Tissue and Cell 41 (2009) 151–168
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Tissue and Cell
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Review
Hydrogenosomes under microscopy
Marlene Benchimol
∗
Universidade Santa Úrsula, Laboratório de Ultraestrutura Celular, Rio de Janeiro, Brazil
article info
Article history:
Received 30 November 2008
Received in revised form 4 January 2009
Accepted 13 January 2009
Available online 17 March 2009
Keywords:
Hydrogenosome
Trichomonas
Electron microscopy
abstract
A hydrogenosome is a hydrogen-producing organelle, evolutionary related to mitochondria and is found
in Parabasalia protozoa, certain chytrid fungi and certain ciliates. It displays similarities to and differences
from mitochondria. Hydrogenosomes are spherical or slightly elongated organelles, although very elon-
gated hydrogenosomes are also found. They measure from 200 nm to 1 m, but under stress conditions
can reach up to 2 m. Hydrogenosomes are surrounded by two closely apposed membranes and present
a granular matrix. Cardiolipin has been detected in their membranes, and frataxin, which is a conserved
mitochondrial protein involved in iron metabolism, was also recently found. Hydrogenosomes have one
or multiple peripheral vesicles, which incorporate calcium. The peripheral vesicle can be isolated from
the hydrogenosomal matrix and can be considered as a distinct hydrogenosomal compartment. Dysfunc-
tional hydrogenosomes can be removed by an autophagic process and further digested by lysosomes.
Hydrogenosomes divide in three different ways, like mitochondria, by segmentation, partition and the
heart form. They may divide at any phase of the cell cycle. Nucleoid or electron dense deposits found in
hydrogenosomes can be consideredartifactsor dysfunctionalhydrogenosomes. The hydrogenosome does
not contain a genome, although DNA has already been detected in one anaerobic ciliate. Hydrogenosomes
can be considered as good drug targets since their metabolism is distinct from mitochondria.
© 2009 Elsevier Ltd. All rights reserved.
Contents
1. Introduction ......................................................................................................................................... 152
2. Similarities to and differences from mitochondria ................................................................................................. 152
3. Hydrogenosome metabolism........................................................................................................................ 153
4. Morphological methods to study hydrogenosomes ................................................................................................ 154
5. Cell fractionation and isolated hydrogenosomes ................................................................................................... 154
6. Medical interest ..................................................................................................................................... 155
7. Hydrogenosome morphology ....................................................................................................................... 159
8. The different hydrogenosome shapes ............................................................................................................... 159
9. The hydrogenosome envelope ...................................................................................................................... 159
10. The peripheral vesicle ............................................................................................................................... 160
11. The matrix of the hydrogenosome .................................................................................................................. 161
12. Fungal hydrogenosomes ............................................................................................................................ 162
13. Hydrogenosome division............................................................................................................................ 162
14. Hydrogenosome behavior in the cell cycle ......................................................................................................... 163
15. Proximity with other cellular structures............................................................................................................ 164
16. Hydrogenosomes and endoplasmic reticulum ..................................................................................................... 164
17. Immunolabeling ..................................................................................................................................... 164
18. Hydrogenosome death .............................................................................................................................. 164
19. Evolutionary origin of the hydrogenosome......................................................................................................... 166
20. The cardiolipin story ................................................................................................................................166
21. The proteome of hydrogenosomes .................................................................................................................. 167
Acknowledgements ................................................................................................................................. 167
References ........................................................................................................................................... 167
∗
Correspondence to: Rua Jornalista Orlando Dantas 59, Botafogo, Rio de Janeiro, RJ, Brazil, CEP 222-31-010. Tel.: +55 21 2237 0440; fax: +55 21 2237 0440.
E-mail address: marleneben@uol.com.br.
0040-8166/$ – see front matter © 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tice.2009.01.001