A book draft before printing often holds extra pages: marginal notes, repetitions, crossed-out paragraphs. The print shop doesn't print them, but the author keeps them in case of edits. The genome of the nematode Auanema rhodense works much the same way: germline cells carry the full draft of 180.9 megabases, while body cells retain only 60 megabases of clean text.
When the embryo reaches 12 cells, DNA begins to be cut in four of the eight cells. Giant blocks of tandem repeats drop out of the chromosomes: identical stretches standing one after another, like pages with a repeated line. The breaks occur at 28 sites, and each one contains a palindromic motif 29 nucleotides long. This motif is almost identical to the one found in the related species Oscheius tipulae, but the scale differs: in O. tipulae only 0.6% of the genome is discarded, while in A. rhodense it is 61%.
By the 30-cell stage, almost all nuclei have already lost the repeats, and only two nuclei keep them: these are the future germline cells. So the draft, from which rough pages are torn out before printing, remains intact only in the germline cells, to pass on all variants to the descendants. And in body cells, only what is needed for life here and now remains.
Auanema rhodense has three sexes: males, females and hermaphrodites. What is more, males pass on only the X chromosome to their offspring, while hermaphrodites produce only sperm carrying two X chromosomes, whereas their eggs contain no X at all.
The idea of cells deliberately throwing away part of their genetic material echoes the motif of forbidden knowledge in science fiction: in Greg Bear's novel Blood Music, for instance, cells rearrange their DNA and acquire a will of their own. Here, though, everything is under the control of evolution rather than rebellion.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.