17 research outputs found

    Characterization, high-resolution mapping and differential expression of three homologous PAL genes in Coffea canephora Pierre (Rubiaceae)

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    Phenylalanine ammonia lyase (PAL) is the first entry enzyme of the phenylpropanoid pathway producing phenolics, widespread constituents of plant foods and beverages, including chlorogenic acids, polyphenols found at remarkably high levels in the coffee bean and long recognized as powerful antioxidants. To date, whereas PAL is generally encoded by a small gene family, only one gene has been characterized in Coffea canephora (CcPAL1), an economically important species of cultivated coffee. In this study, a molecular- and bioinformatic-based search for CcPAL1 paralogues resulted successfully in identifying two additional genes, CcPAL2 and CcPAL3, presenting similar genomic structures and encoding proteins with close sequences. Genetic mapping helped position each gene in three different coffee linkage groups, CcPAL2 in particular, located in a coffee genome linkage group (F) which is syntenic to a region of Tomato Chromosome 9 containing a PAL gene. These results, combined with a phylogenetic study, strongly suggest that CcPAL2 may be the ancestral gene of C. canephora. A quantitative gene expression analysis was also conducted in coffee tissues, showing that all genes are transcriptionally active, but they present distinct expression levels and patterns. We discovered that CcPAL2 transcripts appeared predominantly in flower, fruit pericarp and vegetative/lignifying tissues like roots and branches, whereas CcPAL1 and CcPAL3 were highly expressed in immature fruit. This is the first comprehensive study dedicated to PAL gene family characterization in coffee, allowing us to advance functional studies which are indispensable to learning to decipher what role this family plays in channeling the metabolism of coffee phenylpropanoids

    Inner Bremsstrahlung from <Sup>45</Sup>Ca and <Sup>91</Sup>Y

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    Inner bremsstrahlung accompanying the beta decay from 45Ca And 91Y was measured employing the magnetic deflection method in the energy range 50-250 keV and 150 - 1500 keV respectively. The observed experimental spectra were unfolded to extract the true events, the experimental results were compared with the theory of Knipp, Uhlenbeck and Bloch as also with the Coulomb-corrected theories of Lewis, Ford and Nilsson. Detour effects were also considered following the theory of Ford and Martin. Discrepancies have been observed between experimental and theoretical results. The measured spectral distribution is found to deviate significantly from all the above theories
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