Editing Chloroplast (section)

=== Diatom-derived chloroplasts ===
[[File:Durinskia baltica.jpg|thumb|Durinskia is a genus significant to the study of endosymbiotic events and organelle integration.<ref name="Zerdoner2017">{{cite journal | vauthors = Žerdoner Čalasan A, Kretschmann J, Gottschling M | title = Absence of co-phylogeny indicates repeated diatom capture in dinophytes hosting a tertiary endosymbiont. | journal = Organisms Diversity & Evolution | date = March 2018 | volume = 18 | issue = 1 | pages = 29–38 | doi = 10.1007/s13127-017-0348-0 | s2cid = 3830963 }}</ref>]]

Some dinophytes, like ''[[Kryptoperidinium]]'' and ''[[Durinskia]]'',<ref name="Keeling-2010" /> have a [[diatom]] ([[heterokontophyte]])-derived chloroplast.<ref name="Keeling-2004" /> These chloroplasts are bounded by up to ''five'' membranes,<ref name="Keeling-2004" /> (depending on whether the entire diatom endosymbiont is counted as the chloroplast, or just the red algal derived chloroplast inside it). The diatom endosymbiont has been reduced relatively little—it still retains its original [[Mitochondrion|mitochondria]],<ref name="Keeling-2010" /> and has [[endoplasmic reticulum]], [[ribosome]]s, a [[cell nucleus|nucleus]], and of course, red algal derived chloroplasts—practically a complete [[cell (biology)|cell]],<ref name="Schnepf-1999">{{cite journal | vauthors=Schnepf E, Elbrächter M |doi=10.1080/00173139908559217 |title=Dinophyte chloroplasts and phylogeny – A review |year=1999 |journal=Grana |volume=38 |issue=2–3 |pages=81–97|doi-access=free |bibcode=1999Grana..38...81S }}</ref> all inside the host's [[endoplasmic reticulum lumen]].<ref name="Keeling-2010" /> However the diatom endosymbiont can't store its own food—its storage polysaccharide is found in granules in the dinophyte host's cytoplasm instead.<ref name="Kim-2009" /><ref name="Schnepf-1999" /> The diatom endosymbiont's nucleus is present, but it probably can't be called a [[nucleomorph]] because it shows no sign of [[genome reduction]], and might have even been ''expanded''.<ref name="Keeling-2010" /> Diatoms have been engulfed by dinoflagellates at least three times.<ref name="Keeling-2010" />

The diatom endosymbiont is bounded by a single membrane,<ref name="Hackett-2004" /> inside it are chloroplasts with four membranes. Like the diatom endosymbiont's diatom ancestor, the chloroplasts have triplet thylakoids and [[pyrenoid]]s.<ref name="Schnepf-1999" />

In some of these [[genera]], the diatom endosymbiont's chloroplasts aren't the only chloroplasts in the dinophyte. The original three-membraned peridinin chloroplast is still around, converted to an [[Eyespot apparatus|eyespot]].<ref name="Keeling-2004" /><ref name="Keeling-2010" />