Informational parameters and randomness of mitochondrial DNA.

The informational content of genomes of nuclear and mitochondrial origin is examined. By using the parameters of Shannon's information theory the language of mitochondrial DNA is shown to be more similar to the language of bacterial DNA than to that of nuclear DNA in more evolutionarily advanced animals. Moreover, using the parameters of Kolmogorov's theory on randomness, genes of different organisms (Neurospora crassa and Saccharomyces cerevisiae) coding for the same protein (subunit 9 of ATPase) are shown to have, if both of mitochondrial origin, a similar degree of randomness, whereas genes coding for the same protein, both belonging to the same organisms, exhibit a quite different degree of randomness when one is of mitochondrial origin and the other of nuclear origin. These results are in favor of the symbiotic origin of mitochondria.