From Annemarie.Schmid@SBG.AC.ATTue Apr 29 15:14:02 1997
Date: Tue, 7 Jan 1997 14:41:04 +0100
From: Annemarie Schmid <Annemarie.Schmid@SBG.AC.AT>
To: Multiple recipients of list DIATOM-L <DIATOM-L@IUBVM.UCS.INDIANA.EDU>
Subject: Re: help me with a large form of Diatoma vulgare

Hello from Salzburg, answer to deformed large Diatoma cells.

        You probably have found the cell wall of an initial cell which is
formed within a perizonium that allows the product of sexual reproduction
(auxospores) to expand to maximum size (Geitler 1932, v. Stosch 1962; Mann
1982; Round et al. 1990; Pickett-Heaps et al.1990). I have found auxospores
and inital cells of Diatoma hiemale in the Austrian alps (Styria,
Schladming, Untertal, below the "Heidi-Dorf" of the Mike Douglas' remake of
"Heidi") who did the same. The costae are usually distorted, because
microtubules (MT) are needed for their orientation; and after sexual fusion
the MT system is not yet exactly organised. (As seen with
immunofluorescence, during gamete formation the cytoskeleton is broken down!
AMS pers.obs.).  As in other diatoms, it takes at least one division,
usually more, to get the "normal" shape and pattern of the "species" after
inital cell formation. The swelling in the center is because the zygote is
first spherical before it expands towards both poles. The Circumference of
the center is defined by the first siliceous (closed!) band laid down in the
future cell equator (v. Stosch 1962, Mann 1982), and then often the
following bands are much smaller in diameter, although they are open. The
other possibility (probably more often realised) is that the bands are
rather regular, but the auxospore cell contracts during formation of the
initial valves. This process is described in the literature as "spontaneous
plasmolysis", but it has nothing to do with a real plasmolysis, which is due
to water efflux from the cell due to a hyperosmotic shock.
          The costae can be dislocated, wrongly orientatd and malformed also
when the sampling site is polluted. I found many such deformed Diatoma
vulgare in the Crocodile river in South Africa (during my stay with
Prof.Cholnoky in 1971) and in the Liesing- river near Vienna which at that
time had to suffer from the effluent of a paperfactory.
However, from your description I suspect your cell wall parts stem from an
Initial cell.
        So good luck with your work and best wishes for the New Year 1997!
        Anna Maria M. Schmid

At 11:10 07.01.1997 ITA, you wrote:
>Dear all,
>
>during my survey of fresh water pennant diatoms in Piedmont I founded a
>
>curious form of Diatoma vulgare that I do not succeed
>to classify with my limited bibliography (Barber and Carter - An Atlas of
>British Diatoms, Patrick and Reimer - The diatoms of
>the United States, Van Heurck - Synopsis des diatomees de Belgique).
>Here the description.
>Length 116 microns, width 9 microns, about 10 costae in 10 microns some
>slightly irregular, valve linear, very gently swollen in
>the median portion, ends rounded slightly attenuated.
>Shape and ends resemble those of Diatoma vulgare var. linearis V.H. figure
>12, plate 2, in Patrick and Reimer, but the
>descriptions and the illustrations of my texts report a maximum length
>rather lower (75 microns in P. and R., 116 microns my
>Diatoma).
>It could be a particularly large form of this variety.
>Could somebody give me some suggestion?
>I could furnish a photo also.
>
>Thank you
>
>
>Alessandro Bertoglio
>via Fratelli Carle 32, 10129 Turin, Italy
>Phone  Italy 011 596436
>Email A.Bertoglio@agora.stm.it
>