Screening and identification of Acinetobacter junii for Apocynum vernetum L. fiber enzymatic retting

There are many kinds of ketones with antisepsis functions in the Apocynum vernetum L. fiber (ALF), but its enzymatic retting is difficult. In order to select the appropriate ALF enzymatic retting strain, wastewater from ALF retting was analyzed to screen a strain with high pectinase activity. Of the analyzed strains, the maximum pectinase activity measured was of the #2 strain: 103.2 IU/ml at a zymogenic time of 12 hrs at 37°C. The retting experiments verified that this strain was well suited for ALF; the residual gum rate of ALF was 15.26% and its fiber physicochemical properties were similar to those fibers which were chemically retted. The strain was determined to be a new retting strain, Acinetobacter junii, according to a 16S rDNA sequence analysis in combination with morphology, and biophysical and biochemical tests using fermentation, catalase, methyl red and gelatin liquefaction. As a new pectinase‐producing strain, Acinetobacter junii could be utilized in industrial enzymatic retting productions after further process optimization and can replace the conventional chemical retting process due to its improved fiber quality and reduced environmental pollution.     

Impact of Porcine Pancreas Decellularization Conditions on the Quality of Obtained dECM

Due to the limited number of organ donors, 3D printing of organs is a promising technique. Tissue engineering is increasingly using xenogeneic material for this purpose. This study was aimed at assessing the safety of decellularized porcine pancreas, together with the analysis of the risk of an undesirable immune response. We tested eight variants of the decellularization process. We determined the following impacts: rinsing agents (PBS/NH₃·H₂O), temperature conditions (4 °C/24 °C), and the grinding method of native material (ground/cut). To assess the quality of the extracellular matrix after the completed decellularization process, analyses of the following were performed: DNA concentration, fat content, microscopic evaluation, proteolysis, material cytotoxicity, and most importantly, the Triton X-100 content. Our analyses showed that we obtained a product with an extremely low detergent content with negligible residual DNA content. The obtained results confirmed the performed histological and immuno-fluorescence staining. Moreover, the TEM microscopic analysis proved that the correct collagen structure was preserved after the decellularization process. Based on the obtained results, we chose the most favorable variant in terms of quality and biology. The method we chose is an effective and safe method that gives a chance for the development of transplant and regenerative medicine.     

miR-29 Represses the Activities of DNA Methyltransferases and DNA Demethylases

Members of the microRNA-29 (miR-29) family directly target the DNA methyltransferases, DNMT3A and DNMT3B. Disturbances in the expression levels of miR-29 have been linked to tumorigenesis and tumor aggressiveness. Members of the miR-29 family are currently thought to repress DNA methylation and suppress tumorigenesis by protecting against de novo methylation. Here, we report that members of the miR-29 family repress the activities of DNA methyltransferases and DNA demethylases, which have opposing roles in control of DNA methylation status. Members of the miR-29 family directly inhibited DNA methyltransferases and two major factors involved in DNA demethylation, namely tet methylcytosine dioxygenase 1 (TET1) and thymine DNA glycosylase (TDG). Overexpression of miR-29 upregulated the global DNA methylation level in some cancer cells and downregulated DNA methylation in other cancer cells, suggesting that miR-29 suppresses tumorigenesis by protecting against changes in the existing DNA methylation status rather than by preventing de novo methylation of DNA.     

Using a Fragment‐Based Approach To Target Protein–Protein Interactions

The ability to identify inhibitors of protein–protein interactions represents a major challenge in modern drug discovery and in the development of tools for chemical biology. In recent years, fragment‐based approaches have emerged as a new methodology in drug discovery; however, few examples of small molecules that are active against chemotherapeutic targets have been published. Herein, we describe the fragment‐based approach of targeting the interaction between the tumour suppressor BRCA2 and the recombination enzyme RAD51; it makes use of a screening pipeline of biophysical techniques that we expect to be more generally applicable to similar targets. Disruption of this interaction in vivo is hypothesised to give rise to cellular hypersensitivity to radiation and genotoxic drugs. We have used protein engineering to create a monomeric form of RAD51 by humanising a thermostable archaeal orthologue, RadA, and used this protein for fragment screening. The initial fragment hits were thoroughly validated biophysically by isothermal titration calorimetry (ITC) and NMR techniques and observed by X‐ray crystallography to bind in a shallow surface pocket that is occupied in the native complex by the side chain of a phenylalanine from the conserved FxxA interaction motif found in BRCA2. This represents the first report of fragments or any small molecule binding at this protein–protein interaction site.     

基于自组装的N皇后问题DNA计算算法

N皇后问题是理论计算机科学中一个经典的NP难问题.自Adleman首次运用DNA计算来解决NP问题以来,DNA计算已成为计算机科学的研究热点之一,现有N皇后问题的DNA计算机算法多基于粘贴和剪接模型,存在生化操作复杂度和实验误差较高等问题.本文提出了一种基于DNA自组装模型来求解N皇后问题的DNA计算方法.算法通过减少实验操作步骤数,降低了生化解的错误率.算法使用的tiles分子块种类为O（n²）,生化操作复杂性为O（1）,其中n为皇后的个数.与求解N皇后问题的其它DNA算法的对比分析表明,本算法可提高生化解的准确性,降低算法生化实验的复杂度,具有良好的易操作性.     

Challenges in nucleic acid‐lipid films for transfection

The use of surface‐based methods for the delivery of therapeutics has recently generated increasing interest. These platforms have tremendous potential to minimize detrimental side effects associated with systemic delivery by localizing the therapeutic vehicle, and thus provide higher local doses for improved efficacy. Cationic lipids are one of the most commonly used synthetic carriers for the delivery of genetic cargo, such as DNA and RNA. However, reports on the use of lipid‐based films for gene delivery are scarce. Here we investigate the use of a lipid‐based film for the in vitro delivery of plasmid DNA. Solid DNA‐lipid films show very low levels of transfection, while identical complexes prepared for bolus delivery provide high levels of transfection when used directly. We investigate the mechanism, whereby the activity of these solid‐state films is lost and suggest methods for circumventing these challenges and restoring the efficacy of these films as gene delivery platforms. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3203–3213, 2013     

集成电极的PDMS-玻璃微流控芯片的制备

微流控芯片在分析化学和生物检测方面有着广阔的应用前景。对集成电极的PDMS-玻璃微流控芯片的制备工艺进行了研究与分析。最终使用SU-8快速制备阳模,使用PDMS转移图形得到具有微流控通道的PDMS盖片;在玻璃基板上加工Pt电极,除了需要外露的部分电极外,其他部分以薄层PDMS保护,得到电极基板;将PDMS盖片与电极基板半固化键合制得同时具有加热和温度传导电极以及CE高压电极的PDMS-玻璃芯片。ANSYS模拟分析证明加热芯片热惯性小,加热时温度分布效果好。     

纳米金与生物分子的相互作用及生物传感检测

系统地分析了纳米金与生物分子的相互作用,并从光学比色分析、荧光分析、电化学检测、质量变化检测等几个方面入手,详细介绍了纳米金在DNA检测领域中的应用。     

Functionalization of single- and multi-walled carbon nanotubes with cationic amphiphiles for plasmid DNA complexation and transfection

The possibility of delivering DNA efficiently to cells represents a crucial issue for the treatment of both genetic and acquired diseases. However, even although the efficiency of non-viral transfection systems has improved in the last decade, none have yet proven to be sufficiently effective in vivo. We report herein our results on the functionalization of single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) by two cationic amphiphiles (lipid RPR120535 and pyrenyl polyamine), their use for the complexation of plasmid DNA, and their efficiency in transfecting cells in vitro. The experiments have shown that the efficiency of transfection is higher when using SWNT instead of MWNT, and that transfection efficiency is similar or slightly higher when using nanoplexes (SWNT/lipid RPR120535/DNA) instead of lipoplexes (lipid RPR120535/DNA) and several orders of magnitude higher than that of naked DNA. This study therefore shows both that the transfection is better when using SWNTs and that it is dependent on the nature of the amphiphilic molecules adsorbed on the nanotubes.