what is red dot in ostreopsis
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I love that it's possible in this hobby to ask questions that the professionals don't know the answer to!
Red bodies in ostreopsis from my tank.
They are mentioned in papers and most don't attempt to explain them, but just call them Red or Orange "accumulation bodies".
This paper from 2018 actually did genetic sequencing of the red material in ostreopsis and came up with the result that they are all from Rhodophyte - red algae material that the dinoflagellate ingested!
Genetic Analyses of the rbcL and psaA Genes From Single Cells Demonstrate a Rhodophyte Origin of the Prey in the Toxic Benthic Dinoflagellate Ostreopsis
"The percentage of Ostreopsis cells containing ingested food particles exhibited large spatial and temporal variations among sampling sites, ranging from undetectable level to 29.5%, and was not always associated with Ostreopsis cell abundance. Phylogenetic analyses performed using both plastid-encoded rbcL and psaA genes revealed that all sequences obtained from the ingested food particles of Ostreopsis cells grouped within the class Florideophyceae, Rhodophyta. Our result clearly demonstrates that Ostreopsis species consume various macroalgae from Rhodophyta, but not protists, which have long been thought to be the potential prey."
Wait, but I don't have any red algae anywhere in my system. Nor do most other hobbyists that post pics of ostreopsis with red bodies. How can my ostreopsis be eating them?
But we do! Coralline algae are rhodophytes, and they found genetic sequences from multiple genera of coralline algae.
"many sequences of food particles were also related to species from the order Corallinales within the class Florideophyceae, such as Lithophyllum impressum, Pneophyllum fragile, Spongites tumidus, and Porolithon onkodes.
...Ostreopsis might directly ingest carpospores, which are produced after fertilization by red algae and germinated from their carposporophyte,
... benthic dinoflagellates, including Ostreopsis, are known to be capable of producing a mucopolysaccharide matrix to attach to substrates ... the mucopolysaccharide matrix might also act as a mucus trap for Ostreopsis to attach to and feed on red algal spores, which are released into the marine environment."
Dino mucus catching coralline algae spores as food? cray-zy.
But it's also possible this paper is wrong.
Well, not wrong, but talking about a different phenomenon than we or the other papers have seen.
This is what they observed - which don't really look like our red bodies we see.
And they collected from South Korea where the water temp ranged from 11-29C. So we're talking about a temperate version of ostreopsis that may well have different habits than our tropical strains.
So these other papers might be more on-topic, as I think they are actually talking about the red bodies we see in our ostreopsis.
Investigation of phagotrophy in natural assemblages of the benthic dinoflagellates Ostreopsis, Prorocentrum and Coolia
This was from Brazil and were looking at strains we know make it into the hobby and they found very little (but not zero) ingestion of prey in ostreopsis. And the red bodies didn't react to DNA-stains like digesting prey should.
"From these, only 0.4% of 1195 Ostreopsis cf. ovata and 2.2% of 134 Coolia spp. cells presented evidence of phagotrophy with vacuoles stained by LysoSensor or a DAPI (4',6-diamidino-2-phenylindole) stained inclusion. Stained vacuoles were not registered in the 330 Prorocentrum spp. cells observed. Few O. cf. ovata cells contained round red inclusions ("red spots") that were not stained either by DAPI or LysoSensor, suggesting that these structures are not ingested prey."
These look like a better match to what we see. And they are explained as breakdown locations of cellular organelles, or storage of useful nutrients in pigmented form.
"Moreover, the cytoplasm of dinoflagellates is highly vesiculate and many species contain 'accumulation bodies' or 'polyvesicular bodies' whose function is probably the breakdown of superfluous organelles and membranes."
"Red bodies in Ostreopsis cysts enclosed in hyaline membranes were observed mainly at the end of the bloom by ALIGIZAKI and NIKOLAIDIS (2006). MEKSUMPUN and MONTANI (1995) reported that red-brown inclusions in the marine dinoflagellate Scrippsiella trochoidea are composed of fucoxanthin, 19’ - hexanoyl - fucoxanthin, diadinoxanthin and diatoxanthin. The authors suggested that these pigments are useful for growth of vegetative cells after germination from cysts."
And one final paper along similar lines:
New insights on the life cycle stages of the toxic benthic dinoflagellate Ostreopsis cf. ovata
"Among the vegetative cells, light-colored cells often with orange bodies inside the cytoplasm ...were frequently observed in our cultures. ...These orange bodies may represent incipient accumulation bodies, which are widely described in the literature on dinoflagellate cysts ... Light cells with accumulation bodies showed percent abundances significantly higher in the N-free test (3.39 +-0.33%) than in the control (0.56 +-0.08%, p < 0.001), suggesting that nutrient limitation could stimulate their formation. Some of these cells, isolated and placed in replete culture medium, started to proliferate restoring the typical cytoplasmic color, occasionally after ecdysis, thereby strengthening the hypothesis that their formation is related to nutrient deficiency and may represent a signal of cell stress. The lighter cytoplasm coloration was mainly due to the presence of some translucent bodies. In this study, the significant increase in these light cells in nutrient limiting conditions (40.11 +-3.52% and 13.98 +-1.10%, respectively for the experiment and the control, p < 0.001) strengthens the hypothesis that they may represent an ecophysiological response of vegetative cells to stress conditions, in agreement with Murphy (2001) and Wang et al. (2009) who reported that some algae produce abundant cytoplasmic lipid bodies, particularly in response to environmental stress, such as nitrogen limitation."
This is consistent with when I see them. The red bodies in my above picture tended to happen in cells that were lighter and had less of the typical brown pigmentation. I saw many red bodies during a treatment of metronidazole that stresses and reduces the population of ostreopsis (and causes cyst formation).
So, there you have it. Maybe ingested red algae / coralline algae spores, but possibly just stress, and maybe organelle breakdown due to nutrient stress, and/or in preparation for resting cyst formation.
Red bodies in ostreopsis from my tank.
They are mentioned in papers and most don't attempt to explain them, but just call them Red or Orange "accumulation bodies".
This paper from 2018 actually did genetic sequencing of the red material in ostreopsis and came up with the result that they are all from Rhodophyte - red algae material that the dinoflagellate ingested!
Genetic Analyses of the rbcL and psaA Genes From Single Cells Demonstrate a Rhodophyte Origin of the Prey in the Toxic Benthic Dinoflagellate Ostreopsis
"The percentage of Ostreopsis cells containing ingested food particles exhibited large spatial and temporal variations among sampling sites, ranging from undetectable level to 29.5%, and was not always associated with Ostreopsis cell abundance. Phylogenetic analyses performed using both plastid-encoded rbcL and psaA genes revealed that all sequences obtained from the ingested food particles of Ostreopsis cells grouped within the class Florideophyceae, Rhodophyta. Our result clearly demonstrates that Ostreopsis species consume various macroalgae from Rhodophyta, but not protists, which have long been thought to be the potential prey."
Wait, but I don't have any red algae anywhere in my system. Nor do most other hobbyists that post pics of ostreopsis with red bodies. How can my ostreopsis be eating them?
But we do! Coralline algae are rhodophytes, and they found genetic sequences from multiple genera of coralline algae.
"many sequences of food particles were also related to species from the order Corallinales within the class Florideophyceae, such as Lithophyllum impressum, Pneophyllum fragile, Spongites tumidus, and Porolithon onkodes.
...Ostreopsis might directly ingest carpospores, which are produced after fertilization by red algae and germinated from their carposporophyte,
... benthic dinoflagellates, including Ostreopsis, are known to be capable of producing a mucopolysaccharide matrix to attach to substrates ... the mucopolysaccharide matrix might also act as a mucus trap for Ostreopsis to attach to and feed on red algal spores, which are released into the marine environment."
Dino mucus catching coralline algae spores as food? cray-zy.
But it's also possible this paper is wrong.
Well, not wrong, but talking about a different phenomenon than we or the other papers have seen.
This is what they observed - which don't really look like our red bodies we see.
And they collected from South Korea where the water temp ranged from 11-29C. So we're talking about a temperate version of ostreopsis that may well have different habits than our tropical strains.
So these other papers might be more on-topic, as I think they are actually talking about the red bodies we see in our ostreopsis.
Investigation of phagotrophy in natural assemblages of the benthic dinoflagellates Ostreopsis, Prorocentrum and Coolia
This was from Brazil and were looking at strains we know make it into the hobby and they found very little (but not zero) ingestion of prey in ostreopsis. And the red bodies didn't react to DNA-stains like digesting prey should.
"From these, only 0.4% of 1195 Ostreopsis cf. ovata and 2.2% of 134 Coolia spp. cells presented evidence of phagotrophy with vacuoles stained by LysoSensor or a DAPI (4',6-diamidino-2-phenylindole) stained inclusion. Stained vacuoles were not registered in the 330 Prorocentrum spp. cells observed. Few O. cf. ovata cells contained round red inclusions ("red spots") that were not stained either by DAPI or LysoSensor, suggesting that these structures are not ingested prey."
These look like a better match to what we see. And they are explained as breakdown locations of cellular organelles, or storage of useful nutrients in pigmented form.
"Moreover, the cytoplasm of dinoflagellates is highly vesiculate and many species contain 'accumulation bodies' or 'polyvesicular bodies' whose function is probably the breakdown of superfluous organelles and membranes."
"Red bodies in Ostreopsis cysts enclosed in hyaline membranes were observed mainly at the end of the bloom by ALIGIZAKI and NIKOLAIDIS (2006). MEKSUMPUN and MONTANI (1995) reported that red-brown inclusions in the marine dinoflagellate Scrippsiella trochoidea are composed of fucoxanthin, 19’ - hexanoyl - fucoxanthin, diadinoxanthin and diatoxanthin. The authors suggested that these pigments are useful for growth of vegetative cells after germination from cysts."
And one final paper along similar lines:
New insights on the life cycle stages of the toxic benthic dinoflagellate Ostreopsis cf. ovata
"Among the vegetative cells, light-colored cells often with orange bodies inside the cytoplasm ...were frequently observed in our cultures. ...These orange bodies may represent incipient accumulation bodies, which are widely described in the literature on dinoflagellate cysts ... Light cells with accumulation bodies showed percent abundances significantly higher in the N-free test (3.39 +-0.33%) than in the control (0.56 +-0.08%, p < 0.001), suggesting that nutrient limitation could stimulate their formation. Some of these cells, isolated and placed in replete culture medium, started to proliferate restoring the typical cytoplasmic color, occasionally after ecdysis, thereby strengthening the hypothesis that their formation is related to nutrient deficiency and may represent a signal of cell stress. The lighter cytoplasm coloration was mainly due to the presence of some translucent bodies. In this study, the significant increase in these light cells in nutrient limiting conditions (40.11 +-3.52% and 13.98 +-1.10%, respectively for the experiment and the control, p < 0.001) strengthens the hypothesis that they may represent an ecophysiological response of vegetative cells to stress conditions, in agreement with Murphy (2001) and Wang et al. (2009) who reported that some algae produce abundant cytoplasmic lipid bodies, particularly in response to environmental stress, such as nitrogen limitation."
This is consistent with when I see them. The red bodies in my above picture tended to happen in cells that were lighter and had less of the typical brown pigmentation. I saw many red bodies during a treatment of metronidazole that stresses and reduces the population of ostreopsis (and causes cyst formation).
So, there you have it. Maybe ingested red algae / coralline algae spores, but possibly just stress, and maybe organelle breakdown due to nutrient stress, and/or in preparation for resting cyst formation.
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Wow. I'll have to check and see if I have pics of the red bodies in amphidinium too. I don't recall noticing them.
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Interesting. I found no red bodies in my photos from amphidinium strains I've had.
OP
OP
Wampatom
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Here is a photomicrograph from a nearby region. The thin red structure looks like cyano but it is different than any I have seen before. Source of red?
This is a complex and interesting ecosystem.
This is a complex and interesting ecosystem.
