Isabel Miranda

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A Genetic Code Alteration Is a Phenotype Diversity Generator in the Human Pathogen Candida albicans

PLoS ONE, 2007

Background. The discovery of genetic code alterations and expansions in both prokaryotes and euka... more Background. The discovery of genetic code alterations and expansions in both prokaryotes and eukaryotes abolished the hypothesis of a frozen and universal genetic code and exposed unanticipated flexibility in codon and amino acid assignments. It is now clear that codon identity alterations involve sense and non-sense codons and can occur in organisms with complex genomes and proteomes. However, the biological functions, the molecular mechanisms of evolution and the diversity of genetic code alterations remain largely unknown. In various species of the genus Candida, the leucine CUG codon is decoded as serine by a unique serine tRNA that contains a leucine 59-CAG-39anticodon (tRNA CAG Ser ). We are using this codon identity redefinition as a model system to elucidate the evolution of genetic code alterations. Methodology/Principal Findings. We have reconstructed the early stages of the Candida genetic code alteration by engineering tRNAs that partially reverted the identity of serine CUG codons back to their standard leucine meaning. Such genetic code manipulation had profound cellular consequences as it exposed important morphological variation, altered gene expression, re-arranged the karyotype, increased cell-cell adhesion and secretion of hydrolytic enzymes. Conclusion/Significance. Our study provides the first experimental evidence for an important role of genetic code alterations as generators of phenotypic diversity of high selective potential and supports the hypothesis that they speed up evolution of new phenotypes.

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Determination of the proximate composition, ascorbic acid and heavy metal contents of Star Fruit (Averrhoa carambola)

Global Journal of Pure and Applied Sciences, 2008

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Characterization of crop residues from false banana /Ensete ventricosum/ in Ethiopia in view of a full-resource valorization

PloS one, 2018

False banana /Ensete ventricosum [Welw.] Cheesman/ is exploited as a food crop in Ethiopia where ... more False banana /Ensete ventricosum [Welw.] Cheesman/ is exploited as a food crop in Ethiopia where it represents an important staple food. The plant is harvested and large amounts of biomass residues are originated, mainly from the pseudo stem (i.e., fiber bundles obtained from the leaf sheaths after being scrapped to produce starchy food) and the inflorescence stalk. These materials were studied in relation to their summative chemical composition, composition of lignin, lipophilic and polar extracts. Moreover, their structural characteristics, in view of their valorization, were scrutinized. The analytical studies were performed with the aid of FTIR, GC/MS, Py-GC/MS and SEM. The fiber bundles are aggregates of mainly long and slender fibers with low ash, extractives and lignin contents (3.8%. 4.4% and 10.5% respectively) and high holocellulose and α-cellulose contents (87.5% and 59.6% respectively). The hemicelluloses in the fibers are mostly highly acetylated xylans and the lignin i...

format_quoteInflorescence stalk shows high ash content (12.3% main stalk, 24.6% fines), mainly potassium, with low lignin (5.8%).format_quote

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Pulping yield and delignification kinetics of heartwood and sapwood of maritime pine

Journal of wood chemistry and technology, Oct 1, 2005

In maritime pine (Pinus pinaster Ait.), heartwood represents a substantial part of the tree stem ... more In maritime pine (Pinus pinaster Ait.), heartwood represents a substantial part of the tree stem at final harvest age (80 years) corresponding to 42% at the base of the stem wood diameter and decreasing upward. The rate of heartwood formation was estimated at 0.35 rings/year, beginning at 18 years of age. Differences in the chemical composition between heartwood and sapwood were mainly in the extractives, 19.7% and 5.8%, respectively. The lignin content was 23.1% and 24.5% in the heartwood and sapwood, respectively. Pulping ...

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