Nucleomorph

This article is missing information about inclusions including nucleolus (plus rDNA!), division behavior, mentioned in refs of doi:10.1007/s00709-017-1153-5 (RG link). Please expand the article to include this information. Further details may exist on the talk page. (October 2021)

Diagram of a four membraned chloroplast containing a nucleomorph.

Nucleomorphs are small, vestigial eukaryotic nuclei found between the inner and outer pairs of membranes in certain plastids. They are thought to be vestiges of primitive red and green algal nuclei that were engulfed by a larger eukaryote. Because the nucleomorph lies between two sets of membranes, nucleomorphs support the endosymbiotic theory and are evidence that the plastids containing them are complex plastids. Having two sets of membranes indicate that the plastid, a prokaryote, was engulfed by a eukaryote, an alga, which was then engulfed by another eukaryote, the host cell, making the plastid an example of secondary endosymbiosis.^[1][2]