Osmoregulation in Protists

Brian Jones jbj at rda.frc.maf.govt.nz
Mon Aug 1 17:08:24 EST 1994


In article <CtrKp1.K8x at zoo.toronto.edu>,
Mark Siddall <mes at zoo.toronto.edu> wrote:

>
>Unrelated issue:  Do you really think the Marteliids (Bonamia, Martelia, etc)
>are related to the Haplos?  Many (e.g., Frank Perkins, Gene Burreson)
>would disagree with you.
The whole subject is a minefield for the unwary. Perkins classification
certainly makes sense. But it all depends on the relative weighting that
you are prepared to give the observed structures. So Perkins would
exclude Haplosporidium gammari from the Haplosporidia because the spores
are without orifices.
The Paramyxea are clearly seperate, in that they all sporulate by a
series of endogenous buddings within a stem cell. Bonamia does not fit
into that category either.
Yet at a more superficial level all the above groups, in the cell
organelles they possess, have similarities, not the least of which is the
posession of haplosporosomes.
There is also increasing evidence that these "protozoans" can rapidly
change their genome. If so, then they may be evolving and diverging from
each other much faster than classical taxonomy would allow. I believe
that our ideas on what is related to what may yet change considerably.

At the moment I'm not even sure if NZ 'Bonamia' is the same as European
'Bonamia'. Mike Hine is convinced its a different genus, I'm not so
sure.
>
>>I suspect that the spore forming Ascetosporans (such as
>>Minchinia, Haplosporidium) which tend to be estuarine, unlike
>>Bonamia, require their spore stage to avoid salinity changes associated
>>with freshes and floods which would otherwise kill naked infective
>>stages in the environment.
>>
>
>Actually, given the epispore ornamentation I would suspect a role in dispersal in th water column as well.
>
Yes you may well be right. However, Bonamia, which has no known resistant
spore stage has no problem spreading :-).
Brian Jones




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