nucleomorphn.
/ˈnjuːklɪə(ʊ)mɔːf/, U.S. /ˈn(j)uklioʊˌmɔrf/ Cell Biology.
An organelle found in the chloroplasts of cryptomonads and certain other protists which is bounded by a double membrane, contains genetic material, and is thought to represent the vestigial nucleus of an endosymbiotic algal cell.
ΚΠ
1977 A. D. Greenwood et al. in Brit. Phycol. Jrnl. 12 119 The unique periplastidial matrix in Cryptophyceae containing starch and putative ribosomes may depend on subsidiary genomes, carried possibly in small fibrogranular inclusions limited by fenestrated double membranes, named provisionally ‘nucleomorphs’.
1979 Proc. Royal Soc. B. 204 181 If the presence of DNA..could be confirmed within the nucleomorph then the case for the eukaryotic origin of the chloroplast units of cryptomonads, at least, would be greatly enhanced.
1993 L. Margulis et al. Illustr. Gloss. Protoctista 83/1 Nucleomorph, organelle surrounded by a double membrane resembling a small nucleus, lying between the plastid ER and plastid membrane in cryptomonads.
2001 Guardian 26 Apr. (Science section) 2/4 Compacted into three, minute chromosomes, the nucleomorph contains 551,264 base-pairs of DNA. It is the smallest eukaryote genome sequenced so far.
This is a new entry (OED Third Edition, December 2003; most recently modified version published online March 2022).
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n.1977