Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PROTOZOA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources
PubMed1975

Specific immunity and nonspecific resistance to infection: listeria, protozoa, and viruses in mice and hamsters,.

Specific immunity developed by mice against protozoan (Toxoplasma gondii and Besnoitia jellisoni) and bacterial (Listeria monocytogenes) infections was compared with nonspecific protection conferred by prior infections. The results indicated that homologous immunity protected mice from more than 10-5 LD50 of T. gondii or B. jellisoni, but from only 10-2 LD50 of L. monocytogenes. Heterospecific protection among these organisms was for 10-0.4 minus 10-1.2 LD50. In studies in hamsters specific immunity to protozoan (T. gondii and B. jellisoni) and viral (equine Herpesvirus type 1 and Oriboca virus) infections was compared with nonspecific protection conferred by prior infections with several heterospecific agents: T. gondii; B. jellison; equine Herpesvirus type 1; Oriboca, Ossa, vesicular stomatitis, yellow fever, and Newcastle disease viruses; L. monocytogenes; and the bacillus Calmette-Guerin strain of Mycobacterium tuberculosis. The results indicated that homologous immunity in hamsters was effective against 10-6 minus 10-7 LD50 of T. gondii, B. jellisoni, equine Herpesvirus type 1, or Oriboca virus. Prior infection with Newcastle disease virus protected (probably by interferon induction) against 10-3 LD50 of equine Herpesvirus type 1. Heterospecific protection among other agents was for less than 10 LD50. This insignificant heterospecific protection in infections in which cellular immunity plays a role suggests that both the induction phase and the expression phase are specific.

Animals↗
PubMed1987

Effect of D-propranolol on growth and motility of flagellate protozoa.

Propranolol inhibits sperm motility and has been considered as a spermicide contraceptive. In view of the inhibitory effects of D-propranolol on sperm flagellar activity, we have investigated its effect on motility and growth of two human flagellate, protozoan parasites. D-propranolol had a dose-dependant inhibitory effect on motility of Giardia lamblia and Trichomonas vaginalis with ED50s of 0.38 and 0.66 mmol/l respectively, D-propranolol also inhibited growth of both parasites with ED50s of 0.18 and 0.23 mmol/l for Giardia and Trichomonas respectively. D-propranolol, unlike DL-propranolol is devoid of the unwanted effects of beta-blockade, and thus may be a useful antiprotozoal drug particularly after vaginal placement when it is concentrated in vaginal mucus.

Animals↗
PubMed1991

The sequence flanking translational initiation site in protozoa.

Nucleotide sequences flanking the translational initiation site were compiled from protozoan nuclear genes and were compared in every protozoan group. The entire 5'-untranslated sequences were very rich in A- and T-residues, but poor in G- and C-residues in most protozoan genes except for the flagellated ones. The sequence AAAAATTTTTAAAATTTAAAATGANAT emerged as a consensus sequence flanking the initiation site in the major protozoan group, although the sequences upstream from -4 (four nucleotides upstream from the ATG codon) were divergent among ciliates, sarcodinians, and sporozoans. On the other hand, the consensus sequence for flagellates was revealed to be a simple feature. Only the nucleotide position -3 was occupied with a high frequency of A-residue, in other positions it appeared randomly. These facts suggest that the strong preference for A-residue at the position -3 is a universal feature in nuclear genes for all eukaryotes.

Animals↗
PubMed1996

Phylogenetic position of kinetoplastid protozoa inferred from the protein phylogenies of elongation factors 1alpha and 2.

Partial regions of the mRNA encoding a major part of translation elongation factor 2 (EF-2) from a kinetoplastid protozoan, Trypanosoma cruzi, were amplified by means of polymerase chain reaction and their primary structures were analyzed. The deduced amino acid sequence was aligned with those of other eukaryotic and archaebacterial EF-2s, and the phylogenetic relationships among eukaryotes were inferred by the maximum likelihood (ML) method. ML analyses of EF-2 phylogeny using six different stochastic models of amino acid substitutions consistently suggested that the phylogenetic position of T. cruzi is likely to be closer to higher eukaryotes than that inferred from the phylogeny of small subunit ribosomal RNA (SrRNA). These results are consistent with those for the elongation factor 1alpha (EF-1alpha) phylogeny. When the EF-1alpha and EF-2 phylogenies were totally evaluated, it became much clearer that the divergence of T. cruzi occurred later than that of a mitochondrion-lacking protozoan, Entamoeba histolytica, although this is not conclusive.

Amino Acid Sequence↗
PubMed1991

Evolutionary relationships of avian Eimeria species among other Apicomplexan protozoa: monophyly of the apicomplexa is supported.

Direct, reverse transcriptase-mediated, partial sequencing of the small-subunit (16S-like) ribosomal RNA (srRNA) of Eimeria tenella and E. acervulina was performed. Sequences were aligned by eye with six previously published, partial or complete srRNA sequences of apicomplexan protists (Plasmodium berghei, Theileria annulata, Cryptosporidium sp., Toxoplasma gondii, Sarcocystis muris, and S. gigantea). Six eukaryotic protists (a slime mold, a yeast, two dinoflagellates, and two ciliates) acted as an outgroup for a parsimony-based phylogenetic analysis (PAUP Ver. 3.0). The 188 phylogenetically informative sites (i.e., those positions that neither were unvaried nor had only autapomorphic substitutions) supported a single tree topology 481 steps in length with a consistency index of 0.65 in which the monophyly of the Apicomplexa was supported. The two Eimeria species and S. muris, S. gigantea, and T. gondii formed a pair of monophyletic groups that were sister groups. The two Sarcocystis species were not hypothesized to be sister taxa. The genera Plasmodium and Cryptosporidium were hypothesized to form the sister group to these five coccidia and T. annulata. A priori data-editing techniques that deleted "variable" positions prior to analysis failed to recognize the monophyly of the Apicomplexa when the same parsimony-based tree-building algorithm was used. Inability of the outgroup taxa to root the well-supported ingroup tree (Apicomplexa) at a unique site when these taxa were used individually for this purpose reinforces the need for an appropriate, multiple-taxon outgroup in such analyses.

Animals↗
PubMed1998

Intestinal protozoa important to poultry.

Parasites of two groups are important in poultry, the coccidia and the mastiogophora (flagellates) (Table 1). Most of the Coccidia in poultry are in the genus Eimeria, but a few species of Isospora, Cryptosporidium, and Sarcosporidia are represented. The Eimeria are best known, with seven important species recognized in chickens and several others in turkeys. Diagnosis of coccidiosis is by recognition of classic signs and lesions, by gross examination, and can be aided by microscopic examination of feces and intestinal contents. Control of coccidiosis is by preventive use of anticoccidials and by immunization. Cryptosporidium are common in poultry but little is known of their importance, except for the occasional outbreak of respiratory cryptosporidiosis in turkey poults. Of the flagellates, Histomonas meleagridis is the best known. Infections in turkeys may cause near 100% mortality, but outbreaks in chickens are more often marked by morbidity and subsequent recovery. Recent outbreaks in broiler breeder pullets caused excessive losses from mortality (5 to 20%) culling, and overall poor flock performance. Histomonas organisms are carried by eggs of the cecal worm Heterakis gallinarum enabling them to survive for long periods in soil as a source of infection. In the U.S. there are no products available for treatment of blackhead. Preventive use of anthelminthics to destroy the cecal worm carrier show some promise in reducing exposure.

Animals↗