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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Photosynthetic organisms have a variety of accessory pigments, on which their classification has been based. Despite this variation, it is generally accepted that all chloroplasts are derived fromasingle cyanobacterial ancestor. How the pigment diversity has arisen is the key to revealing their ...
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 22 (1995), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. Plasminogen activator activity was detected in the extract solution of the liver tissues of both stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats by the synthetic substrate assay.2. The total PA activity in the liver extract of WKY (26.8 ± 8.3 i.u.) was about 1.5-fold higher than that of SHRSP (18.5 ± 4.1 i.u., n = 8, P 〈 0.005).3. The enzymography of the liver extract revealed three lytic bands with a molecular weight of 67 kDa, 44 kDa and 38 kDa.4. The inhibitor activity of the liver extract was detected by the reverse fibrin autography method with one lytic resistance hand at 70 kDa.5. Thus, fibrinolytic components exist in the liver tissue of both strains of rats, but their contribution to the stroke requires further study.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant species biology 11 (1996), S. 0 
    ISSN: 1442-1984
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Recent developments in plant molecular genetics have revealed a direct relationship between gene structure and its function in plant structure, development, response to stimuli, and metabolic pathways. The rapid progress in this field depends mainly on intensive efforts at isolation of a series of mutants using selected model plants, such as Arabidopsis thaliana, snapdragon (Antirrhinum majus), rice (Oryza sativa), and maize (Zea mays). Arabidopsis thaliana is a small crucifer, called “botanical Drosophila” because it has some remarkable features: small genome size, short life-cycle, small size, and ease of propagation. More than 200 research groups in many countries have isolated mutants defective in the development of embryo, shoot, flower, and root, as well as in response reactions to physical and chemical stimuli such as gravity, light, nutrients, and phytohormones. Some of the Arabidopsis mutants show aberrant structures that may be identified as non-crucifer characters. For example, a flower mutant, SAKURA. often bears five petals; another mutant, LEUNIG, has no ovarian septum. TERMINAL FLOWER mutant changes indeterminate inflorescence to determinate. Some root mutants do not form lateral roots. Several mutants form one cotyledon. These morphology mutants will provide hints for considering critical genetic changes that may have caused the past evolutionary events.Genes isolated from the morphology mutants are classified into three groups: coding transcription factors, kinases, and other protein motifs. Although the detailed molecular mechanism in the mutants is not known, hierarchical regulatory networks of the genes are being investigated. We will provide examples of the genetic networks at work in organ development, and discuss possible genetic changes that result in drastic morphological variation.
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  • 4
    ISSN: 1432-203X
    Keywords: Arabidopsis thaliana ; Transformation ; Agrobacterium ; T-DNA ; Shoot regeneration ; Transgenic plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The efficiency of Agrobacterium-mediated transformation of Arabidopsis thaliana was compared with different organs, Arabidopsis ecotypes, and Agrobacterium strains. Efficiency of shoot regeneration was examined using hypocotyl, cotyledon and root explants prepared from young seedlings. Hypocotyl expiants had the highest regeneration efficiency in all of the four Arabidopsis ecotypes tested, when based on a tissue culture system of callus-inducing medium (CIM: Valvekens et al. 1988) and shoot-inducing medium (SIM: Feldmann and Marks 1986). Histochemical analysis using the ß-glucuronidase (GUS) reporter gene showed that the gusA gene expression increased as the period of preincubation on CIM was extended, suggesting that dividing cells are susceptible to Agrobacterium infection. In order to obtain transgenic shoots, hypocotyl explants preincubated for 7 or 8 days on CIM were infected with Agrobacterium containing a binary vector which carries two drug-resistant genes as selection markers, and transferred to SIM for selection of transformed shoots. Of four Arabidopsis ecotypes and of three Agrobacterium strains examined, Wassilewskija ecotype and EHA101 strain showed the highest efficiency of regeneration of transformed shoots. By combining the most efficient factors of preincubation period, Arabidopsis ecotype, tissue, and bacterial strain, we obtained a transformation efficiency of about 80–90%. Southern analysis of 124 transgenic plants showed that 44% had one copy of inserted T-DNA while the others had more than one copy.
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  • 5
    ISSN: 1573-5079
    Keywords: chlorophyll ; heme ; Hordeum vulgare ; glutamyl-tRNA reductase ; hemA ; 5-aminolevulinate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Accumulation of chlorophylls and heme is primarily controlled at the level of 5-aminolevulinate (ALA) synthesis in higher plants. ALA is formed from glutamate in three enzymatic steps in plants. Among them, the reduction of glutamyl-tRNAGluto glutamate-1-semialdehyde (GSA) is likely to be a regulatory point of ALA synthesis. This reaction is catalyzed by glutamyl-tRNA reductase (GTR), which is encoded by a hemA gene. We have isolated a novel isoform of a hemA cDNA clone from barley (Hordeum vulgare) that is the third member of the hemA gene family. mRNA of this isoform is accumulated primarily in roots, suggesting that the isoform is regulated in an organ-specific manner by the demand for heme synthesis rather than chlorophyll. Phylogenetic analysis was done using the deduced amino acid sequences of hemA isoforms from barley, cucumber and Arabidopsis thaliana. The results indicate that the existing gene families in these plants arose after the divergence of monocotyledonous and dicotyledonous plants.
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  • 6
    ISSN: 1573-5028
    Keywords: APETALA3 ; Arabidopsis thaliana ; flower homeotic gene ; flower development ; MADS box ; genetic complementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Among the homeotic mutants with altered floral organs, two mutants of Arabidopsis thaliana, apetala3 and pistillata, and two mutants of Antirrhinum majus, deficiens and globosa, have a homeotic conversion of the floral organs in whorl 2 and 3, namely petals to sepals and stamens to carpels. We have isolated a homologue of the DEFICIENS gene from A. thaliana wild type and shown complete complementation of apetala3 mutation by introducing the isolated gene using Agrobacterium-mediated transformation. These results show that the APETALA3 is a homologue of DEFICIENS structurally and functionally. The 5′-upstream region of APETALA3 contains three SRE-like sequence, where MADS box-containing proteins are assumed to bind and regulate expression in tissue-and stage-specific manner.
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  • 7
    ISSN: 1573-5028
    Keywords: amidophosphoribosyltransferase (ATase: EC 2.4.2.14) ; Arabidopsis thaliana ; cold plaque screening ; purine nucleotide biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amidophosphoribosyltransferase (ATase: EC 2.4.2.14) is a key enzyme in the pathway of purine nucleotide biosynthesis. We have identified several cDNA clones whose amino acid sequences exhibit similarity with the known ATases in a cDNA library of young floral buds of Arabidopsis thaliana. The cDNA clones are derived from two genes homologous with each other. These cDNAs represent the first plant representatives of ATase gene. Structural comparison with ATases of other organisms has revealed that the two genes encode [4Fe-4S] cluster-dependent ATases. Northern blot analysis showed that expression level of the genes is different in three organs; one gene is expressed in flowers and roots, while the other gene is mainly expressed in leaves.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 26 (1994), S. 1357-1377 
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; floral development ; floral meristem ; flower mutants ; floral organ development ; inflorescence meristem ; signalling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flower development can be divided into four major steps: phase transition from vegetative to reproductive growth, formation of inflorescence meristem, formation and identity determination of floral organs, and growth and maturation of floral organs. Intercellular and intracellular signalling mechanisms must have important roles in each step of flower development, because it requires cell division, cell growth, and cell differentiation in a concerted fashion. Molecular genetic analysis of the process has started by isolation of a series of mutants with unusual flowering time, with aberrant structure in inflorescence and in flowers, and with no self-fertilization. At present more than 60 genes are identified from Arabidopsis thaliana and some of them have cloned. Although the information is still limited, several types of signalling systems are revealed. In this review, we summarize the present genetic aspects of the signalling network underlying the processes of flower development.
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  • 9
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Surface modified poly(ethylene terephthalate) (PET) films with 2-(methacryloyloxy)ethylphosphorylcholine (MPC) and 2-(glucosyloxy)ethyl methacrylate (GEMA) moieties, PMPC-g-PET and PGEMA-g-PET, were prepared by graft copolymerization using an Ar plasma-post polymerization technique. The degrees of polymerization of the grafts PMPC and PGEMA were P̄n ≈ 30 and P̄n ≈ 40, respectively. The contact angle of the modified PET film decreased from θ = 68° (the original PET film) to θ = 26° for PMPC-g-PET and to θ = 43° for PGEMA-g-PET. The modified PET films adsorb less serum proteins than the original PET film. Egg yolk lecithin did not adsorb on PGEMA-g-PET but adsorbed on PMPC-g-PET. PMPC-g-PET showed activity for the inhibition of fibrin formation and no adhesion of mouse fibroblasts (L-929).
    Additional Material: 10 Ill.
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