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1.
BMC Biol ; 20(1): 56, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-35227266

RESUMO

BACKGROUND: Mitochondria and peroxisomes are the two organelles that are most affected during adaptation to microoxic or anoxic environments. Mitochondria are known to transform into anaerobic mitochondria, hydrogenosomes, mitosomes, and various transition stages in between, collectively called mitochondrion-related organelles (MROs), which vary in enzymatic capacity. Anaerobic peroxisomes were identified only recently, and their putatively most conserved function seems to be the metabolism of inositol. The group Archamoebae includes anaerobes bearing both anaerobic peroxisomes and MROs, specifically hydrogenosomes in free-living Mastigamoeba balamuthi and mitosomes in the human pathogen Entamoeba histolytica, while the organelles within the third lineage represented by Pelomyxa remain uncharacterized. RESULTS: We generated high-quality genome and transcriptome drafts from Pelomyxa schiedti using single-cell omics. These data provided clear evidence for anaerobic derivates of mitochondria and peroxisomes in this species, and corresponding vesicles were tentatively identified in electron micrographs. In silico reconstructed MRO metabolism harbors respiratory complex II, electron-transferring flavoprotein, a partial TCA cycle running presumably in the reductive direction, pyruvate:ferredoxin oxidoreductase, [FeFe]-hydrogenases, a glycine cleavage system, a sulfate activation pathway, and an expanded set of NIF enzymes for iron-sulfur cluster assembly. When expressed in the heterologous system of yeast, some of these candidates localized into mitochondria, supporting their involvement in the MRO metabolism. The putative functions of P. schiedti peroxisomes could be pyridoxal 5'-phosphate biosynthesis, amino acid and carbohydrate metabolism, and hydrolase activities. Unexpectedly, out of 67 predicted peroxisomal enzymes, only four were also reported in M. balamuthi, namely peroxisomal processing peptidase, nudix hydrolase, inositol 2-dehydrogenase, and D-lactate dehydrogenase. Localizations in yeast corroborated peroxisomal functions of the latter two. CONCLUSIONS: This study revealed the presence and partially annotated the function of anaerobic derivates of mitochondria and peroxisomes in P. schiedti using single-cell genomics, localizations in yeast heterologous systems, and transmission electron microscopy. The MRO metabolism resembles that of M. balamuthi and most likely reflects the state in the common ancestor of Archamoebae. The peroxisomal metabolism is strikingly richer in P. schiedti. The presence of myo-inositol 2-dehydrogenase in the predicted peroxisomal proteome corroborates the situation in other Archamoebae, but future experimental evidence is needed to verify additional functions of this organelle.


Assuntos
Amoeba , Archamoebae , Amoeba/genética , Amoeba/metabolismo , Anaerobiose , Archamoebae/genética , Archamoebae/metabolismo , Genômica , Humanos , Mitocôndrias/metabolismo , Peroxissomos/metabolismo , Saccharomyces cerevisiae
2.
J Eukaryot Microbiol ; 69(3): e12889, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35029005

RESUMO

We described Pelomyxa doughnuta sp. nov. and examined it with the use of light, electron, and immunofluorescence microscopy as well as cytochemical methods. The cells of P. doughnuta sp. nov. are usually binuclear, although cells with one, three, or four nuclei are sometimes found in the population. A unique feature of the new species is a dense capsule around the nucleus. It consists of a continuous layer of glycogen 5-20 µm thick. The tubulin cytoskeleton is mainly represented by perinuclear microtubules. P. doughnuta sp. nov. has a filamentous glycocalyx and strongly reduced components of flagellar apparatus. Obligate prokaryotic endocytobionts of two morphotypes are present in the cytoplasm.


Assuntos
Archamoebae , Glicogênio , Núcleo Celular , Citoplasma , Microtúbulos
3.
Mol Biol Evol ; 38(6): 2240-2259, 2021 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-33528570

RESUMO

The transition of free-living organisms to parasitic organisms is a mysterious process that occurs in all major eukaryotic lineages. Parasites display seemingly unique features associated with their pathogenicity; however, it is important to distinguish ancestral preconditions to parasitism from truly new parasite-specific functions. Here, we sequenced the genome and transcriptome of anaerobic free-living Mastigamoeba balamuthi and performed phylogenomic analysis of four related members of the Archamoebae, including Entamoeba histolytica, an important intestinal pathogen of humans. We aimed to trace gene histories throughout the adaptation of the aerobic ancestor of Archamoebae to anaerobiosis and throughout the transition from a free-living to a parasitic lifestyle. These events were associated with massive gene losses that, in parasitic lineages, resulted in a reduction in structural features, complete losses of some metabolic pathways, and a reduction in metabolic complexity. By reconstructing the features of the common ancestor of Archamoebae, we estimated preconditions for the evolution of parasitism in this lineage. The ancestor could apparently form chitinous cysts, possessed proteolytic enzyme machinery, compartmentalized the sulfate activation pathway in mitochondrion-related organelles, and possessed the components for anaerobic energy metabolism. After the split of Entamoebidae, this lineage gained genes encoding surface membrane proteins that are involved in host-parasite interactions. In contrast, gene gains identified in the M. balamuthi lineage were predominantly associated with polysaccharide catabolic processes. A phylogenetic analysis of acquired genes suggested an essential role of lateral gene transfer in parasite evolution (Entamoeba) and in adaptation to anaerobic aquatic sediments (Mastigamoeba).


Assuntos
Archamoebae/genética , Evolução Biológica , Entamoeba histolytica/genética , Genoma de Protozoário , Parasitos/genética , Adaptação Biológica/genética , Anaerobiose/genética , Animais , Archamoebae/metabolismo , Transferência Genética Horizontal , Tamanho do Genoma , Transcriptoma
4.
Protoplasma ; 257(6): 1701-1708, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32829470

RESUMO

The nature and features of organization of reserve polysaccharides in three species of the genus Pelomyxa-P. palustris, P. belevskii, and P. stagnalis-were studied using light and transmission electron microscopy. We applied the periodic acid-Schiff reaction that is a highly selective method for detecting glycogen. The fluorescent dye auramine-SO2 (Au-SO2) was used as a Schiff-type reagent. The densely packed aggregates of glycogen that form the morphologically differentiated organelle-like bodies are revealed in the cytoplasm in all studied species. The organization of these bodies is characterized by the species-specific features, while in most cases, their size and number in the cells vary depending on the season of the year. Although in all the cases we studied, these bodies do not have their own boundary membrane, in fact, they are surrounded by membranous structures. These structures differ in a variety of Pelomyxa species. We concluded that there are two groups of species in the genus Pelomyxa. The first one includes organisms containing glycogen structures in the cytoplasm (P. palustris, P. belevskii, P. stagnalis, P. binucleata, P. corona, P. secunda). No inclusions resembling glycogen bodies were found in P. flava, P. paradoxa, P. gruberi, and P. prima that form the second group.


Assuntos
Archamoebae/química , Microscopia Eletrônica de Transmissão/métodos , Polissacarídeos/metabolismo
5.
Proc Natl Acad Sci U S A ; 117(4): 2065-2075, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31932444

RESUMO

The adaptation of eukaryotic cells to anaerobic conditions is reflected by substantial changes to mitochondrial metabolism and functional reduction. Hydrogenosomes belong among the most modified mitochondrial derivative and generate molecular hydrogen concomitant with ATP synthesis. The reduction of mitochondria is frequently associated with loss of peroxisomes, which compartmentalize pathways that generate reactive oxygen species (ROS) and thus protect against cellular damage. The biogenesis and function of peroxisomes are tightly coupled with mitochondria. These organelles share fission machinery components, oxidative metabolism pathways, ROS scavenging activities, and some metabolites. The loss of peroxisomes in eukaryotes with reduced mitochondria is thus not unexpected. Surprisingly, we identified peroxisomes in the anaerobic, hydrogenosome-bearing protist Mastigamoeba balamuthi We found a conserved set of peroxin (Pex) proteins that are required for protein import, peroxisomal growth, and division. Key membrane-associated Pexs (MbPex3, MbPex11, and MbPex14) were visualized in numerous vesicles distinct from hydrogenosomes, the endoplasmic reticulum (ER), and Golgi complex. Proteomic analysis of cellular fractions and prediction of peroxisomal targeting signals (PTS1/PTS2) identified 51 putative peroxisomal matrix proteins. Expression of selected proteins in Saccharomyces cerevisiae revealed specific targeting to peroxisomes. The matrix proteins identified included components of acyl-CoA and carbohydrate metabolism and pyrimidine and CoA biosynthesis, whereas no components related to either ß-oxidation or catalase were present. In conclusion, we identified a subclass of peroxisomes, named "anaerobic" peroxisomes that shift the current paradigm and turn attention to the reductive evolution of peroxisomes in anaerobic organisms.


Assuntos
Archamoebae/metabolismo , Peroxissomos/metabolismo , Anaerobiose , Archamoebae/genética , Mitocôndrias/genética , Mitocôndrias/metabolismo , Oxirredução , Peroxinas/genética , Peroxinas/metabolismo , Peroxissomos/genética , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Espécies Reativas de Oxigênio/metabolismo
6.
Parasitology ; 146(6): 821-827, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30638175

RESUMO

Amoebae are single-celled parasites frequently colonizing human gut. However, few molecular tools are available for accurate identification. Here, we evaluated a panel of polymerase chain reactions (PCRs) targeting Entamoeba histolytica, Entamoeba dispar, Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Endolimax nana and Iodamoeba bütschlii. Thirty-six faecal samples (18 containing at least one amoeba species by microscopy and 18 microscopy negative for amoebae) were tested. Real-time PCRs were used for detection and differentiation of E. histolytica and E. dispar. Conventional PCR with Sanger sequencing were applied for detection and differentiation of E. coli, E. hartmanni, E. polecki, E. nana and I. bütschlii. All microscopy results were confirmed by DNA-based methods. However, more samples were positive for single and mixed amoebic species by DNA-based assays than by microscopy (22 vs 18 and 7 vs 1, respectively). DNA sequencing allowed identification of E. coli subtypes (ST1 and ST2), showed low intra-specific variation within E. hartmanni, identified two phylogenetically distinct groups within E. nana, and identified Iodamoeba at the ribosomal lineage level. Taking into account the high intra-genetic diversity within some of the species at the small subunit (SSU) rRNA gene level, amplification of SSU rRNA genes with subsequent sequencing represents a useful method for detecting, differentiating and subtyping intestinal amoebae.


Assuntos
Amebíase/diagnóstico , Archamoebae/isolamento & purificação , Endolimax/isolamento & purificação , Entamoeba histolytica/isolamento & purificação , Fezes/parasitologia , Técnicas de Diagnóstico Molecular/métodos , Archamoebae/classificação , Archamoebae/genética , Doenças Assintomáticas , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Endolimax/classificação , Endolimax/genética , Entamoeba histolytica/classificação , Entamoeba histolytica/genética , Humanos , Microscopia , Reação em Cadeia da Polimerase/métodos , RNA Ribossômico 18S/genética , Análise de Sequência de DNA/métodos
7.
Protist ; 168(4): 408-424, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28755578

RESUMO

Pelomyxa palustris is a giant anaerobic/microaerobic amoeba, characterized by a number of exceptional cytological and physiological features, among them the presumed absence of energy producing organelles and the presence of endosymbiotic bacteria. These endosymbionts have been previously distinguished as: a large rectangular-shaped Gram-variable rod with a central cleft; a slender Gram-negative rod; and a slender Gram-positive rod. Using DNA extracted from P. palustris cysts, we have obtained three SSU rRNA gene sequences. We have determined that these sequences are affiliated to three different prokaryotic genera: Methanosaeta (a methanogenic archaea), Syntrophorhabdus (a syntrophic Gram-negative bacteria) and Rhodococcus (an aerobic chemoorganotrophic Gram-positive bacteria). To our knowledge, it is the first time that Syntrophorhabdus has been described as an endosymbiont in association with a methanogen. Strikingly, no traces of Methanobacterium formicicum could be detected, despite this methanogen had allegedly been isolated from trophozoites of P. palustris. It seems that the host and the endosymbionts have established a multipartite syntrophic consortium resembling to some extent those found in sewage treatment plants.


Assuntos
Archamoebae/microbiologia , Deltaproteobacteria/fisiologia , Methanosarcinales/fisiologia , Rhodococcus/fisiologia , Simbiose , Archamoebae/fisiologia , Deltaproteobacteria/classificação , Deltaproteobacteria/genética , Deltaproteobacteria/isolamento & purificação , Methanosarcinales/classificação , Methanosarcinales/genética , Methanosarcinales/isolamento & purificação , Filogenia , RNA Arqueal/genética , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Rhodococcus/classificação , Rhodococcus/genética , Rhodococcus/isolamento & purificação , Análise de Sequência de RNA
8.
Environ Microbiol ; 19(3): 1091-1102, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27902886

RESUMO

p-Cresol and indole are volatile biologically active products of the bacterial degradation of tyrosine and tryptophan respectively. They are typically produced by bacteria in animal intestines, soil and various sediments. Here, we demonstrate that the free-living eukaryote Mastigamoeba balamuthi and its pathogenic relative Entamoeba histolytica produce significant amounts of indole via tryptophanase activity. Unexpectedly, M. balamuthi also produces p-cresol in concentrations that are bacteriostatic to non-p-cresol-producing bacteria. The ability of M. balamuthi to produce p-cresol, which has not previously been observed in any eukaryotic microbe, was gained due to the lateral acquisition of a bacterial gene for 4-hydroxyphenylacetate decarboxylase (HPAD). In bacteria, the genes for HPAD and the S-adenosylmethionine-dependent activating enzyme (AE) are present in a common operon. In M. balamuthi, HPAD displays a unique fusion with the AE that suggests the operon-mediated transfer of genes from a bacterial donor. We also clarified that the tyrosine-to-4-hydroxyphenylacetate conversion proceeds via the Ehrlich pathway. The acquisition of the bacterial HPAD gene may provide M. balamuthi a competitive advantage over other microflora in its native habitat.


Assuntos
Archamoebae/genética , Cresóis/metabolismo , Transferência Genética Horizontal , Genes Bacterianos , Indóis/metabolismo , Animais , Bactérias/genética , Carboxiliases , Óperon , S-Adenosilmetionina/metabolismo
9.
Mol Phylogenet Evol ; 98: 41-51, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26826602

RESUMO

Archamoebae is an understudied group of anaerobic free-living or endobiotic protists that constitutes the major anaerobic lineage of the supergroup Amoebozoa. Hitherto, the phylogeny of Archamoebae was based solely on SSU rRNA and actin genes, which did not resolve relationships among the main lineages of the group. Because of this uncertainty, several different scenarios had been proposed for the phylogeny of the Archamoebae. In this study, we present the first multigene phylogenetic analysis that includes members of Pelomyxidae, and Rhizomastixidae. The analysis clearly shows that Mastigamoebidae, Pelomyxidae and Rhizomastixidae form a clade of mostly free-living, amoeboid flagellates, here called Pelobiontida. The predominantly endobiotic and aflagellated Entamoebidae represents a separate, deep-branching lineage, Entamoebida. Therefore, two unique evolutionary events, horizontal transfer of the nitrogen fixation system from bacteria and transfer of the sulfate activation pathway to mitochondrial derivatives, predate the radiation of recent lineages of Archamoebae. The endobiotic lifestyle has arisen at least three times independently during the evolution of the group. We also present new ultrastructural data that clarifies the primary divergence among the family Mastigamoebidae which had previously been inferred from phylogenetic analyses based on SSU rDNA.


Assuntos
Archamoebae/classificação , Archamoebae/genética , Família Multigênica/genética , Filogenia , Archamoebae/metabolismo , Archamoebae/ultraestrutura , Evolução Molecular , Transferência Genética Horizontal/genética , Mitocôndrias/metabolismo , Fixação de Nitrogênio/genética , Sulfatos/metabolismo
10.
Proc Natl Acad Sci U S A ; 112(22): E2884-90, 2015 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-25986376

RESUMO

Hydrogenosomes and mitosomes are mitochondrion-related organelles (MROs) that have highly reduced and divergent functions in anaerobic/microaerophilic eukaryotes. Entamoeba histolytica, a microaerophilic, parasitic amoebozoan species, which causes intestinal and extraintestinal amoebiasis in humans, possesses mitosomes, the existence and biological functions of which have been a longstanding enigma in the evolution of mitochondria. We previously demonstrated that sulfate activation, which is not generally compartmentalized to mitochondria, is a major function of E. histolytica mitosomes. However, because the final metabolites of sulfate activation remain unknown, the overall scheme of this metabolism and the role of mitosomes in Entamoeba have not been elucidated. In this study we purified and identified cholesteryl sulfate (CS) as a final metabolite of sulfate activation. We then identified the gene encoding the cholesteryl sulfotransferase responsible for synthesizing CS. Addition of CS to culture media increased the number of cysts, the dormant form that differentiates from proliferative trophozoites. Conversely, chlorate, a selective inhibitor of the first enzyme in the sulfate-activation pathway, inhibited cyst formation in a dose-dependent manner. These results indicate that CS plays an important role in differentiation, an essential process for the transmission of Entamoeba between hosts. Furthermore, we show that Mastigamoeba balamuthi, an anaerobic, free-living amoebozoan species, which is a close relative of E. histolytica, also has the sulfate-activation pathway in MROs but does not possess the capacity for CS production. Hence, we propose that a unique function of MROs in Entamoeba contributes to its adaptation to its parasitic life cycle.


Assuntos
Adaptação Biológica/fisiologia , Archamoebae/fisiologia , Evolução Biológica , Vias Biossintéticas/fisiologia , Ésteres do Colesterol/biossíntese , Entamoeba/fisiologia , Mitocôndrias/fisiologia , Cloratos/farmacologia , Ésteres do Colesterol/isolamento & purificação , Biologia Computacional , Relação Dose-Resposta a Droga , Técnica Indireta de Fluorescência para Anticorpo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Mitocôndrias/metabolismo , Filogenia , Reação em Cadeia da Polimerase em Tempo Real , Especificidade da Espécie , Sulfotransferases/genética
11.
Tsitologiia ; 57(1): 62-9, 2015.
Artigo em Russo | MEDLINE | ID: mdl-25872377

RESUMO

Morphology of a pelobiont Pelomyxa secunda (Gruber, 1884) comb. nov. was investigated at light- and electron-microscopical levels. Locomotive forms are elongated or cigar-shaped. The size of active forms varies from 200 to 300 µm. Larger individuals (up to 400 µm) are not able to directed movement. Organism can produce short, usually finger-shaped hyaline pseudopodia at the frontal side or laterally. The cell coat is represented by amorphous glycocalix, up to 300 nm in thickness. A thin periphery cytoplasmic zone is deprived of any organelles, vacuoles, endocytobionts and other inclusions and separated from main cytoplasm by a layer of arranged microfilaments. P. secunda is multinucleate organism; nuclei are of granular type. The nucleolar material is represented by two forms of discrete structures differing in size and electron density. Two or three layers of short microtubules organized in the parallel arrangement are associated with outer side of the nuclear envelop. P. secunda possess two types of obligate prokaryotic endocytobionts lying in individual symbiontophoric vacuoles. Undulipodia, kinetosomes and root microtubular derivatives are not observed in P. secunda cells as well as any developed cytoplasmic microtubular cytoskeleton.


Assuntos
Archamoebae/ultraestrutura , Citoesqueleto de Actina/ultraestrutura , Núcleo Celular/ultraestrutura , Citoplasma/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , Glicocálix/ultraestrutura , Microscopia Eletrônica , Microtúbulos/ultraestrutura , Movimento , Pseudópodes/ultraestrutura , Simbiose/fisiologia , Vacúolos/ultraestrutura
12.
Protist ; 166(1): 14-41, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25553396

RESUMO

Members of the archamoebae comprise free-living and endobiotic amoeboid flagellates and amoebae that live in anoxic/microoxic habitats. Recently, the group has been divided into four separate families, Mastigamoebidae, Entamoebidae, Pelomyxidae, and Rhizomastixidae, whose interrelationships have not been completely resolved. There still are several key members of the archamoebae, notably the genus Mastigella, from which sequence data are missing. We established 12 strains of 5 species of Mastigella and Pelomyxa in culture, examined their morphology and determined their actin gene sequences. In addition, we examined the ultrastructure of three strains and determined and analyzed SSU rDNA sequences of two strains. Our data strongly suggest that Mastigella is specifically related to Pelomyxa, and it is transferred into the family Pelomyxidae. Surprisingly, Mastigella is likely paraphyletic with Pelomyxa forming its internal branch. The two genera share several morphological features that point to their common evolutionary history. Three new species of Mastigella are described: M. erinacea sp. nov., M. rubiformis sp. nov. and M. ineffigiata sp. nov.


Assuntos
Archamoebae/genética , Archamoebae/ultraestrutura , Actinas/genética , Archamoebae/classificação , Análise por Conglomerados , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Filogenia , Proteínas de Protozoários/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
13.
Mol Biol Evol ; 32(4): 1039-55, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25573905

RESUMO

Lateral gene transfer (LGT) is an important mechanism of evolution for protists adapting to oxygen-poor environments. Specifically, modifications of energy metabolism in anaerobic forms of mitochondria (e.g., hydrogenosomes) are likely to have been associated with gene transfer from prokaryotes. An interesting question is whether the products of transferred genes were directly targeted into the ancestral organelle or initially operated in the cytosol and subsequently acquired organelle-targeting sequences. Here, we identified key enzymes of hydrogenosomal metabolism in the free-living anaerobic amoebozoan Mastigamoeba balamuthi and analyzed their cellular localizations, enzymatic activities, and evolutionary histories. Additionally, we characterized 1) several canonical mitochondrial components including respiratory complex II and the glycine cleavage system, 2) enzymes associated with anaerobic energy metabolism, including an unusual D-lactate dehydrogenase and acetyl CoA synthase, and 3) a sulfate activation pathway. Intriguingly, components of anaerobic energy metabolism are present in at least two gene copies. For each component, one copy possesses an mitochondrial targeting sequence (MTS), whereas the other lacks an MTS, yielding parallel cytosolic and hydrogenosomal extended glycolysis pathways. Experimentally, we confirmed that the organelle targeting of several proteins is fully dependent on the MTS. Phylogenetic analysis of all extended glycolysis components suggested that these components were acquired by LGT. We propose that the transformation from an ancestral organelle to a hydrogenosome in the M. balamuthi lineage involved the lateral acquisition of genes encoding extended glycolysis enzymes that initially operated in the cytosol and that established a parallel hydrogenosomal pathway after gene duplication and MTS acquisition.


Assuntos
Archamoebae/genética , Metabolismo Energético/genética , Evolução Molecular , Duplicação Gênica , Transferência Genética Horizontal , Organelas/genética , Anaerobiose/genética , Archamoebae/enzimologia , Archamoebae/metabolismo , Estruturas da Membrana Celular/genética , Estruturas da Membrana Celular/metabolismo , Enzimas/genética , Enzimas/isolamento & purificação , Organelas/enzimologia , Organelas/metabolismo
14.
Tsitologiia ; 56(10): 770-8, 2014.
Artigo em Russo | MEDLINE | ID: mdl-25711087

RESUMO

Morphology of a pelobiont Pelomyxa paradoxa Penard, 1902 was investigated at light- and electron-microscopical levels. Locomoting cells are cigar-shaped. The cells produce many hyaline pseudopodia of digital and conical form at lateral sides of the body. The organism has a pronounced hyaline bulbous uroid with broad peripheral zone of hyaloplasm and many conical hyaline villi. There is a thin layer of amorphous glycocalix at the cell surface. "Structure" and food vacuoles of different size are very abundant in the endoplasm. Two different species of prokaryote endocytobionts are peculiar for P. paradoxa. Uninucleate stage dominates in the life cycle of P. paradoxa. Usually there are no more than 10-12 nuclei in multinucleate forms of P. paradoxa. Pelomyxae nuclei are closely surrounded by thick multilaminar layer and additionally by one more layer, which is formed by small vesicles with electron-dense content. Several irregular-shaped nucleoli are situated at the nucleus periphery. Inside the nucleoli, and sometimes directly in nucleoplasm the small round bodies are revealed, these bodies being formed by tightly packed electron-dense fibrils. Many non-motile flagellae are located mainly in the uroidal zone of the cell. Pronounced lateral root and 50-60 radial microtubules originate from the electrone-dense muft around the kinetosome. All elements of the rootlet system of flagella are limited by peripheral layers of cytoplasm. P. paradoxa occupy an intermediate position between two groups of species of Pelomyxa genus--P. gruberi + P. prima and P. palustris + P. stagnalis + P. belewski, which differ greatly by the organization of their flagella basal apparatus.


Assuntos
Archamoebae/ultraestrutura , Estágios do Ciclo de Vida/fisiologia , Archamoebae/crescimento & desenvolvimento , Membrana Celular/ultraestrutura , Núcleo Celular/ultraestrutura , Citoplasma/ultraestrutura , Flagelos/ultraestrutura , Glicocálix/ultraestrutura , Microtúbulos/ultraestrutura , Pseudópodes/ultraestrutura , Vacúolos/ultraestrutura
15.
Protist ; 164(3): 380-410, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23312407

RESUMO

The archamoebae form a small clade of anaerobic/microaerophilic flagellates or amoebae, comprising the pelobionts (mastigamoebids and pelomyxids) and the entamoebae. It is a member of the eukaryotic supergroup Amoebozoa. We examined 22 strains of 13 species of Mastigamoeba, Pelomyxa and Rhizomastix by light-microscopy and determined their SSU rRNA gene sequences. The SSU rRNA gene sequences of Pelomyxa palustris and Mastigella commutans in GenBank are shown to belong to P. stagnalis and Mastigamoeba punctachora, respectively. Five new species of free-living archamoebae are described: Mastigamoeba abducta, M. errans, M. guttula, M. lenta, and Rhizomastix libera spp. nov. A species of Mastigamoeba possibly living endosymbiotically in Pelomyxa was identified. Rhizomastix libera, the first known free-living member of that genus, is shown to be an archamoeba. R. libera possesses an ultrastructure unique within archamoebae: a rhizostyle formed from a modified microtubular cone and a flagellum with vanes. While many nominal species of pelobionts are extremely hard to distinguish by light microscopy, transient pseudopodial characters are worthy of further investigation as taxonomic markers.


Assuntos
Archamoebae/genética , Endolimax/genética , Entamoeba/genética , Evolução Molecular , Animais , Archamoebae/classificação , Archamoebae/ultraestrutura , DNA de Protozoário/análise , Endolimax/classificação , Endolimax/ultraestrutura , Entamoeba/classificação , Entamoeba/ultraestrutura , Genes de RNAr , Microscopia , Filogenia , Análise de Sequência de DNA , Especificidade da Espécie
16.
Tsitologiia ; 55(11): 778-87, 2013.
Artigo em Russo | MEDLINE | ID: mdl-25509133

RESUMO

Comparative analysis of archamoebae and slime molds morphology revealed that this organisms have a marked similarity in organization of locomotive forms, structure of glycocalix and also in organization of nuclear and flagellar apparatus. A possible scheme of formation the modern diversity of Conosa group was proposed.


Assuntos
Archamoebae/ultraestrutura , Micetozoários/ultraestrutura , Filogenia , Archamoebae/classificação , Archamoebae/fisiologia , Evolução Biológica , Núcleo Celular/ultraestrutura , Flagelos/ultraestrutura , Glicocálix/ultraestrutura , Micetozoários/classificação , Micetozoários/fisiologia
17.
J Bacteriol ; 194(24): 6967-8, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23209223

RESUMO

Here is reported the draft genome sequence of Methanobacterium formicicum DSM 3637, which was isolated from the methane-producing amoeba Pelomyxa palustris. This bacterium was determined to be an endosymbiont living in the cytoplasm of P. palustris and the source of methane; however, the global characteristics of its genome suggest a free-living lifestyle rather than an endosymbiotic one.


Assuntos
Archamoebae/microbiologia , Genoma Arqueal , Methanobacterium/genética , Composição de Bases , Sequência de Bases , DNA Arqueal/genética , Metano/biossíntese , Methanobacterium/isolamento & purificação , Dados de Sequência Molecular , Filogenia , RNA Arqueal/genética , Análise de Sequência de DNA , Simbiose
18.
Plant Cell ; 24(5): 2041-57, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22589468

RESUMO

Actin is an essential multifunctional protein encoded by two distinct ancient classes of genes in animals (cytoplasmic and muscle) and plants (vegetative and reproductive). The prevailing view is that each class of actin variants is functionally distinct. However, we propose that the vegetative plant and cytoplasmic animal variants have conserved functional competence for spatial development inherited from an ancestral protist actin sequence. To test this idea, we ectopically expressed animal and protist actins in Arabidopsis thaliana double vegetative actin mutants that are dramatically altered in cell and organ morphologies. We found that expression of cytoplasmic actins from humans and even a highly divergent invertebrate Ciona intestinalis qualitatively and quantitatively suppressed the root cell polarity and organ defects of act8 act7 mutants and moderately suppressed the root-hairless phenotype of act2 act8 mutants. By contrast, human muscle actins were unable to support prominently any aspect of plant development. Furthermore, actins from three protists representing Choanozoa, Archamoeba, and green algae efficiently suppressed all the phenotypes of both the plant mutants. Remarkably, these data imply that actin's competence to carry out a complex suite of processes essential for multicellular development was already fully developed in single-celled protists and evolved nonprogressively from protists to plants and animals.


Assuntos
Proteínas de Arabidopsis/classificação , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Animais , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Archamoebae/genética , Archamoebae/metabolismo , Clorófitas/genética , Clorófitas/metabolismo , Coanoflagelados/genética , Coanoflagelados/metabolismo , Ciona intestinalis/genética , Ciona intestinalis/metabolismo , Filogenia
19.
Tsitologiia ; 54(1): 58-65, 2012.
Artigo em Russo | MEDLINE | ID: mdl-22567901

RESUMO

The morphology of Mastigamoeba aspera, a type species of the genus Mastigamoeba Schulze, 1875, has been investigated at the light- and electron-microscopical level. Motile individuals are oval or peach-shaped. Motile flagella is situated at the anterior end of uninucleate cells. During locomotion, the surface of mastigamoebes forms many conical or finger-shaped hyaline pseudopodia, wereas bulbous uroid is often formed at the posterior end of the cell. Micropopulations of M. aspera consist of uninucleate flagellate forms as well as multinucleate aflagellate ones. There is a thick layer ofglycocalix on the cell surface where many rod-shaped bacterial ectobionts live. The nucleus is vesicular with spherical central nucleolus. The flagellar apparatus of M. aspera is connected with nucleus to form so called kariomastigont. A single kinetosome is associated with many radial microtubules and a lateral root. A distinct microtubule organization centre (MTOC) is situated at the basal part of the kinetosome. Microtubules of the nuclear cone are connected with the MTOC. This microtubules take part in the formation of kariomastigont. The axoneme has a standart set of microtubules 9(2)+2. Digestive vacuoles are the main component of the cytoplasm of M. aspera. Beside, many light-difracted granules and glycogen bodies were found in the cells. Mitochondria, dictyosomes of the Golgi apparatus and microbodies were not revealed in the cytoplasm of M. aspera.


Assuntos
Archamoebae/ultraestrutura , Axonema/ultraestrutura , Nucléolo Celular/ultraestrutura , Flagelos/ultraestrutura , Bactérias , Grânulos Citoplasmáticos/ultraestrutura , Glicocálix/ultraestrutura , Locomoção , Microscopia Eletrônica , Centro Organizador dos Microtúbulos/ultraestrutura , Pseudópodes/ultraestrutura , Simbiose , Vacúolos/ultraestrutura
20.
Mol Biol Evol ; 29(1): 39-42, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21940643

RESUMO

Iodamoeba is the last genus of obligately parasitic human protist whose phylogenetic position is unknown. Iodamoeba small subunit ribosomal DNA sequences were obtained using samples from three host species, and phylogenetic analyses convincingly placed Iodamoeba as a sister taxon to Endolimax. This clade in turn branches among free-living amoeboflagellates of the genus Mastigamoeba. Two Iodamoeba ribosomal lineages (RL1 and RL2) were detected whose sequences differ by 31%, each of which is found in both human and nonhuman hosts.


Assuntos
Archamoebae/genética , Evolução Molecular , Amebíase/parasitologia , Animais , Archamoebae/classificação , Análise por Conglomerados , Cistos , DNA/análise , DNA/química , Variação Genética , Humanos , Filogenia , Subunidades Ribossômicas Menores de Eucariotos/genética , Suínos
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