摘要:

ABSTRACT.Amblyospora californicais a polymorphic, eukaryotic microsporidian. Three types of sporogony producing three types of spores occur in male larvae and female adults of its mosquito host,Culex tarsalis, and an alternate copepod host,Acanthocyclops vernalis.Development ofA. californicain male larvae includes merogony and sporogony. Karyogamy and meiosis was observed in sporogony in male larvae but not in the female adult or in the copepod. Chromosomal evidence showed that sporogony included two consecutive meiotic divisions and a subsequent mitosis forming an octosporont, ultimately containing eight haploid, uninucleate mature spores. In this species, the haploid number of chromosomes is nine. Macrosporoblasts and macrospores, containing 1, 2 or more nuclei, can be seen in infected male larvae. The stage of sporogony in which cytokinesis was arrested seems to determine the number of nuclei. Those with only one nucleus, we believe are due to failed nuclear division at meiosis. AlthoughA. californicadisplayed a process of karyogamy and meiosis similar to that of the species fromCx. salinarius, they may not be the same species because of the difference in their chromosome numbers.

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01549.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.Some strains ofP. caudatumcontain macronuclear inclusion bodies that are morphologically distinct from bacteria. They vary in number as well as in size in each macronucleus. The inclusion bodies are basically divided into peripheral and inner areas. The peripheral area consists of fibrillar proteins of 22–24 nm in thickness, which are specifically stained with fast green in 45% acetic acid. On the other hand, chromatin‐like granules are within the inner area of large inclusion bodies. The granules within the inner area changed their distribution depending upon the physiological state of their host cells. Transplantation experiments and crossbreeding analyses revealed that genetic factors responsible for the multiplication of the inclusion bodies can ‘infect’ other macronuclei (or cells) via the cytoplasm. These results suggest that the inclusion bodies are a non‐bacterial macronuclear endosymbiont, possibly produced by a virus or a virus‐l

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01550.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.The phylogenetic relationships of taxa representative of blood parasitic adeleids were investigated in a cladistic analysis. Two phylogenetic analyses were performed. Monophyly of species ofHaemogregarina(sensu lato) of some marine fishes with species ofHaemogregarina(sensu stricto) was not supported in either analysis. A new genus,Desserian. g., was created to accommodate these species. The historical burden placed on the genusHaemogregarinaDanilewsky, 1885 as a repository for poorly known and inadequately described species is partially relieved through taxonomic revisions involving the generaHaemogregarina, andDesserian. g.

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01551.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.Using comparisons of complete small subunit rRNA sequences from the ciliated protozoansFurgasonia blochmanni, Obertrumia georgiana, andPseudomicrothorax dubiuswe inferred the phylogenetic position of the Nassulida (Class Nassophorea) within the Ciliophora. In distance matrix analyses the Nassulida share a common ancestry with the colpodean ciliateColpoda inflata.Distance matrix and parsimony methods convincingly demonstrate that the Nassulida plus Colpodida are members of a complex ciliate assemblage that also includes the oligohymenophorans and phyllopharyngeans. These phylogenetic inferences are largely congruent with recent analyses of 23S‐like rRNA gene sequences and morphogenetic features. Groups traditionally thought to represent ancestral lineages now appear as highly derived ciliates. In contrast, heterotrichs which were considered to represent a highly evolved group, diverge at the base of the ciliate

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01552.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.An intranuclear microsporidian was observed in lymphoblasts from the kidney of farmed Atlantic halibut larvae (Hippoglossus hippoglossus). In addition to spores, intranuclear pre‐spore stages were observed. Uninucleated stages with a slight thickening of the cell membrane were the most simple developmental stages observed. Multinucleated developmental stages contain electron‐lucent vesicles and electron‐dense discs. The spores are ovoid and measure 2.9 × 1.2 μm (mean). Sporophorous vesicles, diplokarya and mitochondria were not observed in any of the developmental stages. The developmental stages observed are similar to those of the family Enterocytozoonidae, genusEnterocytozoon.However, there are several differences between the present species andE. bieneusifrom enterocytes in man. The relationship to the other species in the genus,E. salmoniscan only be determined when all the developmental stages of the species from Atlantic halibut are ide

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01553.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.The close contact ofGiardia lambliatrophozoites with mucosal surfaces produces surface indentations of epithelial cells, that progress to areas of microvilli depletion. This interaction is mediated by the lateral crest, a specialized contractile structure in the ventral disc of the parasite. We have analyzed the plasma membrane of the ventral disc using freeze fracture electron microscopy to study the distribution of large integral proteins, and freeze fracture cytochemistry with filipin to reveal sterol‐containing sites. A previously undetected structural specialization was found at the lateral crest as a horseshoe‐shaped membrane domain characterized by a near absence of intramembrane particles, in sharp contrast to the remainder of the ventral disc plasma membrane. In addition, the lateral crest showed a striking paucity of cholesterol‐containing complexes in replicas of trophozoites treated with filipin. These observations demonstrate that the plasma membrane ofG. lambliadisplays a microheterogeneity in the planar distribution of cholesterol and intramembrane particles. Both membrane components are noticeably less abundant at the outer rim of the ventral disc where contraction takes

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01554.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.The completePneumocystis carinii Arp1gene has been sequenced from two cDNA clones. The gene encodes a protein 385 bp in length with an estimated size of 45,000 kD. The A + T% for theArp1gene and a 900‐bp sequence upstream of the gene were 63.7% and 70.3%, respectively. These values are consistant with A + T codon preference displayed byP. cariniiand are similar to values reported for otherP. cariniigenes. The predicted amino acid sequence of theP. cariniiArp1 protein had a similarity of 87.6% withNeurospora crassaArp1, 82.1% similarity with vertebrate centractin, and 71.2% similarity with theSaccharomyces cerevisiaeAct5p. Expression ofArp1mRNA inP. cariniiwas detectable via synthesis of cDNA and subsequent PCR amplification. Affinity purified antibodies againstS. cerevisiaeAct5p, and canine centractin recognized both the recombinantly expressed protein and a 45,000 kD protein inP. cariniinuclear extracts. TheArp1gene is the second member of the actin multigene family that has been identified inP. carini

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01555.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.Toxoplasma gondiiis a ubiquitous apicomplexan parasite and a major opportunistic pathogen under AIDS‐induced conditions, where it causes encephalitis when the bradyzoite (cyst) stage is reactivated. A bradyzoite‐specific Mab, 74.1.8, reacting with a 28 kDa antigen, was used to study bradyzoite development in vitro by immuno‐electron microscopy and immunofluorescence in human fibroblasts infected with ME49 strainT. gondii. Bradyzoites were detected in tissue culture within 3 days of infection. Free floating cyst‐like structures were also identified. Western blotting demonstrated the expression of bradyzoite antigens in these free‐floating cysts as well as in the monolayer. Bradyzoite development was increased by using media adjusted to pH 6.8 or 8.2. The addition of γ‐interferon at day 3 of culture while decreasing the total number of cysts formed prevented tachyzoite overgrowth and enabled study of in vitro bradyzoites for up to 25 days. The addition of IL‐6 increased the number of cysts released into the medium and increased the number of cysts formed at pH 7.2. Confirmation of bradyzoite development in vitro was provided by electron microscopy. It is possible that the induction of an acute phase response in the host cell may be important for bradyzoite differentiation. This system should allow further studies on the effect of various agents on the development

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01556.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.A new genus,Vittaforman. g. is proposed for the human microsporidiumNosema corneumShadduck, Meccoli, Davis&Font, 1990, based on the ultrastructure of developmental stages in the liver of experimentally infected athymic mice. The diplokaryotic arrangement of the nuclei is the only character that conforms with the description of the genusNosema. Sporogony is polysporoblastic, sporonts are ribbon‐shaped, constricting to give rise to linear arrays of sporoblasts and each parasite is enveloped by a complete cistema of host endoplasmic reticulum. Comparison ofN. corneum, with established genera revealed that there were none with the same combination of characters. Consequently it is proposed thatNosema corneumbe placed in a new genus asVittaforma corneaen. com

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01557.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT.Concanavalin A (≥ 50 μg/ml) inhibits pair formation in both of the two complementary mating types ofEuplotes octocarinatusstudied in this investigation. This effect can be reversed by methyl‐α‐d‐mannose. Concanavalin A is accessible for methyl‐α‐d‐mannose until pairs are formed. Methyl‐α‐d‐mannose as well as methyl‐α‐d‐glucose and 2‐acetamido‐2‐deoxy‐d‐glucose alone do not inhibit pair formation unless applied in concentrations ≥ 60 mM. The Concanavalin A‐sensitive phase of preconjugant interaction starts 2 h after cells are induced to conjugate. Based on these observations we suggest that Concanavalin A might exhibit its action by binding to carbohydrate moieties of preconjugation‐specific adhesion molecules and thereby might allosterically block interactions with their counterparts. To identify preconjugation‐specific alterations in number or localization of Concanavalin A‐binding glycoconjugates, we probed western blots of total cell proteins or fixed cells, respectively, with digoxigenin‐labeled Concanavalin A. On Concanavalin A blots 20 different Concanavalin A‐binding glycoconjugates were identified in mating‐competent cells. Localization of Concanavalin A‐binding sites on mating‐competent cells by light microscopy resulted in predominant labeling of a comma‐shaped structure near the paroral membranelle. During the preconjugation period no changes in number or localization of Con A‐bindi

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1995.tb01558.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY