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51.
The implicit membrane model IMM1 is extended to include the effect of transmembrane potential and used to investigate the optimal membrane binding configurations and energies for alamethicin helices. In the absence of voltage, the lowest energy configuration is on the membrane surface with a tilt allowing the N terminus to be fully buried. Slightly higher in energy is an also tilted configuration with the N terminus deeper in the membrane and almost crossing the membrane. In 26A membranes and in the presence of 0.1V voltage, the TM orientation becomes lower in energy. This is consistent with the assumption that voltage induces a transition from the interfacial to the inserted (TM) orientation. This effect of voltage is smaller in thicker membranes. The results are compared to previous experimental and theoretical studies and the findings are discussed in relation to the mechanism of channel formation by alamethicin. 相似文献
52.
Chinoy H Salway F Fertig N Shephard N Tait BD Thomson W Isenberg DA Oddis CV Silman AJ Ollier WE Cooper RG;UK Adult Onset Myositis Immunogenetic Collaboration 《Arthritis research & therapy》2006,8(1):R13
The aim of this study was to investigate HLA class II associations in polymyositis (PM) and dermatomyositis (DM), and to determine how these associations influence clinical and serological differences. DNA samples were obtained from 225 UK Caucasian idiopathic inflammatory myopathy patients (PM = 117, DM = 108) and compared with 537 randomly selected UK Caucasian controls. All cases had also been assessed for the presence of related malignancy and interstitial lung disease (ILD), and a number of myositis-specific/myositis-associated antibodies (MSAs/MAAs). Subjects were genotyped for HLA-DRB1, DQA1 and DQB1. HLA-DRB1*03, DQA1*05 and DQB1*02 were associated with an increased risk for both PM and DM. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype demonstrated strong association with ILD, irrespective of myositis subtype or presence of anti-aminoacyl-transfer RNA synthetase antibodies. The HLA-DRB1*07-DQA1*02-DQB1*02 haplotype was associated with risk for anti-Mi-2 antibodies, and discriminated PM from DM (odds ratio 0.3, 95% confidence interval 0.1-0.6), even in anti-Mi-2 negative patients. Other MSA/MAAs showed specific associations with other HLA class II haplotypes, irrespective of myositis subtype. There were no genotype, haplotype or serological associations with malignancy. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype associations appear to not only govern disease susceptibility in Caucasian PM/DM patients, but also phenotypic features common to PM/DM. Though strongly associated with anti-Mi-2 antibodies, the HLA-DRB1*07-DQA1*02-DQB1*02 haplotype shows differential associations with PM/DM disease susceptibility. In conclusion, these findings support the notion that myositis patients with differing myositis serology have different immunogenetic profiles, and that these profiles may define specific myositis subtypes. 相似文献
53.
1 IntroductionOneaimofthephysicsscienceresearchistodevel opfundamentalandportableconceptswhichhelpunitedifferentresearchfrontiers.Inthisrespect ,Helmholtz’selectricdoublelayer (DEL)theory ,whichwasdevel opedin 1879andrelatedtheelectricandflowparame tersforelectrokinetictransport ,isaseminal,havingprovidedaframeworkforinterpretingawiderangeofelectrokineticphenomena .DespitethesimplicityoftheEDLtheory ,whichwewilldescribeindetail,ithasprovidedachallengeformathematicianstounderstanditsimplic… 相似文献
54.
David Howard 《仿生工程学报(英文版)》2004,1(4)
1 Introduction Many CLAWAR (CLimbing And WAlking Robots)researchers have concentrated on navigation, gait gen-eration and control, rather than mechanical design. Whenprototypes have been developed, it has often been as-sumed that the mechanical design principles are knownand the problem is one of applying them. In practise, thisis far from the truth, as the performance of existing pro-totypes testifies. The most common design approach is tocopy the geometry of insects and mammals wit… 相似文献
55.
Larissa Wakefield Valerie Cornish Hilary Long Akane Kawamura - Current Address: Biology Department VASTox PLC Milton Park Abingdon Oxford UK Xiaoyan Zhang David W. Hein Edith Sim 《Biomarkers》2008,13(1):106-118
Arylamine N-acetyltransferase (NAT) genes in humans and in rodents encode polymorphic drug metabolizing enzymes. Human NAT1 (and the murine equivalent mouse Nat2) is found early in embryonic development and is likely to have an endogenous role. We report the detailed expression of the murine gene (Nat2) and encoded protein in mouse embryos, using a transgenic mouse model bearing a lacZ transgene inserted into the coding region of mouse Nat2. In mouse embryos, the transgene was expressed in sensory epithelia, epithelial placodes giving rise to visceral sensory neurons, the developing pituitary gland, sympathetic chain and urogenital ridge. In Nat2 +/+ mice, the presence and activity of Nat2 protein was detected in these tissues and their adult counterparts. Altered expression of the human orthologue in breast tumours, in which there is endocrine signalling, suggests that human NAT1 should be considered as a potential biomarker for neuroendocrine tissues and tumours. 相似文献
56.
C.?Sunandakumari C.?-L.?Zhang K.?P.?MartinEmail author A.?Slater P.?V.?Madhusoodanan 《In vitro cellular & developmental biology. Plant》2005,41(5):695-699
Summary The types of auxin in Murashige and Skoog (MS) medium containing N
6-benzyladenine (BA) determined indirect morphogenesis, i.e. development to bipolar somatic embryos or monopolar shoots in
Euphorbia nivulia Buch.-Ham. Indirect in vitro morphogenesis depended on growth regulators, explant excision period, and light. Calli induced from explants collected in
March–April were superior in the induction of indirect morphogenesis to those collected in July–August. Light enforced in vitro morphogenesis, while darkness was inhibitory. The presence of kinetin in the medium also inhibited morphogenesis. Calli developed
on explants collected in March–April grown on MS medium fortified with α-naphthaleneacetic acid (NAA) and BA facilitated indirect
organogenesis, while those developed on medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) and BA underwent somatic
embryogenesis. MS medium with 13.3 μM BA and 2.69 μM NAA was the best for induction of shoots from callus, which developed a mean of 15.7 shoots. Shoots were best rooted on half-strength
MS medium enriched with 2.46 μM indole-3-butyric acid with a mean of 5.1 roots per shoot. MS medium supplemented with 2.26 μM 2,4-D and 4.44 μM BA induced the highest number (mean of 13.4) of somatic embryos. Of the embryos transferred on half-strength MS medium containing
2.89 μM gibberellic acid, 78% of embryos developed to the cotyledonary stage. Most cotyledonary embryos (80%) underwent conversion
to plantlets upon being transferred to half-strength MS basal medium in light. The survival rate of organogenesis and embryo-derived
plants was 80 and 90%, respectively. Calli transformed with Agrobacterium tumefaciens showed expression of the gusA transgene and resistance to kanamycin, but did not undergo morphogenesis. 相似文献
57.
Fanni Aspetsberger Matthias Zabel Timothy Ferdelman Ulrich Struck Andreas Mackensen Astrid Ahke Ursula Witte - Present address: University of Aberdeen Aberdeen AB TZ UK 《Marine Biology Research》2007,3(5):342-356
The benthic community in continental slope and deep-sea sediments of the Benguela Upwelling System was supplied with 13C-labelled organic matter (OM) of two different qualities using a benthic chamber lander. Freeze-dried cultures of Skeletonema costatum served as 'fresh' OM. 'Altered' OM of the same material had been additionally dialysed to remove low-molecular weight compounds. In order to investigate the benthic response pattern, mineralization of labelled OM, uptake by macrofauna and incorporation into bacteria were followed over 18-36 h. Total oxygen uptake was not affected beyond natural variation by the OM addition. Mineralization dominated the 13C-labelled phytodetritus processing, constituting 71-95% of the total processed OM. Bacterial incorporation of phytodetrital carbon exceeded macrofaunal uptake at all stations. Stations situated in a major centre of OM deposition showed phytodetritus processing rates on average twice as high as outside the depocentre. Phytodetritus processing was 1.5, 2.5 and 4.3 times higher for fresh than for altered OM at 605, 1019 and 1335 m water depth, respectively. Our observations clearly indicate the importance of OM quality on mineralization rates. 相似文献
58.
The small GTPase Rac and the second messenger cGMP (guanosine 3',5'-cyclic monophosphate) are critical regulators of diverse cell functions. When activated by extracellular signals via membrane signaling receptors, Rac executes its functions through engaging downstream effectors such as p21-activated kinase (PAK), a serine/threonine protein kinase. However, the molecular mechanism by which membrane signaling receptors regulate cGMP levels is not known. Here we have uncovered a signaling pathway linking Rac to the increase of cellular cGMP. We show that Rac uses PAK to directly activate transmembrane guanylyl cyclases (GCs), leading to increased cellular cGMP levels. This Rac/PAK/GC/cGMP pathway is involved in platelet-derived growth factor-induced fibroblast cell migration and lamellipodium formation. Our findings connect two important regulators of cellular physiological functions and provide a general mechanism for diverse receptors to modulate physiological responses through elevating cellular cGMP levels. 相似文献
59.
放线菌噬菌体φHAU3是以吸水链霉菌应城变种10-22为指示菌,筛选获得的一个广谱性噬菌体,其基因组大小约为53kb,具有粘性末端。已成功地将44.7kb的φHAU3 DNA克隆到pIJ255上,构建成噬粒(Phasmid)pIJ8300;46.8kb的φHAU3 DNA克隆到pIJ285上,构建成pIJ8301。采用部分酶解和Southern杂交的方法,制作了pIJ8300和pIJ8301被Asp718和Bgl Ⅱ酶切的限制酶图谱,又综合单,双和多酶切分析的结果,定位了单一的Pvu Ⅱ和NcoI切点。综合噬粒pIJ8300和pIJ8301的特性,已将φHAU3中噬菌体功能的必需区定位在41kb的范围内。这些结果为以φHAU3为母体发展新的放线菌噬菌体奠定了良好的基础。 相似文献
60.
Laura L. Kilarski Loes C. A. Rutten-Jacobs Steve Bevan Rob Baker Ahamad Hassan Derralynn A. Hughes Hugh S. Markus UK Young Lacunar Stroke DNA Study 《PloS one》2015,10(8)