ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb00995.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.Leptomonas seymourisp. n., isolated fromDysdercus suturellus(Hemiptera: Pyrrhocoridae) from Florida, is described and distinguished from other species ofLeptomonasfrom closely related hosts.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb00996.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.Microglomus paxillusis described as a new genus and species of the subclass Protosteliida (Class Eumyceto‐zoa). It has been isolated only once from casuarina bark collected in Oahu, Hawaii. The new organism is characterized by a uninucleate ameboid trophic stage that feeds on bacteria and by sporocarps with spike‐like stalks terminated by microspo‐rangia containing tetrads of ameboid protoplasts or thin‐walled spores. No flagellate cells are produced. The tetrads are typically formed by successive bipartition following conjugate nuclear divisions in the sporogen. The cells of the tetrad are at first binucleate but soon become uninucleate as a result of nuclear degeneration. Variations in the process of sporogenesis are de

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb00997.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.Primary amebic meningoencephalitis was experimentally produced in mice through intranasal instillation of pathogenicNaegleria fowleri. Experimental animals had a 64% mortality, with average time of onset of symptoms or death occurring on the 7–8th day following inoculation. Ultrastructural studies of the olfactory lobes from brains of dead (or sacrificed) animals revealed major concentrations of amebae in the perivascular regions; amebae were also seen to be under attack by host polymorphonuclear leukocytes, and in the lumina of blood vessels. Amebae in brain tissue contained 30 nm intranuclear particles arranged in clusters. In the brains of some mice, dead presumably as a result of amebic meningoencephalitis, particles and crystalloids were observed in the nuclei of degenerating cells of the central nervous system. Some alternatives are examined to explain a possible relationship between ameba intranuclear particles and mouse brain cell intranuclear inclusion

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb00998.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.The source of force generation of beating cilia and flagella is an interaction between the doublet microtubules mediated by the dynein‐1 arms which cause the doublets to slide relative to one another. Previously, we demonstrated direct sliding ofTetrahymenaciliary axonemes by dark field light microscopy. In this paper, the results of such an experiment have been captured on a polylysine‐coated grid surface for whole‐mount electron microscopy. Images in which sliding between doublets has taken place can be identified. We conclude that doublets slide relative to one another with a constant polarity. To produce the observed displacement, the direction of the dynein‐1 arm force generation must be from base to tip, so that the doublet (n), to which the arms are attached, pushes the next doublet (n+ 1) toward the tip. In addition to the functional polarity, the dynein‐1 arms are found to have a structural polarity: they tilt toward the base when viewed along the edges of the A‐subfiber. A scheme is presented which reconciles the finding of a single polarity of active sliding with the geometry of microtubule tip displacement of

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb00999.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.The following problems concerning food vacuoles were studied byin vivoobservations ofTetrahymena: (A) Formation of food vacuoles. The process may be divided into 4 stages. Stage 1—gradual growth of the limiting membrane of the open food vacuole (of short duration). Stage 2—“filling up” of the fully expanded vacuole (of long duration). Stage 3—“closing off” of the vacuole (of brief duration). Stage 4—initial movement of the detached vacuole away from the cy‐tostome. The possible role of the oral components (apart from membranellar beating) in the process is discussed.(B) Change of pH in the food vacuole. After ingestion of heat‐killed yeast stained with indicator dyes (neutral red, bromcresol purple, bromcresol green, bromphenol blue), the observed color changes indicate that pH is neutral in the forming vacuole as well as in newly formed vacuoles; that a pH value of 6.0–5.5 is reached after ∼ 5 min; and that the lowest pH value between 4.0 and 3.5 is reached after 1 hr. Before egestion the pH again increases.(C) Length of the digestive cycle. A determination of the time required to deplete the cells of labeled vacuoles formed during a short exposure, was attempted. Defecation was observed after 1/2 hr and it was frequent after 2 hr. About 25% and 50% of the labeled vacuoles were removed after 1 hr and 2 hr, respectively; however, labeled vacuoles may still be seen in some cells 6 hr after ingestion. The conclusion is that the digestive cycle lasts ∼ 2 hr and that egestion of undigestible mat

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb01000.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS Previously, we found that a mutant strain ofTetrahymena pyriformiswithout food vacuoles failed to grow unless the nutrient media were richly supplemented with vitamins and trace metals. Here we show that calcium folinate alone can replace the extra vitamin supplementation. The mutant requires ∼ 90‐fold higher concentrations of folinate than the wild‐type cells to give similar growth responses in a chemically defined medium. We infer that the food vacuole is an important route of uptake for this vitamin in the wild‐type cells. We found no difference between mutant and wild‐type cells in their requirements for nicotinic acid, pantothenic acid, riboflavin‐monophosphate, and pyridoxal. We infer that an extravacuolar route contributes importantly to uptake of these

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb01001.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.A procedure is described for the isolation of flagella ofCrithidia fasciculata.Herpetomonas samuelpessoaiandLeishmania tarentolaein a highly purified state and giving reasonably good yield. The 3 types of flagella give a similar electrophoretic pattern of proteins. It is shown thatH. samuelpessoaiand, to a lesser extent,C. fasciculataflagella confer protection againstTrypanosoma cruziinfection.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb01002.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.The effect of malaria on the chronic phase of Chagas’disease was investigated in mice. The animals were givenPlasmodium berghei‐infectedred blood cells 2 to 12 months after their initial inoculation with trypomastigotes of 3 different strains ofTrypanosoma cruzi(Y, CL and Gilmar). In all the experiments carried out with one of the strains (CL), a somewhat variable but always considerable percentage of mice (average 39%) relapsed in to the acute phase of Chagas’disease. This relapse was characterized by a significant increase in the number of circulating trypomastigotes. Recrudescence was observed also with a 2nd strain ofT. cruzi(Gilmar), which is similar in many aspects to the CL strain, e.g. the morphology of blood stages, curve of parasitemia and susceptibility to antibodiesin vitro. In mice whose chronic phase was induced by trypomastigotes of the Y strain, malaria infections did not induce a typical acute phase with high parasitemia byT. cruzi. Bloodstream forms of Y parasites differ from those of CL and Gilmar strains morphologically as well as immunologically, i.e. only the Y strain is easily agglutinated and partly inactivated by specific immune serum. In light of this and other known characteristics of the strains used in the present work, the author speculates on mechanisms which allow malaria infections selectively to suppress acquired host resistance to certain strains ofT.

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb01003.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SYNOPSIS.The photoreceptor structures (eyespot‐paraflagellar body‐flagellum) forEuglenaphototaxis were investigated by electron microscopy. The paraflagellar body—the photoreceptor—is a highly ordered crystalline lamellar structure. Optical diffraction of the electron micrographs and resulting filtered images of the paraflagellar body suggest that it is formed of rods in a helical arrangement. The action spectra for phototaxis, thein situspectrum by microspectrophotometry of the paraflagellar body, and flavin analysis of the organism indicate that the photoreceptor molecule is a flavoprotein. The phototaxis action spectrum is similar to the spectrum for O2evolution and implies that similar molecules participate in the photo‐processes. As a result, a photochemical scheme is suggested in which a photo‐excited flavin and a cytochrome participate in the photoprocess. The photochemistry and photoreceptor structures forEuglenaphototaxis are likened to a photoneuro s

ISSN:0022-3921    

DOI:10.1111/j.1550-7408.1977.tb01004.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY