Actinophrys sol, (heliozoan)

Charles Krebs · Post by **Charles Krebs** » Thu Apr 12, 2007 9:57 pm

The heliozoans are great fun to watch. (Except for a few real obvious ones I'm not real good at IDs, so I hope this is, in fact, Actinophrys sol!)

The top image is focused into the cell, the second on it's surface. The third image could be near the end of cellular division... I'll leave that call to someone with more experience. In the third image the large central nucleus is readily seen. The axonemes terminate on the nucleus.

All images: Olympus 40/0.95, Olympus NFK 2.5X, Canon 350D, DIC with electronic flash

Ken Ramos · Post by **Ken Ramos** » Fri Apr 13, 2007 3:00 am

Beautiful images there Charlie, the third does look as though the two are in the process of concluding binary fission but I too am not to sure.

Wolfgang Bettighofer · Fri Apr 13, 2007 3:26 pm

Ken Ramos wrote:Beautiful images there Charlie, the third does look as though the two are in the process of concluding binary fission but I too am not to sure.

I'm also delighted of the Actinophrys images. Thank's a lot, Charles.
But I'm sure it's not a binary fission. Some species of heliozoans like to form groups digesting togehter (in German "Fressgemeinschaft", I don't know how to translate

).
I had the chance to see a similar arrangement of Actinospaerium eichhorni. I'll gonna post it...

Cheers, Wolfgang

bernhardinho · Post by **bernhardinho** » Sun Apr 15, 2007 5:09 am

Hi Charles

a bit late, but nevertheless: here is another reason why it can't be cell division: Heliozoa always encyst before division or in other words they always divide inside of a cyst.

I would translate "Fressgemeinschaft" into feeding community, if this does make any sense to your mother tongue ears

Bye

Bernhard

beetleman · Post by **beetleman** » Sun Apr 15, 2007 10:40 am

Do you mean sharing food together? Wonderful photos Charles. They are beautiful creatures.

Charles Krebs · Post by **Charles Krebs** » Sun Apr 15, 2007 9:33 pm

Bernhard and Wolfgang... I have observed the "group feeding" but I have also seen many references to this type of shot being cell division... that's why I hedged and said I was not sure. Certainly you can find all sorts of misidentified images on the internet, but this particular paper seems very well researched and referenced about Actinophrys division:
http://jcs.biologists.org/cgi/reprint/16/3/499.pdf
(note Fig. 9 through 16, and especially 10 and 18 )
So I still think this is a possibility here.

Wolfgang Bettighofer · Mon Apr 16, 2007 3:41 am

Hi Charles,

many thanks for the link. Until now I don't have much literature discussing physiological details of heliozoans.

So long, Wolfgang

bernhardinho · Post by **bernhardinho** » Mon Apr 16, 2007 10:09 am

Hi Charles,

that is very interesting indeed. I still have to read it more carefully, but am I mistaken that we are dealing with drug and temperature induced results under lab conditions here?

But all the same, I think it is well worth a closer investigation.

Bernhard

Charles Krebs · Post by **Charles Krebs** » Mon Apr 16, 2007 10:38 am

It appears the temperature and colchicine solution "treatments" were used to investigate certain effects, and understand better the method of cytokinesis, but these were compared with other samples maintained at 20 degrees C with no temperature or chemical variation. The author provides other references describing binary fission in Actinophrys.

Wolfgang Bettighofer · Mon Apr 16, 2007 12:54 pm

Hi Charles and Bernhard,

today I checked Grell: "Protozoologie" and found a statement concerning all heliozoa:
"Reproduction via binary fission. Additional sexual processes are only known from Actinophrys sol and members of genus Actinosphaerium."

Cheers, Wolfgang