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At least 667 records · Page 37Linked to original sources
PubMed1991

Glycosylation in parasitic protozoa of the trypanosomatidae family.

Over the last few years enormous interest has been shown in the structures of the glycan moieties of various parasite surface glycoconjugates. Structures have been determined for the glyco-components of glycosylphosphatidylinositol (GPI) protein membrane anchors, for asparagine-linked oligosaccharides, and for the glycans of complex glycolipids. The following attempts to illustrate a few of the most salient observations with regard to the structures and possible functions of parasite surface glycans.

Animals↗
PubMed1979

Clinical and histologic observations of actively induced resistance to Eimeria ferrisi Levine and Ivens, 1965 (Protozoa: Eimeriidae) in the mouse (Mus musculus).

Actively induced resistance to Eimeria ferrisi was studied clinically and histologically in Mus musculus. Results indicated that a partial resistance to challenge was obtained. Initially infected animals had severe symptoms of coccidiosis but the symptoms diminished as the infections progressed. Previously infected mice had only slight symptoms of infection when challenged. Challenge doses produced severe coccidiosis in the non-immune controls although none died. Six mice died at peak patency during the immunizing inoculations. Histologic examination indicated that parasite numbers were reduced in resistant animals. The reduction appeared greatest during late sexual development. Tissues from resistant animals showed little evidence of damage and appeared to contain an increased amount of lymphoid tissue. Tissues from non-immunized mice killed after challenge were heavily infected and contained extruded blood, mucous, and cellular debris in the gut lumen. Considerable destruction of host epithelial cells occurred. The observations are discussed and compared to other coccidial immunity studies.

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↗
PubMed1989

Characterization and immunolocalization of the protein contents of micronemes of Sarcocystis muris cystozoites (Protozoa, Apicomplexa).

Affinity-purified polyclonal antibodies generated against micronemes obtained by the subcellular fractionation of Sarcocystis muris contain two major proteins of 16 and 17 kDa. Antibodies cross-react with microneme antigen of S. tenella and S. cuniculi but not with the S. sp. of wild boar (Sus scrofa). Microneme antigens could be traced by immunoelectron microscopy in metrocytes as early as 47 days postinfection and in gamonts of S. muris in cell cultures up to 4 h after inoculation.

Animals↗
PubMed1992

Loma camerounensis sp. nov. (Protozoa:Microsporida) a parasite of Oreochromis niloticus Linnaeus, 1757 (Teleost:Cichlidae) in fish-rearing ponds in Melen, Yaoundé, Cameroon.

A new microsporidian, Loma camerounensis, was found in the Cichlidae Oreochromis niloticus from the Melen fish-rearing station in Yaoundé, Cameroon. Xenomas were located in the gut from the oesophagus to the intestine, but preferentially in the duodenum. Dimensions of the fresh spores were 3.96 x 2.16 microns. The ultrastructural study indicated the following characteristics: parasite stages arranged in a random, unstratified manner in the xenoma; merogony by multiple fission; sporogonic stages isolated within a sporophorous vesicle containing several sporoblasts and polysporoblastic sporogony. Ultimately the spores appeared to be isolated in a single vesicle, but this was a secondary phenomenon induced by the intervention of tubules that resolved in partitions of the initial sporophorous vesicle.

Animals↗
PubMed1990

Growth, morphology and division of flagellates of the genus Trypanoplasma (Protozoa, Kinetoplastida) in vitro.

Nine strains of trypanoplasms were grown in axenic culture. Cultures of Trypanoplasma borreli Laveran and Mesnil, 1901 from fish hosts Blicca bjoerkna, Cyprinus carpio, Scardinius erythrophthalmus and Tinca tinca and of T. guerneyorum Minchin, 1909 from Esox lucius and Trypanoplasma spp. from the leech Piscicola geometra were maintained in biphasic blood-agar medium SNB-9 supplemented with vitamins and antibiotics. In culture, the flagellates transformed into smaller, elongated stages with a little-developed undulating membrane and into short flagella that were morphologically similar to stages in the leech vector. The cultures were passaged weekly at 17-20 degrees C, but they also grew at 4 degrees C. The flagellates divided by binary fission, which was initiated by the formation of two new anterior flagella. The original anterior flagellum of the mother individual was gradually apposed to the cell surface and became the recurrent flagellum of one of the daughter individuals. In the meantime, nuclear division took place, followed by transverse cleavage of the kinetoplast. The division was completed by longitudinal fission of the mother individual into two offspring. Multiple fission that resulted in rosettes, which then cleaved into several daughter cells, was also observed, as well as some dyskinetoplastic and other anomalous forms. In cultures isolated from tenches with high parasitaemia, non-dividing, long filiform stages were observed. Culture stages were not infective for susceptible fishes.

Animals↗
PubMed1990

Isolation of the pellicle of Toxoplasma gondii (Protozoa, Coccidia): characterization by electron microscopy and protein composition.

Two methods were compared for the isolation of the Toxoplasma gondii pellicle: centrifugation using a discontinuous sucrose gradient and affinity purification by microspheres activated with protein A. Electron microscopy showed that these two means of purification gave similar results, although better yields were obtained with the former than with the latter. Proteins of membrane fractions isolated using sucrose gradient were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Bands in the molecular-weight regions of 19, 22, 35, and 79 kDa appeared to be associated with the T. gondii pellicle.

Animals↗
PubMed1991

Class I and class II ribonuclease H activities in Crithidia fasciculata (Protozoa).

The protozoan Crithidia fasciculata contains two different ribonuclease H activities. These enzymes display similar physical and biochemical characteristics to their homologues in higher eukaryotes, for instance calf thymus class I and class II ribonuclease H. Class I ribonuclease H of lower and higher eukaryotes can be activated by Mg2(+)- and Mn2(+)-ions. However, the presence of Mn2(+)-ions is inhibitory for the Mg2(+)-dependent class II ribonuclease H activity of Crithidia fasciculata and calf thymus. The protozoan class I-homologue enzyme appears to be serologically related to the class I ribonuclease H of calf thymus.

Animals↗