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Eukaryotic Parasites (eukaryotic + parasite)
Selected AbstractsAssociation with host mitochondrial haplotypes suggests that feminizing microsporidia lack horizontal transmissionJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2003J. E. Ironside Abstract The amphipod crustacean Gammarus duebeni hosts two feminizing microsporidian parasites, Nosema granulosis and Microsporidium sp. Samples of G. duebeni were collected from three sites on the Scottish island of Great Cumbrae and screened for microsporidia using polymerase chain reaction. Associations between the prevalence of the two feminizing parasites and haplotypes of the host mitochondrial gene cytochrome oxidase I (COI) were investigated. The prevalence of both parasites varied significantly among the host's COI haplotypes, suggesting that horizontal transmission is rare or absent in the life cycles of the feminizing microsporidia and that all transmission must therefore be vertical. Life cycles in which all transmission is vertical are common among bacterial parasites but have never before been demonstrated in Eukaryotic parasites. [source] 132 Parasites and Phytoplankton, with a Special Emphasis on Dinoflagellate InfectionsJOURNAL OF PHYCOLOGY, Issue 2003M. G. Park Eukaryotic parasites are believed to play important roles in phytoplankton ecology and particularly in bloom dynamics of red-tide dinoflagellates. Apart from the prokaryotic parasites such as viruses and bacteria, certain flagellates and fungi have received some degree of attention as eukaryotic parasites of phytoplankton. Our understanding of fungal parasites is largely based on studies for freshwater diatoms and dinoflagellates, although fungal infections are known for some marine phytoplankton, including diatoms. By comparison, the dinoflagellate genus Amoebophrya and the newly described Perkinsozoa Pavilucifera infectans are widely distributed in coastal waters of the world and are well known as eukaryotic parasites of dinoflagellates. Recent work indicates that these parasites have significant impacts on the ecophysiology and behavior of dinoflagellate hosts. Thus, the ecological roles of Amoebophrya spp. and Pavilucifera infectans should be carefully considered in developing concepts about plankton dynamics and material flows in marine food webs. [source] Structural and functional characterization of a putative polysaccharide deacetylase of the human parasite Encephalitozoon cuniculiPROTEIN SCIENCE, Issue 6 2009Jonathan E. Urch Abstract The microsporidian Encephalitozoon cuniculi is an intracellular eukaryotic parasite considered to be an emerging opportunistic human pathogen. The infectious stage of this parasite is a unicellular spore that is surrounded by a chitin containing endospore layer and an external proteinaceous exospore. A putative chitin deacetylase (ECU11_0510) localizes to the interface between the plasma membrane and the endospore. Chitin deacetylases are family 4 carbohydrate esterases in the CAZY classification, and several bacterial members of this family are involved in evading lysis by host glycosidases, through partial de- N -acetylation of cell wall peptidoglycan. Similarly, ECU11_0510 could be important for E. cuniculi survival in the host, by protecting the chitin layer from hydrolysis by human chitinases. Here, we describe the biochemical, structural, and glycan binding properties of the protein. Enzymatic analyses showed that the putative deacetylase is unable to deacetylate chitooligosaccharides or crystalline ,-chitin. Furthermore, carbohydrate microarray analysis revealed that the protein bound neither chitooligosaccharides nor any of a wide range of other glycans or chitin. The high resolution crystal structure revealed dramatic rearrangements in the positions of catalytic and substrate binding residues, which explain the loss of deacetylase activity, adding to the unusual structural plasticity observed in other members of this esterase family. Thus, it appears that the ECU11_0510 protein is not a carbohydrate deacetylase and may fulfill an as yet undiscovered role in the E. cuniculi parasite. [source] 132 Parasites and Phytoplankton, with a Special Emphasis on Dinoflagellate InfectionsJOURNAL OF PHYCOLOGY, Issue 2003M. G. Park Eukaryotic parasites are believed to play important roles in phytoplankton ecology and particularly in bloom dynamics of red-tide dinoflagellates. Apart from the prokaryotic parasites such as viruses and bacteria, certain flagellates and fungi have received some degree of attention as eukaryotic parasites of phytoplankton. Our understanding of fungal parasites is largely based on studies for freshwater diatoms and dinoflagellates, although fungal infections are known for some marine phytoplankton, including diatoms. By comparison, the dinoflagellate genus Amoebophrya and the newly described Perkinsozoa Pavilucifera infectans are widely distributed in coastal waters of the world and are well known as eukaryotic parasites of dinoflagellates. Recent work indicates that these parasites have significant impacts on the ecophysiology and behavior of dinoflagellate hosts. Thus, the ecological roles of Amoebophrya spp. and Pavilucifera infectans should be carefully considered in developing concepts about plankton dynamics and material flows in marine food webs. [source] | ||||||||||