1,720,987 research outputs found
Cadmium effects on growth and antioxidant enzymes activities in Miscanthus sinensis
No full textPlants of Miscanthus sinensis (cv. Giganteus) were grown in hydroponics for three months in nutrient solution with 0, 2.2, 4.4 and 6.6 mu M CdNO3. Growth parameters, catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities were analysed in leaves and roots collected after 1- and 3-month exposure. Dry biomass of all miscanthus organs was affected by Cd concentration both after 1- and 3-month exposure. No visible symptoms of Cd toxicity were observed in shoots and rhizomes of plants grown in presence of Cd. In contrast, roots became shorter and thicker and the whole root system more dense and compact already after one month of treatment with 6.6 mu M Cd. The lower Cd concentration increased the enzymes activities after 3 months in leaves and only after 1-month in roots, while a decrease in activity was observed at higher Cd concentrations
PRMT11: a new Arabidopsis MBD7 protein partner with arginine methyltransferase activity
No full textSummary
Plant methyl-DNA-binding proteins (MBDs), discovered by sequence homology to their animal counterparts,
have not been well characterized at the physiological and functional levels. In order better to characterize the
Arabidopsis AtMBD7 protein, unique in bearing three MBD domains, we used a yeast two-hybrid system to
identify its partners. One of the interacting proteins we cloned is the Arabidopsis arginine methyltransferase 11
(AtPRMT11). Glutathione S-transferase pull-down and co-immunoprecipitation assays confirmed that the two
proteins interact with each other and can be co-isolated. Using GFP fluorescence, we show that both AtMBD7
and AtPRMT11 are present in the nucleus. Further analyses revealed that AtPRMT11 acts as an arginine
methyltransferase active on both histones and proteins of cellular extracts. The analysis of a T-DNA mutant line
lacking AtPRMT11 mRNA revealed reduced levels of proteins with asymmetrically dimethylated arginines,
suggesting that AtPRMT11, which is highly similar to mammalian PRMT1, is indeed a type I arginine
methyltransferase. Further, AtMBD7 is a substrate for AtPRMT11, which post-translationally modifies the
portion of the protein-containing C-terminal methylated DNA-binding domain. These results suggest the
existence of a link between DNA methylation and arginine methylation
DNA and arginine methylation in Arabidopsis: the relationship between AtMBD7 and AtPRMT11
No full textP01-021
DNA methylation in vertebrate cells marks out functionally specialized regions of the genome and is strongly associated with transcriptional repression. Highly conserved DNA-binding proteins (containing methyl-CpG binding domain, MBD) has been identified and share high specificity in recognizing methylated DNA. In A. thaliana several members of the MBD family have been characterized, showing similarities to animal MBDs. Only few of them can recognize methylated DNA and their physiological and functional significance is still unclear.
To study the role of AtMBD7, the only one bearing three MBD domains, we identified AtPRMT11, an arginine methyltransferase, among the protein partners. Our experiments confirmed that these two proteins interact in vitro and can be isolated together in the same complex. Analyses revealed that AtPRMT11 methylates arginines in an asymmetrical fashion and is active both on histones and cellular proteins. These data reveal for the first time in plants the direct interaction between one member of the MBD family and an arginine methyltransferase, analogously to animals where MBD2 is able to interact with and is modulated by the PRMT5 enzyme (Tan and Nakielny, 2006). Moreover we found that AtPRMT11 can methylate one of the DNA binding domains in AtMBD7 thus suggesting that AtMBD7 might act as a bridge between two global epigenetic mechanisms of gene regulation in plants. Data describing these particular interaction will be presented and discussed
Fluorocromi e fotoproteine per la misura della concentrazione del Ca2+ citosolico in cellule vegetali
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Physiological and biochemical reactions of olive genotypes during site-relevant ozone exposure
No full textOzone (O3) is one of the major atmospheric pollutants in the Mediterranean area and negatively interacts with several biochemical and physiological processes of the plants. Olive is one of the most widely cultivated trees in the Mediterranean climates and previous studies have shown that O3 can potentially interfere with olive trees productivity. In order to test the physiological and biochemical changes induced by realistic O3 levels (100 and 50 ppb, 5 h-1 day) in newly developed olive leaves, the effects of long term (18 months) O3 exposure were investigated on Moraiolo and Frantoio cultivars. Data on gas exchange showed that O3 treatment had significant effects on photosynthetic activity and stomatal conductance with some differences between the two cultivars. X-ray spectra obtained from guard cells of open and closed stomata confirmed the main role of K to establish the differences in the ionic state between open and closed stomata. Moreover, O3 exposure induced a decrease in K and Ca net counts with respect to the control treatment suggesting the development of an adaptive mechanism to O3 which controls stomata responses at reduced ionic levels. Biochemical assays showed that ascorbate peroxidase activity was not affected by O3 treatments in Frantoio, while it increased in Moraiolo plants exposed to 50 ppb of O3
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