Dear Dr. Gosia Czarna ,
Thank you very much for introducing kindly our works on mitochondrial
transformation in Dictyostelium cells.
The PSV (prespore-specific vacuole) is the sole organelle that is formed
only in differentiating prespore cells but never in prestalk cells (Maeda
and Takeuchi 1969), and therefore elucidation of the precise mechanism of
the PSV genesis is of particular importance for understanding the structural
basis of cell or organelle differentiation. Quite interestingly, the
mitochondrion undergoes a drastic transformation to form a unique vacuole
(M-vacuole) just before in prespore differentiation, and this was followed
by a mature PSV in it. Such drastically transforming mitochondria and
PSV-mitochondrion complexes were actually observed in differentiating
prespore cells, and also a considerable number of PSV-mitochondrion
complexes were found in the intermediate fraction between a pure PSV and a
pure mitochondria fractions, which were obtained by isopicnic centrifugation
of cellular components of the prespore cell through a multilayered sucrose
density gradient (Maeda 1971a).
Based on our previous studies (Maeda 1971, Tasaka and Maeda 1983, Oyama
et al. 1984, Takemoto et al. 1985, Matsuyama and Maeda, 1998, Yamaguchi et
al. 2005), it is evident that PSVs are constructed from mitochondria-derived
M-vacuoles with the help of the Golgi complex, as schematically shown in
Fig. 7. That is, mitochondria in differentiating prespore cells are
remarkably expanded, bent and fused at the ends to form a sort of vacuoles
(M vacuoles) prior to PSV formation, as described above, and several
Dd-TRAP1 molecules (mitochondrial molecular chaperon Hsp75) translocate into
the M vacuoles. Subsequently, Golgi vesicles containing DIA2, Dd-GRP94
(Dictyostelium homologue of glucose-regulated endoplasmic reticulum Hsp90;
Morita et al. 2000, Yamaguchi et al. 2005) and other molecules required for
PSV formation fuse with the M vacuole, thus resulting in formation of the
lining membrane and the internal fibrous structure in the M vacuole. The
mitochondrion-PSV complex is eventually twisted at the junction and detached
to form the respective organelles (see the attached figure).
It has been cytochemically determined that the activities of succinic
dehydrogenase and cytochrome c oxidase, typical mitochondrial enzymes, are
specifically detected in the lining membrane of PSV as well as in
mitochondria (Maeda 1971). Also, it has been demonstrated immunoelectoron
microscopically that a monoclonal antibody specific to the lining membrane
of PSVs stains a limited part of the mitochondria adjacent to the PSV-
mitochondrion complexes (Matsuyama and Maeda 1998). On the other hand, a
Golgi origin of PSVs has been proposed by both immunoelectron microscopy
with polyclonal anti-spore IgG and electron microscopic autoradiography with
[3H]-fucose, which is specifically incorporated into prespore cells
(Takemoto et al. 1985). Furthermore, an electron-dense membraneous structure
similar to the lining membrane of PSV is sometimes observed in the Golgi
cistaenae in prespore cells differentiating in a liquid shake culture (Oyama
et al. 1984). Thus it is clear that both mitochondria and Golgi complexes
are cooperatively implicated for PSV formation. The PSV is a functionally
essential structure and it is exocytosed form prespore cells to form the
outermost layer of spore cell wall during culmination (Hohl and Hamamoto
1969, Maeda 1971b), thus giving spores the physico-chemical strength.
These data have been reviewed in "International Review of Cytology, 244,
287-332 (2005) by Y. Maeda".
Yours sincerely,
Yasuo Maeda
----- Original Message -----
From: "Ma³gorzata Czarna" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, June 13, 2013 3:39 AM
Subject: Re: [DICTY] EM mitochondria
Hi Sascha,
I remember that Yasuo Maeda in one of his works ("Formation of a prespore
specific structure from a mitochondrion during development of the cellular
slime mold, Dictyostelium discoideum", Dev Growth Differ 13, 1971) showed
that
in differentiating prespore cells some mitochondria can be transformed into
mitochondrion-vacuole complexes (or probably called PSV complexes).
In this paper there are quite many photos included and, depending on your
experimental conditions, maybe you find something similar to your
mitochondria.
I hope it can help,
Cheers,
Gosia Czarna
Malgorzata Czarna, PhD,
University of Wroclaw
Faculty of Biotechnology
Molecular Biology of the Cell Dept
Przybyszewskiego 63/77
51-148 Wroclaw
Poland
Tel. 0048 71 375 62 73
Fax. 0048 71 375 62 34
On Wed, 12 Jun 2013 17:12:07 +0200, Sascha Thewes wrote
> Dear Dicty researchers,
>
> We did in our lab EM pictures of Dicty cells and found some strange
> looking
> mitochondria. Mitos seem to have wholes or inclusions (see arrows in
> the attached image). As it is the first time for us to make EM
> pictures we are not sure if we just see preparation artefacts or
> something else. Has anybody suggestions?
>
> Thanks for your help,
>
> Sascha.
>
> --
> Sascha Thewes, PhD
> Institute for Biology - Microbiology
> Department of Biology, Chemistry, Pharmacy
> Freie Universität Berlin
> Königin-Luise-Str. 12-16
> 14195 Berlin
> Germany
>
> Phone: +49-(0)30-838-53373
> Fax: +49-(0)30-838-57773
> Email: [log in to unmask]
> Web:
> http://www.biologie.fu-berlin.de/arbeitsgruppen/mikrobiologie/ag_mutzel/inde
> x.html
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