Nexos entre la taxonomía evolutiva y la distribución de las frecuencias de los aminoácidos en genes y proteínas
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Fecha
2008
Autores
Rodríguez Fernández, María Milena
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Universidad Central “Marta Abreu” de las Villas
Resumen
En este trabajo se muestran evidencias acerca de la existencia de diferencias estadísticamente significativas entre varios grupos taxonómicos a través del uso del número de codones estimados que codifican para cada aminoácido (NECk) y de las probabilidades de aparición de estos en las proteínas (pk). Estas variables fueron estimadas utilizando bases de datos construidas a partir del uso de codones en los genes y de secuencias de proteínas provenientes de diferentes organismos vivos. La aplicación de los métodos CHAID y análisis discriminate y la evaluación del desempeño de los mismos permitieron verificar que las diferencias detectadas entre los taxa están en correspondencia con la clasificación biológica. Además de esto, utilizando la distancia de Hellinger entre los vectores pk se calcularon matrices de distancia a partir de las cuales se construyeron árboles filogenéticos que, no solo confirmaron relaciones filogenéticas entre los taxa que están en concordancia con la taxonomía evolutiva sino que, además, sugieren la existencia de, al menos, una gran extinción en algún momento de la historia evolutiva.
Evidences about the existence of statistical significant differences between several taxonomic groups are shown by means of the number of codon used by each amino acid (NECk) and the appearance probabilities of these in proteins (pk). These variables were estimated using databases which were made-up from the codon use in genes and protein sequences taken from different living organisms. The application of CHAID and discriminant methods and their performance evaluation allowed verify that the differences detected between the taxa are in correspondence with their biological classification. Besides this, distance matrices were calculated using the Hellinger distance between pk vectors. From these matrices phylogenetic trees were built that, not only, confirmed the phylogenetic relationships between the taxa that are in agreement with the evolutionary taxonomy but rather, also, they suggest the existence of, at least, a great extinction during the evolutionary history.
Evidences about the existence of statistical significant differences between several taxonomic groups are shown by means of the number of codon used by each amino acid (NECk) and the appearance probabilities of these in proteins (pk). These variables were estimated using databases which were made-up from the codon use in genes and protein sequences taken from different living organisms. The application of CHAID and discriminant methods and their performance evaluation allowed verify that the differences detected between the taxa are in correspondence with their biological classification. Besides this, distance matrices were calculated using the Hellinger distance between pk vectors. From these matrices phylogenetic trees were built that, not only, confirmed the phylogenetic relationships between the taxa that are in agreement with the evolutionary taxonomy but rather, also, they suggest the existence of, at least, a great extinction during the evolutionary history.
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Palabras clave
Taxonomía Evolutiva, Distribución de Frecuencias, Aminoácidos, Genes y Proteínas, Probabilidades