During 1970, in some mammalian viruses (e.g. adenoviruses) it was found that the DNA sequences coding for a polypeptide were not present continuously but were split into several pieces. Therefore, these genes were variously named as split genes or introns (Gilbert, 1978), interrupted genes or intervening sequences (Lewin, 1980), inserts (Weismann, 1978), Junk DNA.For the discovery of split genes in adenoviruses and higher organisms, Richards J.Roberts and Phillip Sharp were awarded Nobel prize in 1993.