key enabler for the origins of human laterality.     

Immobilization of laccase onto modified PU/RC nanofiber via atom transfer radical polymerization method and application in removal of bisphenol A

In this study, 2‐hydroxyethyl methacrylate (HEMA) was used as the monomers for surface grafting on electrospun PU/RC nanofiber membrane via atom transfer radical polymerization (ATRP) method, and the PU/RC‐poly(HEMA) nanofiber membrane was investigated as a carrier for LAC. Free and immobilized LAC was characterized, and efficiency of bisphenol A (BPA) removal was determined. The results indicated that the PU/RC‐poly(HEMA)‐LAC showed relatively higher pH stability, temperature stability, and storage stability than free and PU/RC‐LAC; moreover, more than 60% of the PU/RC‐poly(HEMA)‐LAC activity was retained after 10 cycles of ABTS treatment. Notably, the BPA removal efficiency of PU/RC‐poly(HEMA)‐LAC membrane generally ranged from 87.3 to 75.4% for the five cycles. Therefore, the PU/RC‐poly(HEMA) nanofiber membrane has great potential as a carrier for the LAC immobilization for various industrial applications and bioremediation.