22nd Dec., ’12. In an article entitled, “Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs” published in the  6th Dec. ’12 issue of Nature (492:59-65), Bruce A. Curtis  and his 72 associates (affiliated to  different universities of Canada, the USA,  the UK, Czeck, Germany, France, Sweden, Australia and  New Zealand ) have described  how the genes that encode the various proteins that function in these organelles were transferred to the nucleus  during the course of evolution by a process called Endosymbiotic Gene Transfer (EGT). The above authors have  sequenced the nuclear genomes of two unicellular algae that are remarkable in their genetic and cellular complexity: the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. It may be mentioned here that in both G. theta and B. natans plastids are bound by four membranes. In cryptophytes, the outermost plastid membrane is continuous with the nuclear envelope and a cluster of ribosomes are embedded in it. According to these authors they  co-translationally insert nucleus-encoded, organelle-targeted proteins. Another interesting feaute of these unicellular algae  is that they show between the inner and outer membrane pairs i.e. periplastidial compartment (PPC) containing the nucleomorph (NM). The latter is the relict nucleus of the eukaryotic endosymbiont. The approximate numbers of protein-coding genes in the plastid, mitochondrial (MT), nucleomorph and nuclear genomes of G. theta and B. natans have been determined. Click the figure to view them in higher magnification.