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  • 1
    Electronic Resource
    Electronic Resource
    Multiple origins of hydrogenosomes: functional and phylogenetic evidence from the ADP/ATP carrier of the anaerobic chytrid Neocallimastix sp. (2002)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 44 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A mitochondrial-type ADP/ATP carrier (AAC) has been identified in the hydrogenosomes of the anaerobic chytridiomycete fungus Neocallimastix sp. L2. Biochemical and immunocytochemical studies revealed that this ADP/ATP carrier is an integral component of hydrogenosomal membranes. Expression of the corresponding cDNA in Escherichia coli confers the ability on the bacterial host to incorporate ADP at significantly higher rates than ATP – similar to isolated mitochondria of yeast and animals. Phylogenetic analysis of this AAC gene (hdgaac) confirmed with high statistical support that the hydrogenosomal ADP/ATP carrier of Neocallimastix sp. L2 belongs to the family of veritable mitochondrial-type AACs. Hydrogenosome-bearing anaerobic ciliates possess clearly distinct mitochondrial-type AACs, whereas the potential hydrogenosomal carrier Hmp31 of the anaerobic flagellate Trichomonas vaginalis and its homologue from Trichomonas gallinae do not belong to this family of proteins. Also, phylogenetic analysis of genes encoding mitochondrial-type chaperonin 60 proteins (HSP 60) supports the conclusion that the hydrogenosomes of anaerobic chytrids and anaerobic ciliates had independent origins, although both of them arose from mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.02959.x
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  • 2
    Electronic Resource
    Electronic Resource
    A hydrogenosome with pyruvate formate-lyase: anaerobic chytrid fungi use an alternative route for pyruvate catabolism (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 32 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The chytrid fungi Piromyces sp. E2 and Neocallimastix sp. L2 are obligatory amitochondriate anaerobes that possess hydrogenosomes. Hydrogenosomes are highly specialized organelles engaged in anaerobic carbon metabolism; they generate molecular hydrogen and ATP. Here, we show for the first time that chytrid hydrogenosomes use pyruvate formate-lyase (PFL) and not pyruvate:ferredoxin oxidoreductase (PFO) for pyruvate catabolism, unlike all other hydrogenosomes studied to date. Chytrid PFLs are encoded by a multigene family and are abundantly expressed in Piromyces sp. E2 and Neocallimastix sp. L2. Western blotting after cellular fractionation, proteinase K protection assays and determinations of enzyme activities reveal that PFL is present in the hydrogenosomes of Piromyces sp. E2. The main route of the hydrogenosomal carbon metabolism involves PFL; the formation of equimolar amounts of formate and acetate by isolated hydrogenosomes excludes a significant contribution by PFO. Our data support the assumption that chytrid hydrogenosomes are unique and argue for a polyphyletic origin of these organelles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01434.x
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  • 3
    Electronic Resource
    Electronic Resource
    Cytosolic enzymes with a mitochondrial ancestry from the anaerobic chytrid Piromyces sp. E2 (1998)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The anaerobic chytrid Piromyces sp. E2 lacks mitochondria, but contains hydrogen-producing organelles, the hydrogenosomes. We are interested in how the adaptation to anaerobiosis influenced enzyme compartmentalization in this organism. Random sequencing of a cDNA library from Piromyces sp. E2 resulted in the isolation of cDNAs encoding malate dehydrogenase, aconitase and acetohydroxyacid reductoisomerase. Phylogenetic analysis of the deduced amino acid sequences revealed that they are closely related to their mitochondrial homologues from aerobic eukaryotes. However, the deduced sequences lack N-terminal extensions, which function as mitochondrial leader sequences in the corresponding mitochondrial enzymes from aerobic eukaryotes. Subcellular fractionation and enzyme assays confirmed that the corresponding enzymes are located in the cytosol. As anaerobic chytrids evolved from aerobic, mitochondria-bearing ancestors, we suggest that, in the course of the adaptation from an aerobic to an anaerobic lifestyle, mitochondrial enzymes were retargeted to the cytosol with the concomitant loss of their N-terminal leader sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01130.x
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  • 4
    Electronic Resource
    Electronic Resource
    A divergent ADP/ATP carrier in the hydrogenosomes of Trichomonas gallinae argues for an independent origin of these organelles (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The evolution of mitochondrial ADP and ATP exchanging proteins (AACs) highlights a key event in the evolution of the eukaryotic cell, as ATP exporting carriers were indispensable in establishing the role of mitochondria as ATP-generating cellular organelles. Hydrogenosomes, i.e. ATP- and hydrogen-generating organelles of certain anaerobic unicellular eukaryotes, are believed to have evolved from the same ancestral endosymbiont that gave rise to present day mitochondria. Notably, the hydrogenosomes of the parasitic anaerobic flagellate Trichomonas seemed to be deficient in mitochondrial-type AACs. Instead, HMP 31, a different member of the mitochondrial carrier family (MCF) with a hitherto unknown function, is abundant in the hydrogenosomal membranes of Trichomonas vaginalis. Here we show that the homologous HMP 31 of closely related Trichomonas gallinae specifically transports ADP and ATP with high efficiency, as do genuine mitochondrial AACs. However, phylogenetic analysis and its resistance against bongkrekic acid (BKA, an efficient inhibitor of mitochondrial-type AACs) identify HMP 31 as a member of the mitochondrial carrier family that is distinct from all mitochondrial and hydrogenosomal AACs studied so far. Thus, our data support the hypothesis that the various hydrogenosomes evolved repeatedly and independently.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.03918.x
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  • 5
    Electronic Resource
    Electronic Resource
    The anaerobic chytridiomycete fungus Piromyces sp. E2 produces ethanol via pyruvate:formate lyase and an alcohol dehydrogenase E (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Anaerobic chytridiomycete fungi possess hydrogenosomes, which generate hydrogen and ATP, but also acetate and formate as end-products of a prokaryotic-type mixed-acid fermentation. Notably, the anaerobic chytrids Piromyces and Neocallimastix use pyruvate:formate lyase (PFL) for the catabolism of pyruvate, which is in marked contrast to the hydrogenosomal metabolism of the anaerobic parabasalian flagellates Trichomonas vaginalis and Tritrichomonas foetus, because these organisms decarboxylate pyruvate with the aid of pyruvate:ferredoxin oxidoreductase (PFO). Here, we show that the chytrids Piromyces sp. E2 and Neocallimastix sp. L2 also possess an alcohol dehydrogenase E (ADHE) that makes them unique among hydrogenosome-bearing anaerobes. We demonstrate that Piromyces sp. E2 routes the final steps of its carbohydrate catabolism via PFL and ADHE: in axenic culture under standard conditions and in the presence of 0.3% fructose, 35% of the carbohydrates were degraded in the cytosol to the end-products ethanol, formate, lactate and succinate, whereas 65% were degraded via the hydrogenosomes to acetate and formate. These observations require a refinement of the previously published metabolic schemes. In particular, the importance of the hydrogenase in this type of hydrogenosome has to be revisited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03912.x
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  • 6
    Electronic Resource
    Electronic Resource
    Voltage-Dependent Reversal of Anodic Galvanotaxis in Nyctotherus ovalis (1999)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 46 (1999), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Aerobic and anaerobic ciliates swim towards the cathode when they are exposed to a constant DC field. Nyctotherus ovalis from the intestinal tract of cockroaches exhibits a different galvanotactic response: at low strength of the DC field the ciliates orient towards the anode whereas DC fields above 2–4 V/cm cause cathodic swimming. This reversal of the galvanotactic response is not due to backward swimming. Rather the ciliates turn around and orient to the cathode with their anterior pole. Exposure to various cations, chelators, and Ca2--channel inhibitors suggests that Ca2--channels similar to the “long lasting” Ca2--channels of vertebrates are involved in the voltage-dependent anodic galvanotaxis. Evidence is presented that host-dependent epigenetic factors can influence the voltage-threshold for the switch from anodic to cathodic swimming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1999.tb04623.x
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  • 7
    Electronic Resource
    Electronic Resource
    An anaerobic mitochondrion that produces hydrogen (2005)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 434 (2005), S. 74-79 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Hydrogenosomes are organelles that produce ATP and hydrogen, and are found in various unrelated eukaryotes, such as anaerobic flagellates, chytridiomycete fungi and ciliates. Although all of these organelles generate hydrogen, the hydrogenosomes from these organisms are structurally and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature03343
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  • 8
    Electronic Resource
    Electronic Resource
    Spermatogenesis inDrosophila hydei: A genetic survey (1990)
    Springer
    Development genes and evolution 199 (1990), S. 251-280 
    Details
    ISSN: 1432-041X
    Keywords: Spermatogenesis ; Drosophilia ; Y chromosomal lampbrush loops ; Male sterile mutations ; Cellular differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We constructed balancer-chromosomes for the large autosomes ofDrosophila hydei and screened more than 16000 chromosomes for male sterile mutations in order to dissect spermatogenesis genetically. 365 mutants on the X chromosome and the autosomes 2, 3, and 4 were recovered and analysed cytologically in squash preparations under phase-contrast optics. The majority of the mutations allows a rather advanced differentiation of the spermatozoa. At the light-microscopical level, it is possible to classify these mutations with respect to individualization, coiling or motility of the mutant spermatozoa. In contrast, a small number of mutants exhibits conspicuous, pleiotropic phenotypes. Gonial divisions, the shaping of the spermatocyte nucleus and male meiotic divisions are controlled by X chromosomal or autosomal genes which can mutate to male sterile alleles. A number of nonallelic 3rd chromosome male sterile mutations interfere with the unfolding of the Y chromosomal lampbrush loops. Other autosomal male sterile mutations modify the morphology of these lampbrush loops. Another group of mutations inhibits the formation of the nebenkern while the development of the spermatid nucleus and the flagellum can proceed. Such male sterile mutations can decouple the development of nucleus, protein body, nebenkern, and flagellum of the spermatid. Thus, we can describe spermatogenesis inDrosophila as the coordinate execution of the individual developmental programs of the different components of the spermatozoon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01709505
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  • 9
    Electronic Resource
    Electronic Resource
    Larval length as evidence for maternal effects correlated with thepn/K-pn interaction inDrosophila melanogaster (1971)
    Springer
    Molecular genetics and genomics 111 (1971), S. 373-376 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to confirm the time and the pleiotropic effects of thepn/K-pn interaction the lengths of second instar larvae were measured. Length-frequency distributions of samples of larvae derived from the crosspn/pn; + +/ + + × +/-; ca K-pn/ ca K-pn are bimodal; the one partial collective covers small lethal male larvae, the other partial collective represents the large viable female larvae (Fig. 1a). The expectation that the progeny of the backcrossespn/ +; ca K-pn/ + + × pn/-; + +/ + + andpn/ +; ca K-pn/ + + × +/-; ca K-pn/ ca K-pn also exhibits a bimodal distribution of larval lengths is not fulfilled: during the whole second larval instar the larval lengths are normally distributed (Figs. I c, d). This results indicates that a maternal effect is involved in thepn/K-pn interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569790
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  • 10
    Electronic Resource
    Electronic Resource
    Y chromosome-specific mutations induced by a giant transposon in Drosophila hydei (1987)
    Springer
    Molecular genetics and genomics 207 (1987), S. 455-465 
    Details
    ISSN: 1617-4623
    Keywords: Y chromosome ; Lampbrush loops ; Transposition ; Male fertility genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The w m Co duplication of Drosophila hydei (Dp (1; Y) 16B2-17B1) contains 13–16 bands in salivary gland chromosomes. The duplication resides preferentially in the X heterochromatin or on the Y chromosome. In some stocks frequent (up to 4×10-3) exchanges of the duplication occur between different Y chromosomes (T(X; Y) and free Y) or between the X and the Y chromosome. About 60% of the T(X; Y)-Y exchanges induce mutations in the Y chromosomal male fertility genes of the recipient Y chromosome. From the mutational spectrum generated by the T(X; Y)-Y transpositions and from the variable efficiency as acceptor of different X-Y translocations it can be concluded that the exchanges show a remarkable site specificity: distal positions in the long arm of the Y chromosome are occupied preferentially. More proximal positions in the long arm of insertions into the short arm of the Y chromosome are found only with a lower frequency. No transpositions to the autosomes have been recovered. Duplications are lost with highly differing frequencies. The losses are not linked with insertions of the w m Co element into a new position and are more frequent than transpositions. Therefore, we regard the w m Co element as a giant transposon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331615
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