Oryza glaberrima massive paleolakes in what is now the Western Sahara. As the climate dried, the wild rice retreated and probably became increasingly domesticated as it relied on humans for irrigation. Rice growing in deeper, more permanent water became floating rice. It is believed to have been domesticated 2000–3000 years ago in the inland delta of the Upper Niger River, in what is now Mali. It then spread through West Africa. It has also been recorded off the "east" coast of Africa, in the Zanzibar Archipelago. Wild rice seedheads shatter, scattering the rice grains to seed the next generation. Domestic rice does
Helitron (biology) Helitron (biology) Helitrons are one of the three groups of eukaryotic class 2 transposable elements (TEs) so far described. They are the eukaryotic rolling-circle transposable elements which are hypothesized to transpose by a rolling circle replication mechanism via a single-stranded DNA intermediate. They were first discovered in plants ("Arabidopsis thaliana" and "Oryza sativa") and in the nematode "Caenorhabditis elegans", and now they have been identified in a diverse range of species, from protists to mammals. Helitrons make up a substantial fraction of many genomes where non-autonomous elements frequently outnumber the putative autonomous partner. Helitrons seem to have a major role