Epigenetic regulation of transposable elements in the plant kingdom which allows for self-copying) within the coding of the transposon defines class I elements as autonomous or non-autonomous. Class I transposons can take the form of: Curiously, retrotransposons have been discovered to be the predominant form of transpositional element in plants with large genomes, such as maize and wheat, potentially indicating rapid success of this class of transposon in the creation of hybrids, such as wheat, peppermint and, in the distant past, maize. Plant hybridization often creates polyploids, with double, triple, quadruple or more the number of chromosomes present in the parent generation. Polyploid hybrids seem to be particularly susceptible
Owned-and-operated television stations in the United States as a result). However, Tribune was the only one of the two companies involved in The WB that owned any stations aligned with the network as Time Warner did not own any television stations at the network's launch and would not own one until its 1996 merger with the Turner Broadcasting System, owners of Atlanta superstation WTBS (channel 17, now WPCH-TV; its national feed, TBS, is now a separate basic cable channel). On January 24, 2006, Time Warner and CBS Corporation announced that they would merge The WB with the CBS-owned United Paramount Network to form a new broadcast network