Vascular endothelial growth factor regulates focal adhesion assembly in human brain microvascular endothelial cells through activation of the focal adhesion kinase and related adhesion focal tyrosine kinase

Vascular endothelial growth factor (VEGF) plays a significant role in blood-brain barrier breakdown and angiogenesis after brain injury. VEGF-induced endothelial cell migration is a key step in the angiogenic response and is mediated by an accelerated rate of focal adhesion complex assembly and disassembly. In this study, we identified the signaling mechanisms by which VEGF regulates human brain microvascular endothelial cell (HBMEC) integrity and assembly of focal adhesions, complexes comprised of scaffolding and signaling proteins organized by adhesion to the extracellular matrix. We found that VEGF treatment of HBMECs plated on laminin or fibronectin stimulated cytoskeletal organization and increased focal adhesion sites. Pretreating cells with VEGF antibodies or with the specific inhibitor SU-1498, which inhibits Flk-1/KDR receptor phosphorylation, blocked the ability of VEGF to stimulate focal adhesion assembly. VEGF induced the coupling of focal adhesion kinase (FAK) to integrin alphavbeta5 and tyrosine phosphorylation of the cytoskeletal components paxillin and p130cas. Additionally, FAK and related adhesion focal tyrosine kinase (RAFTK)/Pyk2 kinases were tyrosine-phosphorylated by VEGF and found to be important for focal adhesion sites. Overexpression of wild type RAFTK/Pyk2 increased cell spreading and the migration of HBMECs, whereas overexpression of catalytically inactive mutant RAFTK/Pyk2 markedly suppressed HBMEC spreading ( approximately 70%), adhesion ( approximately 82%), and migration ( approximately 65%). Furthermore, blocking of FAK by the dominant-interfering mutant FRNK (FAK-related non-kinase) significantly inhibited HBMEC spreading and migration and also disrupted focal adhesions. Thus, these studies define a mechanism for the regulatory role of VEGF in focal adhesion complex assembly in HBMECs via activation of FAK and RAFTK/Pyk2.     

黑线姬鼠两亚种(中国东北地区及俄罗斯远东地区的东北亚种和朝鲜半岛的朝鲜亚种) 的线粒体DNA 序列缺少趋异性

为了检测黑线姬鼠两亚种(来自中国东北地区、俄罗斯远东地区的东北亚种和朝鲜半岛的朝鲜亚种)线
粒体DNA 的变异水平并确定朝鲜亚种的分类地位,我们测序分析了两亚种的线粒体DNA 细胞色素b 的部分序列
(1 054 bp)和控制区的部分序列(860 bp),并与基因库中黑线姬鼠相应的单倍型序列进行了比较。可以看出东
北亚种的序列显示出某些分异,可以被分为2 或3 个亚群,所以我们提出需要更多标本的DNA 分析来确定东北
亚种的分类地位。另外,来自韩国的朝鲜亚种的序列,与来自中国东北地区龙江和哈尔滨的东北亚种的两个亚
群相似(1 个亚群是细胞色素b 的两个单倍型,另1 个是控制区的两个单倍型),表明基于线粒体DNA 序列的遗
传多样性与现今基于形态特征对这些姬鼠的分类所得结果是不一致的。因此我们认为来自韩国的朝鲜亚种是一
个只在形态特异上不同于东北亚种的地方亚种,我们建议通过其他DNA 标记来进一步验证其亚种地位。我们还
认为朝鲜半岛不是最近的冰川期黑线姬鼠残遗种的保护区。     

Visual stimuli that elicit appetitive behaviors in three morphologically distinct species of praying mantis

We assessed the differences in appetitive responses to visual stimuli by three species of praying mantis (Insecta: Mantodea), Tenodera aridifolia sinensis, Mantis religiosa, and Cilnia humeralis. Tethered, adult females watched computer generated stimuli (erratically moving disks or linearly moving rectangles) that varied along predetermined parameters. Three responses were scored: tracking, approaching, and striking. Threshold stimulus size (diameter) for tracking and striking at disks ranged from 3.5 deg (C. humeralis) to 7.8 deg (M. religiosa), and from 3.3 deg (C. humeralis) to 11.7 deg (M. religiosa), respectively. Unlike the other species which struck at disks as large as 44 deg, T. a. sinensis displayed a preference for 14 deg disks. Disks moving at 143 deg/s were preferred by all species. M. religiosa exhibited the most approaching behavior, and with T. a. sinensis distinguished between rectangular stimuli moving parallel versus perpendicular to their long axes. C. humeralis did not make this distinction. Stimulus sizes that elicited the target behaviors were not related to mantis size. However, differences in compound eye morphology may be related to species differences: C. humeralis’ eyes are farthest apart, and it has an apparently narrower binocular visual field which may affect retinal inputs to movement-sensitive visual interneurons.     

Nonspecific DNA binding and bending by HUαβ: interfaces of the three binding modes characterized by salt-dependent thermodynamics

Previous isothermal titration calorimetry (ITC) and Förster resonance energy transfer studies demonstrated that Escherichia coli HU_αβ binds nonspecifically to duplex DNA in three different binding modes: a tighter-binding 34-bp mode that interacts with DNA in large (> 34 bp) gaps between bound proteins, reversibly bending it by 140^o and thereby increasing its flexibility, and two weaker, modestly cooperative small site-size modes (10 bp and 6 bp) that are useful for filling gaps between bound proteins shorter than 34 bp. Here we use ITC to determine the thermodynamics of these binding modes as a function of salt concentration, and we deduce that DNA in the 34-bp mode is bent around—but not wrapped on—the body of HU, in contrast to specific binding of integration host factor. Analyses of binding isotherms (8-bp, 15-bp, and 34-bp DNA) and initial binding heats (34-bp, 38-bp, and 160-bp DNA) reveal that all three modes have similar log-log salt concentration derivatives of the binding constants (Sk_i) even though their binding site sizes differ greatly; the most probable values of Sk_i on 34-bp DNA or larger DNA are − 7.5 ± 0.5. From the similarity of Sk_i values, we conclude that the binding interfaces of all three modes involve the same region of the arms and saddle of HU. All modes are entropy-driven, as expected for nonspecific binding driven by the polyelectrolyte effect. The bent DNA 34-bp mode is most endothermic, presumably because of the cost of HU-induced DNA bending, while the 6-bp mode is modestly exothermic at all salt concentrations examined. Structural models consistent with the observed Sk_i values are proposed.     

Genetically engineered transgenic plants with the domain 1 sequence of tobacco mosaic virus 126 kDa protein gene are completely resistant to viral infection

In many plant RNA viruses, Domains 1, 2 and 3 are conserved in replicase proteins. In order to examine the interference of viral replication by the Domain 1 sequence, we generated transgenic plants transformed with DNA corresponding to the Domain 1 sequence of the TMV 126 kDa protein. This DNA sequence includes the TMV RNA from nucleotides 1 to 2,149, which comprises both the 5'-untranslated and methyl transferase region. The transgenic plants obtained showed complete resistance to TMV infection. The presence of the Domain 1 sequence in the plants completely prevented local necrosis in Nicotiana tabacum cv. Xanthi nc, and any systemic development of symptoms in Nicotiana tabacum Xanthi upon TMV inoculation. Most transgenic plants sustained the conferred resistance even under TMV inoculum concentrations up to as high as 1,000 microg/ml. To detect any accumulation of TMV coat protein or viral RNA in infected transgenic plants, immunochemical tests and Northern blot analyses were carried out. Neither viral RNA or coat protein was detectable in the systemic leaves of the completely resistant transgenic plants, whereas they were accumulated in large quantities in all of the control plants. Because of the conservation of Domain 1 in many plant RNA viruses, the acquisition of resistance to virus infection using the Domain 1 sequence appears to be a very effective strategy for breeding of viral resistant plants.     

大仓鼠的核型与B染色体研究

采用骨髓细胞染色体制片法,对分布于山东济南、泰山、东北长白山和陕西西安的大仓鼠的染色体组型、Ｇ－带、Ｃ－带和银染核型进行了分析研究。济南、西安和长白山的标本的二倍体数目和核型相似,２ｎ＝２８,２２ｔ＋４ｍ＋ＸＹ（ｓｔ,ｍ）。泰山标本的二倍体数目为２ｎ＝２８～２９,即在６７５％的中期相中多出了一条形态最小的端着丝粒染色体,这条染色体为Ｂ染色体,可能起源于Ｘ染色体。泰山标本的Ａ染色体组与上述３地标本相同。４地标本的Ｇ－带、Ｃ－带和银染核型相似。除Ｂ染色体外,每个端着丝粒染色体都具有着丝粒异染色质,ＡｇＮＯＲｓ较恒定地出现在Ｎｏｓ２,４,８,９,１３染色体上。也就是说大仓鼠的Ｂ染色体为Ｃ－带阴性,不携带核仁组织者。这种Ｂ染色体Ｃ－带阴性的特征在赤狐、黑家鼠和大林姬鼠朝鲜亚种中亦有报道。     

Effect of apple intake on fecal microbiota and metabolites in humans

The effects of apple intake on the fecal flora, water content, pH, and metabolic activities in eight healthy volunteers and the utilization of apple pectin in vitro were investigated. Although several isolates of Bifidobacterium, Lactobacillus, Enterococcus, and the Bacteroides fragilis group utilized apple pectin, most isolates of Escherichia coli, Collinsela aerofaciense, Eubacterium limosum, and Clostridium perfringens could not. When fecal samples from healthy adults were incubated in liquid broth with apple pectin present or absent, the numbers of Bifidobacterium and Lactobacillus in the former were higher than those in the later. After the intake of apples (2 apples a day for 2 weeks) by eight healthy adult humans, the number of bifidobacteria in feces increased (p < 0.05 on day 7 and p < 0.01 on day 14 of the intake period), and the numbers of Lactobacillus and Streptococcus including Enterococcus tended to increase. However, lecithinase-positive clostridia, including C. perfringens, decreased (p < 0.05), and Enterobacteriaceae and Pseudomonas tended to decrease. Moreover, the concentrations of fecal acetic acid tended to increase on apple intake. The fecal ammonia concentration showed a tendency to reduce and fecal sulfide decreased (p < 0.05) on apple intake. These findings indicate that apple consumption is related to an improved intestinal environment, and apple pectin is one of the effective apple components improving the fecal environment.     

The Embedding Problem for Markov Models of Nucleotide Substitution

Continuous-time Markov processes are often used to model the complex natural phenomenon of sequence evolution. To make the process of sequence evolution tractable, simplifying assumptions are often made about the sequence properties and the underlying process. The validity of one such assumption, time-homogeneity, has never been explored. Violations of this assumption can be found by identifying non-embeddability. A process is non-embeddable if it can not be embedded in a continuous time-homogeneous Markov process. In this study, non-embeddability was demonstrated to exist when modelling sequence evolution with Markov models. Evidence of non-embeddability was found primarily at the third codon position, possibly resulting from changes in mutation rate over time. Outgroup edges and those with a deeper time depth were found to have an increased probability of the underlying process being non-embeddable. Overall, low levels of non-embeddability were detected when examining individual edges of triads across a diverse set of alignments. Subsequent phylogenetic reconstruction analyses demonstrated that non-embeddability could impact on the correct prediction of phylogenies, but at extremely low levels. Despite the existence of non-embeddability, there is minimal evidence of violations of the local time homogeneity assumption and consequently the impact is likely to be minor.     

A different path: Revealing the function of staphylococcal proteins in biofilm formation

Staphylococcus aureus and Staphylococcus epidermidis cause dangerous and difficult to treat medical device-related infections through their ability to form biofilms. Extracellular poly-N-acetylglucosamine (PNAG) facilitates biofilm formation and is a vaccination target, yet details of its biosynthesis by the icaADBC gene products is limited. IcaC is the proposed transporter for PNAG export, however a comparison of the Ica proteins to homologous exo-polysaccharide synthases suggests that the common IcaAD protein components both synthesise and transport the PNAG. The limited distribution of icaC to the Staphylococcaceae and its membership of a family of membrane-bound acyltransferases, leads us to suggest that IcaC is responsible for the known O-succinylation of PNAG that occurs in staphylococci, identifying a potentially new therapeutic target specific for these bacteria.