Dinophysis

Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters. It was first described in 1839 by Christian Gottfried Ehrenberg. Dinophysis are typically medium-sized cells (30-120 μm). The structural plan and plate tabulation are conserved within the genus. Dinophysis thecae are divided into halves by a sagittal fission suture. There are five types of thecae ornamentation in this genus, and those are a useful character for species identification. Dinophysis mainly divide by binary fission. Dinophysis chloroplasts are usually rod-shaped or granular and yellow or brown colored. Some Dinophysis spp. take up kleptoplastids when feeding. Toxic Dinophysis produce okadaic acid, dinophysistoxins, and pectenotoxins, which inhibit protein phosphatase and cause diarrhea. The etymology of this genus name comes from Greek, Dino comes from "" (δεινός) meaning terrible and "" (φύσις) meaning nature. The genus was first described in 1839 by Ehrenberg, which is why the holotype species of this genus is Dinophysis acuta Ehrenberg. It has been found that what were considered different Dinophysis species might just be different life stages. Severe diarrheic shellfish poisoning breakouts in northeast Japan led to the identification of a Dinophysis species that produces toxins, Dinophysis fortii in 1976-77. This genus is difficult to maintain in culture leading to challenges in gaining knowledge of these organisms. Some Dinophysis spp. have kleptoplastids of cryptomonad origin, specifically from the cryptomonad Teleaulax amphioxeia. Dinophysis caudata have acquired these kleptoplastids by engulfing the ciliate Mesodinium rubrum which has engulfed T. amphioxeia plastids. Cryptomonad plastids have four membranes and a nucleomorph and are a product of secondary endosymbiosis. For years it was believed that Dinophysis did not have a sexual cycle. However, it is now apparent that gamete cells can form in Dinophysis acuminata and D. acuta; this was found when small, spherical cells seemed to form inside larger ones.