生物组织散射元平均间距估计的一种新方法

生物组织散射元平均间中划描述生物组织微观结构特性和生物组织超微散射特性的重要参数。本文在对生物组织超声背向散射随机模的基础上,提出了基于生物组织超声背向散射信号突变点检测的工用射元平均间距估计的新方法。该方法是生物组织超声散射分析的有效方法。     

中国濒危兽类栖息地评估与保护研究进展与展望

目前全球物种正以前所未有的速度灭绝,对野生动物栖息地开展有效的评估与科学的保护是阻止濒危物种走向灭绝,保持其可持续生存与发展的重要前提和手段。本文针对我国的食肉类、有蹄类、灵长类、小型兽类、海洋兽类5个类别的濒危兽类,综述了其栖息地评估与保护研究进展的现状和成果,对相关学术成果进行了归纳与分析,以期为栖息地的科学保护与管理梳理出系统、可供借鉴的研究方法和技术手段,并对其理论和技术的挑战进行了展望,提出了我国濒危兽类栖息地评估和保护研究应走向整体化、定量化、智能化,以及多学科交叉融合应用的“精准化”发展方向,为国家生态建设工程的有效实施提供重要技术支撑。     

Reduced β2-GPI is associated with increased platelet aggregation and activation in patients with prolonged isolated thrombocytopenia after allo-HSCT

We aimed to measure platelet function and its relationship with β2-GPI in prolonged isolated thrombocytopenia(PT) after allogeneic hematopoietic stem cell transplantation(allo-HSCT). Fifty-six patients with PT and 60 allo-HSCT recipients without PT(non-PT controls) were enrolled. Platelet aggregation and activation, β2-GPI and anti-β2-GPI antibody levels, vWF antigen,and vWF activity were analyzed. The effect of β2-GPI on platelet aggregation was also measured ex vivo. Results showed that ADP-induced platelet aggregation significantly increased(39%±7.5% vs. 23%±8.5%, P=0.032), and the platelet expression of both CD62 p(33.6%±11.6% vs. 8.5%±3.5%, P0.001) and PAC-1(42.4%±7.6% vs. 6.8%±2.2%, P0.001) was significantly higher in patients with PT than in those without PT. Significantly lower β2-GPI levels(164.2±12 μg m L–1 vs. 234.2±16 μg mL–1,P0.001), higher anti-β2-GPI IgG levels(1.78±0.46 U mL–1 vs. 0.94±0.39 U mL–1, P0.001), and increased vWF activity(133.06%±30.50% vs. 102.17%±25.90%, P0.001) were observed in patients with PT than in those without PT. Both ADPinduced platelet aggregation(n=116, r~2=-0.5042, P0.001) and vWF activity(n=116, r~2=-0.2872, P0.001) were negatively correlated with β2-GPI levels. In summary, our data suggested that platelet aggregation and activation were significantly higher in patients with PT than in those without PT, which might be associated with reduced β2-GPI levels. The reduced β2-GPI levels might be due to the existence of anti-β2-GPI IgG.     

慢病毒载体转录“通读”改进研究进展

自2002年以来,在用γ-逆转录病毒载体治疗X连锁重度复合性免疫缺陷病 (X-SCID) 的10例病人中已有4例因载体整合在原癌基因lmo2等附近而得了白血病。这一事件提高了人们对基因治疗载体安全性的关注。与γ-逆转录病毒载体相比,慢病毒载体因尚未发现有整合在lmo2附近的现象,被认为是安全性较好的基因治疗载体。然而自灭活慢病毒载体与γ-逆转录病毒载体一样存在着转录“通读”的现象。近些年来,科学家们在改善自灭活慢病毒载体的通读率上做了一些工作并取得了一些积极成果。以下对慢病毒载体转录“通读”现象的发生机理和解决途径作了综合描述。     

Amelioration of β^654-thalassemia in mouse model with the knockdown of aberrantly spliced β-globin mRNA

Large amounts of aberrantly spliced mRNA from the β654 allele was present in erythroid cells, which might impair the erythropoiesis.A therapeutic strategy for β-thalassemia was explored by knocking down the aberrantly spliced mRNA of β-globin. Lentiviral vector with siRNA fragment targets on the specific portion of β654-globin aberrantly spliced pre-mRNA was constructed. In HeLa β654 cells, the siRNA vector could reduce approximately 60% of aberrantly spliced mRNA, which was assessed by RT-PCR and qRT-PCR. Furthermore, a disease model of β654 thalassemia mice with lentiviral-mediated siRNA was produced by subzonal injection (named Hβi-Hbbth-4/Hbb+transgenic mice). Our results showed that the hemotological parameters were improved in Hβi-Hbbth-4/Hbb+ transgenic mice. This study provides a potential way for β654-thalassemia therapy by knocking down the aberrantly spliced β-globin mRNA, whilst supporting that the aberrantly spliced β-globin mRNA may aggravate the disease.     

Oligosaccharide polyester and triterpenoid saponins from the roots of Polygala japonica

An oligosaccharide polyester, 1-O-(E)-p-coumaroyl-(3-O-benzoyl)-beta-D-fructofuranosyl-(2-->1)-[6-O-(E)-feruloyl-beta-D-glucopyranosyl-(1-->2)]-[6-O-acetyl-beta-D-glucopyranosyl-(1-->3)-(4-O-acetyl)-beta-D-glucopyranosyl-(1-->3)]-4-O-[4-O-alpha-L-rhamnopyranosyl-(E)-p-coumaroyl]-alpha-D-glucopyranoside (polygalajaponicose I), and four triterpenoid saponins, 3beta, 23, 27-trihydroxy-29-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-olean-12-en-28-oic acid (polygalasaponin XLVII), 3-O-beta-D-glucopyranosyl presenegenin 28-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranosyl ester (polygalasaponin XLVIII), 3-O-beta-D-glucopyranosyl presenegenin 28-O-beta-D-galactopyranosyl-(1-->5)-beta-D-apiofuranosyl-(1-->4)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl ester (polygalasaponin XLIX) and 2beta, 27-dihydroxy-3-O-beta-D-glucopyranosyl 11-oxo-olean-12-en-23, 28-dioic acid 28-O-beta-D-galactopyranosyl-(1-->5)-beta-D-apiofuranosyl-(1-->4)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranosyl ester (polygalasaponin L), in addition to five known compounds have been isolated from the roots of Polygala japonica.     

Structural analysis of the Sil1-Bip complex reveals the mechanism for Sil1 to function as a nucleotide-exchange factor

Sil1 functions as a NEF (nucleotide-exchange factor) for the ER (endoplasmic reticulum) Hsp70 (heat-shock protein of 70 kDa) Bip in eukaryotic cells. Sil1 may catalyse the ADP release from Bip by interacting directly with the ATPase domain of Bip. In the present study we show the complex crystal structure of the yeast Bip and the NEF Sil1 at the resolution of 2.3 ? (1 ?=0.1 nm). In the Sil1-Bip complex structure, the Sil1 molecule acts as a 'clamp' which binds lobe IIb of the Bip ATPase domain. The binding of Sil1 causes the rotation of lobe IIb ~ 13.5° away from the ADP-binding pocket. The complex formation also induces lobe Ib to swing in the opposite direction by ~ 3.7°. These conformational changes open up the nucleotide-binding pocket in the Bip ATPase domain and disrupt the hydrogen bonds between Bip and bound ADP, which may catalyse ADP release. Mutation of the Sil1 residues involved in binding the Bip ATPase domain compromise the binding affinity of Sil1 to Bip, and these Sil1 mutants also abolish the ability to stimulate the ATPase activity of Bip.     

Structural basis for the function of Tim50 in the mitochondrial presequence translocase

Many mitochondrial proteins are synthesized as preproteins carrying amino-terminal presequences in the cytosol. The preproteins are imported by the translocase of the outer mitochondrial membrane and the presequence translocase of the inner membrane. Tim50 and Tim23 transfer preproteins through the intermembrane space to the inner membrane. We report the crystal structure of the intermembrane space domain of yeast Tim50 to 1.83 Å resolution. A protruding β-hairpin of Tim50 is crucial for interaction with Tim23, providing a molecular basis for the cooperation of Tim50 and Tim23 in preprotein translocation to the protein-conducting channel of the mitochondrial inner membrane.     

Crystal structure of the E. coli Hsp100 ClpB N-terminal domain

E. coli Hsp100 ClpB can disaggregate denatured polypeptides by employing ATP hydrolysis. The ClpB N-terminal domain (ClpBN) has been proposed to play important roles in ClpB molecular chaperone activities. We have determined the crystal structure of ClpBN to 1.95 A resolution by MAD methods. The ClpBN monomer contains two subdomains that have similar folds. The crystal structure revealed a hydrophobic groove on the molecular surface. We have constructed ClpB mutants in which the hydrophobic residues within the putative peptide binding groove were replaced by glutamine. These ClpB mutants exhibited severe defects in molecular chaperone activity but retained the wild-type ATPase activity.