The inherent occurrence of complex intron-rich spliceosomal split genes, including regulatory and splicing elements, within pre-biotic random genetic sequences

Growing evidence indicates that complex intron-rich split genes and an advanced spliceosome existed in the earliest eukaryote, and possibly the first life form. We sought to examine how these split genes could have originated in the prebiotic system. We previously found that split coding sequences for complex proteins occur in abundance in random DNA sequences (P. Senapathy, et al, accompanying paper). This study demonstrates that a full complement of exons, introns and regulatory and splicing elements could have also occurred inherently within pre-biotic chemistry by chance. By comparing the characteristics of split genes found in computer-generated random genetic sequences with those of several extant eukaryotes, we show that an abundance of intron-rich split genes akin to those present in modern eukaryotes could have existed in the prebiotic system. These findings answer the post-genomic question of why the earliest life form contained highly complex intron-rich split genes, and, in conjunction with our companion study, show how they could encode a complex spliceosome

Origin of biological information: Inherent occurrence of intron-rich split genes, coding for complex extant proteins, within pre-biotic random genetic sequences

The origin of biological information is an unexplained phenomenon. Prior research in resolving the origin of proteins, based on the assumption that the first genes were contiguous prokaryotic sequences has not succeeded. Rather, it has been established that contiguous protein-coding genes do not exist in practically any amount of random genetic sequences. We found that complex eukaryotic proteins could be inherently encoded in split genes that could exist by chance within mere micrograms to milligrams of random DNA. Using protein amino acid sequence variability, codon degeneracy, and stringent exon-length restriction, we demonstrate that split genes for proteins of extant eukaryotes occur extensively in random genetic sequences. The results provide evidence that an abundance of split genes encoding advanced proteins in a small amount of prebiotic genetic material could have ignited the evolution of the eukaryotic genome