''Amphidinium'' is a genus of dinoflagellates. The type for the genus is '' Amphidinium operculatum'' Claparède & Lachmann. The genus includes the species '' Amphidinium carterae'' which is used as a model organism. As dinoflagellates, ''Amphidinium'' spp. have

chloroplasts A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, ...

. The ''Amphidinium'' chloroplast

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

is unusual in not having a single contiguous circular genome. Instead, chloroplast genes encoded in chloroplast DNA are found on numerous 2-3 kbp minicircles, analogous to plasmids. Most minicircles have only a few protein-coding genes; many have just a single

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

. There are reports of minicircles that do not have known transcripts, like in the ''Amphidinium carterae'' chloroplast genome, although these were not found in the ''Symbiodinium'' sp. Clade C3 chloroplast genome. Minicircle-derived transcripts can be processed in ways not typical of eukaryotes, including the addition of a 3' poly(U) tail, as opposed to the typical poly(A) tail derived from

polyadenylation Polyadenylation is the addition of a poly(A) tail to an RNA transcript, typically a messenger RNA (mRNA). The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In euk ...

of eukaryotic transcripts. Minicircle-derived antisense transcripts are also produced, but without 3' poly(U) tails.

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