Search results for "Ancestor"
showing 3 items of 43 documents
The universal ancestor : an unfinished reconstruction
2015
El cenancestro se define como el ultimo ancestro comun de todos los seres vivos que existen actualmente. Su naturaleza se ha inferido a partir de la identificacion de los genes homologos entre los linajes de arqueas, bacterias y eucariontes. Estas inferencias indican que el cenancestro poseia un sistema de traduccion de proteinas relativamente moderno y era similar en complejidad a una celula actual. Sin embargo, las enzimas claves que se encargan tanto de la replicacion del material genetico como de la biosintesis de membranas celulares no son homologas entre los linajes celulares. Aqui revisamos brevemente la historia del concepto del ultimo ancestro comun y las distintas hipotesis que se…
Elucidating geological and biological processes underlying the diversification of Sulawesi tarsiers.
2009
Because of their exceptionally long independent evolution, a range diminution of their Eocene relatives, and a remarkable subsequent diversification in Southeast Asia, tarsiers are of particular importance to evolutionary primatologists. Little is known, however, on the processes shaping the radiation of these small enigmatic primates—especially on the Indonesian island of Sulawesi, their center of endemism. Geological reconstructions and progress in applying DNA sequence information to divergence dating now provide us with the tools and background to comprehend tarsier dispersal. Here, we describe effects of plate-tectonic movements, Pleistocene sea level changes, and hybridization on the…
Signal Recognition Particle 54 kD Protein (SRP54) from the Marine Sponge Geodia cydonium
2002
In the systematic search for phylogenetically conserved proteins in the simplest and most ancient extant metazoan phylum – Porifera, we have identified and analyzed a cDNA encoding the signal recognition particle 54 kD protein (SRP54) from the marine sponge Geodia cydonium (Demospongiae). The signal recognition particle (SRP) is a universally conserved ribonucleoprotein complex of a very ancient origin, comprising SRP RNA and several proteins (six in mammals). The nucleotide sequence of the sponge cDNA predicts a protein of 499 amino acid residues with a calculated Mr of 55175. G. cydonium SRP54 displays unusually high overall similarity (90 %) with human/mammalian SRP54 proteins, higher th…