''Dinophysis acuta'' is a species of flagellated planktons belonging to the genus '' Dinophysis''. It is one of the few unusual

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

protists that acquire

plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosy ...

s from

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

by endosymbiosis. By forming massive blooms, particularly in late summer and spring, it causes red tides. It produces toxic substances and the red tides cause widespread infection of

seafood Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish. Shellfish include various species of molluscs (e.g. bivalve molluscs such as clams, oysters and mussels, and cephalopods such as octopus an ...

, particularly crabs and mussels. When infected animals are consumed, severe diarrhoea occurs. The clinical symptom is called diarrhetic shellfish poisoning. The main chemical toxins were identified in 2006 as okadaic acid and pectenotoxins. They can produce non-fatal or fatal amounts of toxins in their predators, which can become toxic to humans.

Description

''Dinophysis acuta'' is a marine unicellular protist, and is the largest among ''Dinophysis''. It is an armoured species with a distinct body covering called theca or test. The body is laterally compressed with a small, cap-like epitheca and a much larger hypotheca. It has the double collars (known as cingulum) around the top of the cell, and a further wing (known as the sulcus) running vertically down the cell. It is oblong in shape with almost entirely rounded posterior end, but the tip of the end is slightly pointed. The size ranges from 54 to 94 µm in length and 43 to 60 µm in dorso-ventral width, with the widest region below the middle. The small epitheca is composed of four plates. It is low, flat or weakly convex, and is invisible in lateral view, which is a good identifying feature. The sulcus consists of several irregularly-shaped plates, and it contains the

flagellar A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have fro ...

pore. The hypotheca has four large plates that constitute the majority of the cell. The anterior two-thirds of the hypotheca has convex margins, while the posterior third forms a broad asymmetrical triangle with a straight dorsal edge, and occasionally a slightly concave ventral edge. Reproduction is by simple binary fission. The most unusual cellular structure is the presence of numerous reddish-yellow chloroplasts, which are derived from its prey, which in turn had acquired from algae.

Diarrhetic shellfish poisoning

The first cases of diarrhetic shellfish poisoning (DSP) due to ''D. acuta'' were recorded in 1972 in Peru, but were reported to the scientific community only in 1991. It is a mildest form of seafood poisoning, indicated by severe diarrhoea. The first toxins isolated from the species were pectenotoxins (PTX-2 and PTX-11) in 2003 from specimens collected from the west coast of

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

, New Zealand, and PTX-12 independently at Skjer, Sognefjorden in Norway. In 2004, the presence of okadaic acid esters was reported. Further identification and the importance of these compounds as causal factors of DSP were discovered in 2006.

References

External links

Profile at marine Species Identification PortalSAHFOSMarine Animal Encyclopedia
{{Taxonbar, from=Q18351854 Dinophyceae Species described in 1839 Taxa named by Christian Gottfried Ehrenberg