''Amphidinium'' is a genus of

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s. The type for the genus is ''

Amphidinium operculatum ''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, ''Amp ...

'' Claparède & Lachmann. The genus includes the species ''

Amphidinium carterae ''Amphidinium carterae'' is a species of dinoflagellates. It was first described by Edward M. Hulburt in 1957, and was named in honour of the British phycologist Nellie Carter-Montford. The type locality is Great Pond, Barnstable County, Mas ...

'' which is used as a

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

. As dinoflagellates, ''Amphidinium'' spp. have chloroplasts. 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 Minicircles are small (~4 kb) circular replicons. They occur naturally in some eukaryotic organelle genomes. In the mitochondria-derived kinetoplast of trypanosomes, minicircles encode guide RNAs for RNA editing. In ''Amphidinium'', the chloro ...

, analogous to

plasmids A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; how ...

. 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.

See also

References

Further reading