Transposons have also been the source of important proteins for vertebrates, such as the site-specific recombinases Rag1 and 2. Other authors have proposed global adaptive roles for junk DNA as scavengers of intranuclear chemical mutagens,Afatinib because an excess of non-coding over coding sequences would decrease the probability of mutations in the latter. Indeed, the number of nucleotides damaged by mutagens in coding sequences is expected to be inversely proportional to the size of the non-coding DNA fraction. Genomic DNA content is positively correlated with nuclear and cell volumes in a wide range of organisms. Indeed, bulk DNA, independently of its sequence, seems to determine cell volume as a result of a ‘‘nucleotypic effect’’. Along similar lines, the nucleoskeletal hypothesis posits that optimal cellular function would require a rather constant nucleo/cytoplasmic ratio ensuring an optimal exchange between the two cellular compartments. This implies that DNA itself or its associated proteins should play an architectural role in maintain-ing nuclear volume, which would in turn dictate cell volume. The most striking example of the relationship between genome size and cell volume is provided by ploidy series. This has been clearly shown for yeast autopolyploids. Interestingly, and relevant to what is discussed below,NVP-BEZ235 an increase of the nuclear volume also decreases the flow of mutagens, coming through its surface, per unit of nuclear volume. In this theoretical paper we speculate that proliferation of selfish DNA and by extension the retention of seemingly nonfunctional DNA can have other ‘functions’ connected with the physical properties of the cell which might be critical to ensure the balance between interacting gene products after whole genome duplication events. There is increasing evidence supporting the idea that some stoichiometric balance between and within the subunits of macromolecular complexes must be maintained to ensure their normal functioning.