摘要:

ABSTRACT.The ultrastructural appearance of cortical structures ofProtoopilina australisis described. With respect to kinetosomal architecture and the supports of the surface folds,Protoopalina australishas an ultrastructural identity similar to other opalines. However, microfibrillar tracts and regular arrays of cortical vesicles—evident inOpalinaandCepedea—are absent from the binucleate genera. This new insight, combined with the recent discovery of a new genus (Protozelleriella) is used to revise our understanding of the evolution of slopalines and we favour a common origin for the multinucleate generaOpalinaandCepe

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01245.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Variants of a cloned laboratory stock of the trypanosomatid parasiteCrithidia luciliaehave been distinguished from “parental type” organisms. These variants accumulated spontaneously over time as the protozoan was maintained by continuous passage in a chemically defined medium. Cloned lines of these variants have been isolated by plating on nutrient agar and partially characterized on the basis of their growth characteristics in culture, their colony and cellular morphology as well as their surface protein expression. One cloned line consisted of motile, flagellated forms which, unlike “parental type” organisms, did not adhere to the surface of culture flasks. Another cloned line was composed of non‐adherent, nonmotile, amastigote‐like forms which were further distinguished from “parental type” cells by virtue of their constitutive expression, in nutrient‐replete medium, of high levels of a surface membrane associated 3′‐nucleotidase/nuclease (3′‐N'ase) activity. Both the motile, flagellated and amastigote‐like variants, like the “parental type” organisms, exhibited elevated levels of the 3′‐N'ase activity upon exposure to purine starvation conditions. The variants described are of potential importance in elucidating the mechanism of induction of the highly regulated 3′‐N'ase activity as well as for understanding the cytoskeletal systems and t

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01246.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.We have used ultrastructural techniques in different malarial species to demonstrate a lysosomal system. First, we have tried to localize acid phosphatase, a typical lysosomal label. Its activity was localized in the endoplasmic reticulum and in endocytic vesicles, and in dense‐cored vesicles near the digestive vacuoles, especially inPlasmodium falciparum(FCR3strain). Then, we have studied the different cellular compartments of the malarial parasite by the zinc iodide‐osmium tetroxide technique that heavily contrasted the cellular compartments of the parasite. This experiment led to the observation of a profound rearrangement of the endoplasmic reticulum, especially inP. berghei.A very atypical but functional Golgi apparatus was demonstrated in all the growing stages of the parasite and lysosome‐like vesicles were observed, showing a structure very similar to those of the coated vesicles of a true Golgi complex. The presence of these organelles are in favor of the existence of a lysosomal system and of the endogenicity of some enzymes involved hemoglobin degrad

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01247.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Exocytosis mutants ofTetrahymena thermophilaare deficient in mucus release. Experiments to chromosomally locate two of these mutants are described, using the technique of deletion mapping with nullisomic strains. Oneexolocus has been assigned to chromosome 5.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01248.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Rumen contents were obtained from 23 white‐tailed deer (Odocoileus virginianus), located in the eastern portion of central Ohio. Samples were taken during late fall and winter over a 4‐yr period, 1986–1990. Protozoan numbers ranged from 0.002 to 7.25 × 106per ml of rumen contents, with a mean of 2.96 × 106. Six deer had protozoan concentrations higher than any values previously reported in ruminants. In all 23 animals,Entodinium dubardiwas the only ciliate protozoan species

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01249.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.This paper reports on a new phenomenon in the ciliated protists: cytoplasmically determined early sexual maturity. Stock MN1 of the marine hypotrichEuplotes crassusmatures immediately after conjugation. We analyzed the respective contribuboas of the nucleus and the cytoplasm to the inheritance of this stable condition. A genetic marker, and new methods inE. crassusfor cytoplasmic labeling, production of amicronucleates, and induction of selfing were used. Crosses within and among the early mature (EM) variants and late mature (LM) “wild type” lines were done in ovarious combinations. Descendants of EM conjugants continued to be EM, and descendants of LM continued to be LM, regardless of the different experimental approaches used. The results of the crosses clearly show that the clonally stable, variant EM phenotype is transmitted at conjugation in a non‐Mendelian manner through the cytoplasmic lineage. The expression of the trait is independent of the micronuclear genome, but the precise site and nature of the hereditary basis is un

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01250.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.We studied ontogenetic population changes ofOpalinaandNyctotherus cordiformisin eight species of tadpoles from 10 sites in east‐central Mississippi. Most tadpoles acquiredOpalinaearly in development, while the acquisition ofN. cordiformiswas variable. Developmental stage, species and collection site explained significant amounts of the variation inOpalinadensity of tadpoles (F= 11.6; df = 27, 235;P<0.0001) and metamorphs (F= 7.31; df = 24, 84;P<0.0001). Relationships betweenOpalinadensity and host stage showed either (1) a gradual decrease or (2) a gradual increase throughout host ontogeny.Opalinadensities declined during metamorphosis. Density variations ofN. cordiformiswere explained by host species of tadpoles (F= 9.30; df = 7, 142;P<0.0001) and by host species and stage of metamorphs (F= 5.85; df = 8, 62;P<0.0001).The length of larval period, habitat duration and generation time of the protozoans are suggested as major modifiers of the protozoan densities. Hosts with long larval periods show a decreasing population density and hosts with short developmental periods show a pattern of increasing density. Neither pattern was detected in tadpoles from temporary sites. Metamorphic declines in protozoan density, but not necessarily the loss of protozoans, reflect metamorphic alterations of the gut common to all host

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01251.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.A marine kinetoplastid flagellate,Cryptobia eilatican. sp., is described from the gills of cultured gilt‐head sea breamSparus aurataL. and wild black‐spot sea breamDiplodus noct(Valenciennes) in the Red Sea. The trophozoite is elongated and lacks a contractile vacuole and undulating membrane. The body averages 13.5 × 4.1 μm, anterior flagellum 9.7 μm, and free portion of recurrent flagellum 15.2 μm. The ultrastructural features of the species exhibit great similarity to various previously studied Cryptobiids.Cryptobia eilaticatrophozoites feed on bacteria, show a preference for the branc hial interlamellar crypts, and attach to the host epithelium by means of the recurrent flagellum. Neither penetration into the epithelial cells, nor any direct damage to host tissue was observed.Cryptobia eilaticainhabits a purely marine habitat, but its trophozoite tolerates salinities as low as

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01252.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Mutant strain d48 and d12 cannot express serotype A. In d48, the A i‐antigen gene is present in the micronucleus, but not in the macronucleus. It has recently been shown that d12 contains theAgene in its micronucleus, but its macronucleus lacks the gene. Micronuclear transplantations into enucleated cells were performed to analyze those mutants. Reciprocal transplantation between wild type and d48 confirmed that d48 contains theAgene in the micronucleus and its cytoplasm is defective. Wild type 51 enucleated cells into which were transplanted d12 micronuclei could not express A. Amiccronucleate d12 cells into which were transplanted normal micronuclei from 51 or d48 showed no expression of A. These results show that even if the micronucleus of d12 contains theAgene, it must be abnormal, and its cytoplasm is also defective the same as d48. Genetic analysis showed that heterozygote of d12 and wild type 51 or d48 caused a cure of the cytoplasmic defect of d48 and d12 during the development of macronucle

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01253.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACT.Leishmania majorpromastigotes were grown to late‐log phase and washed and resuspended in an isosmotic buffer. When osmolality was suddenly decreased by 50%, the cells rapidly became shorter and increased in width. Cell volume, calculated assuming a prolate‐ellipsoidal shape, increased 1.4 times after 1 min. Over the next several minutes, the average length and width returned to control values while the volume returned to baseline, indicating the ability to regulate volume. Concomitantly with the swelling, large amounts of alanine and other ninhydrin‐positive substances were released. All of the alanine pool was released within 1 min after reduction of the osmolality by 66%. Cells pre‐loaded with [14C]‐aminoisobutyric acid also released it very rapidly upon hypo‐osmotic stress. Release of ninhydrin‐positive substances resulted from decreased osmolality rather than changes in ionic composition. The same results were obtained if osmolality was decreased by reducing only the NaCl content of the buffer instead of diluting it with water, and mannitol could substitute for the NaCl. Promastigotes were able to grow well over several days in media as low as 154 mOsm/kg. The nature of the signalling mechanism(s) that initiates the rapid shape change and efflux of ninhydrin‐positive substances in response to hypo‐osmotic stress is a

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1990.tb01254.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY