Absolute configuration of an axially chiral sulfonate determined from its optical rotatory dispersion,electronic circular dichroism,and vibrational circular dichroism spectra

The absolute configuration (AC) of an axially chiral sulfonate (aCSO), 3,5‐dimethyl‐2‐(naphthalen‐1‐yl)‐6‐(naphthalen‐1‐yl)benzenesulfonate (labeled as aCSO5), was investigated using optical rotatory dispersion (ORD), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) spectroscopies. All three methods led to the same conclusion and the AC of aCSO5 is reliably determined to be (−)‐(aR , aR ), or conversely (+)‐(aS , aS ).     

Structure and transcription of genes within the β-hbd-adh1 region of Clostridium acetobutylicum P262

Abstract The 1.2-kb DNA fragment upstream of the linked β- hbd (3-hydroxybutyryl-CoA dehydrogenase) and adh1 (NADPH-dependent alcohol dehydrogenase) genes from Clostridium acetobutylicum P262 was sequenced. The upstream region contained an open reading frame (ORFB) which was found to have 44% amino acid identity to the fixB gene products of yRhizobium and Azorhizobium . The β- hbd and ORFB genes were expressed during the acidogenic and solventogenic phases. The β- hbd gene was transcribed on a single mRNA species of 2.0 kb, whereas the ORFB gene was transcribed on two species of mRNA of 2.0 and 3.5 kb, respectively. The adh1 gene was induced or derepressed at the pH breakpoint before the onset of solventogenesis and was transcribed on a single species of mRNA of 2.4 kb.     

Distinctive roles of receptor‐interacting protein kinases 1 and 3 in caspase‐independent cell death of L929

Upon tumour necrosis factor alpha (TNFα) stimulation, cells respond actively by way of cell survival, apoptosis or programmed necrosis. The receptor‐interacting proteins 1 (RIP1) and 3 (RIP3) are responsible for TNFα‐mediated programmed necrosis. To delineate the differential contributions of RIP3 and RIP1 to programmed necrosis, L929 cells were stimulated with TNFα, carbobenzoxy‐valyl‐alanyl‐aspartyl‐[O‐methyl]‐fluoromethylketone (zVAD) or zVAD along with TNFα following RNA interference against RIP1 and RIP3, respectively. RIP1 silencing did not protect cells from TNFα‐mediated cell death, while RIP3 down‐regulation made them refractory to TNFα. The heat shock protein 90 inhibitor geldanamycin (GA) down‐regulated both RIP1 and RIP3 expression, which rendered cells resistant to zVAD/TNFα‐mediated cell death but not to TNFα‐mediated cell death alone. Therefore, the protective effect of GA on zVAD/TNFα‐stimulated necrosis might be attributed to RIP3, not RIP1, down‐regulation. Pretreatment of L929 cells with rapamycin mitigated zVAD‐mediated cell death, while the autophagy inhibitor chloroquine did not affect necrotic cell death. Meanwhile, necrotic cell death by zVAD and TNFα was caused by reactive oxygen species generation and effectively diminished by lipid‐soluble butylated hydroxyanisole. Taken together, the results indicate that RIP1 and RIP3 can independently mediate death signals being transduced by two different death stimuli, zVAD and TNFα. Copyright © 2013 John Wiley & Sons, Ltd.     

便携多路环境数据采集系统

便携多路环境数据采集系统姜仕仁，常杰，葛滢（杭州大学生物科学与技术系，３１００１２）ＡＰｏｒｔａｂｌｅＭｕｌｔｉ－ＰａｓｓａｇｅＥｎｖｉｒｏｎｍｅｎｔａｌＤａｔａＡｕｔｏ－ＳａｍｐｌｉｎｇＳｙｓｔｅｍ．￥ＪｉａｎｇＳｈｉｒｅｎ；ＣｈａｎｇＪｉｅ；Ｇｅ...     

Assessing glycolytic flux alterations resulting from genetic perturbations in E. coli using a biosensor

We describe the development of an optimized glycolytic flux biosensor and its application in detecting altered flux in a production strain and in a mutant library. The glycolytic flux biosensor is based on the Cra-regulated ppsA promoter of E. coli controlling fluorescent protein synthesis. We validated the glycolytic flux dependency of the biosensor in a range of different carbon sources in six different E. coli strains and during mevalonate production. Furthermore, we studied the flux-altering effects of genome-wide single gene knock-outs in E. coli in a multiplex FlowSeq experiment. From a library consisting of 2126 knock-out mutants, we identified 3 mutants with high-flux and 95 mutants with low-flux phenotypes that did not have severe growth defects. This approach can improve our understanding of glycolytic flux regulation improving metabolic models and engineering efforts.     

Purification of a fibrolast-inhibitory factor from Actinobacillus actinomycetemcomitans Y4

Abstract A factor showing inhibitory activity against human gingival fibrolasts was extracted from the cytosol fraction of Actinobacillus actinomycetemcomitans Y4. The activity markedly inhibited the proliferation of human gingival fibrolasts, but had no effect on cell viability or gross morphology. No such activity was found in cytosol fractions from either Porphyromonas gingivalis 381 or Escherichia coli HB101. The extract from A. actinomycetemcomitans Y4 was then purified by anion-exchange chromatography, hydroxyapatite chromatography and gel-filtration chromatography to give a single band on SDS-PAGE with an apparent molecular mass of 65 kDa. The purification ratio was 183-fold with a recovery rate of 5% compared with the crude extract (starting material) when the activity was assessed by direct cell counts.     

Limited repertoire of the C-terminal region of the M protein in Streptococcus pyogenes

We have amplified genomic sequences (emm) that may encode M protein from strains of Streptococcus pyogenes using the polymerase chain reaction (PCR). Genomic DNA from 22 isolates representing 14 M serotypes was selected for the study. Primers which corresponded to the observed N-terminal signal sequence and the variable C-terminal sequences of emm6, emm49 and ennX were used. PCR products using emm6 and emm49 oligonucleotides were classified into two mutually exclusive groups which correspond to the presence or absence of serum opacity factor. These findings support the concept of limited heterogeneity in the C-terminal sequences of the M protein.