Freshwater foraminifera probable Allogromia saxicola

carlos.uruguay · Post by **carlos.uruguay** » Sun Dec 13, 2015 7:19 pm

This organism relatively large, about 350um (0.35mm) long is a freshwater foraminifera.
It lives in a cylindrical and flexible "house". through opening poke a network of very fine "arms" (filopodia).
We assume that it is Allogromia saxicola
Phase contrast and polarized oblique light
Panasonic GH4 camera
Link:
https://www.youtube.com/watch?v=nUl6JfpJZHw
Video frame preview:

Regards
carlos

Jacek · Post by **Jacek** » Sun Dec 13, 2015 11:54 pm

Interesting creature, good video. I like your phasecontrast

Ecki · Post by **Ecki** » Mon Dec 14, 2015 1:12 am

Nice catch!

carlos.uruguay · Post by **carlos.uruguay** » Mon Dec 14, 2015 5:56 am

Thank you Jacek and Ecki

zzffnn · Post by **zzffnn** » Mon Dec 14, 2015 10:44 am

Nice video, thank you for sharing, Carlos.

Your phase contrast work quite well in this case.

It is also interesting to see how polarized oblique did not show this organism very well. I notice that the organism seemed very thin and transparent. What objective did you use there, 4x or 10x? Did you try higher NA objective, adjusting polarization and oblique, and focusing onto the soft tissue (arms) of the organism?

carlos.uruguay · Post by **carlos.uruguay** » Mon Dec 14, 2015 11:31 am

zzffnn wrote:Nice video, thank you for sharing, Carlos.

Your phase contrast work quite well in this case.

It is also interesting to see how polarized oblique did not show this organism very well. I notice that the organism seemed very thin and transparent. What objective did you use there, 4x or 10x? Did you try higher NA objective, adjusting polarization and oblique, and focusing onto the soft tissue (arms) of the organism?

Hi Fan.
This organism is the opposite of thin and transparent.
It has 350um long and its "house", as seen in the photo, is not transparent.
This organism is thick, not thin.
Greater NA, smaller depth of focus therefore less visible layer
I used fluorite objectives 10X, 20X and 40X
Regards

zzffnn · Post by **zzffnn** » Mon Dec 14, 2015 11:37 am

Carlos,

I was talking about the organism's soft tissue only. Not its big and thick "house", which was visualized very well in polarized oblique.

Higher NA may allow you to add in more contrast to visualize its soft tissue better. Its house is naturally contrasty and does not need higher NA, but the soft tissue (protoplasm) may need higher NA and more contrast.

carlos.uruguay · Post by **carlos.uruguay** » Mon Dec 14, 2015 11:52 am

zzffnn wrote:Carlos,

I was talking about the organism's soft tissue only. Not its big and thick "house", which was visualized very well in polarized oblique.

Higher NA may allow you to add in more contrast to visualize its soft tissue better. Its house is naturally contrasty and does not need higher NA, but the soft tissue (protoplasm) may need higher NA and more contrast.

Ahh!
That is because the filming with oblique light was made with a 20X objective and filopodia are very fine.
The 20X fluorite objective has very good NA = 0.5
If you see 0.35 minutes may be seen some filopodia

zzffnn · Post by **zzffnn** » Mon Dec 14, 2015 12:00 pm

Thanks Carlos.
I did see filopodia with oblique pol. It was just that it showed up so much better under phase contrast. So I wonder if we ignored filming that "house" and only focused onto filopodia with higher NA (say NA 0.9-1.25), would we see it more clearly. Just my random thoughts, don't take them too seriously :-)

carlos.uruguay · Post by **carlos.uruguay** » Mon Dec 14, 2015 12:08 pm

zzffnn wrote:Thanks Carlos.
I did see filopodia with oblique pol. It was just that it showed up so much better under phase contrast. So I wonder if we ignored filming that "house" and only focused onto filopodia with higher NA (say NA 0.9-1.25), would we see it more clearly. Just my random thoughts, don't take them too seriously :-)

For that NA, objective 40X or more should be used.
If I had filmed with my 40X fluorite obtective (NA0.75) you could appreciate the filopodia.
I think it is only a problem of magnification, not of NA

Ecki · Post by **Ecki** » Tue Dec 15, 2015 5:26 am

The granuloreticulopodia of the Forminifera are birefringent - so a detailed image of the granuloreticulopodia under polarized light would be most interesting.

carlos.uruguay · Post by **carlos.uruguay** » Tue Dec 15, 2015 5:54 am

Ecki wrote:The granuloreticulopodia of the Forminifera are birefringent - so a detailed image of the granuloreticulopodia under polarized light would be most interesting.

Hi Ecki.
If I am lucky to find again this organism, I will try to film it to more magnification with polarized light. To low magnification with polarizers semi crossed it no showed birefringence.
But the sample was too thick

fpelectronica · Post by **fpelectronica** » Tue Dec 15, 2015 11:32 am

Very nice

carlos.uruguay · Post by **carlos.uruguay** » Tue Dec 15, 2015 11:50 am

Thanks Francisco.