摘要:

SYNOPSIS.Additional information on host interactions with trypanosomatid membranes was obtained from studies of a monomorphic strain ofTrypanosoma bruceiharvested at peak parasitemia from intact and lethally irradiated rats. Pellets of trypanosomes were fixed briefly in glutaraldehyde and processed for thin section electron microscopy or freeze‐cleave replicas. Observations of sectioned material facilitated orientation and comparison of details seen in replicas. Fracture faces of cell body and flagellar membranes as well as 3‐dimensional views of the nuclear membrane were studied. Cell body membranes of 80% of the organisms from intact rats contained random arrays of intramembranous particles (IMP). Aggregated clusters of particles appeared on the fracture faces of 20% of the trypanosomes. Some of these membranes had nonrandomly distributed particles aligned in distinct rows on the outer fracture face of both cell body and flagellum. Many inner face fractures of the cell body membranes had a particle arrangement similar to the longitudinal alignment of cytoskeletal microtubules. No aggregated particle distribution was seen in membranes of trypanosomes harvested from lethally irradiated rats. Replicas of trypanosome pellets also had plasmanemes as a series of attached, empty, coated membrane vesicles. These structures were found in close association with, as well as widely separated from the parasites. The shedding of these vesicles and the variation of particles in cell body membranes are discussed in light of antibody‐induced architectural and antigenic changes in surface properties of trypanosomatids.The convex face of the inner membrane of the nucleus also is covered with randomly arrayed particles. More IMP were observed on the inner than on the outer nuclear membranes. Images of nuclear pores were also seen. The importance of these structures in drug and developmental studies of trypanosomes is discussed.On fracture faces of the flagellar membrane there were miniature maculae adherentes, unique to the inner fracture face and occurring only at regions of membrane apposition between cell body and flagellum. Each cluster of particles exposed by the freeze‐cleave method corresponds to an electron‐dense plaque seen in thin section images. However, because of a unique fracture pattern, these plaques were not revealed on the apposing body membranes, as illustrated in thin sectioned

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03757.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Although large hemoglobin inclusions are observed in intraerythrocyticBabesia microtiparasites, they are absent from parasites freed of hamster red cells by immune lysis with antihamster erythsocyte serum.Babesia microtihas no cytostome. This parasite, therefore, does not appear to feed by phagocytosis of large boluses of hemoglobin, as doesPlasmodium.To determine whetherBabesiacan pinocytose protein, free parasites were fed ferritin in anin vitrosystem. Ferritin was taken up from the entire cell surface into narrow channels within 15 min at 37 C. Only merozoites, with their pellicular complex, failed to take up the protein. By 60 min, the ferritin was highly concentrated in many channels and vesicles, which formed interconnecting stacks. The ferritin‐containing channels became associated with membrane whorls of the multimembranous structure. Membrane whorls were also observed in the process of extrusion in samples incubated for longer times. These events may represent steps in the digestion and excretion of the pinocytosed protein. Empty channels formed whenBabesiawas fed albumin. The diaminobenzidine reaction for hemoprotein was positive for the channels in both free and intraerythrocytic babesias. The staining reaction was completely inhibited by cyanide, but not at all by aminotriazole. These results further suggest thatBabesiapinocytoses hemoglobinin vivo.Plasmodium lophuraeparasites freed of red cells by immune lysis are surrounded by 2 membranes and apparently can ingest ferritin only through the cytostome. Extracellular cytostomal feeding involves both membranes, as it doesin vivo.Ferritin was found in food vacuoles, some of which contained hemoglobin ingested before parasite isolation, connected to or near the cytostome. In bothPlasmodiumandBabesialow temperature inhibited ferritin uptak

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03758.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Babesia microtiis a highly polymorphic organism. To unravel its fine structure and the function of organelles it was necessary to resort often to serial sections. A single plasma membrane covers the organism. In trophozoites approaching reproduction, segments of double membranes can be found below the plasma membrane. In electron micrographs of poor resolution these segments of double membranes look like pieces of thick membranes and they were often thought to be a thick 2nd membrane. Before the segments of double membranes appear 2 other organelles are formed in older trophozoites: micronemes and rhoptries. There are indications that these structures originate from vesicles of the Golgi apparatus. Large dense bodies of the same structure as the host cytoplasm are not food vacuoles but merely invaginations of host cytoplasm, as found in serial sections and in organisms removed from the host cell. Feeding inBabesiaseems to take place by a special organelle composed of tightly coiled double membranes located partly inside and partly outside the parasite. It is assumed that extracellular digestion of host cytoplasm take place through this organelle. The nucleus remains undifferentiated throughout the whole intraerythrocytic stage. It becomes irregular, loboid, but does not divide and remains a single body until the late stage of reproduction when only a small portion, a bud, extends into the forming merozoite.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03759.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.TheGlugea stephani‐induced xenoma in the winter flounder,Pseudopleuronectes americanus, is a large spherical host‐parasite complex, up to 4.0 mm in diameter, with the host and parasite components of the xenoma being most active in the peripheral zone. The xenoma has an extensive periodic acid‐silver methenamine‐positive surface coat covering the plasma membrane. The surface of this membrane is amplified by the presence of numerous folds and fine tubular extensions. The peripheral zone of the xenoma contains many host‐cell mitochondria in addition to numerous microsporidan parasites. At the ultrastructural level, the peripheral zone of the host‐cell cytoplasm appears normal. Inside the peripheral region of the 0.4–1.0 mm xenoma, the host‐cell component largely disintegrates in the presence of microsporidan parasites undergoi

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03760.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Phytomonas davidi(Trypanosomatidae) originally discovered by Lafont in 1909 on the island of Mauritius was rediscovered inEuphorbia cyathophorain Florida. Successful cultures were established in diphasic medium consisting of duck blood agar and modified Phillips’medium as overlay. Optimal growth was obtained when Mansour's medium was used as overlay and poorest growth when Cowperthwaite's medium buffered at pH 5.0 was utilized for this purpose. Marked changes tending toward choanomastigotes rather than the elongate twisted promastigotes were observed in culture

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03761.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Several aposymbiotic strains ofBlastocrithidia culicisandCrithidia oncopeltiwere cultivated in Trager's chemically defined medium as well as in a blood broth, both supplemented with 0.25% (v/v) liver extract concentrate. For all such strains, the liver extract was found to serve as an essential growth factor in the defined medium and as growth promoting additive in the blood broth. The active molecules were found to be water‐soluble, heat stable, dialyzable, and probably nonlipid fractions.Antisera were developed in rabbit against all the available aposymbiotic strains. An almost total cross‐reactivity at very high titers was observed in reciprocal agglutination test using strains with and without the bacterial symbiotes. These results indicate that the loss of the symbiotes does not affect the antigenic identity ofB. culicisandC. oncope

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03762.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Intracardial injection of hamsters with from 5 to 114 million amastigotes or promastigotes ofLeishmania donovaniand screening of the 8th‐day liver impression smears, provides a rapid and reproducible method for assaying infectivity. Amastigotes are at least 10X more infective than promastigotes, and log‐phase promastigotes act as a single infective population for hamst

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03763.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Hyalophysa chattoniBradbury,Hyalophysa IwoffiBradbury&Clamp, andGymnodinioides inkystansMinkiewicz are found on species of palaemonids, astacurans, grapsid crabs, ocypodids, anomurans, and portunids in coastal North Carolina.Hyalophysa tragerisp. n. is described from species ofUcaandSesarma.Its life cycle is like that of other exuviotrophic apostomes.Hyalophysa trageridiffers from other species in the genus in the pattern of its infraciliature and the shape of the macronucleus during the trophont stage.In coastal North Carolina,H. chattoniis euryhaline and infests a great number of species.Hyalophysa Iwoffiis found in many locations on the freshwater shrimpPalaemonetes paludosus(Gibbes), and in one location on the crayfishCambarussp.Hyalophysa trageriis the most limited in range, being found only on semiterrestrial crabs. On some host speciesG. inkystansis found alone, but is sympatric withHyalophysaon others.Possible factors restricting the distribution of these apostomes are discussed. These include the structure of their encysted stages, salinity, and the behavior of their hosts.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03764.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.Past reports ofSynophrya, the only apostome ciliate known to harm its host, indicated that it was restricted in its distribution and in the hosts it can infect. In recent collections of decapods from the off‐shore waters of North Carolina and Georgia, 30% of all specimens were infected withSynophrya.Forty‐four percent of all the species collected had individuals infected withSynophrya, and 63% of all the families collected contained species that had infected individuals. There is no obvious structural or phylogenetic relationship between these families that explain why they are infected. The presence ofSynophryamay be related to salinity since decapods captured in estuaries were never infected and decapods captured close to shore were only rarely infected. The salinities of these waters range from 15–35%, but the salinity of the off‐shore waters where the great majority of infected specimens was found ranges only from

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03765.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SYNOPSIS.During the course of infection in the rat,Trypanosoma lewisiproduces 2 antigenic variants: the 1st represents the initial, reproducing population of cells; and the 2nd the nonreproducing, ablastin‐inhibited adult population. The specificities of the agglutinins elicited by the variants were studied by adsorption and agglutination methods and the newer immunoelectroadsorption technic. It was found that the reproducing variant has a surface antigen that reacts with the agglutinin specific for the adult variant, but this antigen does not become immunogenic until transformation to the adult variant occurs. It was also found, with fractions of immune sera obtained by gel filtration, that the agglutinin specific for the reproducing variant is IgG and that specific for the adult variant, IgM. The antigenic variants of pathogenic and nonpathogenic trypanosomes are compared, and the roles of trypanocidal and ablastic antibodies in the induction of antigenic variation are discusse

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1976.tb03766.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY