Topographical stability of lateral regions of the Schizosaccharomyces pombe plasma membrane as revealed by invagination characteristics

1988 ◽  
Vol 34 (9) ◽  
pp. 1063-1068 ◽  
Author(s):  
Kanji Takeo ◽  
Kazuko Nishimura ◽  
Makoto Miyaji
Keyword(s):  
Plasma Membrane ◽  
Stationary Phase ◽  
Schizosaccharomyces Pombe ◽  
Freeze Fracture ◽  
Exponential Phase ◽  
High Density ◽  
The Stability

The characteristics, especially the stability, of plasma-membrane invaginations in Schizosaccharomyces pombe were studied using freeze-fracture techniques. The plasma membrane of exponential-phase S. pombe was characterized by the uninvaginated growing pole(s) and by the existence of particularly long invaginations, reaching up to 5 μm, in the nongrowing lateral regions. The stationary-phase plasma membrane was characterized by densely invaginated cell poles and by the high density of invaginations. After reinoculation of stationary-phase cells in fresh media, preexisting invaginations in the cell poles disappeared when the latter became the growing pole. In lateral regions of the plasma membrane, however, deep invaginations, characteristic of the stationary phase, were well conserved. The results obtained suggest the topographical stability of nongrowing lateral regions of the S. pombe plasma membrane.

Growth-correlated distribution of two types of plasma membrane particles of Schizosaccharomyces pombe

1987 ◽  
Vol 33 (6) ◽  
pp. 528-533 ◽  
Author(s):  
Kanji Takeo
Keyword(s):  
Plasma Membrane ◽  
Schizosaccharomyces Pombe ◽  
Freeze Fracture ◽  
Exponential Phase ◽  
First Report ◽  
Membrane Particles ◽  
Yeast Plasma Membrane

The particle ultrastructure at or near the growing pole and in lateral regions of the plasma membrane of exponential phase Schizosaccharomyces pombe was examined by means of the freeze-fracture technique. The uninvaginated growing pole was predominantly embedded with small globular particles of 4–8 nm in diameter with no depressions. In contrast, densely invaginated lateral regions, where no growth occurs, were rich in large cratered particles of 10–15 nm in diameter with central depressions. On cytokinesis, the middle of the cell near the division furrow became uninvaginated and was predominantly embedded with small globular particles. This is the first report directly concerning the growth-correlated distribution of yeast plasma membrane particles.

Surface views of spermatozoa as revealed by fracture-flip

1989 ◽  
Vol 92 (3) ◽  
pp. 415-426
Author(s):  
C.A. Forsman ◽  
P. Pinto da Silva
Keyword(s):  
Plasma Membrane ◽  
Random Distribution ◽  
Freeze Fracture ◽  
Fracture Morphology ◽  
High Density ◽  
Surface Textures ◽  
Principal Piece ◽  
Boar Spermatozoa ◽  
Posterior Ring

We have used fracture-flip to produce new, macromolecular-resolution images of the surface of boar spermatozoa. Over the head, acrosomal and postacrosomal regions display sharply demarcated, subtly different surface textures. The rim is particle-poor, as well as a region above the oblique cords over the posterior ring. The tail shows two morphologically distinct domains: (1) the principal piece is covered by a high density of parallel-helical strands and a high density of large globular particles; (2) the midpiece and the neck are covered by smaller particles with apparent random distribution. Rectangular surface specializations frequently seen near the annulus display a waffle-like texture. With the notable exception of the parallel-helical strands of the principal piece the fracture-flip images of the boar spermatozoon can be directly related to the freeze-fracture morphology of its plasma membrane.

scholarly journals The acrosomal membrane of boar sperm: a Golgi-derived membrane poor in glycoconjugates.

1985 ◽  
Vol 100 (2) ◽  
pp. 528-534 ◽  
Author(s):  
A P Aguas ◽  
P Pinto da Silva
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Biochemical Characterization ◽  
Freeze Fracture ◽  
Secretory Vesicle ◽  
High Density ◽  
Con A ◽  
Cytoplasmic Surface ◽  
Acrosomal Membrane ◽  
Boar Sperm

The acrosome is a large secretory vesicle of the sperm head that carries enzymes responsible for the digestion of the oocyte's investments. The event leads to sperm penetration and allows fertilization to occur. Release of the acrosomal enzymes is mediated by the interaction between sperm acrosomal and plasma membranes (acrosome reaction). Biochemical characterization of the acrosomal membrane has been restrained by a lack of methods to isolate uncontaminated fractions of the membrane. Here, we use new methods to expose the membrane to in situ cytochemical labeling by lectin-gold complexes. We study the topology and relative density of glycoconjugates both across and along the plane of the acrosomal membrane of boar sperm. Detachment of the plasma membrane from glutaraldehyde-fixed cells exposed the cytoplasmic surface of the acrosome to the lectin markers; freeze-fractured halves of the acrosomal membrane were marked by "fracture-label" (Aguas, A. P., and P. Pinto da Silva, 1983, J. Cell Biol. 97:1356-1364). We show that the cytoplasmic surface of the intact acrosome is devoid of binding sites for both concanavalin A (Con A) and wheat germ agglutinin (WGA). By contrast, it contains a high density of neuraminidase-resistant anionic sites detected by cationic ferritin. On freeze-fractured sperm, the receptors for Con A partitioned with the exoplasmic membrane half of the acrosomal membrane. The Con A-binding glycoconjugates were accumulated on the equatorial segment of the membrane. A low density of WGA receptors, as well as of intramembrane particles, was found on the freeze-fracture halves of the acrosomal membrane. The plasma membrane displayed, in the same preparations, a high density of receptors for both Con A and WGA. We conclude that the acrosome is limited by a membrane poor in glycoconjugates, which are exclusively exposed on the exoplasmic side of the bilayer. Regionalization of Con A receptors on the acrosome shows that sperm intracellular membranes, like the sperm surface, express domain distribution of glycocomponents.

scholarly journals Role of mRNA Stability in Growth Phase Regulation of Gene Expression in the Group A Streptococcus

2006 ◽  
Vol 189 (5) ◽  
pp. 1866-1873 ◽  
Author(s):  
Timothy C. Barnett ◽  
Julia V. Bugrysheva ◽  
June R. Scott
Keyword(s):  
Gene Expression ◽  
Stationary Phase ◽  
Growth Phase ◽  
Group A Streptococcus ◽  
Exponential Phase ◽  
Northern Hybridization ◽  
Late Exponential Phase ◽  
Group A ◽  
Phase Regulation ◽  
The Stability

ABSTRACT The impressive disease spectrum of Streptococcus pyogenes (the group A streptococcus [GAS]) is believed to be determined by its ability to modify gene expression in response to environmental stimuli. Virulence gene expression is controlled tightly by several different transcriptional regulators in this organism. In addition, expression of most, if not all, GAS genes is determined by a global mechanism dependent on growth phase. To begin an analysis of growth-phase regulation, we compared the transcriptome 2 h into stationary phase to that in late exponential phase of a serotype M3 GAS strain. We identified the arc transcript as more abundant in stationary phase in addition to the sag and sda transcripts that had been previously identified. We found that in stationary phase, the stability of sagA, sda, and arcT transcripts increased dramatically. We found that polynucleotide phosphorylase (PNPase [encoded by pnpA]) is rate limiting for decay of sagA and sda transcripts in late exponential phase, since the stability of these mRNAs was greater in a pnpA mutant, while stability of control mRNAs was unaffected by this mutation. Complementation restored the wild-type decay rate. Furthermore, in a pnpA mutant, the sagA mRNA appeared to be full length, as determined by Northern hybridization. It seems likely that mRNAs abundant in stationary phase are insensitive to the normal decay enzyme(s) and instead require PNPase for this process. It is possible that PNPase activity is limited in stationary phase, allowing persistence of these important virulence factor transcripts at this phase of growth.

Ultrastructure of Saccharomyces cerevisiae strain AG1-7 and its responses to changes in environment

1985 ◽  
Vol 31 (2) ◽  
pp. 109-118 ◽  
Author(s):  
J. H. M. Willison ◽  
G. C. Johnston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Stationary Phase ◽  
Cell Density ◽  
Nitrogen Starvation ◽  
Freeze Fracture ◽  
Ultrastructural Changes ◽  
Lag Phase ◽  
Temperature Sensitive ◽  
Low Cell Density

Asynchronous populations of the budding yeast Saccharomyces cerevisiae strain AG1-7 were examined by freeze-fracture electron microscopy for ultrastructural changes occurring in response to changes in the environment, specifically the following: temperature (23 or 37 °C); cell density (exponential, early stationary, and stationary phases); various periods of nitrogen starvation at low cell density, and return of nitrogen-starved cells to nitrogen-replete medium. This information has been gathered in preparation for ultrastructural examination of comparable responses of temperature-sensitive cell-cycle mutants. The plasma membrane was found to be particularly responsive to changes in environment. A high proportion (75%) of cells in exponential phase populations at 37 °C displayed paracrystalline arrays of plasma membrane particles, whereas this proportion was much lower (20%) at 23 °C in the same medium; plasma membrane grooves were longer at 37 than at 23 °C. In budded cells, the mother cell displayed paracrystalline arrays more frequently than the bud. Entry of cells into stationary phase, either through permitting population growth or by limiting nitrogen supply, resulted in increases in numbers of paracrystalline arrays and grooves. Groove depth also increased. The paracrystalline-array and groove-density responses were independent, both during entry into stationary phase and during the subsequent lag phase. Unusual groove forms appeared during stationary phase in high cell density populations, but not in low cell density nitrogen-starved populations. "Aggregate" and "geometric" tonoplast forms, previously described in strain A364A when grown under some of the conditions used here, were not found in AG1-7 under any of the conditions used here. It was demonstrated that particle-free patches can arise rapidly on the tonoplast of AG1-7 in response to temperature change from 37 to 23 °C. During stationary phase, spherosomes (lipid droplets) increased in size, particularly in response to nitrogen depletion. After 72 h of nitrogen starvation, about 10% of cell volume consisted of spherosomes. Changes in vacuolar content and mitochondrial form were also noted during entry into stationary phase.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Deformation of Yeast Plasma Membrane by Ethidium Bromide

1988 ◽  
Vol 46 ◽  
pp. 254-255
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Thin Section ◽  
Ethidium Bromide ◽  
Freeze Fracture ◽  
Mutagenic Effect ◽  
Yeast Cells ◽  
Hydrophobic Region ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Deep Pits

The mutagenic effect of ethidium bromide on the mitochondrial DNA is well established. Using thin section electron microscopy, it was shown that when yeast cells were grown in the presence of ethidium bromide, besides alterations in the mitochondria, the plasma membrane also showed alterations consisting of 75 to 110 nm-deep pits. Furthermore, ethidium bromide induced an increase in the length and number of endoplasmic reticulum and in the number of intracytoplasmic vesicles.Freeze-fracture, by splitting the hydrophobic region of the membrane, allows the visualization of the surface view of the membrane, and consequently, any alteration induced by ethidium bromide on the membrane can be better examined by this method than by the thin section method.Yeast cells, Candida utilis. were grown in the presence of 35 μM ethidium bromide. Cells were harvested and freeze-fractured according to the procedure previously described.

Freeze-fracture observations on changes in the distribution of Filipin-sterol complexes during epididymal maturation and capacitation of boar spermatozoa

1990 ◽  
Vol 48 (3) ◽  
pp. 90-91
Author(s):  
N. Seki ◽  
Y. Toyama ◽  
T. Nagano
Keyword(s):  
Plasma Membrane ◽  
Essential Role ◽  
Freeze Fracture ◽  
Final Concentration ◽  
Freeze Fracturing ◽  
Physiological Conditions ◽  
Epididymal Maturation ◽  
Cacodylate Buffer ◽  
Sperm Membrane ◽  
Boar Spermatozoa

It is believed that i ntramembra.nous sterols play an essential role in membrane stability and permeability. To investigate the distribution changes of sterols in sperm membrane during epididymal maturation and capacitation, filipin has been used as a cytochemical probe for the detection for membrane sterols. Using this technique in combination with freeze fracturing, we examined the boar spermatozoa under various physiological conditions.The spermatozoa were collected from: 1) caput, corpus and cauda epididymides, 2) sperm rich fraction of ejaculates, and 3)the uterus 2hr after natural coition. They were fixed with 2.5% glutaraldehyde in 0.05M cacodylate buffer (pH 7.4), and treated with the filipin solution (final concentration : 0.02.0.05%) for 24hr at 4°C with constant agitation. After the filipin treatment, replicas were made by conventional freeze-fracture technique. The density of filipin-sterol complexes (FSCs) was determined in the E face of the plasma membrane of head regions.

A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

1993 ◽  
Vol 51 ◽  
pp. 346-347
Author(s):  
Randolph W. Taylor ◽  
Henrie Treadwell
Keyword(s):  
Plasma Membrane ◽  
Life Cycle ◽  
Growth Phase ◽  
Filter Paper ◽  
Physarum Polycephalum ◽  
Freeze Fracture ◽  
Petri Dish ◽  
Wire Screen ◽  
Wide Mouth ◽  
Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

Sign in / Sign up

Export Citation Format

Share Document