No macronuclear regeneration

[paul earl]

It is long known that the process of macronuclear regeneration in
Paramecium aurelia is a mistake. Misreading the sequence of stages in
stained slides caused this error. See Sonneborn (Adv Gen 1: 263-358,
1947), and the most excellent modern view of macronuclear (MA)
development by M Nowacki et al (Curr Biol15:1616–1628, 2005.). Both
green fluorencent protein and FISH are very much underused in ciliate
studies.

When the MA starts to break down, a signal has gone through saying,
"wrong genotype for the old MA." If "same genotype" is the signal, the
old genotype can stay and thereby compete with any other MA anlagen.
Resorption of the old MA without fragmentation is possible, yet seems
unlikely. When MA fragments appear only in exconjugants the wrong
genotype signal might have come from the synkarion. All this is
speculation just as MA regeneration is.

Paul R Earl


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[john kloetzel]

Paul, I realize you speak of Paramecium here.  But one case in which  
Mac regeneration in a ciliate has been shown (clearly, I think, albeit  
cytologically) is in Euplotes.  Check my 1981 paper in J. Protozoology  
28:108-116.  In this case regeneration of the old Mac was induced by UV  
irradiation of the Anlage, preventing its development.  The resultant  
cells should be heterokaryons, with parental Mac and F1 Mic.
        John Kloetzel

On Oct 9, 2006, at 12:11 PM, paul earl wrote:

> It is long known that the process of macronuclear regeneration in  
> Paramecium aurelia is a mistake. Misreading the sequence of stages in  
> stained slides caused this error. See Sonneborn (Adv Gen 1: 263-358,  
> 1947), and the most excellent modern view of macronuclear (MA)  
> development by M Nowacki et al (Curr Biol15:1616–1628, 2005.). Both  
> green fluorencent protein and FISH are very much underused in ciliate  
> studies.
>
> When the MA starts to break down, a signal has gone through saying,  
> "wrong genotype for the old MA." If "same genotype" is the signal, the  
> old genotype can stay and thereby compete with any other MA anlagen.  
> Resorption of the old MA without fragmentation is possible, yet seems  
> unlikely. When MA fragments appear only in exconjugants the wrong  
> genotype signal might have come from the synkarion. All this is  
> speculation just as MA regeneration is.
>
> Paul R Earl
>
>
> _______________________________________________
> Protista mailing list
> Protista@...
> http://www.bio.net/biomail/listinfo/protista
>

**JAK**

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John A. Kloetzel, Ph.D.
Department of Biological Sciences
University of Maryland Baltimore County (UMBC)
1000 Hilltop Circle
Baltimore, MD  21250-0000  USA
Phone:  [phone] or -3913 (Lab)
Fax:  [phone]
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