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At least 289 records · Page 16Linked to original sources
PubMed1982

Biology and histopathology of Thelohanellus nikolskii Achmerov, 1955 (Myxosporea, Myxozoa), a protozoan parasite of the common carp (Cyprinus carpio).

Thelohanellus nikolskii, a myxosporean originating from the Far East, arrived in Hungary through natural waters from neighbouring countries which it had originally reached because of the introduction of the Amur wild carp. T. nikolskii is a specific parasite of carp which produces large cysts on the fins of fry. The cysts usually appear on the fish at the beginning of July, and in August and September cysts containing the mature spores burst. The cysts are easily seen even by the naked eye and are surrounded by a thick capsule composed of connective tissue strengthened by cartilaginous elements. Due to the breaking down of the fins the parasite has pathological significance in fry.

Animals↗
PubMed1979

The erythrocytic entry- and exit-mechanism of Aegyptianella pullorum Carpano, 1928.

The erythrocytic entry- and exit-mechanisms of Aegyptianella pullorum were investigated and characterized by scanning (SEM) and transmission electron microscopy (TEM) using for TEM ruthenium red as a marker of the red cell plasmalemma. The scanned Aegyptianella preparations produced static evidence of an endocytosis followed by an erythrocytic vesiculation as the possible mode of entrance of initial bodies into erythrocytes. The presence of ruthenium red only coating the membrane around the parasitophorous vacuole during the whole invasive process and the complete absence of the stain inside the host cell indicate that the entry of aegyptianellas is accomplished by invagination of the host cell plasmalemma and is not preceded nor followed by its breakage, furthermore unequivocally proving the intracellular parasitism of A. pullorum during its reproductive cycle. One possible mode of exit of initial bodies from parasitized erythrocytes appeared to be the invasive mechanism in reverse order, an exocytosis. Generally, however, the affected erythrocytes are parasitogenically injured, resulting in release of the parasites into the plasma and, subsequently, in host cell lysis.

Animals↗
PubMed1990

Light and electron microscopic observations on the swimbladder stages of Sphaerospora renicola, a parasite of carp (Cyprinus carpio).

The developmental cycle of stages of Sphaerospora renicola, proliferating in the walls of the swimbladder in carp fry and responsible for swimbladder inflammation (= SBI stages) is described. The initial stage, a primary cell containing two secondary cells, grows in size while the secondary cells divide and produce two tertiary cells each by endogenous division. After a supposed disintegration of the grown primary cell, the cell triplets are released to repeat the cycle. The cell divisions are asynchronous and the development of the whole formation may be quite irregular. The cytology of these stages is closely reminiscent of the blood stages of S. renicola and also shares common features with the parasite's sporogonic stages. The SBI stages show typical features of myxosporean organisation, i.e., a "cell-within-cell" arrangement in which the primary cell contains secondary cell(s) in membrane-bound vacuoles and many free ribosomes, in the absence of centrioles. Other salient features of SBI stages are partitions in the nuclei; a small amount of cytoplasm in the early secondary cells; distinct, age-dependent changes in morphology of the nucleus; and atypically shaped Golgi bodies in the cytoplasm or integrated with the nuclear envelope. The cytological features and significance of swimbladder stages are discussed in detail.

Air Sacs↗
PubMed1989

Some ultrastructural data on the spore development in a Henneguya sp. parasite of the gill of a Brazilian fish.

A myxosporean Henneguya sp. was found in the gill filaments of a freshwater fish, Hoplosternum littorale, from the lower Amazon river near Belém, Brazil. Plasmodia were represented by numerous vegetative nuclei, generative cells and sporogony stages. The spore body was ellipsoidal and each valve presented a tapering tail approximately 45.2 microns in length. The spores differed from those of previously described species in their shape and size. The developmental stages are described and discussed. This histozoic species is reported to be pathogenic, inducing great mortality in the host.

Animals↗
PubMed2002

Localization of post-translationally modified alpha-tubulin and pseudocyst formation in tritrichomonads.

The distribution of acetylated tubulin was investigated in members of the Tritrichomonadinae subfamily using a specific monoclonal antibody and indirect immunofluorescence microscopy. Species probed in this study were: Tritrichomonas foetus, T. mobilensis, T. muris, and an unnamed tritrichomonad isolated from the cecum of cotton rats (Sigmodon hispidus). Additionally, the distribution of glutamylated tubulin in T. muris was investigated using the GT 335 antibody to the glutamyl motif. Although acetylated alpha-tubulin was ubiquitously distributed throughout the axostyle and flagella of T. foetus and T. mobilensis, a distinct and unusual labeling pattern was observed in 'T. muris'-type or pseudocyst-forming trichomonads. In trophozoite stages of T. muris and the cotton rat isolate, flagella were intensely labeled, but acetylation of axostylar tubulin appeared to be limited to the anterior and posterior thirds. However, trophozoites labeled with an antibody to alpha-tubulin or glutamylated tubulin demonstrated no such discontinuity in axostylar staining. Additionally, pseudocysts labeled with anti-alpha-tubulin and anti-acetylated alpha-tubulin were all found to possess continuously fluorescent axostyles. That the mid-region axostyle remained unlabeled by anti-acetylated tubulin in trophozoites indicates possible deacetylase activity, which may have functional implications with respect to the life cycle. Glutamylated tubulin appeared to be distributed throughout the axostyle and flagella, which fluoresced brightly in T. muris.

Acetylation↗
PubMed2003

Electron microscopic study of Tetratrichomonas didelphidis and its interaction with a prokaryotic cell.

Tetratrichomonas didelphidis is a flagellate protozoan found in the intestine of the opossum. The parasite lives in a hostile and stressed environment, where it interacts with microorganisms and can survive under extreme conditions for growth, involving strict anaerobiosis or equilibration with air and abundance or absence of nutrients. The in vitro cultivation of this protozoan depends upon Escherichia coli as a growth-promoting partner. In this study, we used scanning and transmission electron microscopy to observe the phagocytosis of bacteria by the protozoan, confirming the strong association between both cells and the growth dependence of T. didelphidis upon E. coli. After adherence to the protozoan surface, the bacteria induced the appearance of crater-like depressions and the ingested bacteria were intracellularly degraded.

Animals↗
PubMed1997

Surface charge and surface carbohydrates of Cyptobia salmositica virulent and avirulent forms and of C. bullocki (Kinetoplastida: Cryptobiidae).

The surface charge and surface carbohydrate residues of the virulent (freshly isolated from the fish blood) and avirulent forms (from culture) of Cryptobia salmositica and one strain of C. bullocki were studied. Measurements of the zeta potential of parasites showed that C. bullocki and the virulent form of C. salmositica had a net negative surface charge of about -15 mV, whereas the attenuated form of C. salmositica showed a surface charge of -7.9 mV. Enzymatic treatments of parasites with neuraminidase, trypsin, or phospholipase C indicated the presence of sialic acid residues, phosphate groups, and protein glycoconjugates as components of the Cryptobia surface that accounted for their surface charge. Residues of alpha-D-man, alpha- and beta-D-gal, alpha-D-galNAc, alpha-L-fuc, and D-glcNAc could be detected on the surface of all parasites by specific fluorescein isothiocyanate (FITC)- and colloidal gold-labeled lectins. The cell surface of the avirulent form of C. salmositica showed the strongest reactivity to almost all lectins tested. A remarkable binding pattern of lectins in the anterior region of parasites was observed.

Animals↗
PubMed2001

Growth kinetic study of Tetratrichomonas didelphidis isolated from opossum Lutreolina crassicaudata and interaction with a prokaryotic cell.

Tetratrichomonas didelphidis is a flagellate protozoan found in the intestine, cecum and colon of opossums, Didelphis marsupialis. This work reports the occurrence of T. didelphidis in another opossum species, Lutreolina crassicaudata. The strain was cultivated in monoxenic culture with Escherichia coli in Diamond (TYM) medium without maltose and with starch solution (trypticase-yeast extract-starch), pH 7.5 at 28 degrees C. The growth kinetic study of T. didelphidis showed a longer time of growth and a higher number of trophozoites when inoculated with E. coli than in axenic cultures, in aerobiosis as well as under anaerobic conditions. Scanning electron microscopy showed that the bacteria adhered throughout the protozoan body and probably evoked endocytic channels, strongly suggesting the existence of endocytosis of rods by T. didelphidis. Our preliminary results suggest that the in vitro culture of T. didelphidis depends on E. coli as a growth-promoting partner, and requires monoxenic cultivation.

Animals↗