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Topic: Hydrogenosomes

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	Hydrogenosome - Wikipedia, the free encyclopedia
		A hydrogenosome is an organelle of ciliates, trichomonads and fungi.
		Hydrogenosomes were discovered in the early 1970s by Lindmark and Müller in the US and by Kulda and others in Prague.
		The anaerobic ciliated protozoan Nyctotherus ovalis, found in the hindgut of several species of cockroach, has numerous hydrogenosomes that are intimately associated with endosymbiotic methane-producing Archaea, the latter using the hydrogen produced by the hydrogenosomes.
	en.wikipedia.org /wiki/Hydrogenosome (343 words)

	NAI: News Stories (Site not responding. Last check: 2007-10-09)
		Because mitochondria and hydrogenosomes share many proteins in common, and because the metabolic pathway followed by hydrogenosomes is thought to be similar to that of the earliest eukaryotes before the development of mitochondria, some scientists believe that hydrogenosomes provide a view of how eukaryotes functioned before the rise of atmospheric oxygen.
		The NWO research team compared the hydrogenosomes of various protozoans and anaerobic fungi and discovered that the contents and form of these cell organelles differ from species to species.
		The researchers concluded that the hydrogenosomes of the different species constantly evolved anew from mitochondria in the course of evolution.
	nai.arc.nasa.gov /news_stories/news_detail.cfm?ID=109 (1048 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		Hydrogenosomes are organelles found in unicellular anaerobic organisms that lack mitochondria.
		Hydrogenosomes are about 1 micrometer in diameter and are so called because they produce molecular hydrogen (Martin and Muller, 1998).
		Hydrogenosomes are, however, markedly different from mitochondria as they lack DNA, cytochromes and the citric acid cycle.
	www.hamline.edu /~arundqui/phys1240/summary/data/hwheeler/207-summary (248 words)

	Presence of a Member of the Mitochondrial Carrier Family in Hydrogenosomes: Conservation of Membrane-Targeting Pathways ...
		Hydrogenosomes and mitochondria undergo biogenesis by binary fission,
		Hydrogenosomes (HY) were subjected to sodium carbonate extraction to separate the soluble fraction (HS), comprising matrix and intermembrane space proteins from the insoluble fraction (HP), consisting of integral membrane proteins.
		Intact hydrogenosomes in SM (250 mM sucrose, 10 mM MOPS [pH 7.2]) at a concentration of 0.5 µg of total protein per ml were subjected to increasing concentrations of trypsin, from 0.02 to 1.0 mg/ml, for 30 min on ice.
	mcb.asm.org /cgi/content/full/20/7/2488 (6408 words)

	The Scientist : Evidence for organelle origin
		Hydrogenosomes resemble mitochondria morphologically, but generally lack a genome, hampering clarification of their origin.
		Considerable debate exists over whether hydrogenosomes evolved from aerobically functioning mitochondria that acquired an anaerobic metabolism or from endosymbionts capable of both aerobic and anaerobic function that mitochondria also descended from.
		Since the hydrogenosomes appeared insensitive to inhibitors of mitochondrial complexes III and IV, future studies could reveal whether the genes for those complexes are missing or inactivated.
	www.the-scientist.com /news/20050303/01 (666 words)

	A Mitochondrial Ancestry of the Hydrogenosomes of Nyctotherus ovalis -- van Hoek et al. 17 (1): 202 -- Molecular ...
		A Mitochondrial Ancestry of the Hydrogenosomes of Nyctotherus ovalis -- van Hoek et al.
		A Mitochondrial Ancestry of the Hydrogenosomes of Nyctotherus ovalis
		Among the 1,000 trees, one in which the ciliate mitochondria and hydrogenosomes were monophyletic had the highest probability in a full likelihood analysis, although the probability was not significantly higher than that of the best tree that did not support this specific monophyly.
	mbe.oxfordjournals.org /cgi/content/full/17/1/202 (1979 words)

	The Scientist : Evolutionary Teamwork
		Genomic analyses across a broad spectrum of organisms have solidified the case for mitochondria and chloroplasts and suggested that less well known organelles, the hydrogenosome and mitosome, are remnants of genome-depleted mitochondrial descendants.
		The hydrogenosome was the first organelle proposed to be a mitochondrial descendent lacking its own genome.
		Hydrogenosomes are surrounded by a double membrane and participate in energy metabolism, yet they lack a genome, have some differences in membrane architecture, and do not participate in respiration.
	www.the-scientist.com /article/display/14665 (1469 words)

	Syaffolee
		The hydrogenosome is a special organelle found in eukaryotic microbes as well as some fungi that like to live in poor oxygen environments.
		In fact, hydrogenosomes have an uncanny likeness to mitochondria--not only do both organelles produce ATP, but morphologically they are similar--they are both surrounded by a double membrane and they both compartmentalize their different metabolic functions.
		Further examination of organelle associated proteins revealed that the hydrogenosome had many of the proteins that were associated with mitochondria except for the ones involved in aerobic respiration.
	www.gamalei.net /syaffolee/2005/03/evolution-of-powerhousesthe.html (635 words)

	Astrobiology Research: Evolution of Biological Complexity
		To better understand the origin and nature of the hydrogenosomes, Johnson and her collaborators will probe the evolutionary and biochemical properties of this organelle in the anaerobic protist Trichomonas vaginalis, using a combination of genomics, proteomics and phylogenetic approaches.
		In brief: (1) to identify genes encoding hydrogenosomal matrix proteins as described above; (2) to identify all proteins in the hydrogenosome; (3) to test whether the putative hydrogenosomal proteins found are localized to the organelle in vivo; and (4) conduct phylogenetic analyses on newly-identifed hydrogenosomal proteins.
		If hydrogenosomes arose from an ancestor different from the mitochondrion, then hypotheses concerning the nature of living eukaryotes will be narrowed to those postulating endosymbiotic associations among a consortium of eubacterial and eukaryotic progenitors.
	www.astrobiology.ucla.edu /pages/res4b.html (2025 words)

	Cellular organelle evolved repeatedly
		Hydrogenosomes, or ‘hydrogen-forming organelles’, are cell organelles that produce hydrogen and energy.
		The microbiologists believe that hydrogenosomes evolved from mitochondria as a result of a drastic ecological change.
		The research team compared the hydrogenosomes of various protozoans and anaerobic fungi and discovered that the contents and form of these cell organelles differ from species to species.
	www.eurekalert.org /pub_releases/2001-07/nofs-coe072601.php (248 words)

	Trichomonas vaginalis Hmp35, a Putative Pore-forming Hydrogenosomal Membrane Protein, Can Form a Complex in Yeast ...
		Purified hydrogenosomes (50 µg of protein per lane) were solubilized with 0.25% or 0.5% n-dodecyl maltoside (ndm, lanes 1 and 2) and 0.5 or 1% Triton X-100 (tx100, lanes 3 and 4).
		Hydrogenosomes were preincubated in isotonic SM buffer for 30 min at 37 °C with increasing concentrations of TCEP and with 10 m
		Isolated hydrogenosomes (250 µg of total protein per 250 µl of buffer) were incubated in isotonic buffer with or without 0.25 mg/ml proteinase K (lanes 1, 2, 7, and 8).
	www.jbc.org /cgi/content/full/278/33/30548 (7749 words)

	Pace University - Haskins Laboratories - Human and Cattle Trichomoniasis
		vaginalis is an aerotolerant anaerobe possessing a redox organelle termed the hydrogenosome which functions in energy metabolism and maintenance of the redox balance of the trichomonad cell, and is more recently considered to be a modified mitochondrion.
		Hydrogenosomes metabolize pyruvate to acetate via ferredoxin-linked enzymes, and produce stoichiometric concentrations of H2, ATP and acetate.
		Due to the low redox potential required to reduce the drug, toxicity to the host is considered minimal unless administered in high doses, as in drug refractory cases (>3.5 g/day for 14 days), when significant toxicity has been reported.
	appserv.pace.edu /execute/page.cfm?doc_id=19666 (413 words)

	[No title]
		Hydrogenosomes are membrane-bound organelles found in a wide variety of anaerobic, amitochondriate eukaryotes, e.g.
		Moreover, the occurence of hydrogenosomes in taxa that are only distantly related suggests that hydrogenosomes evolved several times - and not necessarily from a common ancestor.
		Hydrogenosomes of trichomonads, anaerobic chytrids and ciliates are structurally and biochemically different.
	www.endocytobiology.org /conference1998/abstracts/b1_voncken.html (199 words)

	Fe-Hydrogenase Maturases in the Hydrogenosomes of Trichomonas vaginalis -- Pütz et al. 5 (3): 579 -- Eukaryotic ...
		A putative hydrogenosomal targeting sequence is shown in bold, and peptide sequences from hydrogenosomal protein spot S29 are shaded in gray.
		Iron-ascorbate cleavable malic enzyme from hydrogenosomes of Trichomonas vaginalis: purification and characterization.
		A hydrogenosomal Fe-hydrogenase from the anaerobic chytrid Neocallimastix sp.
	ec.asm.org /cgi/content/full/5/3/579 (3171 words)

	b13
		Now, however, a eukaryotic organelle - the hydrogenosome - has been identified as endosymbiotic in origin, yet it lacks a genome and is entirely dependent on the nucleus for its genetic livelihood.
		Hydrogenosomes are an example of the repeated evolution of biochemically similar organelles.
		Hydrogenosomes can be found in a wide variety of otherwise unrelated anaerobic or microaerobic eukaryotes, almost all of which lack mitochondria..
	www.spiritcrow.com /helix/b13.htm (806 words)

	From the Cover: Mitochondrial-type assembly of FeS centers in the hydrogenosomes of the amitochondriate eukaryote ...
		hydrogenosomal extract was omitted from the reaction mixture.
		the hydrogenosomes, in contrast to its homologs in yeast and
		Identification and Biochemical Characterization of Serine Hydroxymethyl Transferase in the Hydrogenosome of Trichomonas vaginalis
	www.pnas.org /cgi/content/full/101/28/10368 (3548 words)

	NAI News Article: Evolution’s Double Take (Site not responding. Last check: 2007-10-09)
		To survive this loss of oxygen, the researchers say the mitochondria evolved into hydrogenosomes.
		This passing of genetic material from one microorganism to another is called ‘lateral gene transfer.’
		This switch in environmental conditions can be as simple as becoming buried by mud, or being ingested into the gut of an animal.
	nai.arc.nasa.gov /news_stories/news_print.cfm?ID=109 (1001 words)

	Mark van der Giezen - Mitochondrial remnants
		Mitochondria and hydrogenosomes are two forms of the same fundamental organelle.
		A mitochondrial-like targeting signal on the hydrogenosomal malic enzyme from the anaerobic fungus Neocallimastix frontalis: evidence for the hypothesis that hydrogenosomes are modified mitochondria.
		Hydrogenosomes in the anaerobic fungus Neocallimastix frontalis have a double membrane but lack an associated organelle genome.
	web.onetel.com /~vandergiezen/papers-new.htm (641 words)

	k28 The hydrogen hypothesis for the first eukaryote
		Hydrogenosomes are the power house (ATP producing) organelles that occur in some anaerobic eukaryotes in the place of mitochondria that have the power house (ATP producing) role in aerobic eukaryotes.
		Hydrogenosomes waste products are prodigious amounts of hydrogen and, lesser amounts of, carbon dioxide and acetate.
		ller about hydrogenosomes included a slide that showed methogens (bacteria that feed on hydrogen, carbon dioxide and acetate) clustered against and feeding on the wastes of hydrogenosomes (in an anaerobic eukaryote, which they had invaded).
	geowords.com /histbooknetscape/k28.htm (867 words)

	Bioc 811
		Hydrogenosomes and peroxisomes may also be endosymbionts, but they do not contain a genome of their own today.
		Hydrogenosomes are organelles found only in eukaryotes that do not have mitochondria.
		Since this happened in all three cases, the hydrogenosome Hsps and the mitochondrial Hsps appear to have a common bacterial ancestor.
	drnelson.utmem.edu /evolution2.2002.html (5559 words)

	EVOLUTIONARY BIOLOGY: ON THE HYDROGENOSOME
		The hydrogenosomal DNA isolated by Boxma et al exhibits hallmarks of a bona fide mitochondrial genome.
		Like mitochondria, the hydrogenosomes* are bound by distinct double membranes and have an inner membrane with *cristae-like projections.
		It has been postulated that hydrogenosomes evolved from mitochondria by the concomitant loss of their respiration and organellar genomes, and indeed so far no hydrogenosome has been found that has a genome.
	scienceweek.com /2005/sw050527-1.htm (889 words)

	Incorporation of iron into Tritrichomonas foetus cell compartments reveals ferredoxin as a major iron-binding protein ...
		Fe-NTA for 10 min, washed and reincubated in the absence of radioactive iron for 0, 60 or 150 min at 37 °C. Cytosolic and hydrogenosomal fractions obtained by means of differential and Percoll gradient centrifugation were analysed by native gradient PAGE followed by storage phosphorimaging (3000 c.p.m.
		Stability of hydrogenosomal H-I band-associated iron in the presence of the iron chelator.
		to be the endosymbiotic ancestors of mitochondria and hydrogenosomes
	mic.sgmjournals.org /cgi/content/full/149/7/1911 (5160 words)

	Hydrogen peroxide is a product of oxygen consumption by Trichomonas vaginalis (Site not responding. Last check: 2007-10-09)
		An understanding of the oxidative metabolism of the amitochondriate flagellated parasitic protozoan, Trichomonas vaginalis, an extremely common cause of human genito–urinary infections, is paramount in devising strategies for chemotherapy (Milne et al 1978; Lloyd and Petersen 1985).
		The redox-active organelles of trichomonads, the hydrogenosomes (Lindmark and Müller 1973) are responsible for the oxidation of pyruvate (Cerkasov et al 1978).
		Lindmark D G and Müller M 1973 Hydrogenosome, a cytoplasmic organelle of the anaerobic flagellate, Tritrichomonas foetus and its role in pyruvate metabolism; J.
	www.ias.ac.in /jbiosci/september1999/article11.htm (2386 words)

	Evolution's Double Take :: Astrobiology Magazine ::
		Summary (Jun 06, 2002): The origin of hydrogenosomes has been debated for some time.
		Organisms that live in environments without oxygen, such as anaerobic fungi and protozoa (a type of protist), don't use mitochondria at all -- instead their power is generated by hydrogenosomes, organelles that, while similar in many ways to mitochondria, follow a different metabolic pathway.
		Tree of life, divided between three major cell types, those with and without a nucleus (Bacterial Prokaryotes and Animal Eukaryotes), preceded by the root of the tree, Archea.
	www.astrobio.net /news/article24.html (1045 words)

	Iron-Dependent Hydrogenases of Entamoeba histolytica and Giardia lamblia: Activity of the Recombinant Entamoebic Enzyme ...
		Presence of a member of the mitochondrial carrier family in hydrogenosomes: conservation of membrane-targeting pathways between hydrogenosomes and mitochondria.
		Molecular analysis of the hydrogenosomal ferrédoxin of the anaerobic protist Trichomonas vaginalis.
		Hydrogenosome, a cytoplasmic organelle of the anaerobic flagellate Trichomonas foetus, and its role in pyruvate metabolism.
	www.biolbull.org /cgi/content/full/204/1/1 (3724 words)

	Giardia intestinalis, a eukaryote without hydrogenosomes, produces hydrogen -- Lloyd et al. 148 (3): 727 -- Microbiology
		Lindmark, D. and Müller, M. Hydrogenosome, a cytoplasmic organelle of the anaerobic flagellate Tritrichomonas foetus and its role in pyruvate metabolism.
		Yarlett, N., Hann, A. C., Lloyd, D. and Williams, A. Hydrogenosomes in the rumen protozoon Dasytricha ruminantium.
		Hydrogenosomes in a mixed isolate of Isotricha prostoma and Isotricha intestinalis from ovine rumen contents.
	mic.sgmjournals.org /cgi/content/full/148/3/727 (2946 words)

	RU SEP: Müller
		We are working on elucidating the origin of similar metabolic patterns and of the presence of hydrogenosomes in diverse organisms.
		Our studies are performed partly through a comparison of the primary structure and functional properties of key proteins of these organisms with each other and with related proteins of other organisms and partly by functional and biochemical studies on whole cells and their hydrogenosomes.
		Primary structure of the hydrogenosomal adenylate kinase of Trichomonas vaginalis and its phylogenetic relationships.
	www.rockefeller.edu /labheads/muller/muller-sep.html (713 words)

	Research - Cell and Molecular Biosciences - University of Newcastle
		Published data indicate that ciliate and trichomonad hydrogenosomes share common ancestry with mitochondria, but the evolutionary origins of fungal hydrogenosomes have been controversial.
		Moreover, both sequences contain amino-terminal extensions that in heterologous targeting experiments were shown to be necessary and sufficient to locate both proteins and green fluorescent protein to the mitochondria of mammalian cells.
		This finding, that fungal hydrogenosomes use mitochondrial targeting signals to import two proteins of mitochondrial ancestry that play key roles in aerobic mitochondria, provides further strong evidence that the fungal organelle is also of mitochondrial ancestry.
	www.ncl.ac.uk /camb/research/publication/29318 (246 words)

	Inhibition of Polyamine Synthesis Arrests Trichomonad Growth and Induces Destruction of Hydrogenosomes -- Reis et al. ...
		Note that besides hydrogenosomes (H), the gold labeling was also detected in vesicles (*) in drug-treated parasites.
		Since hydrogenosomes are the only redox organelle in trichomonads and under aerobic conditions these structures generate free
		-Succinyl-coenzyme A synthetase from Trichomonas vaginalis is a soluble hydrogenosomal protein with an amino-terminal sequence that resembles mitochondrial presequences.
	aac.asm.org /cgi/content/full/43/8/1919 (2478 words)

	Why Metronidazole Is Active against both Bacteria and Parasites -- Samuelson 43 (7): 1533 -- Antimicrobial Agents and ...
		Organisms containing hydrogenosomes and bacterium-like fermentation enzymes in the cytosol, which are metronidazole sensitive, are indicated to distinguish them from organisms with mitochondria (unmarked) or chloroplasts.
		Structures indicated by dashed rectangles (anaerobic bacteria and the purple bacterium in giardia) are absent now, but their past presence is suggested by bacterium-like nuclear genes.
		A mitochondrial-like targeting signal on the hydrogenosomal malic enzyme from the anaerobic fungus Neocallimastix frontalis: support for hypothesis that hydrogenosomes are modified mitochondria.
	aac.asm.org /cgi/content/full/43/7/1533 (4350 words)

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