摘要:

ABSTRACTTetrahymena pyriformisingestedEscherichia colifor 15–20 min and the fine structure of food vacuoles was analyzed 5, 15, 30, 60, 90, 120, and 180 min after uptake began. From this analysis, eight vacuolar stages could be defined, and three to four stages were found in each sample.Stage 1represents forming and newly detached vacuoles with a random distribution of bacteria.Stage 2is the “dehydration” vacuole in which the bacteria are compacted and a few may lyse.Stage 3, corresponding to the acid phosphatase‐positive stage, has an electron‐dense vacuolar matrix revealing components of lysed bacteria and the translucent coat of intact bacteria.Stage 4is the “halo” stage where centrally located, intact bacteria are surrounded by lysed material being removed by pinocytic activity of the vacuolar membrane.Stage 5represents lysis of bacteria remaining intact until this stage; the stage is apparently followed by a second stage 4.Stage 6contains few bacterial profiles in a smeared homogeneous mass.Stage 7contains numerous vesicular membranous structures which apparently become transferred to the cytoplasm as such.Stage 8represents defecation vacuoles derived from fusion of smaller vacuoles. The main findings are as follows: I) Bacterial lysis may occur during acidification of the vacuole prior to fusion with lysosomes. II) Digestion of bacteria apparently occurs in “bursts” as indicated by the extended time that vacuoles in stages 4 and 5 are present. III) Bacterial membranous structures seem to be transferred directly to the cytoplasm ofTetrahymena. IV) Mass defecation occurs 2 h af

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03120.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA method is described for the isolation and purification of xenosomes, intracytoplasmic bacterial symbionts of the marine hymenostomeParauronema acutum, using percoll gradients. Xenosomes isolated by this procedure retained both their ability to kill susceptibleUronemastrains and to infect homologous and heterologousP. acutumstrains. Unexpectedly, both killer and non‐killer xenosomes were found to contain inclusion bodies, heretofore unseen in fixed whole cell preparations, in the form of double helices, which we have termed H‐bodies. The nature and function of these bodies is unkn

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03121.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA quantitative study of the seasonal distribution of thermotolerant (37°C and 45°C), small free‐living amoebae (FLA) was conducted in Lake Issaqueena, a warm, monomictic lake with steep, sloping banks and a maximum basin depth of 10 m in the Piedmont region of South Carolina.NaegleriaandVahlkampfiawere the most frequently encountered FLA in littoral sediment and surface water samples whereasAcanthamoebawas most commonly isolated from profundal sediment, especially during late summer. In the water column, FLA populations were highest in a persistent detrital layer; however, few amoebae were isolated from a massive (∼1.5 m thick) layer ofOscillatoria. The onlyN. fowleriisolated in this study was from the detrital layer. Discussion of the influence of differences in watershed and basin morphology on variations in the size and generic composition of FLA populations for the aquatic ecosystems of Lake Issaqueena and Willard's Pond is inc

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03122.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA new genus and species of microsporidia,Ovavesicula popilliaen. g., n. sp., is described from the Japanese beetle,Popillia japonica, on the basis of studies by light and electron microscopy. Parasite development primarily occurs within the Malpighian tubules of larvae, and spores are formed in a sporophorous vesicle. Meronts have diplokaryotic nuclei, develop in direct contact with the host cell cytoplasm, and divide by binary fission. Sporonts have unpaired nuclei, develop within a thick sporophorous vesicle, and undergo synchronous nuclear divisions producing plasmodia with 2, 4, 8, 16, and 32 nuclei. Cytokinesis of sporogonial plasmodia does not occur until karyokinesis is complete with 32 nuclei. Intact sporophorous vesicles are ovoid, containing numerous secretory products, and are surrounded by a persistent two‐layered wall. The uninucleate spores are regularly formed in groups of 32, and the polar tube in each has six coil

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03123.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTWe have previously shown that nonimmune human milk killsGiardia lambliatrophozoites in vitro. Killing requires a bile salt and the activity of the milk bile salt‐stimulated lipase. We now show that human small‐intestinal mucus protects trophozoites from killing by milk. Parasite survival increased with mucus concentration, but protection was overcome during longer incubation times or with greater milk concentrations. Trophozoites preincubated with mucus and then washed were not protected. Protective activity was associated with non‐mucin CsCl density gradient fractions. Moreover, it was heat‐stable, non‐dialyzable, and non‐lipid. Whereas whole mucus inhibited milk lipolytic activity, protective mucus fractions did not inhibit the enzyme. Furthermore, mucus partially protectedG. lambliatrophozoites against the toxicity of oleic acid, a fatty acid which is released from milk triglycerides by lipase. These studies show that mucus protectsG. lambliaboth by inhibiting lipase activity and by decreasing the toxicity of products of lipolysis. The ability of mucus to protectG. lambliafrom toxic lipolytic products may help to promote intestinal colonization by th

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03124.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTIsospora elmahalensisn. sp. is described from the Saudi Arabian bird,Pycnonotus leucogenys, from the Elmahala valley. Sporulated oocysts ofI. elmahalensiswere spherical or nearly subspherical, 19.5–22.5 × 18.5–20 (21.34 ± 0.4 × 19.06 ± 0.5) μm. Oocysts lacked a micropyle, residuum, and polar granule. Sporocysts were ovoid, 14–17.5 × 7–12 (16.08 ± 1.05 × 9.9 ± 1.55) μm, and had a Stieda body and sporocyst residuum, but lacked a substiedal body. Sporozoites were elongated with a clear globule at one end. The host bird belongs to the or

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03125.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTRelease of sporozoites from the oocysts ofCryptosporidium baileyiis described from Nomarski interference‐contrast microscopy. Just prior to excystation, the four sporozoites became motile and rearranged themselves within the oocyst. The sporozoites were then rapidly expelled through an opening that formed in the oocyst wall, and the residuum was either released or retained within the oocyst. Excysted sporozoites were crescent shaped and measured 5.0–9.0 μm × 1.0–1.6 μm (x̄= 6.8 × 1.1 μm). Excystation occurred when sodium taurocholate or a mixture of trypsin and sodium taurocholate was present in the incubation medium. High levels of excystation occurred at 37° or 40°C, but excystation did not occur at 4°C. The ability of biles from two avian and two mammalian hosts to produce excystation ofC. baileyiwas also studied. After a 2‐h incubation at 40°C, the percentages of excystation were 69.5% in goat bile, 45.0% in pig bile, 33.0% in chicken bile, and 34.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03126.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTA new species,Pleurotricha indican. sp., is described, characterized by an average size of 220 × 119 μm, a firm and inflexible body, six rows of dorsal kineties, one left and two right rows of marginal cirri, and an “Oxytricha‐like” pattern of ventral cirri. The parts of the macronucleus are variable in shape and number. The comparison with other members of the genus shows thatP. indicadiffers from other congeneric species in the combination of these cha

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03127.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTThe new microsporidium (Microsporida: Pereziidae),Perezia dichroplusaen. sp., infects the epithelial cells of the Malpighian tubules of the Argentine grasshopperDichroplus elongatus. Characteristics of the pathogen include the following: development in direct contact with the host cell cytoplasm; bi‐, tetra‐, and sometimes multinucleate diplokaryotic meronts, rounded or elongate in shape; unikaryotic sporonts and sporogonial plasmodia, elongate in shape; sporoblasts and spores uninucleated; spores highly variable in size (1.6–6.7 by 1.0–2.7 μm, x̄= 3.5 ± 0.09 by 1.5 ± 0.02, n = 100) with eight or fewer polar tube coils and showing a posterior electron‐dense i

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03128.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACTEntosiphon sulcatumis a phagotrophic euglenoid. The tubular ingestion apparatus, called a siphon, is composed of three microtubular rods extending the length of the cell. Within the tube are four large striated vanes arranged much like the blades in a pinwheel. The vanes arise from the microtubular rods and curve towards the center of the feeding apparatus. Sheets of endoplasmic reticulum are positioned adjacent to each of the vanes and surround the perimeter of the apparatus. A cap, supported by a scaffold and anchored into the cytoplasm, covers the opening of the siphon. An elongate invagination of the plasma membrane is positioned adjacent to the edge of the cap and extends downward into the siphon forming the opening. The vanes converge at the anterior end of the siphon and surround the invagination. During feeding, the siphon protrudes from the cell. As the apparatus protrudes the cap is withdrawn to the side, opening the siphon. The vanes spread apart expanding the invagination of the plasma membrane into a large cavity into which ingested food particles are taken.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1987.tb03129.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY