Stentor igneus. the pink ciliate (corrected species)

About the shape and function of different specimens
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tlansing
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Joined: Sat Aug 01, 2020 3:15 pm

Stentor igneus. the pink ciliate (corrected species)

#1 Post by tlansing » Tue Nov 02, 2021 11:04 pm

Recently, I observed the pink ciliate Stentor igneus. It is interesting that the different stentor species have different coloration, especially the famous blue Stentor coeruleus. The photo below shows the fully extended Stentor igneus at low power (160x). The metachronal waves of the membranelles around the mouth of the ciliate can be clearly seen.
Stentor amethystinus1.jpg
Stentor amethystinus1.jpg (74.42 KiB) Viewed 2865 times
The stripes of granules which give the ciliate its pink color are visible in the second, higher-power photo. These pigmented granules appear to serve two principle functions: one, as a deterrent to predation, and two, to orient the cell with respect to light, either toward or away from it.
Stentor amethystinus2.jpg
Stentor amethystinus2.jpg (103.15 KiB) Viewed 2865 times
Interestingly, there was a paper published in 2014 in the Journal of Natural Products (https://pubs.acs.org/doi/pdf/10.1021/np5001363) in which the major component of pigment in the granules was isolated and given the name amethystin. Added after initial posting: After Bruce Taylor's clarification of the correct species shown in this post, I should add that whether amethystin is the same pigment in the granules of S. igneus as in S. amethstinus is not known.
Last edited by tlansing on Tue Nov 09, 2021 9:37 pm, edited 2 times in total.

Bruce Taylor
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Joined: Fri Sep 04, 2015 11:34 am

Re: Stentor amethystinus. the pink ciliate

#2 Post by Bruce Taylor » Mon Nov 08, 2021 9:55 pm

Very nice pictures!

Stentor amethystinus has very dark cytoplasm, densely packed with endosymbiotic algae, and rows of purplish pigment granules. It is almost always found swimming freely, a very broad, pear-shaped (or sometimes amost spherical) cell, like the one in this video: https://www.youtube.com/watch?v=K-MH3VxidFs , and the one in this image by Wim van Egmond: https://www.sciencephoto.com/media/8799 ... micrograph

What you have here is almost certainly Stentor igneus, a slenderly trumpet-shaped species with pink or red cortical granules and no algal endosymbionts (zoochlorellae). For a key to Stentor species, and some more images of Stentor amethystinus showing the characteristic appearance, see: https://www.researchgate.net/publicatio ... ican_lakes

See also the redescriptions of both S. amethystinus and S. igneus in vol. 2 of the "ciliate atlas" by Foissner et al., pp. 340 -350: http://www.wfoissner.at/data_prot/Foiss ... _1-502.pdf

tlansing
Posts: 336
Joined: Sat Aug 01, 2020 3:15 pm

Re: Stentor amethystinus. the pink ciliate

#3 Post by tlansing » Tue Nov 09, 2021 2:48 pm

Hi Bruce, thanks very much for your comments and correction on this particular species of Stentor and the references you included. Always happy to be pointed in the right direction and get your comments!


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