High-Resolution Performance of Polycaprolactone Functionalized with Guanidinium Ionic Liquid for Gas Chromatography

This work firstly reported a new polycaprolactone based material functionalized with guanidinium ionic liquid (PCL-GIL) as the stationary phase with high resolution performance for capillary gas chromatography (GC). It is composed of polycaprolactone (PCL) and guanidinium ionic liquid (GIL) with amphiphilic conformation. The PCL-GIL capillary column coated by static method exhibited high column efficiency of 3942 plates/m and moderate polarity. As a result, the PCL-GIL column exhibited high-resolution capability. For a mixture of 27 analytes with a wide ranging polarity and outperformed the PCL-2OH and HP-35 columns, showing its advantageous separation capability for analytes of diverse types. Moreover, the PCL-GIL column showed high resolving capability for various positional isomers and cis-/trans-isomers, including alkylbenzenes, chlorobenzenes, naphthalenes, bromonitrobenzenes, chloronitrobenzenes, benzaldehydes, phenols, alcohols, respectively. In a word, PCL derivatized by GIL units as a new type of stationary phase has a promising future in GC separations.     

Stromal cell-derived factor 1 (SDF-1) and its receptor CXCR4 improves diabetic retinopathy

Diabetes induced a serious of complications including diabetic retinopathy. Our study aimed to investigate the role of Stromal cell-derived factor 1 (SDF-1) and its receptor CXCR4 in diabetic retinopathy. A mice model of diabetic retinopathy was established, and expression of SDF-1 and CXCR4 in retina was examined by Real-time quantitative PCR (qRT-PCR). Cells of human retinal pigment epithelial cell line ARPE-19 were treated with CXCR4 siRNAs and expression vector, and cell viability was detected by MTT assay. We found that expression of SDF-1 and CXCR4 in retina was significantly downregulated in mice with diabetic retinopathy than in normal healthy mice. High glucose treatment downregulated the expression of SDF-1 and CXCR4 in ARPE-19 cells at both mRNA and protein levels. Transfection with CXCR4 siRNAs decreased, while transfection with CXCR4 expression vector increased cell viability under high glucose treatment. We concluded that SDF-1/CXCR4 pathway improved diabetic retinopathy possibly by increasing cell viability.

Abbreviations: SDF-1: Stromal cell-derived factor 1; CXCL12: C-X-C motif chemokine 12; qRT-PCR: Real-time quantitative PCR     

Wnt/β-Catenin Signaling Protects Mouse Liver against Oxidative Stress-induced Apoptosis through the Inhibition of Forkhead Transcription Factor FoxO3

Numerous liver diseases are associated with extensive oxidative tissue damage. It is well established that Wnt/β-catenin signaling directs multiple hepatocellular processes, including development, proliferation, regeneration, nutrient homeostasis, and carcinogenesis. It remains unexplored whether Wnt/β-catenin signaling provides hepatocyte protection against hepatotoxin-induced apoptosis. Conditional, liver-specific β-catenin knockdown (KD) mice and their wild-type littermates were challenged by feeding with a hepatotoxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet to induce chronic oxidative liver injury. Following the DDC diet, mice with β-catenin-deficient hepatocytes demonstrate increased liver injury, indicating an important role of β-catenin signaling for liver protection against oxidative stress. This finding was further confirmed in AML12 hepatocytes with β-catenin signaling manipulation in vitro using paraquat, a known oxidative stress inducer. Immunofluorescence staining revealed an intense nuclear FoxO3 staining in β-catenin-deficient livers, suggesting active FoxO3 signaling in response to DDC-induced liver injury when compared with wild-type controls. Consistently, FoxO3 target genes p27 and Bim were significantly induced in β-catenin KD livers. Conversely, SGK1, a β-catenin target gene, was significantly impaired in β-catenin KD hepatocytes that failed to inactivate FoxO3. Furthermore, shRNA-mediated deletion of FoxO3 increased hepatocyte resistance to oxidative stress-induced apoptosis, confirming a proapoptotic role of FoxO3 in the stressed liver. Our findings suggest that Wnt/β-catenin signaling is required for hepatocyte protection against oxidative stress-induced apoptosis. The inhibition of FoxO through its phosphorylation by β-catenin-induced SGK1 expression reduces the apoptotic function of FoxO3, resulting in increased hepatocyte survival. These findings have relevance for future therapies directed at hepatocyte protection, regeneration, and anti-cancer treatment.     

Improving the acidic stability of a β-mannanase from Bacillus subtilis by site-directed mutagenesis

β-Mannanase can randomly hydrolyze the (1→4)-β-d-mannosidic linkages in mannans, galactomannans and glucomannans, yielding manno-oligosaccharides. In this study, the β-mannanase (MAN) from Bacillus subtilis B10-02 was overexpressed successfully in B. subtilis 168 as a hexa-histidine tagged, secreted protein. The recombinant enzyme BsMAN6H was not stable under acidic conditions, which restricts its use in food and feed industry. We aimed to improve the acid stability of BsMAN6H by changing several surface-exposed amino acid residues to acidic or neutral ones. Among the mutations, the His54Asp resulted in a shift in the optimal pH from 6.5 to 5.5. Accordingly, the acid stability was improved by a factor of a negative potential on the structure surface around the mutated site. Furthermore, the H54D variant showed the enzyme activity up to 3207.82 U/mL in bioreactors using the cheap Kojac powder as substrate. As a result, a bacterial β-mannanase was produced efficiently with increased acid stability, improving its applicability in the animal feed industry.     

Adiponectin Mediates the Metabolic Effects of FGF21 on Glucose Homeostasis and Insulin Sensitivity in Mice

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银杏胚珠贮粉室的早期发育

对银杏 (GinkgobilobaL .)胚珠贮粉室的早期发育过程以及珠心细胞死亡的细胞学机制进行了研究。DNA电泳出现DNAladder和TUNEL标记说明参与形成贮粉室的珠心细胞死亡是程序性死亡 (PCD)过程 ,并且显示出在贮粉室形成中 ,PCD的发生有一定的空间分布式样。结合扫描电镜观察 ,贮粉室的早期发育可分为 4个阶段 :起始事件是位于珠孔端的 3至 4层珠心细胞纵向伸长 ;接着 ,位于珠心组织最上部 (珠孔端 )的珠心细胞启始死亡 ;然后 ,这些已经纵向伸长的珠心细胞向基地和侧向地逐渐死亡 ,形成一个空腔 ;最后 ,珠孔端珠心表皮细胞以开裂的方式与其余表皮细胞脱离而形成贮粉室的开口。大孢子母细胞时期 ,贮粉室尚未发生 ;四分体阶段 ,贮粉室已经开始形成 ;到雌配子体发育时期 ,贮粉室已经完全产生。反映大孢子发育和贮粉室发生的同步性。     

聚3-羟基丁酸酯（PHB）生物降解过程的研究

利用DS9701菌株对聚3-羟基丁酸酯(PHB)膜进行降解,对降解到不同程度的PHB膜采用扫描电子显微镜观察其表面形态结构的变化,并对其降解产物进行分析测定.结果表明,PHB的生物降解首先发生在PHB表面的非晶部分,随后结晶部分开始降解,并且降解首先发生在球晶的中心部分.DS9701菌株所产生的PHB解聚酶主要降解PHB的第二个酯键,降解产物为二聚体.