MicrobeHunter.com Microscopy Forum

S. Meulleri with recently ingested Cosmarium. 40x darkfield

https://drive.google.com/file/d/1QbiJxZ ... p=drivesdk

Very pretty image! It doesn't show enough detail for ID to species, unfortunately. Even if a moniliform macronucleus were clearly visible, identification is complicated by two other possibilities, S. katashimai and colorless S. polymorphus (without zoochlorellae/algal endosymbionts).

Thanks, Bruce.

The new camera is working out well so far, though I am still working out my imaging workflow kinks.

The long string macronucleii were clearly visible on other focal planes, but not in this image. I will see if the video I have shows more distinguishing features.

Bob

Here are two video's of the same subject. Unfortunately, none of the video's or stills I saved shows the string of nuclei.

What is more apparent to me now is that the green algae appears encapsulated. Is this a symbiont situation?

Regards,

Bob


100x darkfield
https://drive.google.com/file/d/1jQpZU2 ... sp=sharing

200x darkfield
https://drive.google.com/file/d/1fUcoJ2 ... sp=sharing

Bschnitzer wrote: ↑

Wed Jul 06, 2022 5:16 pm

What is more apparent to me now is that the green algae appears encapsulated. Is this a symbiont situation?

No, encapsulated algae are food.

The long string macronucleii were clearly visible on other focal planes

If the macronucleus you observed was in a single "string"--a long tube, or band--this would be S. roeselii. If it was in the form of a "beaded string" (with separate nodules), identification to species is more difficult, because we now have more than one colorless species with a macronucleus in that shape (twenty years ago, only one such form was recognized). From these videos, the shape of the macronucleus is not completely clear, to me. Darkfield microscopy is pretty, but not great for ciliate identification. So, I would skip the species ID, and simply call this "Stentor".

Bruce,

Thanks for the comments. I’m learning the limitations of dark field for sure - naked amoeba just show as an unbound collection of granules.

The string of macronucleii were distinct pearls, so “stentor” will suffice. I do get carried away with trying to ID to species level - blame it on my 50 year old Biology education. Hey, 50 years ago there were a lot fewer species, right?

Sometimes I shoot for pretty and the dark field condenser gives me more hits in that regard. Conversely, I’m sure there are instances where DF illuminates features not apparent or indistinct in BF.

Thanks again.