As dinoflagellates, Amphidinium spp. have chloroplasts. The Amphidinium chloroplast genome is unusual in not having a single contiguous circular genome.[2][3] Instead, chloroplast genes encoded in chloroplast DNA are found on numerous 2-3 kbp minicircles,[2][3] analogous to plasmids. Most minicircles have only a few protein-coding genes; many have just a single gene.[2][3] There are reports of minicircles that do not have known transcripts, like in the Amphidinium carterae chloroplast genome,[3] although these were not found in the Symbiodinium sp. Clade C3 chloroplast genome.[2] Minicircle-derived transcripts can be processed in ways not typical of eukaryotes, including the addition of a 3' poly(U) tail,[3] as opposed to the typical poly(A) tail derived from polyadenylation of eukaryotic transcripts. Minicircle-derived antisense transcripts are also produced, but without 3' poly(U) tails.[3]
