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At least 865 records · Page 48Linked to original sources
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↗
PubMed1999

Immunodetection of the microvillous cytoskeleton molecules villin and ezrin in the parasitophorous vacuole wall of Cryptosporidium parvum (Protozoa: Apicomplexa).

Microvilli - actin - villin - ezrin - Cryptosporidium parvum The sporozoites and merozoites of the Apicomplexan protozoan Cryptosporidium parvum (C. parvum) invade the apical side of enterocytes and induce the formation of a parasitophorous vacuole which stays in the brush border area and disturbs the distribution of microvilli. The vacuole is separated from the apical cytoplasm of the cell by an electron-dense layer of undetermined composition. In order to characterize the enterocyte cytoskeleton changes that occur during C. parvum invasion and development, we used both confocal immunofluorescence and immunoelectron microscopy to examine at the C.parvum-enterocyte interface the distribution of three components of the microvillous skeleton, actin, villin and ezrin. In infected cells, rhodamine-phalloidin and anti-villin and anti-ezrin antibodies recognized ring-like structures surrounding the developing parasites. By immunoelectron microscopy, both villin and ezrin were detected in the parasitophorous vacuole wall surrounding the luminal and lateral sides of the intracellular parasite. In contrast, anti-beta and anti-gamma actin antibodies showed no significant labelling of the vacuolar wall. These observations indicate that the parasitophorous vacuole wall contains at least two microvillus-derived components, villin and ezrin, as well as a low amount of F-actin. These data suggest that C.parvum infection induces a rearrangement of cytoskeleton molecules at the apical pole of the host cell that are used to build the parasitophorous vacuole.

Actins↗
PubMed1998

A survey of tick-borne bacteria and protozoa in naturally exposed dogs from Israel.

Antibody reactivity against seven bacterial or protozoal pathogens was measured in sera derived from 40 dogs suspected of a tick-borne disease. Sera from 73% (29/40) of the dogs reacted with three or more test antigens. Seroreactivity was most prevalent to Babesia canis antigen (90%) followed by Babesia gibsoni (75%), Ehrlichia canis (63%), Rickettsia conorii--Moroccan strain (58%), Rickettsia conorii--Israeli strain no. 2 (28%), Borrelia burgdorferi (10%) or Bartonella vinsonii (berkhoffii) (10%). Seroconversion documented in seven dogs, supported an acute phase diagnosis of ehrlichiosis in four dogs, R. conorii infection in three dogs and babesiosis in one dog. In the remaining dogs, correlation of clinical abnormalities with increased seroreactivity was not established through the design of this study. Although Lyme borreliosis has not been reported in people in Israel, Western blot analysis for antibodies reactive to B. burgdorferi identified genus-specific antiflagellin antibodies indicating that dogs in Israel are exposed to a Borrelia species. Identification of species-specific seroreactivity was not possible and infection with a Borrelia species other than B. burgdorferi is likely. Seroreactivity to B. vinsonii (berkhoffii) in dogs outside the USA is reported here for the first time.

Animals↗
PubMed1996

Protozoa. Amebiasis.

The intestinal protozoan parasite Entamoeba histolytica causes amebic dysentery and amebic liver abscess, and ranks third worldwide among parasitic causes of death. The application of molecular techniques to the study of this organism have led to major advances in understanding the pathophysiology of amebic infection. This article reviews what is currently known about the pathogenesis, clinical manifestations, diagnosis, and treatment of amebiasis.

Animals↗
PubMed1991

RNA editing in kinetoplastid protozoa.

RNA editing produces mature mRNAs by adding and removing uridines within the mitochondrial transcripts. The edited sequence appears to be specified by small complementary RNAs using a non-templated process that may have features resembling RNA splicing. The accumulation of edited mRNAs is developmentally regulated.

Animals↗
PubMed2002

Non-pathogenic trypanosomatid protozoa as a platform for protein research and production.

All currently existing eukaryotic protein expression systems are based on autonomous life forms. To exploit the potential practical benefits associated with parasitic organisms we have developed a new protein expression system based on Leishmania tarentolae (Trypanosomatidae), a protozoan parasite of lizards. To achieve strong transcription, the genes of interest were integrated into the small subunit ribosomal RNA gene. Expression levels obtained were up to 30 mg of recombinant protein per liter of suspension culture and increased linearly with the number of integrated gene copies. To assess the system's potential for production of post-translationally modified proteins, we have expressed human erythropoietin in L. tarentolae. The recombinant protein isolated from the culture supernatants was biologically active, natively processed at the N-terminus, and N-glycosylated. The N-glycosylation was exceptionally homogeneous, with a mammalian-type biantennary oligosaccharide and the Man(3)GlcNAc(2) core structure accounting for >90% of the glycans present. L. tarentolae is thus the first described biotechnologically useful unicellular eukaryotic organism producing biantennary fully galactosylated, core-alpha-1,6-fucosylated N-glycans.

Animals↗
PubMed2001

Encystation in parasitic protozoa.

Giardia and Entamoeba parasites encase themselves in a carbohydrate-rich cyst for travel from host to host. Both parasites upregulate their Golgi apparatus during this process, yielding organelles that are now found to be similar to those of higher eukaryotes. In fact, unusual enzymes and structural proteins used for cyst wall synthesis, the complexity of the secretory pathways used to transport materials to the developing cyst walls, as well as unexpected mechanisms of gene regulation and parasite-host and parasite-parasite information exchange, are revealing a high level of sophistication in these organisms that occupy low branch points in the eukaryotic lineage.

Animals↗
PubMed2001

Nucleoside transporters of parasitic protozoa.

Protozoan parasites are incapable of synthesizing purine nucleotides de novo and so must salvage preformed purines from their hosts. This process of purine acquisition is initiated by the translocation of preformed host purines across parasite or host membranes. Here, we report upon the identification and isolation of DNAs encoding parasite nucleoside transporters and the functional characterization of these proteins in various expression systems. These potential approaches provide a powerful approach for a thorough molecular and biochemical dissection of nucleoside transport in protozoan parasites.

Animals↗
PubMed2003

Pentamidine uptake and resistance in pathogenic protozoa: past, present and future.

Diamidines, and pentamidine in particular, have a long history as valuable chemotherapeutic agents against infectious disease. Their selectivity is due mostly to selective accumulation by the pathogen, rather than the host cell; and acquired resistance is frequently the result of changes in transmembrane transport of the drug. Here, recent progress in elucidating the mechanisms of diamidine transport in three important protozoan pathogens, Trypanosoma brucei, Leishmania and Plasmodium falciparum, is reviewed, and the implications for drug resistance are discussed.

Animals↗