Very unusual one to me and not well represented in the sample.

Have problems identifying an organism? Ask for help here.
Post Reply
Message
Author
apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Very unusual one to me and not well represented in the sample.

#1 Post by apochronaut » Wed Aug 09, 2017 12:27 am

I came across a lone individual of this species, in a very diverse sample, while using it to test objectives. My camera wasn't mounted and I chased it all over the place, prior to leaving to get the camera and eventually lost it, finding neither it, or another, in numerous complete scans of the slide. It was very motile and moved in a somewhat predictable fashion, with a regular back and forth oar like motion of the single forward flagella and a regular unusual undulation within it's cell membrane. I rinsed the slide back into it's container with distilled water.

After several attempts to find another, amongst what sometimes seemed like a miniature moshpit , several days later I did happen upon another, albeit displaying somewhat differing behaviour than it's relative.

The first thing about these, is that they display one flagella, which is very active and seems to be used to propel the organism either forwards or backwards, depending on the way it is used. I can't tell which is the anterior or posterior of this little shapechanger, because it gives no clues. In one direction, presumably it's chosen one, it can be quite quick, moving roughly 50 um/sec., using it's flagella in an anterior position, alternatively as a left and right oar. Otherwise, it can use the flagella in a posterior position, where it rotates in a corkscrew fashion, driving the body forward, like a propeller.

In all this flagella managed motility, the body also partakes in a form of undulation, which changes direction depending on the direction of motility. During the drawn form of motility, with the flagella acting like a pair of oars alternately, a top shaped bulb forms at the other end and then flows forward, distending the body up to the flagella end, while the cytoplasm flows backward, yet filling another top shaped bulb , which then flows forward, again. This repeats in a regular fashion, somewhat resembling undulation, and seems as though it might assist in the forward motion.
When the flagella is used as a propeller, the body protrudes an elongated projection forward from the anterior end, , searching with a small wiggling motion, while the top shaped bulb, undulates towards it, from the flagella end. It's motion forward resembles more that of the searching form of the amoeba in this mode, with flowing cytoplasm, rather than the rapid swimming of a Euglena , characteristic of the other mode.
I have never seen anything like this.

The pictures below, were taken exclusively of the second noted form of motion, with the flagella rotating in a corkscrew motion like a propeller.
Each pair of pictures, shows the top shaped bulb at the posterior end, followed by the distention evident, after the bulb moved forward to the anterior end. I use anterior and posterior to denote the rear and front, relative to the direction of motion.

First pair: bright medium phase.
Second pair : dark medium phase
Third pair, in the second set of pictures : B-Minus L phase
Third and forth in the second set, show the bulbous formation in mid-body.
Attachments
Bright M  phase 97x objective <br /> posterior distention
Bright M phase 97x objective
posterior distention
DSC02489 (1024x566).jpg (101.92 KiB) Viewed 4678 times
Bright M phase 97x objective<br /> anterior distention
Bright M phase 97x objective
anterior distention
DSC02490 (1024x547).jpg (99.23 KiB) Viewed 4678 times
Dark M phase 97x objective<br /> posterior distention
Dark M phase 97x objective
posterior distention
DSC02492 (1024x560).jpg (107.19 KiB) Viewed 4678 times
Dark M phase 97x objective <br /> anterior distention
Dark M phase 97x objective
anterior distention
DSC02491 (1024x552).jpg (112.84 KiB) Viewed 4678 times
Last edited by apochronaut on Wed Aug 09, 2017 12:48 am, edited 2 times in total.

apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: Very unusual one to me and not well represented in the sample.

#2 Post by apochronaut » Wed Aug 09, 2017 12:33 am

B- Minus L and mid body distention pictures.
Attachments
B-Minus L phase 97x objective<br /> posterior distention.
B-Minus L phase 97x objective
posterior distention.
DSC02495 (1024x556).jpg (118.55 KiB) Viewed 4677 times
B-Minus L phase 97x objective<br /> anterior distention.
B-Minus L phase 97x objective
anterior distention.
DSC02496 (1024x557).jpg (136.55 KiB) Viewed 4677 times
B-Minus L  phase 97x objective<br /> mid body distention
B-Minus L phase 97x objective
mid body distention
DSC02499 (1024x561).jpg (160.06 KiB) Viewed 4677 times
Dark M phase 97x objective <br /> mid body distention
Dark M phase 97x objective
mid body distention
DSC02494 (1024x558).jpg (104.82 KiB) Viewed 4677 times

User avatar
zzffnn
Posts: 3200
Joined: Sat Jun 20, 2015 3:57 am
Location: Houston, Texas, USA
Contact:

Re: Very unusual one to me and not well represented in the sample.

#3 Post by zzffnn » Wed Aug 09, 2017 1:44 am

It may be a small Peranema, though I am not positive:
http://www.photomacrography.net/forum/v ... hp?t=34971

Bruce Taylor should be able to tell you more, if you contact him.

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Very unusual one to me and not well represented in the sample.

#4 Post by Bruce Taylor » Wed Aug 09, 2017 3:44 am

It's a heterotrophic euglenid called Astasia. :) That style of movement is called "metaboly."

apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: Very unusual one to me and not well represented in the sample.

#5 Post by apochronaut » Wed Aug 09, 2017 10:55 am

Thanks for the i.d. , Bruce. So, metaboly is the change of shape due to the flow of cytoplasm, similar to ameboid movement.
What about the reversal of direction? The latter version of locomotion I saw, which resulted in the pictures, was very slow and did seem somewhat ameboid : creeping rather than swimming. Would that perhaps be a feeding period? There seemed to be frequent visits of various individuals of some sort of spirochaete. I couldn't tell whether they were doing this voluntarily or whether they were being drawn by the corkscrew action of the flagella.

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Very unusual one to me and not well represented in the sample.

#6 Post by Bruce Taylor » Wed Aug 09, 2017 1:05 pm

apochronaut wrote:Thanks for the i.d. , Bruce. So, metaboly is the change of shape due to the flow of cytoplasm, similar to ameboid movement.
It's true that euglenoids like Peranema and Astasia can look somewhat amoeboid, especially when the critter is squirming in a tight spot, compressed by a coverslip, or curling up on themselves in order to change direction. However, the mechanism of euglenoid metaboly is quite different from amoeboid movement. Amoebae use actin polymerization to quickly form cytoskeletal structures that thrust out the cell membrane, typically forming either wide, flat sheets (lamellipodia) or relatively narrow projections of various kinds (pseudopodia). Euglenoid bodies are enveloped by a pellicle made up of narrow microtubular strips, generally arranged in a spiral around the cell. These can slide against one another, allowing the remarkable alterations of cell shape that occur during "euglenoid movement". In highly metabolic euglenoids like Astasia, you'll often see bulges that pulse along the body, usually from front to back (somewhat reminiscent of peristalsis in smooth muscle). The general effect tends to be more "wormlike" than amoeboid, because the shape of the cell (while very changeable) is always constrained by the encircling microtubular strips that make up the pellicle.

User avatar
zzffnn
Posts: 3200
Joined: Sat Jun 20, 2015 3:57 am
Location: Houston, Texas, USA
Contact:

Re: Very unusual one to me and not well represented in the sample.

#7 Post by zzffnn » Wed Aug 09, 2017 1:19 pm

Bruce,

Please enlighten me - is Peranema supposed to be much bigger than Astasia? Or is there some other difference? More metabolic movements from Astasia? I searched briefly but could not find modern distinction, except for from an old book: https://books.google.com/books?id=d35is ... ma&f=false

Oftentimes, microscopists cannot see the second flagella of Peranema to tell it from uniflagellate like Astasia.

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Very unusual one to me and not well represented in the sample.

#8 Post by Bruce Taylor » Wed Aug 09, 2017 1:59 pm

Oftentimes, microscopists cannot see the second flagella of Peranema to tell it from uniflagellate like Astasia.

Technically, all euglenids are biflagellate (or "biciliate", as some prefer). In some, like Euglena (and, I believe, Astasia), the second flagellum is too short to emerge from the reservoir. In other "uniflagellate" euglenids, like Peranema, the recurrent flagellum is attached to the cell body.

Peranema can easily be identified by its "ciliary gliding." As the cell moves forward through the water, it holds its relatively thick cilium (flagellum) stiffly in front of it, with only a small area at the tip moving. At one time, it was thought that the moving tip provided the propulsion, but it seems that is not the case. In fact, you can inhibit the flagellum from moving by chemical means, and the cell will continue to glide serenely forward! The propulsion seems to occur on the rigid surface of the thick flagellum itself, by a type of cell surface motility (similar to that which drives diatoms, perhaps).

Here's a brief guide to heterotrophic flagellates, with a simple key: https://www.ncbi.nlm.nih.gov/pubmed/24239731

And a video of Peranema gliding, by my good friend Carlos: https://www.youtube.com/watch?v=SASEhSGxxsg
Last edited by Bruce Taylor on Wed Aug 09, 2017 2:26 pm, edited 1 time in total.

Bruce Taylor
Posts: 986
Joined: Fri Sep 04, 2015 11:34 am

Re: Very unusual one to me and not well represented in the sample.

#9 Post by Bruce Taylor » Wed Aug 09, 2017 2:21 pm

I've uploaded a video that shows euglenid spiral pellicle strips sliding against one another as the cell squirms. The red Euglena here is less metabolic than apochronaut's Astasia, but the mechanism is essentially the same.


apochronaut
Posts: 6272
Joined: Fri May 15, 2015 12:15 am

Re: Very unusual one to me and not well represented in the sample.

#10 Post by apochronaut » Fri Aug 11, 2017 11:05 am

The population of Astasia has mushroomed in the sample during the ensuing 4 days, although most of them appear very motile and are swimming in direct straight trips, rather than displaying much in the way of metaboly.

Post Reply