Dissipative particle dynamics of non-spherical particles using a Gaussian density model

The Gaussian density molecular model has been adapted for dissipative particle dynamics. The model, when combined with a soft potential, is shown to be a very flexible mesoscale model exhibiting a wide range of phase behaviour. The soft potential allows relatively large time steps to be used and hence a more rapid equilibration. In addition, the model can be used to study both uniaxial and biaxial systems. We have undertaken a number of pilot studies and have demonstrated that the Gaussian model is able to identify nematic–isotropic phase transitions in liquid crystals and the formation of ordered discotic phases.     

嗜热蓝藻优雅粘囊藻藻胆体的特性和别藻蓝蛋白的亚基组成

研究了优雅粘囊藻藻胆体（ＰＢＳ）的特性。从聚丙烯酰胺凝胶电泳（ＰＡＧＥ）、吸收光谱和二阶导数图谱可证明,它的ＰＢＳ含有一种红色藻胆蛋白,两种Ｃ－藻蓝蛋白和三种别藻蓝蛋白。但是,用ＰＡＧＥ和羟基磷灰石柱层析分离和纯化所得藻胆蛋白,一般仅得到一种Ｃ－ＰＣ和一种亚基组成特殊的别藻蓝蛋白ＡＰＣ。这种ＡＰＣ吸收光谱和荧光发射相同于已报告的ＡＦＣ６６０ｎｍ。但是它的亚基组成是（αα′ββ′）２而不是（α′α２β２β′）Ｌｃ１０或（αβ）３。     

Structure of cDNA clones for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from a fern (Asplenium cataractarum rosenstock,aspleniaceae), and its comparison with those of various seed plants

We isolated the small subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisCO SSu) from a fern,Asplenium cataractarum and determined its 34 N-terminal amino acid sequence. We obtained a cDNA clone that contains the entire coding region of the SSu from the same fern species, using synthetic oligonucleotide probes derived from the above amino acid sequence. It contains a 525 bp open reading frame capable of coding for a polypeptide with 174 amino acids, 31 bp 5′-and 206 bp 3′-noncoding regions. It was also elucidated that the precursor to the SSu contains a transit peptide of 53 amino acid residues and a mature protein of 121 residues. We compared the deduced amino acid sequence of the fern SSu with those of 11 other vascular plant species (including gymnosperms, monocots and dicots). As low as 55% homology was observed between those of a fern and seed plants. Constancy of the amino acid substitution rate in RuBisCO SSu was supported by our relative rate test. Amino acid substitution rate per year per site for RuBisCO SSu was calculated to be 0.81×10⁻⁹ assuming that the separation between pteridophytes and seed plants arose 380 million years ago.     

Eicosapentaenoic acid inhibits TNF-alpha-induced matrix metalloproteinase-9 expression in human keratinocytes, HaCaT cells

Eicosapentaenoic acid (EPA) is an omega-3 (ω-3) polyunsaturated fatty acid (PUFA), which has anti-inflammatory and anti-cancer properties. Some reports have demonstrated that EPA inhibits NF-κB activation induced by tumor necrosis factor (TNF)-α or lipopolysaccharide (LPS) in various cells. However, its detailed mode of action is unclear. In this report, we investigated whether EPA inhibits the expression of TNF-α-induced matrix metalloproteinases (MMP)-9 in human immortalized keratinocytes (HaCaT). TNF-α induced MMP-9 expression by NF-κB-dependent pathway. Pretreatment of EPA inhibited TNF-α-induced MMP-9 expression and p65 phosphorylation. However, EPA could not affect IκB-α phosphorylation, nuclear translocation of p65, and DNA binding activity of NF-κB. EPA inhibited TNF-α-induced p65 phosphorylation through p38 and Akt inhibition and this inhibition was IKKα-dependent event. Taken together, we demonstrate that EPA inhibits TNF-α-induced MMP-9 expression through inhibition of p38 and Akt activation.     

Rice RNA-dependent RNA polymerase 6 acts in small RNA biogenesis and spikelet development

Higher plants have evolved multiple RNA-dependent RNA polymerases (RDRs), which work with Dicer-like (DCL) proteins to produce different classes of small RNAs with specialized molecular functions. Here we report that OsRDR6, the rice (Oryza sativa L.) homolog of Arabidopsis RDR6, acts in the biogenesis of various types and sizes of small RNAs. We isolated a rice osrdr6-1 mutant, which was temperature sensitive and showed spikelet defects. This mutant displays reduced accumulation of tasiR-ARFs, the conserved trans-acting siRNAs (tasiRNAs) derived from the TAS3 locus, and ectopic expression of tasiR-ARF target genes, the Auxin Response Factors (including ARF2 and ARF3/ETTIN). The loss of tasiR-mediated repression of ARFs in osrdr6-1 can explain its morphological defects, as expression of two non-targeted ARF3 gene constructs (ARF3muts) in a wild-type background mimics the osrdr6 and osdcl4-1 mutant phenotypes. Small RNA high-throughput sequencing also reveals that besides tasiRNAs, 21-nucleotide (nt) phased small RNAs are also largely dependent on OsRDR6. Unexpectedly, we found that osrdr6-1 has a strong impact on the accumulation of 24-nt phased small RNAs, but not on unphased ones. Our work uncovers the key roles of OsRDR6 in small RNA biogenesis and directly illustrates the crucial functions of tasiR-ARFs in rice development.     

鸡发育过程肌组织核提抽物结合活性与AChRγ亚基基因持续表达的关系

烟碱样乙酰胆碱受体 ( n ACh R)是由 4种亚基组成的五聚体 .哺乳类动物出生后γ亚基由ε亚基取代 ,迄今为止鸡 n ACh Rγ基因是否存在上述置换规律尚无定论 .为探索发育过程鸡骨骼肌n ACh R基因表达是否存在γ/ε亚基的置换及其机制 ,采用 RT- PCR技术和凝胶阻滞试验检测了鸡胚发育 9d至出生后 6周小鸡 γ基因表达的动力学及骨骼肌核抽提物的 DNA结合活性 .RT-PCR检测结果显示 ,在鸡胚发育 9d至出生后 6周的雏鸡骨骼肌组织均检出有 γ亚基 m RNA转录 .提示与哺乳类不同 ,出生前后鸡骨骼肌组织 ACh Rγ亚基基因持续表达 ,不存在 γ/ε亚基的置换表达规律 .以 γ基因 - 2 60 /- 2 4 0 (含 E盒与 M- CAT盒重叠序列 )和 - 2 39/- 50 (含 M- CAT盒及 GC富含区 )片段为探针 ,分别与鸡胚发育 9d至出生后 2周小鸡骨骼肌的核抽提物进行凝胶阻滞试验 .在发育各阶段的骨骼肌核抽提物中均有识别 - 2 39/- 50片段的结合活性存在 ,但在出生后 2周小鸡骨骼肌的核抽提物中未检出 - 2 60 /- 2 4 0结合活性 .结果提示 ,在出生后第 1 4d的肌核抽提物中存在的、识别并结合 - 2 39/- 50片段的活性物质与鸡 ACh Rγ基因在出生后持续表达有关 .     

Caveolin-1 activates Rab5 and enhances endocytosis through direct interaction

Caveolin-1, a constitutive protein of the caveolae, is implicated in processes of vesicular transport during caveolae-mediated endocytosis. However, the molecular mechanisms of caveolae-mediated endocytosis are not yet clearly defined. Here, we show the physiological role of the Rab5-caveolin-1 interaction during caveolae-mediated endocytosis. Rab5 was found in caveolae-enriched fractions and Rab5 directly bound to caveolin-1. Furthermore, binding sites of Rab5 to caveolin-1 were identified in the scaffold (SD), transmembrane (TM), and C-terminus (CC) domains, and the Rab5 binding domain of caveolin-1 was required for CTXB uptake. Subsequently, we performed a GST-R5BD pull-down assay to determine whether the Rab5 binding domain of caveolin-1 is involved in Rab5 activity or not. The results showed that overexpression of the Rab5 binding domain of caveolin-1 increase the amount of Rab5-GTP in Cos-1 cells. These findings imply that caveolin-1 controls the Rab5 activity during the caveolae-mediated endocytosis.     

后基因组时代的结核新疫苗研究

利用蛋白质组技术、生物信息学的DNA芯片等技术筛选适当的保护性抗原,重点在亚单位疫苗的DNA疫苗方面构建预防性和治疗性的疫苗,并配合使用亚单位疫苗,DNA疫苗和减毒活疫苗是值得重视的方向。     

牛肠激酶催化亚基工程菌的构建

目的：构建牛肠激酶催化亚基工程菌。方法：将带有牛肠激酶催化亚基（bEKL）的结构基因进行克隆,将克隆产物纯化后,构建bEKL克隆质粒,后构建bEKL表达质粒,并将表达质粒制导入备感受态细胞,进行蛋白表达。结果：琼脂糖电泳验证牛肠激酶催化亚基基因已经成功地插入表达载体,序列与预期设计一致。结论：表达质粒构建成功。     

无细胞百日咳工艺中PO4^3—影响DTaP免疫效力分析

用0.02mol/L磷酸盐缓冲液和不用磷酸盐缓冲液透析生产无细胞百日咳（aP）,按《2000年版生物制品规程》制备和检定氢氧化铝吸附无细胞百日咳、白喉、破伤风联合疫苗（DTaP）。发现用磷酸盐缓冲液和不用磷酸盐缓冲液透析生产aP组成DTaP免疫效力差异非常显著,后者100％（10／10）合格,前者合格率只有27％（3／11）,用钼兰法测定DTaP中PO4^3-离子浓度。结果表明后者的PO4^3-浓度只是前者的1／10,PO4^3-依次影响白喉、破伤风、百日咳免疫效价。