The use of microorganisms as reducing and stabiliz-ing agents in biogenic syntheses of metal nanoparticles is an attractive approach. There is a large number of potential bioagents able to yield big amounts of various biomole-cules, and to prepare nanoparticles of diverse physico-chemical properties. Microscopic fungi and algae are widely studied for the preparation of nanoparticles, mainly because of their ability to produce vast amounts of extra-cellular proteins, enzymes, and other metabolites that can actively participate in the metal reduction and also contrib-ute to the nanoparticle stabilization. This results in highly stable metal nanoparticles with interesting properties that can be used, for example, as antimicrobial agents (especially Ag or Cu nanoparticles) or as catalysts. This review summarizes the main, promising representatives of microscopic fungi, yeasts, and algae used for the prepara-tion of nanoparticles of various metals.
The limited availability of biological samples hinders phylogenetic efforts to define structural differences among various biological groups. A novel workflow enabling the analysis of protists in low cell numbers by electron microscopy (EM) is described with cysts of Giardia intestinalis, a single-celled eukaryotic parasite. Correlative light and electron microscopy (CLEM) allows for the selection of individual cells and is economical in terms of time and cost. We describe a cyst purification protocol in combination with an adhesive coating for fixation and ultrathin embedding that results in excellent preservation of cell morphology. The application of advanced structural and analytical EM methods, such as high-resolution field emission scanning electron microscopy (FESEM), focused ion beam tomography (FIB/SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis, is demonstrated. The workflow represents a new approach for studying the cellular and organelle architecture of rare and "difficult to culture" microorganisms.
Until now, Hemistasia phaeocysticola was the only representative of the monogeneric family Hemistasiidae available in culture. Here we describe two new axenized hemistasiids isolated from Tokyo Bay, Japan. Like in other diplonemids, cellular organization of these heterotrophic protists is characterized by a distinct apical papilla, a tubular cytopharynx contiguous with a deep flagellar pocket, and a highly branched mitochondrion with lamellar cristae. Both hemistasiids also bear a prominent digestive vacuole, peripheral lacunae, and paraflagellar rods, are highly motile and exhibit diverse morphologies in culture. We argue that significant differences in molecular phylogenetics and ultrastructure between these new species and H. phaeocysticola are on the generic level. Therefore, we have established two new genera within Hemistasiidae - Artemidia gen. n. and Namystynia gen. n. to accommodate Artemidia motanka, sp. n. and Namystynia karyoxenos, sp. n., respectively. A. motanka permanently carries tubular extrusomes, while in N. karyoxenos, they are present only in starving cells. An additional remarkable feature of the latter species is the presence, in both the cytoplasm and the nucleus, of the endosymbiotic rickettsiid Candidatus Sneabacter namystus.
- MeSH
- Eukaryota * klasifikace genetika fyziologie ultrastruktura MeSH
- fylogeneze * MeSH
- pohyb MeSH
- zátoky parazitologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Japonsko MeSH
Fornicata (Metamonada) is a group of Excavata living in low-oxygen environments and lacking conventional mitochondria. It includes free-living Carpediemonas-like organisms from marine habitats and predominantly parasitic/commensal retortamonads and diplomonads. Current modest knowledge of biodiversity of Fornicata limits our ability to draw a complete picture of the evolutionary history in this group. Here, we report the discovery of a novel fornicate, Iotanema spirale gen. nov. et sp. nov., obtained from fresh feces of the gecko Phelsuma madagascariensis. Our phylogenetic analyses of the small subunit ribosomal RNA gene demonstrate that I. spirale is closely related to the free-living, marine strain PCS and the Carpediemonas-like organism Hicanonectes teleskopos within Fornicata. Iotanema spirale exhibits several features uncommon to fornicates, such as a single flagellum, a highly reduced cytoskeletal system, and the lack of the excavate ventral groove, but shares these characters with the poorly known genus Caviomonas. Therefore, I. spirale is accommodated within the family Caviomonadidae, which represents the third known endobiotic lineage of Fornicata. This study improves our understanding of character evolution within Fornicata when placed within the molecular phylogenetic context.
- MeSH
- cytoskelet ultrastruktura MeSH
- Eukaryota klasifikace genetika ultrastruktura MeSH
- feces parazitologie MeSH
- fylogeneze MeSH
- ještěři parazitologie MeSH
- molekulární evoluce MeSH
- ribozomální DNA genetika MeSH
- RNA ribozomální genetika MeSH
- sekvenční analýza DNA metody MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
We report discovery of a new lineage of anaerobic marine amoebae and amoeboflagellates, Anaeramoeba gen. nov., represented by six newly described species. The trophic form of Anaeramoeba spp. is an amoeba corresponding to the uncommon flabellate or flamellian morphotype - it is fan-shaped and produces an anterior, flattened hyaline zone and posterior hyaline projections. In contrast to other representatives of these morphotypes, cells of Anaeramoeba spp. possess acristate mitochondrion-related organelles associated with prokaryotic symbionts, and a large acentriolar centrosome. Surprisingly, two Anaeramoeba species form morphologically unique flagellates with two or four isokont, thickened flagella. Phylogenetic analyses of the SSU rRNA gene showed that Anaeramoeba spp. form a clade, which is not robustly related to any other eukaryotic lineage. We accommodate Anaeramoeba in a new family Anaeramoebidae, which we classify as Eukaryota incertae sedis.
Trimastigids are free-living, anaerobic protists that are closely related to the symbiotic oxymonads, forming together the taxon Preaxostyla (Excavata: Metamonada). We isolated fourteen new strains morphologically corresponding to two species assigned to Trimastix (until now the only genus of trimastigids), Trimastix marina and Trimastix pyriformis. Unexpectedly, marine strains of Trimastix marina branch separately from freshwater strains of this morphospecies in SSU rRNA gene trees, and instead form the sister group of all other Preaxostyla. This position is confirmed by three-gene phylogenies. Ultrastructural examination of a marine isolate of Trimastix marina demonstrates a combination of trimastigid-like features (e.g. preaxostyle-like I fibre) and ancestral characters (e.g. absence of thickened flagellar vane margins), consistent with inclusion of marine T. marina within Preaxostyla, but also supporting its distinctiveness from 'freshwater T. marina' and its deep-branching position within Preaxostyla. Since these results indicate paraphyly of Trimastix as currently understood, we transfer the other better-studied trimastigids to Paratrimastix n. gen. and Paratrimastigidae n. fam. The freshwater form previously identified as T. marina is described as Paratrimastix eleionoma n. sp., and Trimastix pyriformis becomes Paratrimastix pyriformis n. comb. Because of its phylogenetic position, 'true' Trimastix is potentially important for understanding the evolution of mitochondrion-related organelles in metamonads.
- MeSH
- druhová specificita MeSH
- Eukaryota klasifikace genetika izolace a purifikace ultrastruktura MeSH
- flagella ultrastruktura MeSH
- fylogeneze * MeSH
- organely ultrastruktura MeSH
- RNA ribozomální 18S genetika MeSH
- vodní organismy klasifikace genetika izolace a purifikace ultrastruktura MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A new species, Paramarteilia canceri sp. n., is described using light and electron microscopy from the edible crab Cancer pagurus L. captured from the English Channel. No external symptoms were noted, although infected animals were typically lethargic and unresponsive to external stimuli. Organs of infected animals were shrunken and collapsed compared with apparently healthy individuals. Although the infection was systemic, marked host responses were only noted in the hepatopancreas where the parasite induced a pronounced haemocytic infi ltration. Prevalence of infection throughout the study was 1.1%, with a maximum monthly prevalence of 3%. The intracellular parasite was typically 15 µm in length and composed of a primary cell containing up to three secondary cells derived by internal cleavage. Each secondary cell contains two bicellular spores. The parasite is readily differentiated from the other described paramyxean species by a combination of the number of secondary and tertiary cells. In light of this new discovery, a revision of the order Paramyxida Chatton, 1911 is proposed based upon comparison to the original descriptions of this parasite group in various species of invertebrate hosts. The proposed classifi cation is based on the number of cells within the spores (tertiary cells), so that only three genera remain within the order, namely Marteilia Grizel, Comps, Bonami, Cousserans, Duthoit et Le Pennec, 1974, Paramarteilia Ginsburger-Vogel et Desportes, 1979 and Paramyxa Chatton, 1911. Subsequent discrimination of species is based on a combination of the number of secondary cells within the primary cell and the number of tertiary cells within secondary cells. It is proposed that the genus Marteilioides Comps, Park et Desportes, 1986 is suppressed and the type species of the genus, M. chungmuensis Comps, Park et Desportes, 1986, is transferred to Marteilia and that the other representative of the genus, M. branchialis Anderson et Lester, 1992, is transferred to Paramarteilia. Further, Paramyxoides Larsson et Koie, 2005 is considered as a junior synonym of Paramyxa and its type and only species, Paramyxoides nephtys Larsson et Koie, 2005, is transferred to Paramyxa.
Jednobuněčná eukaryota jako Giardia intestinalis nebo Entamoeba histolytica byly a jsou považovány za amitochondriální. Ovšem v roce 1999 byla u těchto druhů popsána nová organela - mitosom. Morfologicky je podobný mitochondriím, ale na druhou stranu neobsahuje vlastní DNA a není schopen tvořit energii ve formě ATP. Jakou má mitosom funkci? Jaký je původ mitosomu? Existuje příbuznost mezi mitochondrií a mitosomem? Odpověď na tyto otázky budou hledat následující řádky.
Unicellular eucaryotes (Giardia intestinalis, Entamoeba histolytica and next) were and still are considered to be amitochondrial. However, a new organelle, mitosome, was described in these species, in 1999. Morphologically, mitosome looks like mitochondria, but on the other hand mitosome has no intrinsic DNA and it is unable to produce energy in the form of ATP. What is function of mitosome? What is the origin of mitosome? Does any relationship exist between mitosome and mitochondria? This article searches the answers.
A list of myxozoan genera is presented in the current taxonomical scheme. These genera are defined; their type species and most important pathogens along with their hosts are listed. Simultaneously, definitions of actinospore stages representing sexual stages of the myxosporean life cycle are given; altogether, 17 actinospore collective groups with 180 types have been described. Life cycles of the two classes of the phylum Myxozoa, Malacosporea and Myxosporea, are briefly outlined with specification of the appropriate terms. Up to now, 4 malacosporean and 2,180 myxosporean species assigned to a total of 62 genera, have been established. The surviving classification of myxosporeans, based on spore morphology, is discussed in the context of the still fragmentary data resulting from SSU rDNA sequence analyses. The main task for the future is a rigorous, detailed morphological description combined with molecular techniques in establishment of new species and in revision of the existing ones. Establishment of a classification acceptable from morphological, biological and phylogenetical viewpoints is necessary.
- MeSH
- Eukaryota klasifikace genetika růst a vývoj ultrastruktura MeSH
- klasifikace MeSH
- stadia vývoje MeSH
- terminologie jako téma MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
