Dinosterol is a type of

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

produced by several genera of dinoflagellates. It is a 4α-methyl

sterol Sterol is an organic compound with formula , whose molecule is derived from that of gonane by replacement of a hydrogen atom in position 3 by a hydroxyl group. It is therefore an alcohol of gonane. More generally, any compounds that contain the gon ...

(4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol), a derivative of dinosterane, rarely found in other classes of protists. This sterol and others have been considered as class-specific, being

biomarker In biomedical contexts, a biomarker, or biological marker, is a measurable indicator of some biological state or condition. Biomarkers are often measured and evaluated using blood, urine, or soft tissues to examine normal biological processes, pa ...

s for dinoflagellates, although dinosterol is produced in minor amounts by a small number of other phytoplankton, such as the marine

diatom A diatom ( Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising se ...

''Navicula speciosa''. and

Prymnesiophytes The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for '' Prymnesium''), are a clade of algae. The names Haptophyceae or Prymnesiophyceae are sometimes used instead. This ending implies classification at ...

of the genus ''Pavlova''. Dinosterols show similar abundances as

dinocyst Dinocysts or dinoflagellate cysts are typically 15 to 100 µm in diameter and produced by around 15–20% of living dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic- ...

s. Other studies found a nonlinear or did not find a direct link between dinocyst abundances and sterol concentrations. Dinosterol has been used as indicator for dinoflagellate production in the Cariaco Basin. Hydrogen isotope ratios in dinosterols can serve to reconstruct salinity semi-quantitatively. Some studies have shown that certain

dinoflagellates 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 ...

produce sterols that have the potential to serve as genera-specific biomarkers. Recent work showed that dinoflagellate genera, which formed discrete clusters in the 18S rDNA-based phylogeny, shared similar sterol compositions. This suggested that the sterol compositions of dinoflagellates are explained by the evolutionary history of this lineage.

References

{{Reflist Sterols