脂肪细胞因子 CTRP4转基因鼠的构建与鉴定

目的：建立人CTRP4基因的转基因小鼠,为脂肪细胞因子CTRP4的体内功能研究奠定基础。方法首先构建人CTRP4的转基因小鼠线性化表达载体,再利用显微注射的方法将载体注射入小鼠受精卵,从而构建人CTRP4的首建鼠（ Founder ）并与野生型小鼠交配繁殖得到F1代阳性小鼠,再通过近亲繁殖与测交的方法,得到CTRP4转基因纯合子小鼠,并通过PCR和western blot 的方法对纯合子小鼠进行鉴定。结果得到人CTRP4转基因小鼠纯合子小鼠两个品系,western blot鉴定该转基因小鼠心脏,肝脏,脑,肾脏等多种组织中均呈现CTRP4高表达。结论成功构建了人CTRP4转基因小鼠纯合子小鼠。     

珍稀鹤类巢址的空间聚类识别方法

依据2003年到2005年松嫩平原西部地区珍稀鹤类巢址调查数据,利用三种不同类型的指数进行分析研究:(1)拓扑指数,Voronoi图面积;(2)统计指数,Morishita指数;(3)空间指数,分维数.结果表明珍稀鹤类巢址空间格局具有明显的空间聚类分布,这三个指数使我们对珍稀鹤类巢址的聚类现象有了定量的认识,加深对自然保护区资源保护的重要性.     

甘薯愈伤组织中的淀粉酶

从甘薯愈伤组织和块根可溶性提取物中淀粉酶的非变性凝胶电泳和活性染色发现 ,愈伤组织和块根的淀粉酶完全不同。前者有 4种不同大小的淀粉酶 (2种α 淀粉酶和 2种 β 淀粉酶 ) ,而后者只有一种 (β 淀粉酶 ) ;其次 ,块根 β 淀粉酶对EDTA和 β 巯基乙醇都不敏感 ,而愈伤组织的淀粉酶对EDTA和 β 巯基乙醇都敏感。这些结果表明甘薯愈伤组织中不仅淀粉酶同工酶的数量多 ,而且包括α和 β两种类型。     

Expression and characterization of a functional human insulin-like growth factor I receptor

Stable transfectants of Chinese hamster ovary (CHO) cells were developed that expressed the protein encoded by a human insulin-like growth factor I (IGF-I) receptor cDNA. The transfected cells expressed approximately 25,000 high affinity receptors for IGF-I (apparent Kd of 1.5 X 10(-9) M), whereas the parental CHO cells expressed only 5,000 receptors per cell (apparent Kd of 1.3 X 10(-9) M). A monoclonal antibody specific for the human IGF-I receptor inhibited IGF-I binding to the expressed receptor and immunoprecipitated polypeptides of apparent Mr values approximately 135,000 and 95,000 from metabolically labeled lysates of the transfected cells but not control cells. The expressed receptor was also capable of binding IGF-II with high affinity (Kd approximately 3 nM) and weakly recognized insulin (with about 1% the potency of IGF-I). The human IGF-I receptor expressed in these cells was capable of IGF-I-stimulated autophosphorylation and phosphorylation of endogenous substrates in the intact cell. This receptor also mediated IGF-I-stimulated glucose uptake, glycogen synthesis, and DNA synthesis. The extent of these responses was comparable to the stimulation by insulin of the same biological responses in CHO cells expressing the human insulin receptor. These results indicate that the isolated cDNA encodes a functional IGF-I receptor and that there are no inherent differences in the abilities of the insulin and IGF-I receptors to mediate rapid and long term biological responses when expressed in the same cell type. The high affinity of this receptor for IGF-II also suggests that it may be important in mediating biological responses to IGF-II as well as IGF-I.     

Exploring the Potential Health Impact and Cost-Effectiveness of AIDS Vaccine within a Comprehensive HIV/AIDS Response in Low- and Middle-Income Countries

Background

The Investment Framework Enhanced (IFE) proposed in 2013 by the Joint United Nations Programme on HIV/AIDS (UNAIDS) explored how maximizing existing interventions and adding emerging prevention options, including a vaccine, could further reduce new HIV infections and AIDS-related deaths in low- and middle-income countries (LMICs). This article describes additional modeling which looks more closely at the potential health impact and cost-effectiveness of AIDS vaccination in LMICs as part of UNAIDS IFE.

Methods

An epidemiological model was used to explore the potential impact of AIDS vaccination in LMICs in combination with other interventions through 2070. Assumptions were based on perspectives from research, vaccination and public health experts, as well as observations from other HIV/AIDS interventions and vaccination programs. Sensitivity analyses varied vaccine efficacy, duration of protection, coverage, and cost.

Results

If UNAIDS IFE goals were fully achieved, new annual HIV infections in LMICs would decline from 2.0 million in 2014 to 550,000 in 2070. A 70% efficacious vaccine introduced in 2027 with three doses, strong uptake and five years of protection would reduce annual new infections by 44% over the first decade, by 65% the first 25 years and by 78% to 122,000 in 2070. Vaccine impact would be much greater if the assumptions in UNAIDS IFE were not fully achieved. An AIDS vaccine would be cost-effective within a wide range of scenarios.

Interpretation

Even a modestly effective vaccine could contribute strongly to a sustainable response to HIV/AIDS and be cost-effective, even with optimistic assumptions about other interventions. Higher efficacy would provide even greater impact and cost-effectiveness, and would support broader access. Vaccine efficacy and cost per regimen are critical in achieving cost-effectiveness, with cost per regimen being particularly critical in low-income countries and at lower efficacy levels.     

Pyridoxal phosphate inhibits dynamic subunit interchange among serine hydroxymethyltransferase tetramers

Cytoplasmic serine hydroxymethyltransferase (cSHMT) is a tetrameric, pyridoxal phosphate (PLP)-dependent enzyme that catalyzes the reversible interconversion of serine and tetrahydrofolate to glycine and methylenetetrahydrofolate. The enzyme has four active sites and is best described as a dimer of obligate dimers. Each monomeric subunit within the obligate dimer contributes catalytically important amino acid residues to both active sites. To investigate the interchange of subunits among cSHMT tetramers, a dominant-negative human cSHMT enzyme (DNcSHMT) was engineered by making three amino acid substitutions: K257Q, Y82A, and Y83F. Purified recombinant DNcSHMT protein was catalytically inactive and did not bind 5-formyltetrahydrofolate. Coexpression of the cSHMT and DNcSHMT proteins in bacteria resulted in the formation of heterotetramers with a cSHMT/DNcSHMT subunit ratio of 1. Characterization of the cSHMT/DNcSHMT heterotetramers indicates that DNcSHMT and cSHMT monomers randomly associate to form tetramers and that cSHMT/DNcSHMT obligate dimers are catalytically inactive. Incubation of recombinant cSHMT protein with recombinant DNcSHMT protein did not result in the formation of hetero-oligomers, indicating that cSHMT subunits do not exchange once the tetramer is assembled. However, removal of the active site PLP cofactor does permit exchange of obligate dimers among preformed cSHMT and DNcSHMT tetramers, and the formation of heterotetramers from cSHMT and DNcSHMT homodimers does not affect the activity of the cSHMT homodimers. The results of these studies demonstrate that PLP inhibits dimer exchange among cSHMT tetramers and suggests that cellular PLP concentrations may influence the stability of cSHMT protein in vivo.     

Conserved serine and histidine residues are critical for activity of the ER-type signal peptidase SipW of Bacillus subtilis

Type I signal peptidases (SPases) are required for the removal of signal peptides from translocated proteins and, subsequently, release of the mature protein from the trans side of the membrane. Interestingly, prokaryotic (P-type) and endoplasmic reticular (ER-type) SPases are functionally equivalent, but structurally quite different, forming two distinct SPase families that share only few conserved residues. P-type SPases were, so far, exclusively identified in eubacteria and organelles, whereas ER-type SPases were found in the three kingdoms of life. Strikingly, the presence of ER-type SPases appears to be limited to sporulating Gram-positive eubacteria. The present studies were aimed at the identification of potential active site residues of the ER-type SPase SipW of Bacillus subtilis, which is required for processing of the spore-associated protein TasA. Conserved serine, histidine, and aspartic acid residues are critical for SipW activity, suggesting that the ER-type SPases employ a Ser-His-Asp catalytic triad or, alternatively, a Ser-His catalytic dyad. In contrast, the P-type SPases employ a Ser-Lys catalytic dyad (Paetzel, M., Dalbey, R. E., and Strynadka, N. C. J. (1998) Nature 396, 186-190). Notably, catalytic activity of SipW was not only essential for pre-TasA processing, but also for the incorporation of mature TasA into spores.