Freeze-fracture electron microscopic studies of age-related plasma membrane changes in Sporothrix schenckii

1987 ◽  
Vol 33 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Manabu Maeda ◽  
Yasuo Kitajima ◽  
Yukiko Shikano ◽  
Shunji Mori
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Agar Medium ◽  
Freeze Fracture ◽  
Sporothrix Schenckii ◽  
Brain Heart Infusion ◽  
Brain Heart Infusion Agar ◽  
Age Related ◽  
Yeastlike Cells ◽  
Infusion Agar

Characteristics of the plasma membrane of Sporothrix scheckii cells as revealed by freeze-fracture techniques have been classified into eight types (Y1, Y2a, Y2b, Y3a, Y3b, Y4a, Y4b, and Y5) in yeastlike cells grown under the following two conditions: brain heart infusion agar medium at 27 °C, and brain heart infusion agar medium at 37 °C. Type Y1 cells are yeastlike cells having smooth plasma membranes without any invagination. Typical characteristics of the other types are as follows: type Y2a, smooth plasma membranes with few trenchlike invaginations; type Y2b, wavy plasma membranes with few oval or irregularly formed invaginations; type Y3a, plasma membranes with many randomly distributed trenchlike invaginations; type Y3b, plasma membranes with many cocoonlike or irregularly formed invaginations; type Y4a, plasma membranes with longer trenchlike invaginations; type Y4b, plasma membranes with irregularly formed, enlarged invaginations; and type Y5, smooth or wavy plasma membranes with aggregations of intramembranous particles and with many vacuoles between cell walls and plasma membranes or in the cytoplasm in some cells. By counting the proportion of each type of yeastlike cell under the two conditions and with different cultivation periods, it appears that plasma membrane types change as aging progresses in the following order: type Y1, Y2a, Y3a, Y4a, and Y5 in conidia and type Y1, Y2b, Y3b, Y4b, and Y5 in yeastlike vegetative cells. These observations provide us with an important advantage when studying the effects of antifungal agents on the plasma membrane of Sporothrix scheckii, as it is important to know the natural course of changes in membrane structure during aging.

Speculative cell cycle in yeast-phase growth of Sporothrix schenckii: plasma membrane ultrastructure as revealed by freeze-fracture electron microscopy

1988 ◽  
Vol 34 (9) ◽  
pp. 1083-1089 ◽  
Author(s):  
Manabu Maeda ◽  
Yasuo Kitajima ◽  
Shunji Mori
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Freeze Fracture ◽  
Sporothrix Schenckii ◽  
Brain Heart Infusion ◽  
Phase Growth ◽  
Yeast Phase ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron ◽  
Yeastlike Cells

The cell cycle in yeast-phase growth of Sporothrix schenckii was investigated by light microscopy and freeze-fracture electron microscopy after a 3- to 7-day cultivation on brain heart infusion agar medium at 37 °C. Mother yeastlike cells were able to bear daughter yeastlike cells. They were also able to produce germ tubes that had the potential to develop into pseudohyhae and hyphae. On the other hand, hyphae or pseudohyphae born from yeastlike cells were able to bear yeastlike cells directly. These results lead us to propose a hypothetical cell cycle for yeast-phase growth involving yeastlike vegetative cells, pseudohyphae, and hyphae.

scholarly journals Análise da atividade antimicrobiana de probióticos e sua adesividade a bráquetes ortodônticos: estudo in vitro

2019 ◽  
Vol 48 ◽  
Author(s):  
Thayse Caroline de Abreu BRANDI ◽  
Amanda Nunes MONTEIRO ◽  
Hugo Leandro Azevedo da SILVA ◽  
Adriano Gomes da CRUZ ◽  
Lucianne Cople MAIA ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Brain Heart Infusion ◽  
Brain Heart Infusion Agar ◽  
Infusion Agar

Resumo Introdução A presença de aparelho ortodôntico fixo dificulta a higienização e potencializa o acúmulo de biofilme bacteriano nas superfícies dentárias. O desenvolvimento de produtos que minimize isso é desejo de pesquisadores em todo o mundo. Objetivo Verificar a ação bacterapêutica de produtos lácteos contendo ou não probióticos sob pool de Streptococcus mutans (SM) (ATCC 25175) e S salivarius (SS) (ATCC 7073), além da adesão desses produtos à superfície de bráquetes ortodônticos. Material e método Pool de cepas ATCC de SM e SS foi formado e plaqueado sobre placa de Petri contendo meio de cultura brain heart infusion ágar (BHI). Após formação do meio, um orifício foi feito no centro da placa seguido do seu preenchimento com 150 µL dos produtos a serem testados, formando os seguintes grupos: GL - Leite bovino; GLP - Leite bovino com probiótico; GLF - Leite fermentado; e GLFP - Leite fermentado com probiótico. Na sequência, as placas foram incubadas por 48h, em estufa a 37ºC. A seguir, foi feita a medição do halo formado entre o produto e o meio com régua milimetrada. Já no disco de membrana, foi formado biofilme com o mesmo pool de cepas, sob discos de membrana. Em seguida, foi feita a diluição seriada contendo o produto de acordo com o grupo: P1 (água); P2 (L); P3 (LP); P4 (LFP), seguida do plaqueamento e a contagem total de micro-organismos. Para a adesividade dos produtos lácteos, bráquetes ortodônticos foram submergidos em cada solução (GL, GLP, GLF e GLFP) e foram incubadas a 37°C/24h. Posteriormente, cada bráquete foi transferido para um ependorf contendo solução salina estéril, que foi submetida a diluições seriadas, posteriormente incubadas a 37°C/48h sob microaerofilia para contagem das UFC/mL. Para análise dos dados, utilizaram-se os testes Levene, Shapiro-Wilk e Kruskal-Wallis. O nível de significância adotado foi de 5% (α = 0,05). Resultado Não houve formação de halo de inibição entre os produtos e o meio de cultura (p<0,05); no disco de membrana, não foram observadas diferenças estatísticas entre os grupos (p=0,679); os grupos tratados com leite bovino com probiótico e leite fermentado com probiótico apresentaram adesividade aos bráquetes ortodônticos (p=0,056). Conclusão Os achados do presente estudo permitem concluir que, em estudos in vitro, não foi possível verificar a bacterioterapia a partir de produtos lácteos contendo ou não probióticos em cepas de SM e SS.

scholarly journals Surface membrane vesicles from mononuclear cells stimulate erythroid stem cells to proliferate in culture

Blood ◽  
1982 ◽  
Vol 60 (3) ◽  
pp. 583-594 ◽  
Author(s):  
N Dainiak ◽  
CM Cohen
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Mononuclear Cells ◽  
Surface Membrane ◽  
Freeze Fracture ◽  
Membrane Vesicles ◽  
Cell Types ◽  
Target Cells ◽  
Freeze Fracture Electron Microscopy

Abstract In order to examine the contribution of cell surface materials to erythroid burst-promoting activity (BPA), we separated media conditioned by a variety of human cell types into pellets and supernatants by centrifugation. When added to serum-restricted cultures of nonadherent human marrow cells, pellets contained about half of the total stimulatory activity. Freeze-fracture electron microscopy of the pellets revealed the presence of unilamellar membrane vesicles ranging from 0.10 to 0.40 microM in diameter. The amount of BPA in culture increased with added vesicle concentration in a saturable fashion. Preparation of leukocyte conditioned medium (LCM) from 125I-wheat germ agglutinin labeled cells and studies comparing the glycoprotein composition of vesicles with that of leukocyte plasma membranes suggest that LCM-derived vesicles are of plasma membrane origin. Moreover, partially purified leukocyte plasma membrane preparations also contained BPA. While disruption of vesicles by freezing/thawing and hypotonic lysis did not alter BPA, heat, trypsin, or pronase treatment removed greater than 65% of BPA, implying that vesicle surface rather than intravesicular molecules express BPA. Results of BPA assays performed in two-layer clots indicated that proximity to target cells is required for vesicle BPA expression. We conclude that membrane vesicles spontaneously shed from cell surfaces may be important regulators of erythroid burst proliferation in vitro.

scholarly journals Cytochemical evidence for the presence of phospholipids in epithelial tight junction strands.

1993 ◽  
Vol 41 (5) ◽  
pp. 649-656 ◽  
Author(s):  
F W Kan
Keyword(s):  
Plasma Membrane ◽  
Tight Junction ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Freeze Fracture ◽  
Fracture Face ◽  
Gold Particles ◽  
Pancreatic Cells ◽  
Specific Association

Previous freeze-fracture experiments using either glutaraldehyde-fixed and cryoprotected specimens or unfixed rapid-frozen samples led to the proposal that cylindrical strands of the tight junction (TJ) observed in freeze-fracture preparations are inverted cylindrical micelles made up of membrane lipids and, possibly, membrane proteins. However, no one has yet been able to directly label the structural fibrils of the TJ. To test the hypothesis that TJ strands observed on freeze-fracture preparations are composed at least partially of lipids, we have combined the phospholipase A2-gold and the fracture-label techniques for localization of phospholipids. Phospholipase A2, purified from bee venom, was adsorbed on gold particles and used for specific labeling of its substrate. Phospholipase A2-colloidal gold (PLA2-CG) complex was applied to freeze-fractured preparations of rat exocrine pancreatic cells and testicular Sertoli cells, both of which are known to have extensive TJ complexes on their plasma membranes. Fracture-label replicas of exocrine pancreatic cells revealed specific association of gold particles with TJ fibrils on the protoplasmic fracture-face of the plasma membrane. The majority of these gold particles were observed either directly on the top of the TJ fibrils or adjacent to these cylindrical structures. A high density of PLA2-CG labeling was also observed over the complementary exoplasmic fracture-face of the TJ complex. This intimate association of PLA2-CG labeling with the TJ is particularly evident in the Sertoli cell plasma membrane, where rows of gold particles were observed to be superimposed on parallel arrays of cylindrical strands of the TJ complex. The present findings provide direct cytochemical evidence to support the hypothesis that cylindrical TJ strands observed in freeze-fracture preparations contain phospholipids.

scholarly journals Methicillin-Resistant Staphylococcus aureus Grown on Vancomycin-Supplemented Screening Agar Displays Enhanced Biofilm Formation

2015 ◽  
Vol 59 (12) ◽  
pp. 7906-7910 ◽  
Author(s):  
Wenjiao Chang ◽  
Ding Ding ◽  
Shanshan Zhang ◽  
Yuanyuan Dai ◽  
Qing Pan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Prolonged Exposure ◽  
Brain Heart Infusion ◽  
Polysaccharide Intercellular Adhesin ◽  
Methicillin Resistant ◽  
Content Type ◽  
Brain Heart Infusion Agar ◽  
Infusion Agar

ABSTRACTBrain heart infusion agar containing 3 mg/liter vancomycin (BHI-V3) was used to screen for heterogeneous vancomycin-intermediateStaphylococcus aureus(hVISA). There was markedly greater biofilm formation by isolates that grew on BHI-V3 than by strains that did not grow on BHI-V3. Increased biofilm formation by hVISA may be mediated by FnbA- and polysaccharide intercellular adhesin-dependent pathways, and upregulation ofatlAandsarAmay also contribute to enhanced biofilm formation by hVISA upon prolonged exposure to vancomycin.

scholarly journals Anchorage-dependent surface distribution and partition during freeze-fracture of viral transmembrane glycoproteins.

1990 ◽  
Vol 38 (10) ◽  
pp. 1421-1426 ◽  
Author(s):  
M R Torrisi ◽  
A Pavan ◽  
L V Lotti ◽  
G Migliaccio ◽  
M C Pascale ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Sindbis Virus ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Viral Proteins ◽  
Low Ph ◽  
Surface Distribution ◽  
Transfected Cells ◽  
Cytosolic Side ◽  
Infected Cells

We have compared in the same cell type the surface distribution and partition in freeze-fractured plasma membranes of Sindbis virus glycoproteins in three different situations: (i) in permanently transformed cells that express the glycoproteins as the only viral product; (ii) in cells in which prebound viruses were forced to fuse with the plasma membrane by low pH treatment; (iii) in virus-infected cells. We report here that the viral proteins expressed on the surface of transfected cells show a uniform and unclustered distribution; conversely, in Sindbis virus-infected cells they appear clustered, regionally distributed, and always associated with budding viruses (i.e., interacting with the nucleocapsid on the cytosolic side of the membrane). Furthermore, the viral proteins expressed on transfected cells or implanted by low pH-mediated fusion partition during freeze-fracture with the exoplasmic faces of the cell plasma membranes, whereas an opposite partition is observed in infected cells. These results strongly suggest that in infected cells the clustering and the partition with the protoplasmic faces of the plasma membrane depend only on the strong "anchorage" of the glycoproteins to the nucleocapsid.

scholarly journals Thrombocytopoiesis--analysis by membrane tracer and freeze-fracture studies on fresh human and cultured mouse megakaryocytes.

1984 ◽  
Vol 99 (2) ◽  
pp. 390-402 ◽  
Author(s):  
D Zucker-Franklin ◽  
S Petursson
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Precursor Cell ◽  
Membrane Domains ◽  
Thin Sections ◽  
Energy Dependent ◽  
First Time ◽  
Later Phase ◽  
Peripheral Cytoplasm

The origin of platelets (Pt) from megakaryocytes (MK) is beyond question, but the mechanism whereby Pts are released from the precursor cell is still debated. A widely-held theory claims that the MK plasma membrane invaginates to form demarcation membranes (DMS), which delineate Pt territories. Accordingly, Pts would be derived mostly from the periphery of the MK, and the MK and Pt plasma membranes would have to be virtually identical. Since, on morphologic grounds, this theory is untenable, several aspects of thrombocytopoiesis were reexamined with the help of membrane tracer and freeze-fracture analyses of freshly-collected human and cultured mouse MK. To our surprise, freeze-cleavage of the MK plasma membrane revealed that the vast majority of intramembranous particles (IMP) remained associated with the protoplasmic leaflet (P face), whereas the partition coefficient of IMPs of the platelet membrane was the reverse. This is the first time that any difference between MK and Pt membranes has been determined. Replicas of freeze-fractured MK that were in the process of thrombocytopoiesis revealed an additional novel phenomenon, i.e., numerous areas of membrane discontinuity that appeared to be related to Pt discharge. When such areas were small, the IMP were lined up along the margin of the crevice. At a later phase, a labyrinth of fenestrations was observed. Thin sections of MK at various stages of differentiation showed that Pt territories were fully demarcated before connections of the DMS with the surface could be found. Therefore, the Pt envelope is probably not derived from invaginations of the MK plasma membrane. When living, MK were incubated with cationic ferritin or peroxidase at 37 degrees C, the tracers entered into the DMS but did not delineate all membranes with which the DMS was in continuity, suggesting the existence of distinctive membrane domains. Interiorization of tracer was not energy-dependent, but arrested at low temperatures. At 4 degrees C the DMS remained empty, unless there was evidence that Pts had been released. In such instances, the tracers outlined infoldings of peripheral cytoplasm that was devoid of organelles. Thus, the majority of Pts seem to originate from the interior of the MK, and the surface membranes of the two cells differ in origin and structure. The observations do not only throw new light on the process of thrombocytopoiesis, but also strengthen the possibility that MKs and Pts may be subject to different stimuli.

scholarly journals Membrane particle changes attending the acrosome reaction in guinea pig spermatozoa

1977 ◽  
Vol 74 (2) ◽  
pp. 561-577 ◽  
Author(s):  
DS Friend ◽  
L Orci ◽  
A Perrelet ◽  
R Yanagimachi
Keyword(s):  
Plasma Membrane ◽  
Guinea Pig ◽  
Acrosome Reaction ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Phosphatidylcholine Liposomes ◽  
Acrosomal Membrane ◽  
Large Particles ◽  
Fracture Appearance ◽  
Preparatory Stage

To examine the freeze-fracture appearance of membrane alterations accompanying the preparation of sperm membranes for fusions-the first preparatory stage occurring before physiological release of the acrosomal content, the second afterward-we induced the acrosome reaction in capacitated guinea pig spermatozoa by adding calcium to the mixture. The most common features observed before fusion of the acrosomal and plasma membranes were the deletion of fibrillar intramembranous particles from the E-fracture faces of both membranes, and the clearance of globular particles from the P face of the plasma membrane-events taking place near the terminus of the equatorial segment. Large particles, &gt;12nm, remained not far from the cleared E-face patches. The P face of the outer acrosomal membrane is virtually clear from the outset. In addition, when fusion was completed, occasional double lines of large particles transiently embossed the P face of the plasma membrane (postacrosomal) side of the fusion zone. Behind the line of fusion, another series of particle-cleared foci emerged. We interpreted these postfusion membrane clearances as a second adaptation for sperm-egg interaction. Induction of the acrosome reaction in media containing phosphatidylcholine liposomes resulted in their apparent attachment, incorporation, or exchange in both the originally and secondarily cleared regions. Our observations support the concepts that membranes become receptive to union at particle- deficient interfaces, and that the physiologically created barren areas in freeze-fracture replicas may herald incipient membrane fusion.

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