ABSTRACT
Many questions concerning the prokaryotic origins of nuclear genes are presently incompletely understood, and current ideas concerning their origins are changing rapidly with the advent of completely sequenced genomes. The most widely known view holds that eukaryotes are derived from an evolutionary ancestor common to all Archaea. The eocyte view, favoured by our laboratory, differs from this view in two ways. First, it posits that the Archaea are not a true (monophyletic) evolutionary group because a major hyperthermophilic group, the eocytes (crenarchaeotes), is phylogenetically closer to the eukaryotes. Second, it is becoming clear that ribosomal RNA molecule does not represent the evolution of life as claimed by the Archaeal theory, but is representative of only a limited part of the genome. It is becoming clearer and clearer that eukaryotic genomes have significant contributions from eubacteria. Even the mechanism by which the nucleus was formed may have involved an endosymbiosis between two bacterial types.
