Comment Re:First time? (Score 2) 45
Well, we all have retroviral genes in our genomes; so in one way there certainly has been "mergings", at least at the genetic level. But the nature of the two organelles being referred to; mitochondria and chloroplasts, in indeed different. Mitochondria originated as free-living Alphaproteobacteria that could, apparently, produce ATP through oxidization. Chloroplasts are the descendants of cyanobacteria, who could produce ATP from photosynthesis.
Both mitochondria and chloroplasts weren't merely enveloped by more primitive eukaryotic cells, they're division and reproduction is timed to that of the host cell, so that when the host cell divides, so do to these organelles. Additionally, both mitochondria and chloroplasts have lost a lot of genes over the 1.5 to 2 billion years that they have been incorporated into eukaryotic cell lines. Another critical aspect of both these types of organelles is that their genomes are not merely honed down to what look like the essentials for producing energy, but that those genomes are very conserved even as compared to the host cells.
If this is the case, even it's early in the evolution of this endosymbiotic relationship, it is a significant discovery.