Bone marrow-derived stem cells contribute skin regeneration in skin and soft tissue expansion

Skin and soft tissue expansion stimulates the proliferation of skin epidermal basal cells and increase the dermal collagen deposition and angiogenesis. To explore the contribution of bone marrow‐derived stem cells (BMSCs) to the generation of “new” skin during the expansion, we used a chimeric mouse model in which the donor C57BL mice were engrafted with the bone marrow of enhanced green fluorescent protein (EGFP) transgenic mice. BMSCs were collected from the tibia and femur of EGFP⁺ transgenic mice, and then injected into normal C57BL mice via the tail vein (chimeric mice). Skin was obtained at different times (days 0, 7, 14, 21, 28, and 35). Skin stromal‐derived factor‐1 (SDF‐1) expression was evaluated. The number, distribution, and phenotype changes of EGFP⁺ cells in the skin were also evaluated by means of fluorescent microscopy. EGFP⁺ cells were present stably in the normal skin. The number of EGFP⁺ cells of the Group A mice changed with the tension, and reached the peak on day 21(17.1 ± 6.7%), as compared with either Group B (5.5 ± 1.0%) or Group C (5.1 ± 0.9%). The SDF‐1 expression in the expanded skin was significant increased (≈11‐fold, P < 0.01) compared to non‐expanded skin on day 21. Immunofluorescence showed EGFP⁺ cells were converted into vascular endothelial cells, epidermal cells, and spindle‐shaped dermal fibroblasts. Strain can promote the expression of SDF‐1 and facilitate the differentiation and proliferation of BMSCs in the expanded skin. J. Cell. Physiol. 226: 2834–2840, 2011. © 2011 Wiley‐Liss, Inc.     

The mechanism of myoblast deformation in response to cyclic strain - A cytomechanical study

Mechanical strain is one of the important epigenetic factors that cause deformation and differentiation of skeletal muscles. This research was designed to investigate how myoblast deformation occurs after cyclic strain loading. Myoblasts were passaged three times and harvested; various cyclic strains (2.5kPa, 5kPa and 10kPa) were then loaded using a pulsatile mechanical system. The adaptive response of the myoblasts was observed at different time points (0.5h, 1h, 6h and 12h) post-loading. At the early stage of cyclic strain loading (<1h), almost no visible morphological changes were observed in the myoblasts. The actin cytoskeleton showed a disordered arrangement and a weak fluorescence expression; there was little expression of talin. At 6h and 12h post-loading, the myoblasts changed their orientation to parallel (in the 2.5kPa and 5kPa groups) or perpendicular (in the 10kPa group) to the direction of strain. Fluorescence expression of both the actin cytoskeleton and talin was significantly increased. The results suggest that cyclic strain has at least two ways to regulate adaptation of myoblasts: (1) by directly affecting actin cytoskeleton at an early stage post-loading to cause depolymerization; and (2) by later chemical signals transmitted from the extracellular side to intracellular side to initiate repolymerization.     

血清S-100B蛋白和NSE含量变化评估脑损伤程度的意义

目的探讨颅脑损伤后血清S-100B蛋白、神经元特异性烯醇化酶(NSE)水平变化及其在损伤程度的临床意义。方法采用酶联免疫测定法检测90例颅脑损伤患者入院时及入院后6、12、24h和3、7天血清S-100B蛋白、NSE水平,并分析其与颅脑损伤严重程度的关系。同时选择30例健康体检者作为对照组进行比较分析。结果颅脑损伤后血清S-100B蛋白、NSE水平较对照组明显升高(P0.05或P0.01);重型组患者的血清S-100B蛋白和NSE水平明显高于轻、中型组患者(P0.05或P0.01);动态检测结果显示,血清S-100B蛋白在伤后12h达峰值(P0.05),NSE含量在伤后24h达峰值(P0.05),然后缓慢下降。GCS评分与S-100B、NSE浓度呈负相关(分别为r=-0.814,P0.01;r=-0.726,P0.05)。结论颅脑损伤后血清S-100B蛋白、NSE水平升高,其与脑损伤程度有较好的相关性,2种标记物水平对颅脑损伤程度有较高的评估价值。     

人胎盘滋养层细胞培养与体外hCG释放的研究

本研究的目的是了解细胞滋养层细胞和合胞体滋养层细胞体外分化和生物学特性。方法:采用酶消化和Percoll密度梯度离心法,对人足月胎盘细胞滋养层细胞进行分离、纯化和体外培养。采用放射免疫法(RIA)检测细胞培养上清液hCG含量的变化。结果:经分离和纯化的细胞滋养层细胞在体外培养中生长良好,通过细胞分裂和融合形成合胞体滋养层细胞,随着合胞体滋养层细胞的生长,细胞培养上清液中hCG含量显著升高。我们认为从胎盘中分离和纯化的细胞滋养层细胞在体外培养中可分化和融合形成合胞体滋养层细胞,体外hCG含量的增加与合胞体滋养层细胞生长有关。     

Genome-wide regulation of 5hmC, 5mC, and gene expression by Tet1 hydroxylase in mouse embryonic stem cells

DNA methylation at the 5 position of cytosine (5mC) in the mammalian genome is a key epigenetic event critical for various cellular processes. The ten-eleven translocation (Tet) family of 5mC-hydroxylases, which convert 5mC to 5-hydroxymethylcytosine (5hmC), offers a way for dynamic regulation of DNA methylation. Here we report that Tet1 binds to unmodified C or 5mC- or 5hmC-modified CpG-rich DNA through its CXXC domain. Genome-wide mapping of Tet1 and 5hmC reveals mechanisms by which Tet1 controls 5hmC and 5mC levels in mouse embryonic stem cells (mESCs). We also uncover a comprehensive gene network influenced by Tet1. Collectively, our data suggest that Tet1 controls DNA methylation both by binding to CpG-rich regions to prevent unwanted DNA methyltransferase activity, and by converting 5mC to 5hmC through hydroxylase activity. This Tet1-mediated antagonism of CpG methylation imparts differential maintenance of DNA methylation status at Tet1 targets, ultimately contributing to mESC differentiation and the onset of embryonic development.     

铁皮石斛腋芽的快速繁殖

目的利用组织培养技术建立铁皮石斛的高效快繁体系,克隆繁殖种苗,为野生居群的恢复提供材料。方法以铁皮石斛腋芽为外植体,研究不同浓度和配比的基本培养基、激素以及天然提取物对腋芽萌发生长,丛生芽的诱导增殖以及壮苗生根的影响,比较不同培养阶段的增殖倍数,筛选各时期的最适培养基。并对试管苗的形态学特征进行了调查。结果1/2MS+NAA 0.2 mg/L+BA 1 mg/L适合腋芽的成活生长。BA与香蕉汁组合有利于丛生芽的诱导增殖,其最适比例为1/2MS+NAA 0.5 mg/L+BA 2.0 mg/L+香蕉汁100 g/L,增殖倍数最大可达14.0,平均增殖倍数为6.4。培养基中添加100 g/L香蕉汁或200 g/L马铃薯汁均有利于壮苗生根。结论铁皮石斛通过腋芽形成丛生芽途径建立高效的快繁技术体系获得优质种苗是可行的。     

Biochemical characterization of indole prenyltransferases: filling the last gap of prenylation positions by a 5-dimethylallyltryptophan synthase from Aspergillus clavatus

The putative prenyltransferase gene ACLA_031240 belonging to the dimethylallyltryptophan synthase superfamily was identified in the genome sequence of Aspergillus clavatus and overexpressed in Escherichia coli. The soluble His-tagged protein EAW08391 was purified to near homogeneity and used for biochemical investigation with diverse aromatic substrates in the presence of different prenyl diphosphates. It has shown that in the presence of dimethylallyl diphosphate (DMAPP), the recombinant enzyme accepted very well simple indole derivatives with L-tryptophan as the best substrate. Product formation was also observed for tryptophan-containing cyclic dipeptides but with much lower conversion yields. In contrast, no product formation was detected in the reaction mixtures of L-tryptophan with geranyl or farnesyl diphosphate. Structure elucidation of the enzyme products by NMR and MS analyses proved unequivocally the highly regiospecific regular prenylation at C-5 of the indole nucleus of the simple indole derivatives. EAW08391 was therefore termed 5-dimethylallyltryptophan synthase, and it filled the last gap in the toolbox of indole prenyltransferases regarding their prenylation positions. K(m) values of 5-dimethylallyltryptophan synthase were determined for L-tryptophan and DMAPP at 34 and 76 μM, respectively. Average turnover number (k(cat)) at 1.1 s(-1) was calculated from kinetic data of L-tryptophan and DMAPP. Catalytic efficiencies of 5-dimethylallyltryptophan synthase for L-tryptophan at 25,588 s(-1)·M(-1) and for other 11 simple indole derivatives up to 1538 s(-1)·M(-1) provided evidence for its potential usage as a catalyst for chemoenzymatic synthesis.     

Selection of aptamers against inactive Vibrio alginolyticus and application in a qualitative detection assay

Aptamers against inactive Vibrio alginolyticus were selected from an 82-nt ssDNA random library by systematic evolution of ligands by exponential enrichment. After 15 rounds of selection, the final pool of aptamers was highly specific for inactivated V. alginolyticus and had a dissociation constant of 27.5 ± 9.2 nM. Using these aptamers and PCR, V. alginolyticus could be detected at 100 cells/ml. Sequencing of the final pool of aptamers revealed that some sequences, termed high-frequency aptamers, appeared more than once; these may be of practical application. All sequences obtained were divided into nine families according to their homology tree, some conserved sequences were also found in each of the six families. One sequence was found in significant proportions of the aptamers, suggesting that this conserved sequence might be important for forming the three-dimensional aptamer structure.     

对人肠道病毒及其感染的再认识

长期以来,由于人肠道病毒种类众多,以隐性感染为主,引起的疾病症状从轻到重、表现多样,病原检测手段有限等原因,人们对人肠道病毒及其感染的基础与临床研究缺乏全面了解和认识。随着病毒学、分子生物学等技术的发展,特别是近年来各国频发人肠道病毒所致手足口病的流行,有必要对其及所致疾病再认识。     

CTSB promotes porcine preadipocytes differentiation by degrading fibronectin and attenuating the Wnt/β-catenin signaling pathway

The process of preadipocytes differentiation plays a vital role in adipose tissue expansion and many factors are involved in this event. Cathepsin B (CTSB), secreted from lysosome, has been reported in regulating a variety of physiological processes. In this study, we demonstrated CTSB promotes lipid accumulation and adipogenic genes expression in porcine primary preadipocytes by degrading fibronectin (Fn), a key component of extracellular matrix. Lithium chloride (LiCl) is an activator of Wnt/β-catenin signaling through stabilizing β-catenin. We found that CTSB can relieve the anti-adipogenic effects of LiCl, indicating that CTSB could impact Wnt/β-catenin signaling pathway. Interestingly, Fn is an important target gene of Wnt/β-catenin. So we considered that CTSB promote preadipocytes differentiation by suppressing these two pathways.