Green algae, land plants, and other photosynthetic eukaryotes possess plastids, such as chloroplasts, which have evolved from cyanobacterial ancestors via endosymbiosis. An early evolutionary merger between heterotrophic eukaryotes and cyanobacteria called primary endosymbiosis gave rise to the first photosynthetic eukaryotes. A series of plastid acquisitions involving engulfment of eukaryotic ...

Endosymbiosis allows hosts to acquire new functional traits such that the combined host and endosymbiont can exploit vacant ecological niches and occupy novel environments [1, 2]; consequently, endosymbiosis affects the structure and function of ecosystems [3, 4]. However, for many endosymbioses, it is unknown whether their evolutionary basis is mutualism or exploitation [5-9]. We estimated the...

The ciliate Paramecium bursaria and the green alga Chlorella species can establish endosymbiosis by mixing them through the host digestive vacuoles. Pulse-labeling of alga-free Paramecium cells with isolated symbiotic algae for 1.5 min and chasing for various times showed presence of four cytological phenomena which are indispensable for the algal reinfection. (1) Some algae acquire temporal re...

The acquisition of photosynthesis by eukaryotic cells through enslavement of a cyanobacterium represents one of the most remarkable turning points in the history of life on Earth. In addition to endosymbiotic gene transfer, the acquisition of a protein import apparatus and the coordination of gene expression between host and endosymbiont genomes, the establishment of a metabolic connection was ...

Chloroplasts are present in organisms belonging to the kingdom Plantae. These organelles are thought to have originated from photosynthetic cyanobacteria through endosymbiosis. During endosymbiosis, most cyanobacterial genes were transferred to the host nucleus. Therefore, most chloroplast proteins became encoded in the nuclear genome and must return to the chloroplast after translation. The N-...

Primary plastids descend from the cyanobacterial endosymbiont of an ancient eukaryotic host, but the initial selective drivers that stabilized the association between these two cells are still unclear. One hypothesis that has achieved recent prominence suggests that the first role of the cyanobiont was in energy provision for a host cell whose reserves were being depleted by an intracellular ch...

Reductive genome evolution is seen in organisms living in close association with each other, such as in endosymbiosis, symbiosis, and parasitism. The reduced genomes of endosymbionts and parasites often exhibit similar features such as high gene densities and A+T compositional bias. Little is known about how the regulation of gene expression has been affected in organisms with highly compacted ...

The origin of eukaryotes is a fundamental, forbidding evolutionary puzzle. Comparative genomic analysis clearly shows that the last eukaryotic common ancestor (LECA) possessed most of the signature complex features of modern eukaryotic cells, in particular the mitochondria, the endomembrane system including the nucleus, an advanced cytoskeleton and the ubiquitin network. Numerous duplications o...