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  • 1
    ISSN: 1617-4623
    Keywords: Key wordsSchizosaccharomyces pombe ; DNA-damage inducibility ; Damage-responsive element ; Upstream activating sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Schizosaccharomyces pombe rhp51 + gene encodes a recombinational repair protein that shares significant sequence identities with the bacterial RecA and the Saccharomyces cerevisiae 1RAD51 protein. Levels of rhp51 + mRNA increase following several types of DNA damage or inhibition of DNA synthesis. An rhp51:: ura4 fusion gene was used to identify the cis-acting promoter elements involved in regulating rhp51 + expression in response to DNA damage. Two elements, designated DRE1 and DRE2 (for damage-responsive element), match a decamer consensus URS (upstream repressing sequence) found in the promoters of many other DNA repair and metabolism genes from S. cerevisiae. However, our results show that DRE1 and DRE2 each function as a UAS (upstream activating sequence) rather than a URS and are also required for DNA-damage inducibility of the gene. A 20-bp fragment located downstream of both DRE1 and DRE2 is responsible for URS function. The DRE1 and DRE2 elements cross-competed for binding to two proteins of 45 and 59 kDa. DNase I footprint analysis suggests that DRE1 and DRE2 bind to the same DNA-binding proteins. These results suggest that the DRE-binding proteins may play an important role in the DNA-damage inducibility of rhp51 + expression.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Photosynthesis research 18 (1988), S. 277-286 
    ISSN: 1573-5079
    Keywords: CO2 uptake ; high-temperature acclimation ; Opuntia ficus-indica ; photosystems I and II ; whole chain electron transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inhibition and recovery of net CO2 uptake and three photosynthetic electron transport reactions as well as plant survival following high-temperature treatments were investigated for Opuntia ficus-indica. For plants maintained at 30°C/20°C day/night air temperatures, treatment at 60°C for 1 h irreversibly inhibited net CO2 uptake and photosynthetic electron transport, resulting in plant death in about 60 days. When a plant maintained at 30°C/20°C was treated at 55°C for 1 h, net CO2 uptake was completely inhibited 1 d after the treatment but fully recovered in 60 d. Differential inactivation of photosystem (PS) I, PSII, and whole chain electron transport activities occurred; PSI was the most tolerant of 55°C and took the least time (45 d) for total recovery. All 30°C/20°C plants survived a 1-h treatment at 55°C, although some pale green areas were observed on the cladode surfaces. In contrast to growing at 30°C/20°C, plants acclimated to 45°C/35°C survived 60°C for 1 h without showing any necrotic or pale green areas on the cladode surfaces. When such a plant was transferred to 30°C/20°C following the high-temperature treatment, recovery in net CO2 uptake began in 1 d and progressed to complete recovery by 30 d. Growth temperatures thus influence the possibility for recovery of photosynthetic reactions and ultimately the survival of O. ficus-indica following a high-temperature exposure.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5079
    Keywords: Crassulacean acid metabolism ; CO2 enrichment ; Opuntia ficus-indica ; PEPCase ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Responses of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase) to an elevated atmospheric CO2 concentration were determined along with net CO2 uptake rates for the Crassulacean acid metabolism species Opuntia ficus-indica growing in open-top chambers. During the spring 13 months after planting, total daily net CO2 uptake of basal and first-order daughter cladodes was 28% higher at 720 than at 360 μl CO2 l-1. The enhancement, caused mainly by higher CO2 assimilation during the early part of the night, was also observed during late summer (5 months after planting) and the following winter. The activities of Rubisco and PEPCase measured in vitro were both lower at the elevated CO2 concentration, particularly under the more favorable growth conditions in the spring and late summer. Enzyme activity in second-order daughter cladodes increased with cladode age, becoming maximal at 6 to 10 days. The effect ofelevated CO2 on Rubisco and PEPCase activity declined with decreasing irradiance, especially for Rubisco. Throughout the 13-month observation period, O. ficus-indica thus showed increased CO2 uptake when the atmospheric CO2 concentration was doubled despite lower activities of both carboxylating enzymes.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1617-4623
    Keywords: Schizosaccharomyces pombe ; DNA-damage inducibility ; Damage-responsive element ; Upstream activating sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheSchizosaccharomyces pombe rhp51 + gene encodes a recombinational repair protein that shares significant sequence identities with the bacterial RecA and theSaccharomyces cerevisiae RAD51 protein. Levels ofrhp51 + mRNA increase following several types of DNA damage or inhibition of DNA synthesis. Anrhp51::ura4 fusion gene was used to identify the cis-acting promoter elements involved in regulatingrhp51 + expression in response to DNA damage. Two elements, designated DRE1 and DRE2 (fordamage-responsiveelement), match a decamer consensus URS (upstream repressing sequence) found in the promoters of many other DNA repair and metabolism genes fromS. cerevisiae. However, our results show that DRE1 and DRE2 each function as a UAS (upstream activating sequence) rather than a URS and are also required for DNA-damage inducibility of the gene. A 20-bp fragment located downstream of both DRE1 and DRE2 is responsible for URS function. The DRE1 and DRE2 elements cross-competed for binding to two proteins of 45 and 59 kDa. DNase I footprint analysis suggests that DRE1 and DRE2 bind to the same DNA-binding proteins. These results suggest that the DRE-binding proteins may play an important role in the DNA-damage inducibility ofrhp51 + expression.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
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