排序方式: 共有56条查询结果,搜索用时 574 毫秒
1.
The Role of Auxin and Gibberellin in Controlling Lignin Formation in Primary Phloem Fibers and in Xylem of Coleus blumei Stems 总被引:2,自引:1,他引:1 下载免费PDF全文
The hypothesis that auxin (IAA) and gibberellic acid (GA3) control the formation of lignin is confirmed for the primary phloem fibers and for the secondary xylem in the stem of Coleus blumel Benth. Indoleacetic acid alone, or a combination of high IAA/low GA3 (w/w), induced short phloem fibers with thick secondary walls, that contained lignin rich in syringyl units (high ratio of syringyl/guaiacyl). On the other hand, a combination of high GA3/low IAA (w/w), which promoted the differentiation of long phloem fibers with thin walls, decreased the relative content of the syringyl units (low syringyl/guaiacyl ratio). In the secondary xylem, these hormonal treatments yielded only slight changes in the noncondensed monomeric guaiacyl units, confirming the relative stability of the guaiacyl lignification pattern in this tissue. In the xylem, indoleacetic acid alone, or a combination of high IAA/low GA3 induced lignin poor in syringyl units (low syringyl/guaiacyl ratio). A combination of high GA3/low IAA promoted a relatively slight increase in syringyl yield, indicating greater responsiveness of the syringyl lignification pattern to growth regulators. The possible functional and technological significance of our results is discussed. 相似文献
2.
Jennifer MP Woo Zhuofeng Lin Mohamad Navab Casey Van Dyck Yvette Trejo-Lopez Krystal MT Woo Hongyun Li Lawrence W Castellani Xuping Wang Noriko Iikuni Ornella J Rullo Hui Wu Antonio La Cava Alan M Fogelman Aldons J Lusis Betty P Tsao 《Arthritis research & therapy》2010,12(3):R93
Introduction
The purpose of this study was to evaluate the effects of L-4F, an apolipoprotein A-1 mimetic peptide, alone or with pravastatin, in apoE-/-Fas-/-C57BL/6 mice that spontaneously develop immunoglobulin G (IgG) autoantibodies, glomerulonephritis, osteopenia, and atherosclerotic lesions on a normal chow diet.Methods
Female mice, starting at eight to nine weeks of age, were treated for 27 weeks with 1) pravastatin, 2) L-4F, 3) L-4F plus pravastatin, or 4) vehicle control, followed by disease phenotype assessment.Results
In preliminary studies, dysfunctional, proinflammatory high-density lipoproteins (piHDL) were decreased six hours after a single L-4F, but not scrambled L-4F, injection in eight- to nine-week old mice. After 35 weeks, L-4F-treated mice, in the absence/presence of pravastatin, had significantly smaller lymph nodes and glomerular tufts (PL, LP < 0.05), lower serum levels of IgG antibodies to double stranded DNA (dsDNA) (PL < 0.05) and oxidized phospholipids (oxPLs) (PL, LP < 0.005), and elevated total and vertebral bone mineral density (PL, LP < 0.01) compared to vehicle controls. Although all treatment groups presented larger aortic root lesions compared to vehicle controls, enlarged atheromas in combination treatment mice had significantly less infiltrated CD68+ macrophages (PLP < 0.01), significantly increased mean α-actin stained area (PLP < 0.05), and significantly lower levels of circulating markers for atherosclerosis progression, CCL19 (PL, LP < 0.0005) and VCAM-1 (PL < 0.0002).Conclusions
L-4F treatment, alone or with pravastatin, significantly reduced IgG anti-dsDNA and IgG anti-oxPLs, proteinuria, glomerulonephritis, and osteopenia in a murine lupus model of accelerated atherosclerosis. Despite enlarged aortic lesions, increased smooth muscle content, decreased macrophage infiltration, and decreased pro-atherogenic chemokines in L-4F plus pravastatin treated mice suggest protective mechanisms not only on lupus-like disease, but also on potential plaque remodeling in a murine model of systemic lupus erythematosus (SLE) and accelerated atherosclerosis. 相似文献3.
Molecular architecture of the ribosome‐bound Hepatitis C Virus internal ribosomal entry site RNA 下载免费PDF全文
Justus Loerke Jochen Ismer Andrea Schmidt Tarek Hilal Thiemo Sprink Kaori Yamamoto Thorsten Mielke Jörg Bürger Tanvir R Shaikh Marylena Dabrowski Peter W Hildebrand Patrick Scheerer Christian MT Spahn 《The EMBO journal》2015,34(24):3042-3058
Internal ribosomal entry sites (IRESs) are structured cis‐acting RNAs that drive an alternative, cap‐independent translation initiation pathway. They are used by many viruses to hijack the translational machinery of the host cell. IRESs facilitate translation initiation by recruiting and actively manipulating the eukaryotic ribosome using only a subset of canonical initiation factor and IRES transacting factors. Here we present cryo‐EM reconstructions of the ribosome 80S‐ and 40S‐bound Hepatitis C Virus (HCV) IRES. The presence of four subpopulations for the 80S•HCV IRES complex reveals dynamic conformational modes of the complex. At a global resolution of 3.9 Å for the most stable complex, a derived atomic model reveals a complex fold of the IRES RNA and molecular details of its interaction with the ribosome. The comparison of obtained structures explains how a modular architecture facilitates mRNA loading and tRNA binding to the P‐site. This information provides the structural foundation for understanding the mechanism of HCV IRES RNA‐driven translation initiation. 相似文献
4.
5.
Renato M Salgado Luciane P Capelo Rodolfo R Favaro Jocelyn D Glazier John D Aplin Telma MT Zorn 《Reproductive biology and endocrinology : RB&E》2009,7(1):60
Background
Remodeling of the extracellular matrix is one of the most striking features observed in the uterus during the estrous cycle and after hormone replacement. Versican (VER) is a hyaluronan-binding proteoglycan that undergoes RNA alternative splicing, generating four distinct isoforms. This study analyzed the synthesis and distribution of VER in mouse uterine tissues during the estrous cycle, in ovariectomized (OVX) animals and after 17beta-estradiol (E2) and medroxyprogesterone (MPA) treatments, either alone or in combination. 相似文献6.
7.
8.
A novel lignin in poplar trees with a reduced caffeic acid/5-hydroxyferulic acid O-methyltransferase activity 总被引:10,自引:1,他引:9
Jan Van Doorsselaere Marie Baucher Emmanuelle Chognot Brigitte Chabbert Marie-Thérèse Tollier Michel Petit-Conil Jean-Charles Leplé Gilles Pilate Daniel Cornu Bernard Monties Marc Van Montagu Dirk Inzé Wout Boerjan Lise Jouanin 《The Plant journal : for cell and molecular biology》1995,8(6):855-864
Lignin is a polymeric constituent of the cell wall that needs to be removed during the paper making process. Bi-specific caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT) catalyses the O-methylation of caffeic acid and 5-hydroxyferulic acid to ferulic acid and sinapic acid, respectively. These compounds are intermediates in the biosynthesis of the lignin precursors. Therefore, COMTs are potential target enzymes for reducing the amount, or modifying the composition, of lignin in plants. Different antisense and sense constructs have been expressed of a gene encoding a COMT from poplar (Populus trichocarpa x P. deltoides) in a P. tremula x P. alba clone under the control of the cauliflower mosaic virus 35S promoter. From all analysed transformants, four lines transformed with an antisense construct had a reduced COMT activity. Two showed a 50% reduction of COMT activity, which altered only slightly the monomeric composition. In the two other transformants, the COMT activity was reduced by 95%. In the latter case, the syringyl/ guaiacyl ratio (S/G) was reduced by sixfold (due to a decrease of S and an increase of G), as analysed by thioacidolysis. A new component of lignin, the 5-hydroxyguaiacyl residue, was detected among the thioacidolysis products. Moreover, in contrast to the white/yellow colour of wild-type wood, the xylem of the transgenic lines with a 95% reduction of COMT activity was pale rose. A similar phenotype was observed in brown-midrib mutants of maize and sorghum, known for their altered lignification. Although the lignin composition was consistently modified, the lignin content of the transgenic poplars was similar to that of the controls. 相似文献
9.
Josué I. Beltrán-López Andrea Romero-Maldonado Elizabeth Monreal-Escalante Bernardo Bañuelos-Hernández Luz MT Paz-Maldonado Sergio Rosales-Mendoza 《Plant cell reports》2016,35(5):1133-1141
Key message
An algae-based vaccine model against atherosclerosis was developed with positive findings in terms of antigen yield and immunogenicity in mouse.Abstract
Several immunotherapies against atherosclerosis have been evaluated at the preclinical level thus far, with some of them currently under evaluation in clinical trials. In particular, the p210 epitope from ApoB100 is known to elicit atheroprotective responses. Considering that Chlamydomonas reinhardtii is an attractive host for the production and delivery of subunit vaccines, in this study a chimeric protein consisting of the B subunit of the cholera toxin and the p210 epitope from ApoB100 (CTB:p210) has been expressed in C. reinhardtii chloroplast as an attempt to establish an oral vaccine candidate against atherosclerosis. The Chlamydomonas-made CTB:p210 protein was successfully expressed at levels of up to 60 µg per g of fresh weight biomass. The antigenic activity of the CTB and the p210 moiety was preserved in the CTB:p210 chimera. Moreover the algae-made CTB:p210 showed an immunogenic activity, when orally administered to BALB/c mice, as evidenced the presence of anti-p210 serum antibodies in mice treated with the algae-derived CTB:p210. The antibody response lasts for at least 80 days after the last boost. This experimental model is proposed as a convenient tool in the development of low cost atherosclerosis vaccines of easy compliance and friendly delivery. Further studies will determine the therapeutic potential of this algae-made vaccine in atherosclerosis animal models.10.
Monoclonal antibodies to adult chicken myosin light chains were generated and used to quantitate the types of myosin light-chain (MLC) isoforms expressed during development of the pectoralis major (PM), anterior latissimus dorsi (ALD), and medial adductor (MA) muscles of the chicken. These are muscles which, in the adult, are composed predominantly of fast, slow, and a mixture of fiber types, respectively. Three distinct phases of MLC expression characterized the development of the PM and MA muscles. The first identifiable pase occurred during the period of 5-7 d of incubation in ovo. Extracts of muscles from the pectoral region (which included the presumptive PM muscle) contained only fast MLC isoforms. This period of exclusive fast light-chain synthesis was followed by a phase (8- 12 d of incubation in ovo) in which coexpression of both fast and slow MLC isoforms was apparent in both PM and MA muscles. During the period, the composition of both fast and slow MLC isoforms in the PM and MA muscles was identical. Beginning at day 12 in ovo, the ALD was also subjected to immunochemical analyses. The proportion of fast and slow MLCs in this muscle at day 12 was similar to that present in the other muscles studied. The third development phase of MLC expression began at approximately 12 d of incubation in ovo and encompassed the transition in MLC composition to the isoform patterns incubation in ovo and encompassed the transition in MLC composition to the isoform patterns typical of adult muscle. During this period, the relative proportion of slow MLC rose in both the MA and ALD and fell in the PM. By day 16, the third fast light chain, LC(3f), was apparent in extracts of both the PM and MA. These results show that there is a developmental progression in the expression of MLC in the two avian muscles studied from day 5 in ovo; first, only fast MLCs are accumulated, then both fast and slow MLC isoforms are expressed. Only during the latter third of development in ovo is the final MLC isoform pattern characteristic of a particular muscle type expressed. 相似文献