| methanogenic bacteria as endosymbionts of the ciliate nyctotherus ovalis in the cockroach hindgut. | production of methane in the hindgut of the cockroach periplaneta americana was found to vary, depending on the feeding regimen. methane production was positively correlated with the numbers of the ciliate nyctotherus ovalis living in the cockroach hindgut. defaunation of the cockroaches by means of low concentrations of metronidazole (flagyl) resulted in a quick drop of methane production. addition of the methanogenic substrates acetate and formate to isolated hindguts stimulated methane produc ... | 1991 | 1908205 |
| evolution of anaerobic ciliates from the gastrointestinal tract: phylogenetic analysis of the ribosomal repeat from nyctotherus ovalis and its relatives. | the 18s and 5.8s rdna genes and the internal transcribed spacers its-1 and its-2 of ciliates living in the hindgut of frogs, millipedes, and cockroaches were analyzed in order to study the evolution of intestinal protists. all ciliates studied here belong to the genus nycrotherus. phylogenetic analysis revealed that these ciliates from a monophyletic group that includes the distantly related anaerobic free-living heterotrichous ciliates metopus palaeformis and metopus contortus. the intestinal c ... | 1998 | 9729884 |
| voltage-dependent reversal of anodic galvanotaxis in nyctotherus ovalis. | 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. expo ... | 1999 | 10461384 |
| a hydrogenosomal [fe]-hydrogenase from the anaerobic chytrid neocallimastix sp. l2. | the presence of a [fe]-hydrogenase in the hydrogenosomes of the anaerobic chytridiomycete fungus neocallimastix sp. l2 has been demonstrated by immunocytochemistry, subcellular fractionation, western-blotting and measurements of hydrogenase activity in the presence of various concentrations of carbon monoxide (co). since the hydrogenosomal hydrogenase activity can be inhibited nearly completely by low concentrations of co, it is likely that the [fe]-hydrogenase is responsible for at least 90% of ... | 2002 | 11891051 |
| comparison of 16s rrna gene sequences of genus methanobrevibacter. | the phylogeny of the genus methanobrevibacter was established almost 25 years ago on the basis of the similarities of the 16s rrna oligonucleotide catalogs. since then, many 16s rrna gene sequences of newly isolated strains or clones representing the genus methanobrevibacter have been deposited. we tried to reorganize the 16s rrna gene sequences of this genus and revise the taxonomic affiliation of the isolates and clones representing the genus methanobrevibacter. | 2004 | 15128464 |
| an anaerobic mitochondrion that produces hydrogen. | 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 metabolically quite different, just like mitochondria where large differences also exist. these differences have led to a continuing debate about the evolutionary origin of hydrogenosomes. here we show that the h ... | 2005 | 15744302 |
| variation in macronuclear genome content of three ciliates with extensive chromosomal fragmentation: a preliminary analysis. | the genome architecture of ciliates, including features such as nuclear dualism and large-scale genome rearrangements, impacts gene and genome evolution in these organisms. to better understand the structure of macronuclear chromosomes in ciliates with extensively processed chromosomes, a sample of complete macronuclear chromosomes was sequenced from three ciliate species: metopus es (class [cl]: armophorea), nyctotherus ovalis (cl: armophorea), and chilodonella uncinata (cl: phyllopharyngea). b ... | 2007 | 17552979 |
| macronuclear genome structure of the ciliate nyctotherus ovalis: single-gene chromosomes and tiny introns. | nyctotherus ovalis is a single-celled eukaryote that has hydrogen-producing mitochondria and lives in the hindgut of cockroaches. like all members of the ciliate taxon, it has two types of nuclei, a micronucleus and a macronucleus. n. ovalis generates its macronuclear chromosomes by forming polytene chromosomes that subsequently develop into macronuclear chromosomes by dna elimination and rearrangement. | 2008 | 19061489 |
| the mitochondrial genomes of the ciliates euplotes minuta and euplotes crassus. | there are thousands of very diverse ciliate species from which only a handful mitochondrial genomes have been studied so far. these genomes are rather similar because the ciliates analysed (tetrahymena spp. and paramecium aurelia) are closely related. here we study the mitochondrial genomes of the hypotrichous ciliates euplotes minuta and euplotes crassus. these ciliates are only distantly related to tetrahymena spp. and paramecium aurelia, but more closely related to nyctotherus ovalis, which p ... | 2009 | 19895685 |
| the organellar genome and metabolic potential of the hydrogen-producing mitochondrion of nyctotherus ovalis. | it is generally accepted that hydrogenosomes (hydrogen-producing organelles) evolved from a mitochondrial ancestor. however, until recently, only indirect evidence for this hypothesis was available. here, we present the almost complete genome of the hydrogen-producing mitochondrion of the anaerobic ciliate nyctotherus ovalis and show that, except for the notable absence of genes encoding electron transport chain components of complexes iii, iv, and v, it has a gene content similar to the mitocho ... | 2011 | 21378103 |
| the [fefe] hydrogenase of nyctotherus ovalis has a chimeric origin. | the hydrogenosomes of the anaerobic ciliate nyctotherus ovalis show how mitochondria can evolve into hydrogenosomes because they possess a mitochondrial genome and parts of an electron-transport chain on the one hand, and a hydrogenase on the other hand. the hydrogenase permits direct reoxidation of nadh because it consists of a [fefe] hydrogenase module that is fused to two modules, which are homologous to the 24 kda and the 51 kda subunits of a mitochondrial complex i. | 2007 | 18021395 |
| spatiotemporal control of functional specification and distribution of spindle microtubules with 13, 14 and 15 protofilaments during mitosis in the ciliate nyctotherus. | the formation of microtubules with more than 13 protofilaments in the ciliate nyctotherus ovalis leidy seems to be a highly ordered process. such microtubules are restricted to the nucleoplasm and, moreover, to certain stages of nuclear division. they assemble during anaphase of micronuclear mitosis and during the elongation phase of macronuclear division. the number of microtubules with more than 13 protofilaments in the micronuclear nucleoplasm increases as anaphase progresses. furthermore, as ... | 1985 | 2866192 |
| evidence for intermediate-like filaments in a heterotrichous ciliate. | in the heterotrichous ciliate nyctotherus ovalis, a meshwork of 10 nm filaments present in the cell cortex surrounds cytostome and cytoproct and is connected by thin strands to a perinuclear coat. like intermediate filaments (if) of higher organisms the filaments are insoluble in non-ionic detergent, and paracrystals can be formed after dissolution in 8 m urea. the cross-reactions of these filaments with monoclonal anti-vimentin and anti-cytokeratin antibodies suggest that they share common epit ... | 1990 | 23195973 |
| contribution of anaerobic protozoa and methanogens to hindgut metabolic activities of the american cockroach, periplaneta americana. | the ciliate nyctotherus ovalis occurs in high numbers in the hindgut of the american cockroach (periplaneta americana) and harbors methanogenic bacteria as endosymbionts. the contribution of these hindgut microorganisms to metabolic and developmental processes of p. americana was studied by comparing cultures of cockroaches in which the composition of the hindgut microbial population was altered in various ways. rearing the insects protozoan free resulted in increased insect generation time, dec ... | 1992 | 1514803 |
| effect of host diet and hindgut microbial composition on cellulolytic activity in the hindgut of the american cockroach, periplaneta americana. | cellulase activity measured as filter paper digesting activity (fpase) and carboxymethyl cellulase (cmcase) was demonstrated in hindgut extracts of the cockroach periplaneta americana. the highest activities measured amounted to 0.89 and 0.12 u . ml for cmcase and fpase, respectively. the cellulolytic capacity of the hindgut population increased dramatically when protozoa were present, and the activities were found to vary depending on the feeding regimen. cellulose-rich diets induced high proto ... | 1994 | 16349275 |
| a mitochondrial ancestry of the hydrogenosomes of nyctotherus ovalis. | | 2000 | 10666720 |
| hydrogenosomes: convergent adaptations of mitochondria to anaerobic environments. | hydrogenosomes are membrane-bound organelles that compartmentalise the final steps of energy metabolism in a number of anaerobic eukaryotes. they produce hydrogen and atp. here we will review the data, which are relevant for the questions: how did the hydrogenosomes originate, and what was their ancestor? notably, there is strong evidence that hydrogenosomes evolved several times as adaptations to anaerobic environments. most likely, hydrogenosomes and mitochondria share a common ancestor, but a ... | 2001 | 16351844 |
| organelles in blastocystis that blur the distinction between mitochondria and hydrogenosomes. | blastocystis is a unicellular stramenopile of controversial pathogenicity in humans. although it is a strict anaerobe, blastocystis has mitochondrion-like organelles with cristae, a transmembrane potential and dna. an apparent lack of several typical mitochondrial pathways has led some to suggest that these organelles might be hydrogenosomes, anaerobic organelles related to mitochondria. we generated 12,767 expressed sequence tags (ests) from blastocystis and identified 115 clusters that encode ... | 2008 | 18403202 |
| the cultivation of nyctotherus ovalis and endamoeba blattae. | | 1932 | 17731541 |
| evidence for three "classes" of microtubules in the interpolar space of the mitotic micronucleus of a ciliate and the participation of the nuclear envelope in conferring stability to microtubules. | exposure of nyctotherus ovalis to low temperatures or vinblastine caused similar reactions of "classes" of microtubules (mt) present in the mitotic micronucleus of this ciliate towards both treatments. however, differences of sensitivity between certain "classes" of mt at individual mitotic stages exist. unlike the kinetochore mt (kmt) of most other eukaryotic cells, kmt in nyctotherus completely disassemble after incubation at 6-8 degrees c (60 min) and most disappear after prolonged exposure t ... | 1982 | 6813060 |