摘要:

The interaction between theToxoplasmaparasitophorous vacuole and vimentin‐type intermediate filaments in Vero cells was investigated via immunofluorescence microscopy. A significant rearrangement of host cell vimentin around theToxoplasmaparasitophorous vacuoles occurs throughout the course of infection. Host cell vimentin associates with the parasitophorous vacuoles within an hour after invasion. This vimentin overcoating of the vacuole is initiated at the host cell nuclear surface. During parasite multiplication, vimentin retains a closely defined association with the cytosolic surface of the parasitophorous vacuole. In addition, the vimentin intermediate filaments originating from the host cell nuclear surface are progressively rearranged around the enlarging parasitophorous compartment. During infections, the order of vimentin cytoskeleton is normal throughout the cell and appears redefined only at the vicinity of the parasitophorous vacuole. Depolymerization of the intermediate filaments was achieved with the phosphatase inhibitors okadaic acid and calyculin A. Disruption of the intermediate filament networks resulted in displacement of the parasitophorous vacuoles from the host cell nuclear surface. The data indicate that host cell vimentin binds to theToxoplasmaparasitophorous vacuoles and that the host intermediate filament network serves to dock the parasite compartment to the host cell nuclear surfac

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05936.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Intrachromosomal variant surface glycoprotein (VSG) genes inTrypanosoma bruceiare expressed by a mechanism involving gene conversion. The 3’boundary of gene conversion is usually within the last 130 bp of the VSG gene, a region of partially conserved sequences. We report here the loss of the predominant telomeric A VSG gene in the cloned variant antigenic type (VAT) 5A3, leaving only an intrachromosomal A VSG gene (the A‐B gene). The nucleotide sequence of the A‐B VSG gene reveals that it lacks the normal VSG 3′ sequence. Surprisingly, we find cells expressing this A‐B VSG gene in relapse populations arising from VAT 5A3. Since the A VSG mRNAs from these cells have a normal 3′ sequence, the incomplete A‐B VSG gene must be expressed via a partial gene conversion that supplies the functional 3’end. Although the A‐B VSG gene is no longer predominant like the telomeric A VSG gene, it is still expressed more frequently than other intrachromosomal VSG genes, suggesting that factors other than a telomeric location determine whether a VSG gene is expressed ea

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05937.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Mixed life cycle stages of rat‐derivedPneumocystis cariniiwere isolated from host lungs and their sterols were compared with those present in lungs from normal and immunosuppressed uninfected rats. Gas‐liquid chromatography consistently detected, resolved, and quantified 9, 10, and 20 sterol components in the total nonsaponifiable neutral lipid fraction of lungs from normal rats, lungs from immunosuppressed uninfected rats, andP. cariniipreparations, respectively. In all samples, cholesterol was the most abundant sterol present, comprising 97%, 93%, and 78% of total sterols in lungs from normal rats, lungs from immunosuppressed uninfected rats, andP. carinii, respectively. Tentative identifications of several rat lung andP. cariniiminor sterols were made based on gas‐liquid chromatogram retention times and fragmentation patterns from mass spectral analyses. Campesterol (ergost‐5‐en‐3‐ol), cholest‐5‐en‐3‐one, andβ‐sitosterol (stigmast‐5‐en‐3‐ol) were among the minor components present in both types of lung controls, and were also components ofP. cariniisterols. In contrast to lung controls, the sterols ofP. cariniiwere enriched in C28and C29sterols with one or two double bonds, and a hydroxyl group at C‐3 (ergost‐5‐en‐3‐ol, ergost‐7‐en‐3‐ol, ergosta‐dien‐3‐ol, stigmast‐5‐en‐3‐ol, stigmast‐7‐en‐3‐ol and stigmasta‐dien‐3‐ol). Steryl esters ofP. carinii, probably stored in cytoplasmic lipid droplets, were dominated by those present in the host lung. In separate studies. 3‐hydroxy‐3‐methylglutaryl coenzyme A activity, a key enzyme in the regulation of sterol biosynthesis, was detected in purifiedP. cariniipreparations and incorporation of radiolabeled squalene and mevalonate was observed. Together, these results suggest that the parasite readily takes up and incorporate

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05938.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Book review in this ArticleGrassé, P.‐P.&Doumenc, D.1993. Abrégé de Zoologie.Foissner, W.1993.Class Colpodea (Ciliophora). InMatthes, D.

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05939.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05940.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1066-5234    

DOI:10.1111/j.1550-7408.1994.tb05941.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY