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At least 19 recordsLinked to original sources
PubMed1999

Ecology of testate amoebae (Protozoa: Rhizopoda) on peatlands in western Russia with special attention to niche separation in closely related taxa.

Testate amoebae (Protozoa: Rhizopoda) are frequently used as indicators of past environmental changes, and the interpretation of fossil assemblages depends upon our knowledge of ecological affinities of taxa in modern environments. A variety of taxonomic approaches have been used in fossil studies, mostly involving grouping of closely related taxa. This paper presents data from peatlands in western Russia relating surface wetness parameters to species occurrence. Relationships between species abundance, water table depth and soil moisture are modelled using weighted averaging, and species niches are calculated as optima and tolerance for these parameters. Niche separation of closely related taxa is examined in detail and it is shown that there is often a gradient of hydrological preference within each group of taxa. Wet to dry gradients include those found in the Trigonopyxis arcula group (T. arcula var. major > T. arcula > T. minuta), the Assulina-Valkanovia group (A. seminulum > A. muscorum > V. elegans), and the Trinema lineare group (T. lineare var. truncatum/ T. lineare > T. lineare var. terricola), all of which are associated with a large to small size gradient. In addition, spined forms within the Euglypha and Placocista genera are shown to consistently occur in wetter habitats than glabrous forms or those with shorter spines. It is concluded that palaeoecological studies should attempt the lowest taxonomic divisions possible within these groups, to maximise the ecological indicator value of the assemblages recorded.

Amoeba↗
PubMedDate not supplied

[Blastocystis galli sp. n. (Protista: Rhizopoda) from the intestines of domestic hens].

A new species, Blastocystis galli, parasitic in blind processes of large intestine was found in domestic hens. Sizes of blastocysts are 7.5-35.0 x 6.25-30.0 (18.67 x 17.05) microns. The parasite form varies from round to ellipsoid. There were found stages with 1 to 4 nuclei and stages containing 8 to 32 small daughter individuals. Outside blastocysts are covered with structured glycocalyx. Under glycocalyx there is a plasmatic membrane. Cytoplasm contains a great number of ribosomes and mitochondria with cristae resembling in their shape oval or round small sacs. Nucleus contains nucleolus. Chromatin mass is concentrated on one of the poles of the nucleus as individual bodies. Semilunar in form chromatin mass was not found. Golgi apparatus is represented by a number of plates grouped in a pile. Most part of the cell is occupied by reproductive organelles divided by cytoplasmatic membranes into compartments. On the basis of its ultrafine organization. B. galli is assigned to the kingdom Protista, type Rhizopoda, class Lobosea, subclass Gymnamoebia, order Blastocystida.

Animals↗
PubMed1989

Application of isoenzymatic typing to the identification of nonaxenic strains of Naegleria (Protozoa, Rhizopoda).

Isoenzymatic typing of the different species of Naegleria was studied by comparing isoelectric focusing on axenic and nonaxenic strains using the most discriminating enzymes: lactate dehydrogenase (LDH), malic enzyme (ME), beta-hydroxybutyrate dehydrogenase (beta-HBDH), superoxide dismutase (SOD), and acid phosphatase (AP). The results show that bacteria in nonaxenic cultures have no influence on the interpretation of zymograms. The specificity of the enzymatic patterns of each strain is maintained in all of these enzymatic systems except LDH. With SOD, the existence of a supplementary isoenzyme among all of the nonaxenic strains is probably linked to an enzymatic induction phenomenon.

Animals↗
PubMed2003

Accurate enumeration and identification of Testacea (Protozoa, Rhizopoda) in forest soil using scanning electron microscopy.

A new procedure is used for separating Testacea from soil, based on dispersion, sequential centrifugation settling, and subsequent filtration of the soil suspension. Combined with scanning electron microscopy (SEM), this procedure allows accurate enumeration of Testacea, with a recovery rate of 90% and more precise counting (relative standard deviation, RSD: 5%) of Testacea than in previous works.

Amoeba↗
PubMed2002

Vertical distribution and abundance of gymnamoebae (Rhizopoda) in bottom sediments of the brackish water Nivå Bay (Baltic Sea, The Sound).

The sandy sediments of Nivå Bay (Baltic Sea, The Sound, Denmark) are often covered with the mats of sulphur bacteria and are temporarily anoxic. The vertical distribution and abundance of naked amoebae species in three sediment cores from this bay were studied. Amoebae were most abundant and diverse in the upper 1 cm of sediment, and their number and diversity decreased with increasing depth into the sediment. Amoebae were recovered from both upper oxygenated and deep anoxic layers of sediments. The species composition and abundance of amoebae was very heterogeneous, even at spatial scales of several centimeters, suggesting the existence of microhabitats selectively occupied by particular species. All species found were recorded from aerobic cultures and some of these amoebae occur in both the aerobic and anaerobic layers of the sediment. Minimal possible number of amoebae in the sediments, estimated for the first time as areal abundance integrated for depth was: core 1 -597 cm(-2); core 2 -1,110 cm(-2); core 3 -1,430 cm(-2). These abundances are probably best regarded as "potential" abundances of amoebae hidden in the sediments, as the question of the ratio between active and resting amoebae remains open.

Amoebida↗
PubMed2003

Spatial distribution of gymnamoebae (Rhizopoda, Lobosea) in brackish-water sediments at the scale of centimeters and millimeters.

In order to study micro-spatial distribution of amoebae, an intact slice of sandy sediment from the brackish-water Nivå Bay (Baltic Sea, The Sound), 40 x 24 mm in size and 2 mm in thickness was gently sectioned into cubes, 2 x 2 x 2 mm in size. Each cube was inoculated into enrichment media to reveal the biodiversity of amoebae. Seventeen species of amoebae were recovered. The 2-D map of amoebae species distribution in the slice, consisting of 240 2 x 2 mm cells was drawn and analyzed. Results show heterogeneous distribution of amoebae at the scale of centimeters and millimeters and confirm the idea of the presence of microhabitats, selectively occupied by amoebae species. Three types of distribution patterns were found: random, aggregated and equally spaced. Microelectrode studies indicated that amoebae distribution was not related to the dissolved oxygen content in the sediment. The studied slice of sediment contained several pronounced "hotspots" of amoebae biodiversity, where up to four species co-occur in the same area. Seven species of amoebae numbered 1-4 specimens in the studied slice (i.e. there was 0.5-2 cell ml(-1)). Analysis of the amoebae distribution map shows the high probability of undersampling rare amoebae species during faunistic studies.

Animals↗
PubMed1989

srRNA evolution and phylogenetic relationships of the genus Naegleria (Protista: Rhizopoda).

A rapid RNA sequencing technique was used to partially sequence the small-subunit ribosomal RNA (srRNA) of four species of the amoeboid genus Naegleria. The extent of nucleotide sequence divergence between the two most divergent species was roughly similar to that found between mammals and frogs. However, the pattern of variation among the Naegleria species was quite different from that found for those species of tetrapods characterized to date. A phylogenetic analysis of the consensus Naegleria sequence showed that Naegleria was not monophyletic with either Acanthamoeba castellanii or Dictyostelium discoideum, two other amoebas for which sequences were available. It was shown that the semiconserved regions of the srRNA molecule evolve in a clocklike fashion and that the clock is time dependent rather than generation dependent.

Animals↗
PubMedDate not supplied

[The cultivation of Blastocystis (Rhizopoda: Lobosea) from hens and ducks].

The method of cultivation of Blastocystis galli from hens and Blastocystis sp. from ducks was worked out. Blastocystis grow on nutrient medium at pH 7.0 to 7.2 in a wide range of temperatures from 30 to 45 C. Optimum temperatures for cultivation are 41 to 42 C. The growth of cultures was obtained on biphase egg medium. Solid phase of the medium presents coagulated contents of the hen's egg. Liquid phase can be made of Henk's solution with the addition of 30% of fresh or lyophilizinic hen serum or horse serum. Henk's solution can be replaced by medium 199 (we observed the growth of culture on medium 199 without addition of blood serum). In all variants of medium we added antibiotics on a per--1 ml of medium basis: ampicillini--4 thousand units, streptomycini--1 thousand units. After 2 to 3 passages antibiotics can be excluded from the medium. Optimum medium is that with the addition of 30% of fresh hen serum. Passages go well at the transfer of 15-20% culture after 72 to 96 hours. The size of cultural stages varied within the limits of 2.5-56.2 x 2.5-56.2 microns and 2.5-110 x 2.5-110 microns for Blastocystis sp. and B. galli, respectively, the number of nuclei in one individual varied from 1 to 64, seldom over 100.

Animals↗
PubMedDate not supplied

[A new species of Blastocystis anseri (Protista: Rhizopoda) from domestic geese].

A new species, Blastocystis anseri, was found in domestic goose. Sizes of blastocyst in culture are 7.5-46.2 x 7.5-46.2 m. Method of cultivation of Blastocystis anseri on biphase egg medium was worked out. Liquid phase can be made of Hank's solution or 199 medium with an addition of 30-40% hen or bovine serum. Optimum temperature for cultivation is 39 +/- 0.5 degree, ph 7.0-7.2.

Animals↗
PubMedDate not supplied

[A finding of Blastocystis galli (Rhizopoda, Lobosea) in domestic turkeys].

Blastocysts tentatively assigned to the species Blastocystis galli were found in the turkey Meleagris gallopavo from Tajikistan and Uzbekistan. Length and width of blastocysts from turkeys vary in a wider range (2.5--55.1 x 2.5--51.3 mkm) than length and width of blastocysts from hens. The shape of blastocysts varies from round and oval to ellipsoid and amoeboid.

Animals↗
PubMedDate not supplied

[The specificity of blastocysts (Rhizopoda: Lobosea)].

The analysis of specificity of blastocysts was based on the data on host association and on experimental data. In experiments we failed to infect the geese (Anser anser) with Blastocystis galli taken from the fowl (Gallus gallus) and also failed to infect the fowl with B. suis taken from the pigs (Sus scrofa domestica). Experimental data and field observations of blastocysts distribution among different groups of hosts point out that the same species of blastocysts can not parasitize in hosts belonging to different classes and orders. The examination of 89 fish specimens belonging to 14 species of Osteichthyes taken from the Neman delta did not discover any blastocysts.

Animals↗
PubMedDate not supplied

Molecular evolutionary analyses of nuclear-encoded small subunit ribosomal RNA identify an independent rhizopod lineage containing the Euglyphina and the Chlorarachniophyta.

The Rhizopoda comprise a diverse assemblage of protists which depend on lobose or filose pseudopodia for locomotion. The biochemical and morphological diversity of rhizopods has led to an uncertain taxonomy. Ribosomal RNA sequence comparisons offer a measure of evolutionary relatedness that is independent of morphology and has been used to demonstrate a polyphyletic origin of the Lobosea. We sequenced complete small subunit ribosomal RNA coding regions from the filose amoebae, Euglypha rotunda and Paulinella chromatophora (Euglyphina) to position these taxa in the eukaryote phylogeny. The neighbor-joining analyses show that E. rotunda and P. chromatophora share a monophyletic origin and are not closely related to any lobose amoebae in our analyses. Instead, the Euglyphina form a robust sister group to the Chlorarachniophyta. These results provide further evidence for the polyphyly of the Rhizopoda and support the creation of a new amoeboid lineage which includes the Euglyphina and the chlorarachniophyte algae; taxa with tubular mitochondrial cristae and filose or reticulate pseudopodia.

Animals↗
PubMed1998

A revised six-kingdom system of life.

A revised six-kingdom system of life is presented, down to the level of infraphylum. As in my 1983 system Bacteria are treated as a single kingdom, and eukaryotes are divided into only five kingdoms: Protozoa, Animalia, Fungi, Plantae and Chromista. Intermediate high level categories (superkingdom, subkingdom, branch, infrakingdom, superphylum, subphylum and infraphylum) are extensively used to avoid splitting organisms into an excessive number of kingdoms and phyla (60 only being recognized). The two 'zoological' kingdoms, Protozoa and Animalia, are subject to the International Code of Zoological Nomenclature, the kingdom Bacteria to the International Code of Bacteriological Nomenclature, and the three 'botanical' kingdoms (Plantae, Fungi, Chromista) to the International Code of Botanical Nomenclature. Circumscriptions of the kingdoms Bacteria and Plantae remain unchanged since Cavalier-Smith (1981). The kingdom Fungi is expanded by adding Microsporidia, because of protein sequence evidence that these amitochondrial intracellular parasites are related to conventional Fungi, not Protozoa. Fungi are subdivided into four phyla and 20 classes; fungal classification at the rank of subclass and above is comprehensively revised. The kingdoms Protozoa and Animalia are modified in the light of molecular phylogenetic evidence that Myxozoa are actually Animalia, not Protozoa, and that mesozoans are related to bilaterian animals. Animalia are divided into four subkingdoms: Radiata (phyla Porifera, Cnidaria, Placozoa, Ctenophora), Myxozoa, Mesozoa and Bilateria (bilateral animals: all other phyla). Several new higher level groupings are made in the animal kingdom including three new phyla: Acanthognatha (rotifers, acanthocephalans, gastrotrichs, gnathostomulids), Brachiozoa (brachiopods and phoronids) and Lobopoda (onychophorans and tardigrades), so only 23 animal phyla are recognized. Archezoa, here restricted to the phyla Metamonada and Trichozoa, are treated as a subkingdom within Protozoa, as in my 1983 six-kingdom system, not as a separate kingdom. The recently revised phylum Rhizopoda is modified further by adding more flagellates and removing some 'rhizopods' and is therefore renamed Cercozoa. The number of protozoan phyla is reduced by grouping Mycetozoa and Archamoebae (both now infraphyla) as a new subphylum Conosa within the phylum Amoebozoa alongside the subphylum Lobosa, which now includes both the traditional aerobic lobosean amoebae and Multicilia. Haplosporidia and the (formerly microsporidian) metchnikovellids are now both placed within the phylum Sporozoa. These changes make a total of only 13 currently recognized protozoan phyla, which are grouped into two subkingdoms: Archezoa and Neozoa the latter is modified in circumscription by adding the Discicristata, a new infrakingdom comprising the phyla Percolozoa and Euglenozoa). These changes are discussed in relation to the principles of megasystematics, here defined as systematics that concentrates on the higher levels of classes, phyla, and kingdoms. These principles also make it desirable to rank Archaebacteria as an infrakingdom of the kingdom Bacteria, not as a separate kingdom. Archaebacteria are grouped with the infrakingdom Posibacteria to form a new subkingdom, Unibacteria, comprising all bacteria bounded by a single membrane. The bacterial subkingdom Negibacteria, with separate cytoplasmic and outer membranes, is subdivided into two infrakingdoms: Lipobacteria, which lack lipopolysaccharide and have only phospholipids in the outer membrane, and Glycobacteria, with lipopolysaccharides in the outer leaflet of the outer membrane and phospholipids in its inner leaflet. (ABSTRACT TRUNCATED)

Animal Population Groups↗
PubMedDate not supplied

Small subunit ribosomal DNA suggests that the xenophyophorean Syringammina corbicula is a foraminiferan.

Xenophyophorea are giant deep-sea rhizopodial protists of enigmatic origins. Although species were described as Foraminifera or sponges in the early literature, the xenophyophoreans are currently classified either as a class of Rhizopoda or an independent phylum. To establish the phylogenetic position of Xenophyophorea, we analysed the small subunit (SSU) rRNA gene sequence of Syringammina corbicula Richardson, a newly described xenophyophorean species from the Cape Verde Plateau. The SSUrDNA analyses showed that S. corbicula is closely related to Rhizammina algaeformis, a tubular deep-sea foraminiferan. Both species branch within a group of monothalamous (single-chambered) Foraminifera, which include also such agglutinated genera as Toxisarcon, Rhabdammina, and Saccammina, and the organic-walled genera Gloiogullmia and Cylindrogullmia. Our results are congruent with observations of similar cytoplasmic organisation in Rhizammina and Syringammina. Thus, the Xenophyophorea appear to be a highly specialised group of deep-sea Foraminifera.

Animals↗