Chytrids

Davidson, C., Benard, M.F., and Shaffer, H.B. et al. (2007). Effects of chytrid and carbaryl exposure on survival, growth and skin peptide defenses in foothill yellow-legged frogs. Environmental Science and Technology 41, 1771-1776. 

Anaerobic environments, such as swamps, marine and freshwater sediments, and the body cavities of animals, are teeming with large numbers of single-ceUed eukaryotes (protists) that, like all cells, must produce ATP to survive. Some of these protists, such as ciUates, trichomonads, and chytrid... 

Voncken FGJ, Boxma B, van Hoek A, et al. 2002. A hydrogenosomal Fe-hydrogenase from the anaerobic chytrid Neocallimastix sp L2. Gene 284 103-12. 

In recent years it has become clear that there are not only mitochondria that function as described in biochemical textbooks, but that many different types of mitochondria exist, which exhibit a large variety in metabolic properties (Tielens et al. 2002). It is now also clear that the same holds true for hydrogenosomes. Firstly, there are obvious metabolic differences between the hydrogenosomes of Trichomonads and those of chytrid fungi and of anaerobic ciliates. Secondly, substantial differences in metabolism also exist within the large community of anaerobic ciliates (Fig. 3,4, and 5). 

Hackstein JHP, Baker SE, van Hellemond JJ, Tielens AGM (2007) Hydrogenosomes of Anaerobic Chytrids an Alternative Way to Adapt to Anaerobic Environments (in this volume). Springer, Heidelberg... 

The metabolism of anaerobic chytrids has not been studied in great detail, but it is known that most anaerobic chytrids studied so far produce formate, acetate, succinate, lactate and ethanol besides hydrogen and carbon dioxide when growing on cellulose, glucose or fructose as a carbon source (Julliand et al. 1998). Such a mixed acid fermentation is very similar to bacterial mixed acid fermentations that are, for example, well known for facultative anaerobic enteric bacteria, such as Escherichia coli. 

Many different data, which will be discussed below, are consistent with a mitochondrial origin of the hydrogenosomes of anaerobic chytrids their morphology, the mitochondrial-type targeting signals that are used to import proteins, the ADP/ATP carriers and mitochondrial-type chaperones, and all this supplemented by genomic analyses of separate hydrogenosomal proteins. 

Chytrid hydrogenosomes took rather different from the pictures of mitochondria in textbooks (Fig. 4). However, serial sectioning followed by electron microscopical analysis revealed a structure resembling the ultrastructure... 

Cytosolic enzymes with a mitochondrial ancestry from the anaerobic chytrid Piromyces sp. E2. Mol Microbiol 30 1017-1027... 

Akhmanova A, Voncken FGJ, Hosea KM, Harhangi H, Keltjens JT, den Camp HJMO, Vogels GD, Hackstein JHP (1999) A hydrogenosome with pyruvate formate-lyase anaerobic chytrid fungi use an alternative route for pyruvate catabolism. Mol Microbiol 32 1103-1114... 

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