Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant <Emphasis Type="Italic">Bacillus subtilis</Emphasis> and <Emphasis Type="Italic">Candida maltosa</Emphasis>

Background  

Xylose mother liquor has high concentrations of xylose (35%-40%) as well as other sugars such as L-arabinose (10%-15%), galactose (8%-10%), glucose (8%-10%), and other minor sugars. Due to the complexity of this mother liquor, further isolation of xylose by simple method is not possible. In China, more than 50,000 metric tons of xylose mother liquor was produced in 2009, and the management of sugars like xylose that present in the low-cost liquor is a problem.     

Porous quaternized chitosan nanoparticles containing paclitaxel nanocrystals improved therapeutic efficacy in non-small-cell lung cancer after oral administration

Clinical application of paclitaxel (PTX) is limited because of its poor solubility in aqueous media. To overcome this hurdle, we devised an oral delivery system by encapsulating PTX into N-((2-hydroxy-3-trimethylammonium) propyl) chitosan chloride (HTCC) nanoparticles. These nanoparticles were small (~130 nm), had a narrow size distribution, and displayed high loading efficiency owing to the homogeneous distribution of PTX nanocrystals. The matrix hydrophilicity and porous structure of the obtained nanoparticles accelerated their degradation and improved drug release. In vitro and in vivo transport experiments had proved that the presence of positive charges enhanced the intestinal permeability of these nanoparticles. Further in vitro experiment of cytotoxicity showed that the PTX-loaded HTCC nanoparticle (HTCC-NP:PTX) was more effective than native PTX owing to enhanced cellular uptake. Drug distribution in tissues and in vivo imaging studies confirmed the preferred accumulation of HTCC-NP:PTX in subcutaneous tumor tissue. Subsequent tumor xenograft assays demonstrated the promising therapeutic effect of HTCC-NP:PTX on inhibition of tumor growth and induction of apoptosis in tumor cells. Additional investigation into side effects revealed that HTCC-NP:PTX caused lower Cremophor EL-associated toxicities compared with Taxol. These results strongly supported the notion that HTCC nanoparticle (HTCC-NP) is a promising candidate as an oral carrier of PTX for cancer therapy.     

绵羊Myostatin基因敲除载体的构建

根据Myostatin基因突变可导致肌肉量激增而产生"双肌"表型的特点,构建绵羊Myostatin基因置换型敲除栽体.利用LA-PCR技术成功地扩增得到绵羊Myostatin基因同源臂序列,其中同源长臂4.9kb,包括全部的exonl,intronl,exon2及部分启动子和大部分intron2;同源短臂1.1kb,包括部分exon3和31非翻译区序列,将二者连入PloxpⅡ正负筛选敲除骨架载体,利用骨架载体上Neo基因替代Myostatin基因的exon3,从而成功构建专门针对Myostatin第3外显子区域缺失的置换型敲除载体PloxpⅡ-OVIS-MSTN.酶切和测序鉴定证明载体构建正确,为后续获得绵羊Myostatin基因缺失型体细胞株奠定试验基础.     

适于转基因油菜RT73品系特异性检测的标准分子构建及其适用性鉴定

针对目前转基因产品检测标准物质缺乏的难题,构建适于转基因油菜RT73品系特异性检测的标准分子pEASY-RT73.其包含转基因油菜RT73品系3'端侧翼序列,油菜内标准基因HMG和PEP片段.对其在定性和定量检测中的适用性进行了实验室内部验证,结果表明,标准分子pEASY-RT173高度特异于转基因油菜RT73品系.以标准分子为标准品的普通PCR扩增中,3个目标片段的检测下限(LOD)均为10拷贝.实时荧光PCR检测的LOD均为25拷贝,定量下限(LOQ)均为50拷贝.以标准分子为标准品构建的标准曲线反应效率介于0.96-1.02间,相关系数均大于0.999.分别以PEP和HMG为内标准基因对5个盲样的测试结果显示,测量值与设定值间偏差(Bias)介于-14.13%-14.29%间,SD小于0.20,RSD小于18.0%.因此,标准分子pEASY-RT73可很好地替代植物来源阳性标准品用于转基因油菜Rt73及其来源产品品系特异性检测.     

DC-SIGN胞外区基因的克隆、蛋白表达及抗体制备

旨在构建DC-SIGN胞外区基因原核表达质粒,诱导蛋白表达并制备多克隆抗体。用PCR的方法扩增编码DC-SIGN胞外区的基因序列,将其克隆到原核表达载体pET-28a(+)中,利用大肠杆菌表达系统表达DC-SIGN胞外区蛋白,用H is抗体做W estern Blotting鉴定目的蛋白的免疫原性。用纯化的DC-SIGN胞外区蛋白免疫日本大耳白兔,制备多克隆抗体。通过酶联免疫吸附试验(ELISA)检测抗体效价,免疫荧光法检测其特异性。结果显示,原核表达载体pET-28 a(+)-DC-SIGN胞外区基因成功构建,可在大肠杆菌BL21(DE3)中高效表达,获得相对分子质量约20 kD的DC-SIGN胞外区蛋白,经Westernb lotting鉴定为正确。纯化后的蛋白免疫大耳白兔,制备的多克隆抗体具有较强免疫原性和特异性。本研究得到了纯化的DC-SIGN胞外区蛋白,并制备了具有特异性和高效价的抗体,为研究DC-SIGN生物学功能提供试验基础。     

长期定位施肥对石灰性紫色水稻土古菌群落结构的影响

为了认识长期施肥对石灰性紫色水稻土培肥和肥力演化的作用,结合变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)和限制性酶切片段长度多态性(RFLP)技术,研究了稻麦轮作下农家肥(M)、氮肥+农家肥(NM)、氮磷肥+农家肥(NPM)、氮磷钾肥+农家肥(NPKM)、无肥(CK)、氮肥(N)、氮磷肥(NP)、氮磷钾肥(NPK)等不同施肥制度对石灰性紫色水稻土古菌群落结构的影响.研究结果表明,长期定位施肥明显影响土壤中的古菌组成.在长期施用氮肥+农家肥、氮磷肥和氮磷钾肥+农家肥处理的土壤中,古菌多样性指数低于农家肥、氮磷肥+农家肥、无肥、氮肥和氮磷钾肥处理.在DGGE图谱的基础上,分别选择种植水稻和小麦的氮磷钾肥处理土壤样品,对古菌克隆子的16S rDNA序列进行了系统发育分析,发现水稻七古菌与各种土壤及水体环境的古菌极其相似.对DGGE图谱的聚类分析发现,不管是种植水稻还是小麦,8种施肥处理的古菌都聚在3个群里.种植水稻时,M和NPK处理下的土壤古菌聚成第一个群,NP处理下的聚成第二个群,另外5种施肥处理(NPKM,NM,Ck,N和NPM)聚成第三个群.种植小麦时,NPKM和M处理下的土壤古菌聚成一个群,NP处理下的聚成第二个群,N、NPK、NM、NPM和CK处理下的聚成第三个群.聚类分析结果显示,作物类型会影响土壤古菌群落结构.     

Putative Phosphorylation Sites On WCA Domain of HA2 Is Essential For Helicoverpa armigera Single Nucleopolyhedrovirus Replication

Protein phosphorylation is one of the most common post-translational modification processes that play an essential role in regulating protein functionality.The Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) orf2-encoded nucleocapsid protein HA2 participates in orchestration of virus-induced actin polymerization through its WCA domain,in which phosphorylation status are supposed to be critical in respect to actin polymerization.In the present study,two putative phosphorylation sites (232Thr and 2...     

Effect of mechanical pressure on the thickness and collagen synthesis of mandibular cartilage and the contributions of G proteins

To investigate the role of mechanical pressure on cartilage thickness and type II collagen synthesis, and the role of G protein in that process, in vitro organ culture of mandibular cartilage was adopted in this study. A hydraulic pressure-controlled cellular strain unit was used to apply hydrostatic pressurization to explant cultures. The explants were compressed by different pressure values (0 kPa, 100 kPa, and 300 kPa) after pretreatment with or without a selective and direct antagonist (NF023) for the G proteins. After 4, 8 and 12 h of cell culture under each pressure condition, histological sections of the explants were stained with hematoxylin-eosin to investigate the thickness of the cartilage. Immunohistochemical staining was used to observe type II collagen expressions. The results showed that a hydrostatic pressure of 100 kPa significantly reduced the thickness of the proliferative layer in condylar cartilage without affecting the thickness of the transitional layer. Hydrostatic pressures of 100 kPa and 300 kPa significantly enhanced the synthesis of type II collagen. G proteins are involved not only in the proliferation and differentiation of condylar cartilage regulated by prolonged pressure, but also in the process of collagen production in condylar cartilage stimulated by pressure.