Resurrection of an ancestral gene: functional and evolutionary analyses of the Ng<Emphasis Type="Italic">rol</Emphasis> genes transferred from<Emphasis Type="Italic"> Agrobacterium</Emphasis> to<Emphasis Type="Italic"> Nicotiana</Emphasis>

The Ngrol genes, which have high similarity in sequence to the rol genes of Agrobacterium rhizogenes, are present in the genome of untransformed plants of Nicotiana glauca. It is thought that bacterial infection resulted in the transfer of the Ngrol genes to plants early in the evolution of the genus Nicotiana, since several species in this genus contain rol-like sequences but others do not. Plants transformed with the bacterial rol genes exhibit various developmental and morphological changes. The presence of rol-like sequences in plant genomes is therefore thought to have contributed to the evolution of Nicotiana species. This paper focuses on studies of the Ngrol genes in present-day plants and during the evolution of the genus Nicotiana. The functional sequences of several Ngrol genes may have been conserved after their ancient introduction from a bacterium to the plant. Resurrection of an ancestral function of one of the Ngrol genes, as examined by physiological and evolutionary analyses, is also described. The origin of the Ngrol genes is then considered, based on results of molecular phylogenetic analyses. The effects of the horizontal transfer of the Ngrol genes and mutations in the genes are discussed on the plants of the genus Nicotiana during evolution.Seishiro Aoki is the recipient of the Botanical Society Award for Young Scientist, 2002.     

The autonomy of functional biology: a reply to Rosenberg

Rosenberg has recently argued that explanations supplied by (what he calls) functional biology are mere promissory notes for macromolecular adaptive explanations. Rosenberg's arguments currently constitute one of the most substantial challenges to the autonomy, irreducibility, and indispensability of the explanations supplied by functional biology. My responses to Rosenberg's arguments will generate a novel account of the autonomy of functional biology. This account will turn on the relations between counterfactuals, scientific explanations, and natural laws. Crucially, in their treatment of the laws' relation to counterfactuals, Rosenberg's arguments beg the question against the autonomy of functional biology. This relation is considerably more subtle than is suggested by familiar slogans such as Laws support counterfactuals; accidents don't.     

Purification and characterization of T cell protein tyrosine phosphatase reveals significant functional homology to protein tyrosine phosphatase-1B

We have developed a protocol for rapid purification of T cell protein tyrosine phosphatase (TCPTP) and the structurally related protein tyrosine phosphatase-1B (PTP-1B) from bacterial cells. The pH profile for TCPTP was bell-shaped with an optimum of 5.5. The catalytic domain and full-length versions of TCPTP bound a potent inhibitor with affinities similar to those of PTP-1B. The K(m) values for the catalytic domains of TCPTP and PTP-1B increased with increasing ionic strength, whereas the k(cat) values remained unchanged. Arrhenius plots revealed that TCPTP and PTP-1B possess similar activation energies of 25.3+/-1.2 and 18.4+/-3.0 kJ/mol, respectively. Increasing solvent microviscosity (up to 40% (w/v) sucrose) did not affect k(cat)/K(m) of either enzyme. However, high sucrose concentrations protected both enzymes from thermal inactivation. These studies show that, although they share a 72% amino acid sequence identity within their catalytic domains, TCPTP and PTP-1B are functionally very similar in vitro.     

脑血红素加氧酶系统的作用研究

血红素加氧酶（HO）是降解血红素的微粒体酶系统,催化降解血红素生成一氧化碳（CO）、胆绿素和铁离子,同工酶HO-1和HO-2广泛分布于脑中,具有不同的调控机制,可能发挥着调节NO水平,抗氧化应激,参与神经元退行性变等重要作用。     

LIM蛋白家族的研究进展

LIM蛋白是分子结构中含有一个或多个LIM结构域的蛋白质家族,该家族中的蛋白质通过其LIM结构域与某些结构蛋白,激酶,转录调控因子等多种蛋白质相互作用,对某些基因的表达,细胞分化与发育,细胞骨架形成等发挥重要调控作用。本文介绍LIM蛋白家族的分类与功能,LIM蛋白及其与其他蛋白之间的相互作用,以及LIM蛋白在心血管系统中的作用。     

The plastid translocon component TOC36 exhibits an affinity for the bacterial protein translocation process

The 44-kDa envelope polypeptides are active components of the plastid translocon, but their role in plastid protein import remains elusive. One form from Brassica napus (bnToc36B) was previously observed to exert a significant overall effect on bacterial protein translocation, but the nature of the influence requires further characterization. The experimental strategies employed in this study thus focus specifically on the nature of the bnToc36B-bacterial Sec translocon relationship to gain an understanding of Toc36's function. BnToc36B's presence in bacteria created a number of effects related to the protein transport process that together point to functional interactions with the bacterial Sec translocon. These effects are (1) reduced sensitivity to azide impairment as measured by a higher recovery rate from azide treatment, (2) reduced sensitivity to suboptimal temperatures manifesting as sustained levels of protein synthesis and translocation, (3) sustained levels of growth and beta-lactamase transport in high ampicillin concentrations, and (4) evidence for a physical affinity for the bacterial translocon. A reduction in overall SecA levels and a more stable SecA profile, when subjected to azide treatment, was observed in bnToc36B-containing bacteria. The implications of the bacterial data are discussed.     

Effects of simvastatin and L-arginine on vasodilation,nitric oxide metabolites and endogenous NOS inhibitors in hypercholesterolemic subjects

Hypercholesterolemia is linked to endothelial dysfunction and enhancement of the endogenous inhibitor of NO synthase. The statins have lipid-lowering and pleiotropic properties, which could exert protective effects on the endothelium in hypercholesterolemia. The association of l -arginine with simvastatin could promote a further improvement on endothelial function in this condition. Thus, we investigated whether simvastatin, with or without supplementation with l -arginine, could improve endothelium-dependent vasodilation. In this study, 25 hypercholesterolemic subjects were treated according to the following protocol: washout period of 1 month; simvastatin (20 mg/day) for 2 months; simvastatin (20 mg/day)+ l -arginine (7 g/day) for 2 months. From these patients, 10 were chosen at random for evaluation of vascular function by high resolution ultrassonography of the brachial artery. In subjects treated with simvastatin plus l -arginine, an increase of l -arginine levels (68%) and l -arginine/asymmetric dimethylarginine (ADMA) ratio (67%) were observed. Simvastatin reduced the plasma concentrations of NO metabolites nitrite+nitrate (NOx: 34%), S -nitrosothiols (RSNO: 42%), total cholesterol (25%), low density lipoprotein (LDL)-cholesterol (36%) and the LDL-cholesterol/high density lipoprotein (HDL)-cholesterol ratio (34%). Simvastatin, associated or not to l -arginine, did not affect ADMA levels and endothelium-dependent vasodilation. Our data showed that simvastatin reduced the plasma concentrations of NOx and RSNO without affecting either the levels of ADMA or endothelium-dependent vasodilation in hypercholesterolemia.     

参芪扶正注射液对急性淋巴细胞白血病化疗患者造血和免疫功能的影响

目的:观察参芪扶正注射液对急性淋巴细胞白血病化疗患者造血及免疫功能的影响。方法:收集96例处于初治诱导缓解治疗阶段的急性淋巴细胞白血病患者,并将其随机分为治疗组和对照组。治疗组48例患者在进行常规化疗的同时给予参芪扶正注射液250 m L,1次/天,共28天;对照组48例患者仅接受常规化疗,两组患者均给予相同的支持对症治疗。治疗结束后,观察两组患者的疾病缓解率、治疗前后造血系统、T和B淋巴细胞亚群的变化情况。结果:化疗结束后,治疗组患者的疾病缓解率为89.6%,对照组为83.3%,两组比较无统计学差异(P0.05);化疗14天及化疗结束后1周,治疗组患者的白细胞、红细胞计数和血红蛋白水平明显高于对照组(P0.05);且化疗结束后1周,治疗组患者的CD3+、CD4+及CD4+/CD8+含量均明显高于对照组(P0.05)。而两组患者治疗前后的血小板计数、CD3-CD19+含量比较均不具有统计学差异(P0.05)。结论:参芪扶正注射液辅助治疗不仅能够改善化疗所致的急性淋巴细胞白血病患者的骨髓抑制,而且能够提高其细胞免疫功能,有助于患者化疗后的恢复。     

神经网络提高肝细胞癌磁共振波谱诊断正确率

通过评价31磷磁共振波谱(31Phosphorus Magnetic Resonance Spectroscopy,31P-MRS)来辨别三种诊断类型:肝细胞癌,正常肝和肝硬化。运用反向传输神经网络(BP)和径向基函数神经网络(RBF)分析31P-MRS数据,分别建立神经网络模型,进行肝细胞癌的诊断分类以期提高识别率。实验结果证明,应用神经网络模型后,31P-MR波谱对活体肝细胞癌的诊断正确率从89.47%提高到97.3%,且BP更优于RBF。