神经生长因子介导的促神经生长化合物筛选系统的建立

为了合理评价化合物的促神经再生活性.用溴化四唑蓝(MTT)、分化计数、图象处理等方法，借助FK506、GPI1046阳性化合物，建立了一个基于PC12细胞存活和分化的化合物筛选系统.结果表明，无论在细胞存活实验还是在分化实验中，FK506、GPI1046都可以明显增强神经生长因子(NGF)的效应，即有促神经再生的作用.也就是说，这一系统将有助于从组合化学方法合成的化合物文库中，筛选出具有促神经再生活性的化合物.     

The AMPA Receptor Subunit GluA1 is Required for CA1 Hippocampal Long-Term Potentiation but is not Essential for Synaptic Transmission

AMPA receptors mediate the majority of excitatory glutamatergic transmission in the mammalian brain and are heterotetramers composed of GluA1-4 subunits. Despite genetic studies, the roles of the subunits in synaptic transmission and plasticity remain controversial. To address this issue, we investigated the effects of cell-specific removal of GluA1 in hippocampal CA1 pyramidal neurons using virally-expressed GluA1 shRNA in organotypic slice culture. We show that this shRNA approach produces a rapid, efficient and selective loss of GluA1, and removed?>?80% of surface GluA1 from synapses. This loss of GluA1 caused a modest reduction (up to 57%) in synaptic transmission and when applied in neurons from GluA3 knock-out mice, a similar small reduction in transmission occurred. Further, we found that loss of GluA1 caused a redistribution of GluA2 to synapses that may compensate functionally for the absence of GluA1. We found that LTP was absent in neurons lacking GluA1, induced either by pairing or by a theta-burst pairing protocol previously shown to induce LTP in GluA1 knock-out mice. Our findings demonstrate a critical role of GluA1 in CA1 LTP, but no absolute requirement for GluA1 in maintaining synaptic transmission. Further, our results indicate that GluA2 homomers can mediate synaptic transmission and can compensate for loss of GluA1.

     

Physiological and regulatory characterization of KatA and KatY in Yersinia pestis

The catalase or catalase-peroxidase activity commonly exists in many pathogens and plays an important role in resisting the oxidative burst of phagocytes helping the pathogen persistently colonize in the host. Yersinia pestis is a facultative pathogen and the causative agent of plague. KatY has been identified as a thermosensing antigen with modest catalase activity in this pathogen. Here Y. pestis KatA and KatY were experimentally confirmed as a monofunctional catalase and bifunctional catalase-peroxidase, respectively. Their expression induced by H2O2 was proven to be mediated by the oxidative regulator, OxyR. Expression of KatA changed with growth phases and was crucial to its traditional physiological role in protecting Y. pestis cells against toxicity of exogenous H2O2. KatY was regulated by temperature and H2O2, two major elements of phagolysosomal microenvironments. Consistent with the above results, gene expression of katY increased significantly during intracellular growth of Y. pestis compared with that in vitro growth. However, a DeltakatY mutant was fully virulent to mice, suggesting that KatY is not required for Y. pestis virulence.     

Effects of culture conditions on osteogenic differentiation in human mesenchymal stem cells

Human bone marrow-derived mesenchymal stem cells (hBMMSCs) must differentiate into osteogenic cells to allow for successful bone regeneration. In this study, we investigated the effects of different combinations of three soluble osteogenic differentiation-inducing factors [L-ascorbic acid (AC), beta-glycerophosphate (betaG), and bone morphogenic protein-2 (BMP-2)] and the presence of a hydroxyapatite (HA) substrate on hBMMSC osteogenic differentiation in vitro. hBMMSCs were cultured in medium containing various combinations of the soluble factors on culture plates with or without HA coating. After 7 days of culture, alkaline phosphatase (ALP) activity, calcium deposition, and osteoprotegerin (OPG) and osteopontin (OPN) expression were measured. The effects of individual and combined factors were evaluated using a factorial analysis method. BMP-2 predominantly affected expression of early markers of osteogenic differentiation (ALP and OPG). HA had the highest positive effect on OPN expression and calcium deposition. The interaction between AC, betaG, and HA had the second highest positive effect on ALP activity.     

PConPy--a Python module for generating 2D protein maps

PConPy is an open-source Python module for generating protein contact maps, distance maps and hydrogen bond plots. These maps can be generated in a number of publication-quality vector and raster image formats. Contact maps can be annotated with secondary structure and hydrogen bond assignments. PConPy offers a more flexible choice of contact definition parameters than existing toolkits, most notably a greater choice of inter-residue distance metrics. PConPy can be used as a stand-alone application or imported into existing source code. A web-interface to PConPy is also available for use. AVAILABILITY: The PConPy web-interface and source code can be accessed from its website at http://www.csse.unimelb.edu.au/~hohkhkh1/pconpy/. CONTACT: hohkhkh1@csse.unimelb.edu.au     

恶性肿瘤组织中结核杆菌DNA的检测

目的　探讨结核杆菌感染与恶性肿瘤的关系。方法　采用多聚酶链反应（ＰＣＲ） 技术检测两种恶性肿瘤组织中结核杆菌ＤＮＡ（ＴＢ－ ＤＮＡ） 。结果４１ 例恶性肿瘤组织中检出ＴＢ－ ＤＮＡ 阳性患者８ 例,占１９．５ ％ ,且ＴＢ－ＤＮＡ 阳性患者肿瘤发病部位基本与结核病的好发部位一致。结论 结核杆菌感染可能与一些恶性肿瘤存在特殊相关性。     

Phytoplankton biomass and production in northern South China Sea during summer: Influenced by Pearl River discharge and coastal upwelling

Chlorophyll a and primary production were studied in northern South China Sea during summer from 2007 to 2008. Microplankton dominated total phytoplankton biomass in the coast, while picoplankton dominated in the offshore. Algae bloom caused by Thalassionema nitzschioides was found at the subsurface of upwelling regions (D2, C2) in 2008, and maximum of phytoplankton abundance reached 1.58 × 10⁶ ind L^?1. Integrated primary production ranged from 189.3 to 976.2 mg m^?2 d^?1 in 2007, and ranged from 652.1 to 6601 mg m^?2 d^?1 in 2008. PP showed positive relationship with IPP (p < 0.01) and negative relationship with SST (p < 0.05). Coastal upwelling and Pearl River discharge sustained high PP, and played important role in regulating the phytoplankton biomass and production.