A question about Paramecium conjugation

billporter1456 · Post by **billporter1456** » Tue Apr 01, 2014 3:04 pm

I'm working on a little video about "love life" among Paramecia. It's light-hearted rather than scientific, but will have a few educational tidbitsI. There is a short (<30 seconds) segment of the video that shows 3 Paramecia more or less attached to one another. As it happens, two of those three eventually began conjugation.

I've been watching Paramecia for a relatively short period of time, so I don't know what might be common as opposed to uncommon. I'm wondering whether my video clip shows something unusual or whether it's just common behavior.

https://www.youtube.com/watch?v=gs-b3Xg4xi4

Bruce Taylor · Post by **Bruce Taylor** » Tue Apr 01, 2014 7:25 pm

It's not too unusual to see three conjugants trying to get it on. Typically, the urge to have sex comes over many members of a population at the same time (usually because of particular environmental conditions, such as moderate food scarcity). If paramecia of compatible mating types bump into one another while they are in a receptive state, conjugation will ensue. With lots of sexed-up paramecia in a culture together, this sort of thing is bound to happen.

billporter1456 · Post by **billporter1456** » Wed Apr 02, 2014 3:49 am

Bruce Taylor wrote:It's not too unusual to see three conjugants trying to get it on. Typically, the urge to have sex comes over many members of a population at the same time (usually because of particular environmental conditions, such as moderate food scarcity). If paramecia of compatible mating types bump into one another while they are in a receptive state, conjugation will ensue. With lots of sexed-up paramecia in a culture together, this sort of thing is bound to happen.

Bruce, many thanks for providing this information. While I my main goal with this video is amusement/entertainment, I want to provide at least some educational value. Can I quote you in the description that will appear below the YouTube video?

Bruce Taylor · Post by **Bruce Taylor** » Wed Apr 02, 2014 7:20 am

Sure.

billporter1456 · Post by **billporter1456** » Wed Apr 02, 2014 8:32 am

Bruce Taylor wrote:Sure.

In addition to quoting you in the video's description, maybe I'll put you in the credits as a technical consultant. I can't pay you for that job, but I'll tell my accountant to send you 1% of the net world-wide revenue.

Ecki · Post by **Ecki** » Fri Apr 04, 2014 11:18 pm

When Paramecium gets ready for conjugation it turns into a so called "preconjugant" and will release gamones (mating signaling proteins) on the glycocalix, mostly in the adoral region.

When one or more preconjugants meet, they loosely stick together in "clusters". This is called agglutination and acts as a trigger for the next phase of the conjugation cycle. During agglutination the clila and trichocysts are retracted into the cell at the area, where the cell membranes of the conjugates will later fuse. The micronucleus, which sits in a concavity of the macronucleus, will leave the concavity and move into the cytoplasm. When two compatible mating types are ready, they will leave the cluster and turn from preconjugants to conjugants.

Now they stick together more tightly in a so called hold-fast reaction. The plasm membranes of the two conjugants fuse and a plasm bridge is created. The diploid micronucleus divides twice to form four haploid nuclei. Three will die and one divides again. This is the sexual devision and the result are two sexual pronuclei. One is called the migratory nucleus and the other one the stationary nucleus. Now the migratory nucleus will find its way to the plasm bridge. Note that the migratory nucleus is actively moving, it is not "transported"! It moves to the stationary nucleus of the mating partner and the two pronuclei will fuse to a synkaryon. After some devisions we have 4 "normal" Parameciums, postconjugants. These can not turn into preconjugants for a while!

So conjugation really is a cycle: postconjugant -> preconjugant -> conjugate -> postconjugant ...

When paramecium has had approximately 200 binary fissions without a conjugation, some species can "reset" their genes. It is called autogamy and here the two pronuclei of the same species will fuse to produce the synkaryon.

Best regards
Ecki

Bruce Taylor · Post by **Bruce Taylor** » Sat Apr 05, 2014 6:54 am

Well, there you go: clustering is not just common, it's a normal phase in the sexual cycle. Thanks for the additional info., Ecki!

I see that one of the long-predicted "mating type substances" has finally been identified, too: http://www.sciencedirect.com/science/jo ... 24739/44/2 (second article, Olignobene et al.)

billporter1456 · Post by **billporter1456** » Sat Apr 05, 2014 7:13 am

Ecki wrote:When Paramecium gets ready for conjugation it turns into a so called "preconjugate" and will release gamones (mating signaling proteins) on the glycocalix, mostly in the adoral region.

When one or more preconjugates meet, they stick together in "clusters". This is called agglutination and acts as a trigger for the next phase of the conjugation cycle. During agglutination the clila and trichocysts are retracted into the cell at the area, where the cell membranes of the conjugates will later fuse. The micronucleus, which sits in a concavity of the macronucleus, will leave the concavity and move into the cytoplasm. When two compatible mating types are ready, they will leave the cluster and turn from preconjugates to conjugates.

The plasm membranes of the two conjugates fuses and a plasm bridge is created. The diploid micronucleus divides twice to form four haploid nuclei. Three will die and one divides again. This is the sexual devision and the result are two sexual pronuclei. One is called the migration nucleus and the other one the stationary or resting nucleus. Now the migration nucleus will find its way to the plasm bridge where the plasm membranes of the conjugates fused. Note that the migration nucleus is actively moving, it is not "transported"! It moves to the stationary nucleus of the mating partner and the two pronuclei will fuse. After some devisions we have 4 "normal" Parameciums, postconjugates. These can not turn into preconjugates for a while!

So conjugation really is a cycle: postconjugate -> preconjugate -> conjugate -> postconjugate ...

When paramecium has had approximately 200 binary fission without a conjugation, some species can "reset" their genes. It is called autogamy and here the two pronuclei of the same species will fuse to produce 4 new parameciums.

Best regards
Eckhard

Hi Ecki,

I very much appreciate your detailed and informative reply! I believe I must now find a way to incorporate some of this information in the video. May I quote some of your remarks in the description that will appear below the YouTube video?

Best Regards,
Bill

Ecki · Post by **Ecki** » Sun Apr 06, 2014 2:34 am

Yesterday morning after I wrote the post about the conjugation details, I edited the post to make some corrections and then I must have pressed "preview" rather than "submit". My autocorrect function makes matters worse, it always changes conjugant in conjugate

@Bill, sure you can use this for your video. You have captured the agglutination of Paramecium.

Please find hereafter the corrected posting:

When Paramecium gets ready for conjugation it turns into a so called "preconjugant" and will release gamones (mating signaling proteins) on the glycocalix, mostly in the adoral region.

When one or more preconjugants meet, they loosely stick together in "clusters". This is called agglutination and acts as a trigger for the next phase of the conjugation cycle. During agglutination the clila and trichocysts are retracted into the cell at the area, where the cell membranes of the conjugates will later fuse. The micronucleus, which sits in a concavity of the macronucleus, will leave the concavity and move into the cytoplasm. When two compatible mating types are ready, they will leave the cluster and turn from preconjugants to conjugants.

Now they stick together more tightly in a so called hold-fast reaction. The plasm membranes of the two conjugants fuse and a plasm bridge is created. The diploid micronucleus divides twice to form four haploid nuclei. Three will die and one divides again. This is the sexual devision and the result are two sexual pronuclei. One is called the migratory nucleus and the other one the stationary nucleus. Now the migratory nucleus will find its way to the plasm bridge. Note that the migratory nucleus is actively moving, it is not "transported"! It moves to the stationary nucleus of the mating partner and the two pronuclei will fuse to a synkaryon. After some devisions we have 4 "normal" Parameciums, postconjugants. These can not turn into preconjugants for a while!

So conjugation really is a cycle: postconjugant -> preconjugant -> conjugant -> postconjugant ...

When paramecium has had approximately 200 binary fissions without a conjugation, some species can "reset" their genes. It is called autogamy and here the two pronuclei of the same species will fuse to produce the synkaryon.

billporter1456 · Post by **billporter1456** » Sun Apr 06, 2014 6:42 am

Ecki wrote:Yesterday morning after I wrote the post about the conjugation details, I edited the post to make some corrections and than I must have pressed "preview" rather than "submit". My autocorrect function makes matters worse, it always changes conjugant in conjugate

@Bill, sure you can use this for your video. You have captured the agglutination of Paramecium.

Hi Ecki,

Again, I must thank you. It was very generous of you to take the time to edit your post! As a result of you and Bruce responding to my question, I now feel confident that I will be giving good information in the description of the YouTube video. Having spent most of my professional life as an educator, it is important to me that my videos provide information that is accurate and I have found this forum and its knowledgeable posters an invaluable source of help in this endeavor.

Regards,
Bill