蹲跳、反向跳和下落跳的膝关节屈伸肌群肌电信号分析

目的：通过观察肌电图（EMG）的变化,了解运动员与普通中学生在纵跳过程中,膝关节屈伸肌群工作特点,为运动员科学选材提供依据。方法：30名男女青少年运动员和30名男女普通中学生进行各种形式纵跳（蹲跳、反向跳、下落跳）,测试膝关节屈伸肌群的EMG变化情况。结果：主动肌（股外肌）EMG的变化存在性别差异,随着下肢工作强度的增加,男运动员积分肌电图（iEMG)和平均功率频率（Fmean)均没有显著变化,女运动员iEMG增加,Fmean没有显著变化,对抗肌（股二头肌）,随着下肢工作强度的增加。青少年运动员EMG活动变化较小,而普通中学生的EMG活动明显增加。结论：在增加工作负荷的过程中,男运动员膝关节伸肌群以提高效率为主,女运动员以提高肌肉的募集数量为主;运动员的对抗肌协调水平高于普通中学生。     

广东金山温泉沉积物中原核与真核微生物多样性初步分析

[目的]本研究旨在采用不同的PCR引物对广东省恩平市金山温泉的高温水底沉积物微生物多样性进行初步的分析.[方法]采用改进的玻璃珠法抽提温泉沉积物中环境基因组DNA,通过对用4对引物分别扩增得到的原核微生物16S rRNA基因和真核微生物ITS序列的分析,将所得到的数据与国际基因数据库GenBank进行相似性比较并构建系统发育树.[结果]研究发现原核类群G的 14个优势克隆中7个都属于蛭弧菌属(Bdellovibrio).与它们最相似的序列是从海洋中分离到的两个菌株 Bacteriovorax sp. NE1 (EF092445)和Bdellovibrio sp. JS5 (AF084859),相似性分别为96%和99%.原核类群X的4个序列主要属于蓝细菌类群,其中JS-X2与在美国黄石公园温泉发现的Uncultured Cyanobacterium (L35331)有95%的相似性,并且与已经全基因组测序的嗜热蓝细菌聚球藻Thermosynechococcus elongatus BP-1 (47118315)有89%的相似性.真核类群Z有三个类群,分别是Penicillium sp.,Lodderomyces sp.和Gloeotinia sp..其中大部分序列与青霉属相似性在88%～ 90%之间.[结论]所得到的结果显示金山温泉中的微生物多样性十分丰富.     

Microsatellite mapping of a Triticum urartu Tum. derived powdery mildew resistance gene transferred to common wheat (Triticum aestivum L.)

A powdery mildew resistance gene from Triticum urartu Tum. accession UR206 was successfully transferred into hexaploid wheat (Triticum aestivum L.) through crossing and backcrossing. The F₁ plants, which had 28 chromosomes and an average of 5.32 bivalents and 17.36 univalents in meiotic pollen mother cells (PMC), were obtained through embryos rescued owing to shriveling of endosperm in hybrid seed of cross Chinese Spring (CS) × UR206. Hybrid seeds were produced through backcrossing F₁ with common wheat parents. The derivative lines had normal chromosome numbers and powdery mildew resistance similar to the donor UR206, indicating that the powdery mildew resistance gene originating from T. urartu accession UR206 was successfully transferred and expressed in a hexaploid wheat background. Genetic analysis indicated that a single dominant gene controlled the powdery mildew resistance at the seedling stage. To map and tag the powdery mildew resistance gene, 143 F₂ individuals derived from a cross UR206 × UR203 were used to construct a linkage map. The resistant gene was mapped on the chromosome 7AL based on the mapped microsatellite makers. The map spanned 52.1 cM and the order of these microsatellite loci agreed well with the established microsatellite map of chromosome arm 7AL. The resistance gene was flanked by the microsatellite loci Xwmc273 and Xpsp3003, with the genetic distances of 2.2 cM and 3.8 cM, respectively. On the basis of the origin and chromosomal location of the gene, it was temporarily designated PmU.     

Immunomodulation and antitumor activities of different-molecular-weight polysaccharides from Porphyridium cruentum

The extracellular polysaccharides (EPSs) isolated from Porphyridium cruentum were degraded by hermetical-microwave and H₂O₂ under ultrasonic waves. Six products were obtained with molecular weights of 6.53, 256, 606, 802.6, 903.3 and 1002 kDa. The antitumor and immunomodulatory activities of different-molecular-weight (MW) polysaccharides were evaluated by the S180-tumor-bearing mouse model in vivo and peritoneal macrophage activation in vitro. The degraded EPSs all showed clear immunomodulation to different extents. The MW of the EPSs had a notable effect on their activity. The 6.53-kDa fragment had the strongest immunoenhancing activity. Different doses of EPS all inhibited the growth of the implanted S180 tumor. The tumor inhibition index at high, middle and low doses was 53.3%, 47.5% and 40.5%, respectively. In addition, three different concentrations of EPS significantly increased lymphocyte proliferation, which indicated the unique mechanism of the antitumor effect of EPS.     

Dopamine-related and caspase-independent apoptosis in dopaminergic neurons induced by overexpression of human wild type or mutant alpha-synuclein

Human wild type (WT) and mutant alpha-synuclein (alpha-syn) genes were overexpressed using a Tet-on expression system in stably transfected dopaminergic MN9D cells. Their overexpression induced caspase-independent and dopamine-related apoptosis not rescued by general caspase inhibitor Z-VAD-FMK. While apoptosis due to overexpression of WT alpha-syn was completely abrogated by a specific tyrosine hydroxylase (TH) inhibitor, alpha-methyl-p-tyrosine (alpha-MT), the inhibitor only partially rescued apoptosis caused by overexpression of alpha-syn mutants. In addition, overexpression of mutants enhanced the toxicity of 1-methyl-4-phenylpyridinium (MPP+) and 6-hydroxyldopamine (6-OHDA) to MN9D cells, whereas overexpression of WT protected MN9D cells against MPP+ toxicity, but not against 6-OHDA. We conclude that WT alpha-syn is beneficial to dopaminergic neurons but its overexpression in the presence of endogenous dopamine makes it a potential threat to the cells. In contrast, mutant alpha-syn not only caused the loss of WT protective function but also the gain-of-toxicity which becomes more serious in the presence of dopamine and neurotoxins.     

Kinetic analysis of the zinc-dependent deacetylase in the lipid A biosynthetic pathway

The first committed step of lipid A biosynthesis in Gram-negative bacteria is catalyzed by the zinc-dependent hydrolase LpxC that removes an acetate from the nitrogen at the 2' '-position of UDP-3-O-acyl-N-acetylglucosamine. Recent structural characterization by both NMR and X-ray crystallography provides many important details about the active site environment of LpxC from Aquifex aeolicus, a heat-stable orthologue that displays 32% sequence identity to LpxC from Escherichia coli. The detailed reaction mechanism and specific roles of active site residues for LpxC from A. aeolicus are further analyzed here. The pH dependencies of k(cat)/K(M) and k(cat) for the deacetylation of the substrate UDP-3-O-[(R)-3-hydroxymyristoyl]-GlcNAc are both bell-shaped. The ascending acidic limb (pK(1)) was fitted to 6.1 +/- 0.2 for k(cat) and 5.7 +/- 0.2 for k(cat)/K(M). The descending basic limb (pK(2)) was fitted to 8.0 +/- 0.2 for k(cat) and 8.4 +/- 0.2 for k(cat)/K(M). The pH dependence of the E73A mutant exhibits loss of the acidic limb, and the mutant retains only 0.15% activity versus the wild type. The pH dependencies of the other active site mutants H253A, K227A, H253A/K227A, and D234N remain bell-shaped, although their significantly lower activities (0.25%, 0.05%, 0.007%, and 0.57%, respectively) suggest that they contribute significantly to catalysis. Our cumulative data support a mechanism for LpxC wherein Glu73 serves as the general base for deprotonation and activation of the zinc-bound water.     

Viral tegument proteins restrict cGAS-DNA phase separation to mediate immune evasion

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Bioactive thin film of acidic fibroblast growth factor fabricated by layer-by-layer assembly

A new class of bioactive thin films using growth factors as building blocks has been fabricated via layer-by-layer assembly (LBL) technique. Acid fibroblast growth factor (aFGF) in the presence of heparin was used as negatively charged polyelectrolytes, while poly(ethyleneimine) (PEI) was chosen as a positively charged counterpart. The self-deposition process and surface morphology of the resultant multilayers were monitored and detected by UV-vis absorbance spectra, advanced contact angle measurements, and scanning force microscopy (SFM) observations. Cell culture was performed to assess the efficiency of the growth factors. The fibroblasts proliferated faster on the surface assembled with five bilayers of (aFGF/heparin)/PEI with apparent higher cytoviability than on those surfaces modified by one bilayer of (aFGF/heparin)/PEI, five bilayers of aFGF/PEI, or five bilayers of heparin/PEI, and tissue culture polystyrene. Enhanced secretion of collagen type I and interleukin 6 (IL-6) by the fibroblasts seeded on the five bilayers of (aFGF/heparin)/PEI was also verified by immunohistochemical examination. The bioactivity of the (aFGF/heparin)/PEI multilayers could be largely preserved when stored at -20 degrees C.