Paulinella amoebe

René · Post by **René** » Wed May 18, 2011 9:33 am

This is one of those crazy things: an amoebe but also able to grow on sunlight. Professionally, very boringly called mixotrophic, but nevertheless intriguing.

It's called Paulinella chromatophora, it has 2 chromophores (duh) called cyanelles because it's not really a chloroplast, and it's not even known whether it is acually an organelle or a symbiontic cyanobacteria. But maybe that's trivial, in any case it is related to Synechococcus, an omnipresent cyanobacterium.

The wall of this amoeboid organism is typically banded with overlapping scales, well visible with an oil immersion lens:

Sample derived from a freshwater lake in the north of the Netherlands, size 25um.

Best wishes, René

fpelectronica · Post by **fpelectronica** » Wed May 18, 2011 1:12 pm

Interesting
Francisco

René · Post by **René** » Wed May 18, 2011 11:57 pm

Thanks Francisco, I forgot to add the top right photo is autofluorescence with a 365nm UV led and longpass barrier (>420nm). Unfortunately I haven't got a specific filterblock for cyanofluorescence (yet), but I am working on that. Images are made on an Oly inverted (IMT2) with 20x/0.7 and 60x/1.4 lenses in a 2ml sedimentation chamber. It seems the critter is rare, an inverted microscope makes it a lot easier to find.

BTW, another Paulinella species I do find regularly in marine samples is Paulinella ovalis. It is a lot smaller and has the same type of lorica with scales.

It was originally described as a chrysophyte flagellate by Wulff (as Calycomonas), it has only recently been redescribed as an amoebe. What appeared to be a flagellum sticking out of the lorica actually was a very thin pseudopodium. I have seen similar thin pseudopodial threads from this Paulinella chromatophora, but they are hard to capture on an image. You can see bits on the first lower image at high mag.

Best wishes, René

BTW, found a wonderful article by Michael Melkonian on the original description by Lauterborn: http://dblab.rutgers.edu/...linella/pdfs/16171191.pdf

Cactusdave · Post by **Cactusdave** » Thu May 19, 2011 2:29 am

Fine images of an organism I had never heard of. It certainly looks like it could have a symbiotic cyanobacterium inside. You have a very nice setup.

René · Post by **René** » Fri May 20, 2011 4:29 am

Cactusdave wrote:Fine images of an organism I had never heard of. It certainly looks like it could have a symbiotic cyanobacterium inside. You have a very nice setup.

Yep, it's pretty rare, but widespread nonetheless. But the symbiotic relationship, even at 60my old, is not old in evolutionary sense. The specialists are talking about evolution in progress. Watch while it happens, so to say. If you have some spare time, that is...

The Oly setup is not mine personally... certainly as good as it gets. With your Diaphot you should be able to reach the same level

Best wishes, Rene

Mitch640 · Post by **Mitch640** » Fri May 20, 2011 6:28 am

Very nice images. The overlapping scales are particularly interesting.

Cactusdave · Post by **Cactusdave** » Fri May 20, 2011 6:44 am

Thanks Rene. The Nikon Diaphot is a fine (if rather large

) microscope, but mine had been at the tender mercies of just too many graduate students before I acquired it and is a little weary in the mechanics and optics to give of its very best.