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  • 1
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The aim of this study was to determine whether increases in stromal superoxide dismutase (SOD; EC 1.15.1.1), ascorbate peroxidase (APX; EC 1.11.1.11) and glutathione reductase (GR; EC 1.6.4.2) via transformation could reduce photosystem (PS) II photoinhibition at low temperature for cotton (Gossypiumhirsutum L.) plants and to determine by what mechanism this protection may be realized. During 3-h exposures of lincomycin-treated leaf discs to 10°C and a photon flux density of 500 μmol m−2 s−1, all transgenic plants exhibited significantly greater PSII activity and O2 evolution than did wild-type plants. Also, the rate constant of PSII photoinactivation was significantly lower for all transgenic plants than for wild-type plants. No significant differences existed between genotypes in non-photochemical quenching of chlorophyll a fluorescence and the regulated component of the thermal dissipation of excitation energy. The relationship between changes in variable to maximum chlorophyll fluorescence (Fv/Fm) and the time-dependent averaged excessive light exposure was similar for all genotypes. This observation excluded the possibility that differences in PSII photodamage were due to improvements in the direct protection of PSII from active oxygen by antioxidant enzyme overproduction. Similar decreases in Fv/Fm during the stress treatment for all genotypes when leaves were pre-treated with 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea (DCMU) suggested that the effect of overproduction involved events downstream of PSII in the electron transfer pathway. Since all transgenic plants exhibited a significantly higher photochemical quenching of chlorophyll fluorescence during the chilling treatment, we concluded that, under the conditions used in this study, the enhancement of the protection of PSII from photodamage by increasing the stromal antioxidant enzyme activity in cotton leaves was due to the maintenance of a higher rate of electron transport and, consequently, a lower reduction state of QA.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Transgenic tobacco seedlings that overexpress a cDNA encoding an enzyme with both glutathione S-transferase (GST) and glutathione peroxidase (GPX) activity had GST- and GPX-specific activities approximately twofold higher than wild-type seedlings. These GST/GPX overexpressing seedlings grew ...
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 62 (1984), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cotyledons of sunflower seedlings (Helianthus annuus L. cv. Giant gray stripe) expand and their protein content first rises then begins to decrease during the first three days of growth. Storage protein structures, which are visible with scanning electron microscopy, undergo modification that leads to storage protein disappearance by day 4 post-imbibition. Expansion of cotyledons detached from seeds prior to imbibition is greatly reduced, total protein levels remain high, and storage protein structures remain visible in cells of these cotyledons. Incubation of excised cotyledons in 1.0 μM benzyladenine or kinetin increases the rates of cotyledon expansion and storage protein loss to levels higher than in intact seedling cotyledons, Incubation in 10 μM indole-3-acetic acid inhibits cotyledon expansion and protein mobilization. More rapid hydrolysis of storage proteins in cotyledons of intact seedlings or detached cotyledons treated with cytokinin is further indicated in day 2 specimens by SDS-polyacrylamide gel electrophoresis. These results suggest a possible mechanism for regulation of cotyledon development by interactions of the promotive effects of cytokinin and inhibitory effects of auxin.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 15 (1990), S. 789-791 
    ISSN: 1573-5028
    Keywords: cDNA ; chloroplast ; Cu/Zn superoxide dismutase ; nucleotide sequence ; Pisum sativum L. ; insertion element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 17 (1991), S. 1271-1274 
    ISSN: 1573-5028
    Keywords: manganese superoxide dismutase ; cDNA ; mitochondrial transit peptide ; Pisum sativum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5028
    Keywords: β-conglycinin ; seed storage protein ; trans-acting factors ; transcriptional regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the α′ and β subunit genes of β-conglycinin is differentially regulated during soybean embryo development. Although both are expressed solely in developing seeds during mid to late stages of embryo development, the α′ subunit is expressed more highly on a per gene basis, and α′ subunit mRNA begins to accumulate three to five days earlier than β subunit mRNA. In cultured cotyledons, β subunit genes respond to changes in methionine or abscisic acid levels, whereas expression of the α′ subunit gene(s) is unaffected by these changes. To investigate the mechanisms by which these genes are transcriptionally regulated, we examined the interactions of nuclear proteins with upstream sequences from the α′ and β subunit genes. Four distinct DNA binding factors were identified in nuclear extracts from developing soybean seeds. These factors are termed Soybean Embryo Factors (SEF) 1 through 4. SEF binding sites are distributed non-uniformly between the α′ and β subunit genes, and the amount of protein binding is modulated over the course of embryo development. DNA footprinting revealed the sequences recognized by three of these factors. Factors which behave in a manner similar to that of SEF3 were also identified in nuclear extracts from developing tobacco and sunflower seeds.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 17 (1991), S. 1263-1265 
    ISSN: 1573-5028
    Keywords: catalase ; cDNA ; nucleotide sequence ; Pisum sativum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 22 (1993), S. 873-885 
    ISSN: 1573-5028
    Keywords: β-conglycinin ; gene expression ; legumin box ; seed storage protein ; vicilin box
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes encoding the β-conglycinin seed storage proteins of soybean are expressed only in seeds during specific stages of development. The different subunits of β-conglycinin, α′, α and β, are encoded by distinct members of a gene family. Yet there are marked differences in the regulation of the genes encoding the α′/α and β subunits. Previous work (Chen et al., EMBO J 7: 297–302, 1988) identified a seed specific transcriptional enhancer upstream of a gene encoding the α′ subunit. Mutations were made within this region to discern its functional components. Among those identified is a 62 bp region (between −77 and −140) that contains a vicilin box consensus sequence as well as a sequence that binds the soybean nuclear factor SEF4 in vitro. A second region, which contains a sequence homologous to the core of the legumin box consensus (i.e., CATGCAT-like or RY repeat element) at −246, was also shown to affect the activity of this enhancer in transgenic plants. A series of 5′ terminal deletions were used to identify regulatory elements upstream of the β subunit gene. Two regions were identified (from −553 to −442 and from −308 to −72) that, when deleted, led to a marked reduction in gene expression. Both of these elements contain sequences that bind SEF4 in vitro. The distal element also contains an AT-rich segment that recognizes a second nuclear factor, SEF1, in vitro. Neither of these elements contains any homology to the vicilin box consensus.
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  • 9
    ISSN: 1432-2048
    Keywords: β-Conglycinin gene sequence ; Glycine (β-conglycinin) ; Seed development ; Storage protein (seed)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract β-Conglycinin, and abundant storage protein in soybean (Glycine max (L.) Merr.) seeds, is a trimeric protein consisting of various isomers containing the three subunits, α′, α and β. Accumulation of the β-subunit is unique because it appears to be regulated by a variety of developmental and environmental signals. In this paper we describe the isolation and characterization of a genomic clone encoding the β-subunit of β-conglycinin. The genomic clone was characterized by restriction-enzyme mapping and partial DNA sequence analysis, by immunoprecipitation of a hybrid-selected invitro translation product, and by RNA blot hybridization reactions. An mRNA of approx. 1700 nucleotides hybridized to an internal 2-kilobase (kb) region of this 4.4-kb cloned DNA restriction fragment and was translated to yield a polypeptide with an approximate molecular weight of 48 kilodalton. This polypeptide is immunoprecipitable by antibody against β-conglycinin and is of appropriate size to represent the precursor polypeptide of the β-subunit. When this sequence was used as a probe in RNA blot hybridization experiments, the β-gene transcript was first detected by stage K and accumulated through stage O during soybean seed development, coincident with appearance of the β-subunit. Partial DNA sequence analysis of the 5′ end of the gene confirmed that the isolated gene encoded a β-subunit, based upon the previously reported amino terminal sequence for this protein. Genomic DNA blot hybridization analyses indicate that multiple DNA restriction fragments are highly homologous to this cloned β-gene sequence.
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  • 10
    ISSN: 1573-5028
    Keywords: 14-3-3 protein ; Arabidopsis/ ; ascorbate peroxidase ; oxidative stress ; peroxisome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An Arabidopsis 14-3-3 protein, AFT1, was used as a ‘bait’ in the two-hybrid system to identify its interacting proteins. One of the candidate proteins, APX3, was identified as a putative peroxisomal membrane-bound ascorbate peroxidase. Ascorbate peroxidases are important defense enzymes that protect plant cells from oxidative stress damage. DNA blot analysis indicates that APX3 is encoded by a single-copy gene in the Arabidopsis genome. RNA blot analyses show that APX3 transcript levels increase slightly in response to cold, UV light, and treatments with hydrogen peroxide and paraquat. The activity of APX3 in Arabidopsis may be controlled in two ways: its enzymatic activity through protein-protein interactions and its transcription by transcriptional or posttranscriptional regulation.
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