Anaerobic ciliates

It has recently been reported that Giardia mitosomes, Trichomonas hydrogenosomes and mitochondria share a similar mode of protein targeting and translocation (Dolezal et al. 2005 Regoes et al. 2005). The import of Giardia IscU and ferredoxin into the organelle was shown to be dependent on 

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There exists a rather broad agreement that the anaerobic ciliates evolved secondarily from aerobic ancestors since several ciliate taxa comprise both aerobic and anaerobic species. Phylogenetic studies indicate that hydrogenosomes have arisen independently at least three to four times in ciliates (Fig. 1 Clarke et al. 1993 Embley and Finlay 1994 Embley et al. 1995, 2003 Fenchel and Finlay 1995 Hirt et al. 1998 Hackstein et al. 2001,2002). The existence in... 

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). 

Embley TM, Finlay BJ, Dyal PL, Hirt RP, Wilkinson M, Williams AG (1995) Multiple origins of anaerobic ciliates with hydrogenosomes within the radiation of aerobic ciliates. Proc R Soc Lond Ser B-Biol Sci 262 87-93... 

Hackstein JHP, de Graaf RM, van Hellemond JJ, Tielens AGM (2007) Hydrogenosomes of Anaerobic Ciliates (in this volume). Springer, Heidelberg... 

The hydrogenosomal metabolism has been studied in more detail in the chytridiomycetes Piromyces and Neocallimastix. Notably, the hydrogenosomes of these organisms are clearly different from those known of tri-chomonads and anaerobic ciliates, structurally and metabolically. Most importantly, the hydrogenosomes of Neocallimastix sp. L2 and Piromyces sp. E2 contain PFL as key enzyme, and not PDH (as in N. ovalis) or PFO (as in Trichomonas vaginalis) (Fig. 2). 

Akhmanova et al. 1998b). Chytrid hydrogenosomes are therefore clearly distinct from the hydrogenosomes of Trichomonas, and of those from anaerobic ciliates (see later). 

Hydrogenosomes of Anaerobic Ciliates At Least One Appears to Be a Missing Link... 

Goosen NK, van der Drift C, Stumm CK, Vogels GD (1990a) End products of metabolism in the anaerobic ciliate Trimyema compressum. FEMS Microbiol Lett 69 171-175... 

Goosen NK, Wagener S, Stumm CK (1990b) A comparison of 2 strains of the anaerobic ciliate Trimyema compressum Arch Microbiol 153 187-192... 

Hackstein JHP, van Hoek AHAM, Leunissen JAM, Huynen M (2002) Anaerobic ciliates and their methanogenic endosymbionts. In Seckbach J (ed) Symbiosis mechanisms and model systems. Kluwer, Dordrecht, pp 451-464... 

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