Efficient reductive amination process for enantioselective synthesis of L-phosphinothricin applying engineered glutamate dehydrogenase

Applied Microbiology and Biotechnology - The objective of this study was to identify and exploit a robust biocatalyst that can be applied in reductive amination for enantioselective synthesis of...     

Computational haemodynamics in two idealised cerebral wide-necked aneurysms after stent placement

Endovascular stents are being commonly used to treat cerebral wide-necked aneurysms recently. The effect of a stent placed in the parent artery is not only to protect the parent artery from occlusion, due to extension of coils and thrombosis, but also to act as flow diverter to vary the haemodynamics in the aneurysm. In this article, two idealised cerebral wide-necked aneurysms were created, one was sidewall aneurysm with curved parent vessel and the other was terminal aneurysm with the bifurcated parent vessel. The plexiglass models of the two aneurysms were ‘treated’ with commercial porous intravascular stents. The stented physical models were scanned by Micro-CT and the numerical models of the two idealised cerebral wide-necked aneurysms after stent placement were constructed from the scanned image files. The pulsatile flow of non-Newtonian fluid inside the models was simulated by using computational fluid dynamics package. From the simulated flow dynamics, various haemodynamic characteristics such as velocity contours, wall shear stress and oscillatory shear index (OSI) were computed. The velocity of the jet entering the sacs reduced after stent was deployed across the necks of both sidewall and terminal aneurysms; the wall shear stress on the distal neck of sidewall aneurysm reduced, the wall shear stress on the dome of the terminal aneurysm increased and the OSI on the dome of the terminal aneurysm reduced. Therefore, stent placement not only promotes thrombus formation in both aneurysm models but also reduces the regrowth risk of the sidewall aneurysm and the rupture risk of the terminal aneurysm.     

Profile and Determinants of Retinal Optical Intensity in Normal Eyes with Spectral Domain Optical Coherence Tomography

Purpose

To investigate the profile and determinants of retinal optical intensity in normal subjects using 3D spectral domain optical coherence tomography (SD OCT).

Methods

A total of 231 eyes from 231 healthy subjects ranging in age from 18 to 80 years were included and underwent a 3D OCT scan. Forty-four eyes were randomly chosen to be scanned by two operators for reproducibility analysis. Distribution of optical intensity of each layer and regions specified by the Early Treatment of Diabetic Retinopathy Study (ETDRS) were investigated by analyzing the OCT raw data with our automatic graph-based algorithm. Univariate and multivariate analyses were performed between retinal optical intensity and sex, age, height, weight, spherical equivalent (SE), axial length, image quality, disc area and rim/disc area ratio (R/D area ratio).

Results

For optical intensity measurements, the intraclass correlation coefficient of each layer ranged from 0.815 to 0.941, indicating good reproducibility. Optical intensity was lowest in the central area of retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer and photoreceptor layer, except for the retinal pigment epithelium (RPE). Optical intensity was positively correlated with image quality in all retinal layers (0.553<β<0.851, p<0.01), and negatively correlated with age in most retinal layers (-0.362<β<-0.179, p<0.01), except for the RPE (β = 0.456, p<0.01), outer nuclear layer and photoreceptor layer (p>0.05). There was no relationship between retinal optical intensity and sex, height, weight, SE, axial length, disc area and R/D area ratio.

Conclusions

There was a specific pattern of distribution of retinal optical intensity in different regions. The optical intensity was affected by image quality and age. Image quality can be used as a reference for normalization. The effect of age needs to be taken into consideration when using OCT for diagnosis.     

猪肌肉组织Col3a1基因表达的发育性变化及其对肌内胶原特性的影响

以30—90妇体重莱芜猪和40—100kg体重鲁莱黑猪共84头去势公猪为试验对象（每组6头）,采用相对定量RT-PCR方法,以β-actin作为内标,研究肌肉中编码Ⅲ型胶原的Col3al基因表达的发育性变化及其对肌肉中胶原蛋白含量和性质（溶解度）的影响。结果表明：研究的两个品种猪肌肉中Col3al基因表达的发育性变化基本一致,即随体重的增加,肌肉中Col3al mRNA表达呈逐渐增加趋势,但莱芜猪和鲁莱黑猪分别在70妇和80妇体重组表达量略有下降。总体上莱芜猪肌肉组织Col3al mRNA表达丰度显著高于鲁莱黑猪（P〈0．05）。相关分析表明,莱芜猪肌肉组织Col3al mRNA表达的发育性变化与总胶原和不溶性胶原含量呈极显著正相关（P〈0．01）,与胶原溶解度呈极显著负相关（P〈0．01）。鲁莱黑猪肌肉组织Col3al mRNA表达的发育性变化与不溶性胶原和胶原溶解度分别呈显著正相关和负相关妒〈0．05）。研究结果提示：猪肌肉组织中Col3al基因表达具有明显的体重发育和品种特征,其mRNA表达对于肌内胶原的含量和性质有重要影响。     

Attenuation of fibrosis <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> with <Emphasis Type="Italic">SPARC</Emphasis> siRNA

Introduction  

SPARC is a matricellular protein, which, along with other extracellular matrix components including collagens, is commonly over-expressed in fibrotic diseases. The purpose of this study was to examine whether inhibition of SPARC can regulate collagen expression in vitro and in vivo, and subsequently attenuate fibrotic stimulation by bleomycin in mouse skin and lungs.     

Electrochemical sensing DNA damage with nano-titanium dioxide and repair with a medicinal herb species resveratrol

We have developed a simple electrochemical method to detect DNA damage caused by the photovoltaic effect of nano-TiO(2). Meanwhile, we have found that resveratrol, a Chinese Traditional Medicinal Herb species, can have a repairing effect to the oxidized DNA, which can also be detected with the proposed technique in this paper.     

Cutting edge: primary B lymphocytes preferentially expand allogeneic FoxP3+ CD4 T cells

Despite the unequivocal role of B lymphocytes as effecter cells in humoral immunity, studies have reported that B cells are tolerogenic. The impact of B cell-mediated tolerance and its underlying mechanisms are incompletely understood. Using primary B cells as APCs and allogeneic CD4 T cells as responder cells in mixed leukocyte reactions, we find that B cells preferentially expand FoxP3(+) over FoxP3(-) CD4 T cells in the absence of exogenous cytokines. The preferential expansion of Foxp3(+) T cells is further enhanced by a partial blockade of class II MHC-TCR interaction but diminished by stimulatory anti-CD28 Ab or at high B to T cell ratios. Gamma irradiation of B cells selectively abrogates their ability to expand isolated CD25(+) but not CD25(-) CD4 T cells; exogenous IL-2 supplement can partially restore this function. B cell-expanded CD25(+) T cells express high levels of FoxP3 and are highly inhibitory in an Ag-specific manner.     

Body Weight-Supported Treadmill Training Ameliorates Motoneuronal Hyperexcitability by Increasing GAD-65/67 and KCC2 Expression via TrkB Signaling in Rats with Incomplete Spinal Cord Injury

Neurochemical Research - Spasticity is a typical consequence after spinal cord injury (SCI). The critical reasons are reducing the synthesis of Gamma-Aminobutyric Acid (GABA), glycine and potassium...     

Methyl-CpG-Binding Domain Protein MBD7 Is Required for Active DNA Demethylation in Arabidopsis

Although researchers have established that DNA methylation and active demethylation are dynamically regulated in plant cells, the molecular mechanism for the regulation of active DNA demethylation is not well understood. By using an Arabidopsis (Arabidopsis thaliana) line expressing the Promoter RESPONSIVE TO DEHYDRATION 29A:LUCIFERASE (ProRD29A:LUC) and Promoter cauliflower mosaic virus 35S:NEOMYCIN PHOSPHOTRANSFERASE II (Pro35S:NPTII) transgenes, we isolated an mbd7 (for methyl-CpG-binding domain protein7) mutant. The mbd7 mutation causes an inactivation of the Pro35S:NPTII transgene but does not affect the expression of the ProRD29A:LUC transgene. The silencing of the Pro35S:NPTII reporter gene is associated with DNA hypermethylation of the reporter gene. MBD7 interacts physically with REPRESSOR OF SILENCING5/INCREASED DNA METHYLATION2, a protein in the small heat shock protein family. MBD7 prefers to target the genomic loci with high densities of DNA methylation around chromocenters. The Gypsy-type long terminal repeat retrotransposons mainly distributed around chromocenters are most affected by mbd7 in all transposons. Our results suggest that MBD7 is required for active DNA demethylation and antisilencing of the genomic loci with high densities of DNA methylation in Arabidopsis.DNA methylation is an important epigenetic marker for genome stability and the regulation of gene expression in both plants and animals (Law and Jacobsen, 2010; He et al., 2011). In plants, the molecular mechanisms for DNA methylation have been well characterized by the use of powerful genetic screening systems (Bartee et al., 2001; Lindroth et al., 2001; Matzke et al., 2004; He et al., 2009). A transgene or an endogenous gene may be silenced because of DNA hypermethylation in the promoter region. Screenings for mutants with release of the silenced marker genes have identified many components that are involved in RNA-directed DNA methylation (RdDM) and in maintaining DNA methylation (Matzke and Birchler, 2005; Law and Jacobsen, 2009; He et al., 2011; Bender, 2012). DNA methylation is catalyzed by DNA methyltransferases including DNA METHYLTRANSFERASE1 (MET1) and CHROMOMETHYLASE3 (CMT3), which maintain symmetric CG and CHG methylation, respectively, during DNA replication, and DOMAINS REARRANGED METHYLASE2 (DRM2) and CMT2, which are required for establishing CHG and asymmetric CHH methylation during each cell cycle. DRM2 also catalyzes CG methylation (Law and Jacobsen, 2010; Haag and Pikaard, 2011; He et al., 2011; Zemach et al., 2013; Stroud et al., 2014). Twenty-four-nucleotide small RNAs produced through the RdDM pathway target genomic regions to guide the establishment of DNA methylation by DRM2 (Cao et al., 2003).DNA methylation can be actively removed by a subfamily of bifunctional DNA glycosylases/lyases including REPRESSOR OF SILENCING1 (ROS1; Gong et al., 2002) and its paralogs DEMETER and DEMETER-LIKE2/3 (Gehring et al., 2006; Ortega-Galisteo et al., 2008). DNA methylation can also be passively lost during DNA replication when DNA methylation cannot be maintained (Zhu, 2009). Promoter RESPONSIVE TO DEHYDRATION 29A:LUCIFERASE (ProRD29A:LUC) in the ProRD29A:LUC/Promoter cauliflower mosaic virus 35S:NEOMYCIN PHOSPHOTRANSFERASE II (Pro35S:NPTII) transgenic Arabidopsis (Arabidopsis thaliana) line has been used as a marker to identify ros1 and ros3 mutants in which both ProRD29A:LUC and Pro35S:NPTII are silenced (Gong et al., 2002; Zheng et al., 2008). ROS3 is an RNA-binding protein that facilitates the function of ROS1 in active DNA demethylation at certain genomic loci. Using Pro35S:NPTII as a selection marker for kanamycin-sensitive mutants and the 35S-SUC2 transgene or a chop PCR marker for assaying DNA methylation at the 3′ region of At1g26400 from transfer DNA (T-DNA) insertion mutants, researchers recently identified two genes involved in active DNA demethylation: ROS4/INCREASED DNA METHYLATION1 (IDM1) and ROS5/IDM2 (Li et al., 2012; Qian et al., 2012, 2014; Zhao et al., 2014). ROS4/IDM1 is a plant homeodomain-finger domain-containing histone acetyltransferase that catalyzes histone H3 lysine18 (H3K18) and lysine23 (H3K23) acetylation (Li et al., 2012; Qian et al., 2012). ROS5/IDM2 is a member of the small heat shock protein family that interacts physically with ROS4/IDM1 for the regulation of active DNA demethylation. Genetic analysis indicates that ROS1, ROS4/IDM1, and ROS5/IDM2 are in the same genetic pathway and that ROS4/IDM1 and ROS5/IDM2 may form a protein complex for the regulation of active DNA demethylation (Qian et al., 2014; Zhao et al., 2014).During the genetic screening for kanamycin-sensitive mutants using the ProRD29A:LUC/Pro35S:NPTII transgenic line in this study, we identified another mutant, mbd7, where the Pro35S:NPTII transgene is specifically silenced. MBD7 is a methyl-CpG-binding domain (MBD) protein containing three MBD motifs that bind in vitro to methylated symmetric CG sites. MBD7 localizes to all highly CpG-methylated chromocenters in vivo (Zemach and Grafi, 2003; Zemach et al., 2008). Recruitment of MBD7 to chromocenters is disrupted in decrease in DNA methylation1 (ddm1) and met1, two mutants with great reductions in DNA methylation, suggesting that DNA methylation is required for proper MBD7 localization (Zemach et al., 2005). In this study, we found that MBD7 interacts physically with ROS5/IDM2 and is required for the active DNA demethylation of certain genomic loci, especially for the Gypsy-type long terminal repeat (LTR) retrotransposons with high densities of DNA methylation around chromocenters in Arabidopsis.