Conjugation and fission occurring at the same time in Amphileptus

[billporter1456]

This video appears to show both sexual reproduction (conjugation) and asexual reproduction (fission or division) occurring AT THE SAME TIME in the organism Amphileptus. I am no expert and welcome comments and explanations for what is happening in the video. (Come on, Bruce, tell me what's happening.)

[billbillt]

Hi Bill P.,

To me you are absolutely correct.. It does appear that you captured both kinds of reproduction here.. Interesting!!... Thanks for posting..

BillT

[billporter1456]

Hi Bill P.,

To me you are absolutely correct.. It does appear that you captured both kinds of reproduction here.. Interesting!!... Thanks for posting..

BillT

I am wondering why none of the experts on this or other forums have chimed in to explain this. Maybe Bruce Taylor will help us understand what's happening here. Thanks for watching!

[billbillt]

It is Saturday, the weekend I think....

[billporter1456]

It is Saturday, the weekend I think....

Thanks for the heads up!

[Microbia]

Congratulations on capturing so interesting event!

[billporter1456]

Congratulations on capturing so interesting event!

Thanks Microbia! I guess it remains to be seen just how interesting it is. Right at this moment I am watching a Lacrymaria that lost its head. Got it caught somehow and finally just pulled it off. Doubt it can regrow it while I watch.

Update: It did grow back while I watched. I was hoping it would complete the recovery by catching something to eat, but it didn't do that. I then did something I very rarely do; I flushed the water back into the sample jar. So maybe he's eating something right now.

Another update: The regrown "head" wasn't a fully formed head, but it was more than just a neck.

[vasselle]

Bonjour
Très belle vidéo
Cordialement seb

[billporter1456]

Bonjour
Très belle vidéo
Cordialement seb

Thank you, seb!

[billbillt]

It is Saturday, the weekend I think....

Thanks for the heads up!

Hi Bill P.,

I meant no offense... It just seems some people stay away from the forum on weekends.. I guess they take a break..

The Best,
BillT

[Bruce Taylor]

That's a really interesting video, Bill!

First, a small clarification. Despite what we often read (often in reputable sources!), ciliates have only one kind of reproduction: asexual fission, or cell division. Conjugation is a sexual phenomenon, which does not increase numbers (nobody gets pregnant ). The fission which follows conjugation is of the normal kind, no different from that which occurs vegetatively, or that which follows autogamy (another ciliate sexual phenomenon, in which divided micronuclei within a single cell are fused).

So, exactly what is going on here? It's hard to be sure, because 1) the video shows only one conjugal event, and 2) there is very little recorded information about amphileptid life cycles. As you probably know, ciliate life cycles vary quite a bit from one genus to the next, and both conjugation and fission occur in many different ways. For instance, some ciliates produce "unequal" mating partners (like the micro and macro conjugants of some peritrichs). Is the unequal size of these amphileptid conjugants an example of that? We'd have to observe typical behaviour on the population, to be certain of that (a single observation can't tell us much). On the basis of other pleurostomatid conjugations I've watched, I would suspect that "unequal conjugants" is not standard in this species, but it would be fun to be wrong about that! However, your notion that the smaller fellow is simply a recent divider is very likely true. In any case, since you have access to this breeding population, your observations would be far more useful than any armchair speculation from the likes of me.

What we seem to have here is a large, well-fed amphileptid on the verge of fission that has formed a conjugal bond with a smaller partner of a compatible mating type. That, in itself, is slightly unusual. Classically, vegetative cell division occurs when food is plentiful, and everyone is growing fat. Conjugation tends to occur when food is scarce, and environmental conditions are worsening. So, in populations where everybody is "doing it," you typically don't see a lot of cell division going on, but that is not to say that it can't occur. That a fat, well-fed ciliate has consented to mate with a small (and perhaps hungry?) one is not necessarily that odd. It's known that ciliates can put each other in a conjugal mood by releasing certain aphrodisiac chemicals (gamones). Do amphileptids do that? I don't think anybody knows. In any case, my best guess about your video is that it shows a large, plump critter, already preparing to divide vegetatively, which has found an irresistible partner, with whom it has begun conjugation.

It raises some questions, for me. For instance, what is the state of the fissile organism's micronuclei at this point? Since division is under way, nuclear mitosis has presumably occurred. Is meiosis also occurring in the mitotic products? And if so, is it occurring in both halves of the dividing critter (proter and opisthe)? Beats me!

[Radazz]

Really fascinating capture, Bill!
Thanks for sharing.

[billporter1456]

First, let me thank you for your comprehensive, informative, and thoughtful reply! I have now heard back from a couple of people who have published articles on Amphileptus and neither of them have seen this, so apparently it's not that common.

However, your notion that the smaller fellow is simply a recent divider is very likely true.

The basis of this guess is what I observed a couple of hours later. Again I saw a conjugating pair with the considerably larger organism beginning to divide. Following the division, the two conjugants remained attached, but the now separated, fairly small, and newly divided Amphileptus engaged in conjugation just 60 seconds after separating. I had thought that follow a normal binary fission in a ciliate, it took a while for the organism to reach "sexual maturity" and be capable of conjugation. I may be wrong about that, but 60 seconds is impressively precocious. Also, in the video you watched, division completed about 5 minutes after the organism developed a noticeable "waist." I thought ciliate division usually took an hour or so.

What we seem to have here is a large, well-fed amphileptid on the verge of fission that has formed a conjugal bond with a smaller partner of a compatible mating type. That, in itself, is slightly unusual. Classically, vegetative cell division occurs when food is plentiful, and everyone is growing fat. Conjugation tends to occur when food is scarce, and environmental conditions are worsening. So, in populations where everybody is "doing it," you typically don't see a lot of cell division going on, but that is not to say that it can't occur. That a fat, well-fed ciliate has consented to mate with a small (and perhaps hungry?) one is not necessarily that odd. It's known that ciliates can put each other in a conjugal mood by releasing certain aphrodisiac chemicals (gamones). Do amphileptids do that? I don't think anybody knows. In any case, my best guess about your video is that it shows a large, plump critter, already preparing to divide vegetatively, which has found an irresistible partner, with whom it has begun conjugation.

It raises some questions, for me. For instance, what is the state of the fissile organism's micronuclei at this point? Since division is under way, nuclear mitosis has presumably occurred. Is meiosis also occurring in the mitotic products? And if so, is it occurring in both halves of the dividing critter (proter and opisthe)? Beats me!

Yes, I can't imagine division occurring in the midst of all the stuff happening with micro and macro nuclei during conjugation. So I'm guessing that either the transfer of genetic material hasn't started yet or has finished. I watched the conjugating pair for a couple of hours after the fission but eventually lost interest in them.

Again, thanks so much for chiming in on this. My original question was whether this is common or unusual, and I am becoming convinced that it's unusual.

Finally, regarding the second observation of this behavior I mentioned, I am going to upload to YouTube the full-length of recorded video. It's about 17 minutes and essentially unedited. If you watch it at 2X speed it will only take you about 8.5 minutes. You are certainly under no obligation to watch it or comment on it, but I'd love to know what you think. You'll see why I guess that the smaller conjugant in the video you have already watched was a newly divided organism. Here's the 17 minute video that I would normally edit down to 2-3 minutes:

[billporter1456]

Really fascinating capture, Bill!
Thanks for sharing.

Thanks, Radazz, I'm glad you liked it.

[Bruce Taylor]

Following the division, the two conjugants remained attached, but the now separated, fairly small, and newly divided Amphileptus engaged in conjugation just 60 seconds after separating. I had thought that follow a normal binary fission in a ciliate, it took a while for the organism to reach "sexual maturity" and be capable of conjugation. I may be wrong about that, but 60 seconds is impressively precocious. Also, in the video you watched, division completed about 5 minutes after the organism developed a noticeable "waist." I thought ciliate division usually took an hour or so.

That is pretty quick work. When talking about "normal" sex & division in ciliates, though, keep in mind that most of the published data concern a few model organisms, such as Paramecium, Tetrahymena and Euplotes. It is quite possible (likely even) that nobody really knows what is "normal" for this species of Amphileptus. Rapid fission and quick maturation of exconjugants, followed by prompt conjugation, might well be a strategy it uses to ensure renewal of populations in hard times. As I mentioned above, there's a lot of variation in life cycles from one ciliate species to the next, and you might have hit upon something unrecorded. It might be interesting to keep an eye on these guys, if you can keep them in culture.

You are certainly under no obligation to watch it or comment on it, but I'd love to know what you think. You'll see why I guess that the smaller conjugant in the video you have already watched was a newly divided organism.

I look forward to it.

[billporter1456]

Following the division, the two conjugants remained attached, but the now separated, fairly small, and newly divided Amphileptus engaged in conjugation just 60 seconds after separating. I had thought that follow a normal binary fission in a ciliate, it took a while for the organism to reach "sexual maturity" and be capable of conjugation. I may be wrong about that, but 60 seconds is impressively precocious. Also, in the video you watched, division completed about 5 minutes after the organism developed a noticeable "waist." I thought ciliate division usually took an hour or so.

That is pretty quick work. When talking about "normal" sex & division in ciliates, though, keep in mind that most of the published data concern a few model organisms, such as Paramecium, Tetrahymena and Euplotes. It is quite possible (likely even) that nobody really knows what is "normal" for this species of Amphileptus. Rapid fission and quick maturation of exconjugants, followed by prompt conjugation, might well be a strategy it uses to ensure renewal of populations in hard times. As I mentioned above, there's a lot of variation in life cycles from one ciliate species to the next, and you might have hit upon something unrecorded. It might be interesting to keep an eye on these guys, if you can keep them in culture.

You are certainly under no obligation to watch it or comment on it, but I'd love to know what you think. You'll see why I guess that the smaller conjugant in the video you have already watched was a newly divided organism.

I look forward to it.

Yes, one of the Chinese biologists I have been emailing suggested that I culture them but I'm just not up to it. By the way, the other Chinese fellow just emailed me a few minutes ago and said, among other things, "I have already studied on taxonomy of pleuronematid ciliates, such as Amphileptus, for ten years, but I did not notice this kind of behavior." And if you are really looking forward to watching 17 unedited minutes of rather poor quality video, Here it is:

[Bruce Taylor]

Well, that was quite magnificent! As you said, the division was accomplished with exceptional speed, and the back-ender (opisthe) had barely detached before another lascivious Amphileptus latched onto it. Love is in the air...or, to be more precise, gamones are in the water. Hypothetically, I can imagine that the ability to divide, during a conjugal "orgy" in a stressed ciliate population, would confer certain advantages (effectively doubling the chance of a successful rejuvenating conjugation), however I don't recall having read anything about it, and haven't seen it myself.

Did either of your Chinese correspondents (lemme guess...Weibo Song and/or X. Lin?) suggest a species ID? (Unless I'm seeing wrongly, it seems to have rows of contractile vacuoles on both the dorsal and ventral side, so maybe that would suggest something like A. pleurosigma, rather than A. meleagris)

[billporter1456]

Well, that was quite magnificent! As you said, the division was accomplished with exceptional speed, and the back-ender (opisthe) had barely detached before another lascivious Amphileptus latched onto it. Love is in the air...or, to be more precise, gamones are in the water. Hypothetically, I can imagine that the ability to divide, during a conjugal "orgy" in a stressed ciliate population, would confer certain advantages (effectively doubling the chance of a successful rejuvenating conjugation), however I don't recall having read anything about it, and haven't seen it myself.

Did either of your Chinese correspondents (lemme guess...Weibo Song and/or X. Lin?) suggest a species ID? (Unless I'm seeing wrongly, it seems to have rows of contractile vacuoles on both the dorsal and ventral side, so maybe that would suggest something like A. pleurosigma, rather than A. meleagris)

My two Chinese correspondents are Dr. Honbo Pan and Dr. Hongon Long, with Pan being a taxonomist who has, "studied on taxonomy of pleuronematid ciliates, such as Amphileptus, for ten years." Pan, upon watching the first video, said, "Did you observe most of this Amphileptus species have the same behavior? Anyway, it is likely a new reproductive strategy which helps organisms survive under a changing environment." So he didn't contradict "Amphileptus" in the title of the video. On the other hand, Dr. Long, to whom Dr. Pan referred me, said, "I am hesitant to call your bug Amphileptus, as you know, many Pleurostomatida species look like this, more accurate identification is needed and Hongbo Pan is an excellent expert on this." I would be glad to send along the email addresses of these two, in fact, here they are: hpan@rhrk.uni-kl.de (Pan) and longh@indiana.edu (Long). I found them both extremely helpful and pleasant to communicate with. I refrained from telling either of them that the main reason the video quality wasn't great was my use of cheap Chinese optics. You and Pan must share a love for taxonomy, so the two of you will probably hit it off splendidly!

Finally, I'm so pleased you find this topic of interest. I posted stuff about this on four other forums and got interest from only one person, namely Wim van Egmond.

Update: I just got an email from Dr. Long who, after watching the 17 minute video, said, "That could really indicate absence of an immaturity phase, which is different from most known model ciliates."

[Bruce Taylor]

OK, I think the term of art for what we're seeing here is "preconjugation division." Evidently, in certain litostomes, like Dileptus margaritifer, Didinium and some spathidiids, conjugation is preceded by a preconjugation cell division. Since, as I mentioned above, division classically occurs during times of plenty, this unusual type of division was referred to in early literature as a "hunger division."

Pleurostomatids are litostomes, and I do suspect that this is a form of preconjugation division (i.e. a type of division that occurs during what Visscher calls "epidemics of conjugation.") I've only skimmed the literature so far, but I think that's the right track...

When I've had the chance to read up on it a bit more, I'll post a little bibliography.

(BTW, "preconjugation division" also occurs in some non-litostome ciliates, but Denis Lynn thinks it evolved convergently in those groups.)

[billporter1456]

Thanks Bruce! I appreciate the time and effort you have put into this topic. I think I understand a few things now, such as why there was such a size disparity between the conjugants and the fact that the exchange of genetic material that occurs during conjugation must have happened either before or after the fission, not during it. I'm happy to have stumbled across something that, apparently, is not commonly seen.

[Bruce Taylor]

something that, apparently, is not commonly seen.

And even less commonly noticed and described!

As I said in my previous post, I think we're seeing a "conjugation epidemic" in which some form of "preconjugation division" is playing a role. Evidently, not all the conjugants have undergone this division, since some of them are full-sized. The participation of "well fed individuals" in the conjugal frenzy is consistent with observations on Dileptus, made by Richard Hertwig in 1904 (Visscher, 1927). Your observation of a very rapid fission in progress during conjugation is something new, but I suspect it fits into the general pattern of a "special cell division" which precedes (or, in this case, also accompanies!) conjugation.

Published references to the phenomenon are pretty scarce, and so far I have found nothing that describes it in any pleurostomatid. It is documented in some other litostome groups, notably: spathidiida (by Foissner & Xu, 2007), Dileptus margaritifer, misidentified as D. gigas (by Hertwig, 1904 and Visscher, 1927) and Didinium (Prandtl, 1906). Denis Lynn considers it a feature of litostomes, generally (Ciliated Protozoa, 188).

Other terms for the phenomenon include "hunger division" (Hertwig) and "progamic division" (commonly used in descriptions of peritrichs, which divide unequally to produce "male" microconjugants that promptly swim off to mate with sessile "female" macroconjugants).

The best overview of the subject is in I. B. Raikov's long essay on conjugation in vol. 4 of Chen's Research in Protozoology (see below). Visscher's excellent description of preconjugation division in Dileptus is also very helpful. I can provide copies, if you want.

A few selected sources:

Foissner, Wilhelm, and Kuidong Xu. Monograph of the Spathidiida (Ciliophora, Haptoria): Vol I: Protospathidiidae, Arcuospathidiidae, Apertospathulidae. Vol. 81. Springer Science & Business Media, 2007.

Lynn, Denis. The ciliated protozoa: characterization, classification, and guide to the literature. Springer Science & Business Media, 2008.

Raikov, I. B. "Nuclear phenomena during conjugation and autogamy in ciliates." Research in protozoology 4 (1972): 146-289.

VĎAČNÝ, PETER, and Wilhelm Foissner. "Morphology, conjugation, and postconjugational reorganization of Dileptus tirjakovae n. sp.(Ciliophora, Haptoria)." Journal of Eukaryotic Microbiology 55.5 (2008): 436-447.

Visscher, J. Paul. "Conjugation in the ciliated protozoon, Dileptus gigas, with special reference to the nuclear phenomena." Journal of morphology 44.3 (1927): 383-415.

[zzffnn]

Thank you very much, Bill and Bruce, for sharing and spending time on research.

I did not say much (so as not to dilute/divert your discussions), but I am finding the video and discussions fascinating and learned a bit from them. I am sure other members feel the same.

[billporter1456]

Bruce, I'm somewhat overwhelmed by the extent of your research on this topic. I am clearly beyond my depth here and, with your permission, I'd like to send a copy of your posts to Dr. Pan. He's planning on researching the topic himself, but it would be extremely helpful in his efforts to see what you have done.

[Bruce Taylor]

Bruce, I'm somewhat overwhelmed by the extent of your research on this topic. I am clearly beyond my depth here and, with your permission, I'd like to send a copy of your posts to Dr. Pan. He's planning on researching the topic himself, but it would be extremely helpful in his efforts to see what you have done.

By all means, and he's quite welcome to communicate with me directly (can't remember if you have my email...if not, send me a PM).

[billporter1456]

Bruce, I'm somewhat overwhelmed by the extent of your research on this topic. I am clearly beyond my depth here and, with your permission, I'd like to send a copy of your posts to Dr. Pan. He's planning on researching the topic himself, but it would be extremely helpful in his efforts to see what you have done.

By all means, and he's quite welcome to communicate with me directly (can't remember if you have my email...if not, send me a PM).

Bruce, thanks for the email address. Now I can bug you directly!