The plasma membrane of pityrosporum has natural markers to show how the cell grows

1978 ◽  
Vol 36 (2) ◽  
pp. 404-405
Author(s):  
Kanji Takeo ◽  
Ei-Ichi Nakai
Keyword(s):  
Plasma Membrane ◽  
Spiral Groove ◽  
Left Handedness ◽  
Left Handed ◽  
Specimen Holder ◽  
Inner Surface ◽  
Freeze Etching ◽  
Pityrosporum Orbiculare ◽  
Tinea Versicolor ◽  
Spiral Grooves

Pityrosporum is a lipophilic yeast containing the causative agent of tinea versicolor, and has spiral grooves on the inner surface of the cell wall and the plasma membrane. Detailed studies on the plasma membrane of this organism revealed the existence of asymmetry around the plasma membrane, peculiar mode of the growth of this organism, mode of spiral groove formation, and a possible mechanism of groove formation. One strain each of Pityrosporum orbiculare and P. pachydermatis and ten strains of P. ovale were grown on a potato yeast extract agar, supplemented with 1% olive oil at 27-37°C for 1-20 days. Cultures were directly transferred to the specimen holder of the freeze-etching apparatus without no pretreatment. 40% glycerol was added before cooling.All the strains tested of the genus Pityrosporum had only left-handed spiral grooves of the plasma membrane. Left-handedness of the spiral grooves of Pityrosporum was confirmed by scanning electron microscopy which occasionally revealed left-handed spiral grooves on the outer surface of the wall.

Mode of cell growth of Malassezia (Pityrosporum) as revealed by using plasma membrane configurations as natural markers

1986 ◽  
Vol 32 (5) ◽  
pp. 389-394 ◽  
Author(s):  
K. Takeo ◽  
E. Nakai
Keyword(s):  
Plasma Membrane ◽  
Cell Growth ◽  
Freeze Fracture ◽  
Mature Cell ◽  
Left Handed ◽  
Wall Growth ◽  
Spiral Grooves

The mode of cell growth of Malassezia was studied by freeze–fracture using the plasma membrane configurations of this organism as natural markers. The plasma membrane of the mature cell bodies of M. pachydermatis had a ring swelling, and on each side of the ring, one set of straight and spiral grooves and circumvallate bulgings. The cell always divided at the ring swelling (M. pachydermatis) or depression (M. furfur), soon followed by budding there. A new set of similar configurations formed on the bud. In all the 12 strains of Malassezia studied, the spiral grooves in the mother and bud parts were both left-handed but opposite in the direction of elongation. By comparing distances between the spiral grooves in short and long buds and in mothers, the bud tip was suggested as the major, and adjacent regions as the minor, sites of wall growth. Some characterizations of the plasma membrane invaginations, especially in relation to the mode of cell growth, were also described.

scholarly journals STRUCTURAL FEATURES OF MESOSOMES (CHONDRIOIDS) OF BACILLUS SUBTILIS AFTER FREEZE-ETCHING

1968 ◽  
Vol 39 (2) ◽  
pp. 251-263 ◽  
Author(s):  
N. Nanninga
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Plasma Membrane ◽  
Outer Surface ◽  
Osmium Tetroxide ◽  
Close Association ◽  
Membrane Surface ◽  
Bacterial Membranes ◽  
Inner Surface ◽  
Freeze Etching

Freeze-etched cells of Bacillus subtilis have been studied with the electron microscope. The outer surface of the plasma membrane, i.e. the side facing the cell wall, is covered with numerous granules and short strands, each measuring approximately 50 A in diameter. These strands are occasionally seen to enter the cell wall. The inner surface of the plasma membrane, i.e. the side facing the cytoplasm, appears to be sparsely dotted with small particles measuring about 50 A. The envelope of mesosomes differs from the plasma membrane. Blunt protrusions arise from its outer surface; the inner surface appears smooth. Stalked particles, as described by other investigators after negative staining with phosphotungstic acid, were not observed on any membrane surface in our material. Preparations were also made of specimens prefixed in osmium tetroxide prior to freeze-etching. Under these conditions the bacterial membranes appeared to be surprisingly well preserved. In contrast to directly frozen, unfixed cells, some osmium tetroxide-fixed preparations showed a differentiation in cytoplasm and nucleoplasm, which made it possible to observe the close association of the mesosome with the latter.

New Dimensions in Freeze-Etching

1969 ◽  
Vol 27 ◽  
pp. 202-203 ◽  
Author(s):  
Russell L. Steere ◽  
Michael Moseley
Keyword(s):  
Fracture Surfaces ◽  
Aluminum Specimen ◽  
Specimen Holder ◽  
Freeze Etching ◽  
The Right

A redesigned specimen holder and cap have made possible the freeze-etching of both fracture surfaces of a frozen fractured specimen. In principal, the procedure involves freezing a specimen between two specimen holders (as shown in A, Fig. 1, and the left side of Fig. 2). The aluminum specimen holders and brass cap are constructed so that the upper specimen holder can be forced loose, turned over, and pressed down firmly against the specimen stage to a position represented by B, Fig. 1, and the right side of Fig. 2.

Ultrastructure and development of urediospore ornamentation in Melampsora lini

1971 ◽  
Vol 49 (12) ◽  
pp. 2067-2073 ◽  
Author(s):  
L. J. Littlefield ◽  
C. E. Bracker
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Outer Surface ◽  
Spore Wall ◽  
Wall Material ◽  
Wild Type ◽  
Melampsora Lini ◽  
Inner Surface ◽  
External Position ◽  
Basal Portion

The urediospores of Melampsora lini (Ehrenb.) Lev. are echinulate, with spines ca. 1 μ long over their surface. The spines are electron-transparent, conical projections, with their basal portion embedded in the electron-dense spore wall. The entire spore, including the spines, is covered by a wrinkled pellicle ca. 150–200 Å thick. The spore wall consists of three recognizable layers in addition to the pellicle. Spines form initially as small deposits at the inner surface of the spore wall adjacent to the plasma membrane. Endoplasmic reticulum occurs close to the plasma membrane in localized areas near the base of spines. During development, the spore wall thickens, and the spines increase in size. Centripetal growth of the wall encases the spines in the wall material. The spines progressively assume a more external position in the spore wall and finally reside at the outer surface of the wall. A mutant strain with finely verrucose spores was compared to the wild type. The warts on the surface of the mutant spores are rounded, electron-dense structures ca. 0.2–0.4 μ high, in contrast to spines of the wild type. Their initiation near the inner surface of the spore wall and their eventual placement on the outer surface of the spore are similar to that of spines. The wall is thinner in mutant spores than in wild-type spores.

Ehud, Stigma, and the Management of Spoiled Identity

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
David J. Chalcraft
Keyword(s):  
Social Stigma ◽  
The Other ◽  
Social Model ◽  
Erving Goffman ◽  
Self Identity ◽  
Social Model Of Disability ◽  
Left Handedness ◽  
Left Handed ◽  
Moral Career ◽  
The One

The story of Ehud, and his assassination of the Moabite King Eglon (Judges 3: 12–30), continues to entertain readers and hearers alike. The story also perplexes, largely on moral grounds. This paper utilises the sociology of Erving Goffman and insights from disability studies to re-tell the story of Ehud as someone who is doubly stigmatised. That is, Ehud not only carriers the stigma of left-handedness but is also disabled; moreover, the Moabite King is also disabled/immobile because of his obesity. I take the biblical text as conveying that Ehud is left-handed by necessity given the impairment in his right hand/arm. Adopting a social model of disability, I apply Goffman’s account of the management of spoiled identity developed in his book Stigma (1963) to explore how the narrative depicts various dimensions of social stigma and Ehud’s moral career as he attempts to manage his spoiled identity and the degrees of societal acceptance and rejection he experiences in different contexts. The key arguments of Goffman are summarised before I apply central concepts from Goffman to the biblical story. Concepts include “moral career,” the distinction between social, personal and ego (self-) identity, and the key distinction between a person with a stigma being discredited (because the impairment is obvious and seen by all), on the one hand, or bearing a stigma that is discreditable (that is, it would discredit them if found out), on the other.

scholarly journals Paracrystalline arrays of membrane-to-membrane cross bridges associated with the inner surface of plasma membrane

1978 ◽  
Vol 77 (2) ◽  
pp. 323-328 ◽  
Author(s):  
WW Franke ◽  
C Grund ◽  
E Schmid ◽  
E Mandelkow
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Cultured Cells ◽  
Membrane Surface ◽  
Hexagonal Lattice ◽  
Interparticle Distance ◽  
Macromolecular Complexes ◽  
Inner Surface ◽  
Cross Bridges ◽  
Plasma Membrane Surface

In cultured cells of the rat kangaroo PtK2 line, veils of the cell surface were observed which consisted of only plasma membrane and paracrystalline arrays of membrane-associated particles sandwiched in between. These membrane-to-membrane cross-bridging 9-to 11-nm wide particles were somewhat coumellar-shaped and were arranged on a hexagonal lattice with an interparticle distance of 16nm. At higher magnification, they revealed an unstained core, thus suggesting a ringlike substructure. Similar arrays of paracrystal-containing veils, which were rather variable in size and frequency, were also observed in other cultured cells. It is hypothesized that these paracrystals represent protein macromolecular complexes associated with the inner plasma membrane surface which crystallize when plasma membranes come into close intracellular contact and other components of the subsurface network are removed.

scholarly journals Aetiological factors in left-handedness

2005 ◽  
Vol 133 (11-12) ◽  
pp. 532-534 ◽  
Author(s):  
Sanja Milenkovic ◽  
Goran Belojevic ◽  
Radojka Kocijancic
Keyword(s):  
Genetic Factors ◽  
The Body ◽  
Intrauterine Environment ◽  
Foetal Development ◽  
Ultrasound Exposure ◽  
The Past ◽  
Left Handedness ◽  
Left Handed ◽  
Efferent Pathways ◽  
Genetically Determined

Lateralisation associates the extremities and senses of one side of the body, which are connected by afferent and efferent pathways, with the primary motor and sensory areas of the hemisphere on the opposite side. Dominant laterality denotes the appearance of a dominant extremity or sense in the performance of complex psychomotor activities. Laterality is manifested both as right-handedness or left-handedness, which are functionally equivalent and symmetrical in the performance of activities. Right-handedness is significantly more common than left-handedness. Genetic theory is most widely accepted in explaining the onset of lateralisation. According to this theory, the models of brain organisation asymmetry (anatomical, functional, and biochemical) are strongly, genetically determined. However, the inability to clearly demonstrate the association between genetic factors and left-handedness has led researchers to investigate the effects of the environment on left-handedness. Of particular interest are the intrauterine environment and the factors influencing foetal development, of which hormones and ultrasound exposure are the most significant. It has been estimated that an extra five cases of nonright-handed lateralisation can be expected in every 100 males who were exposed to ultrasound in utero compared to those who were not. Socio-cultural pressure on left-handed individuals was much more severe in the past, which is confirmed by scientific findings that left-handedness is present in 13% of individuals in their twenties, while in less than 1% of individuals in their eighties.

scholarly journals The incidence of left-handedness: a meta-analysis [1993]

2019 ◽  
Author(s):  
Ian Christopher McManus
Keyword(s):  
Sex Difference ◽  
Meta Analysis ◽  
Birth Cohorts ◽  
Future Studies ◽  
Left Handedness ◽  
Left Handed ◽  
Method Of Measurement ◽  
Males And Females ◽  
Older Subjects ◽  
Unpublished Manuscripts

A meta-analysis is reported of 88 studies, examining 100 study populations, in which the handedness of 284665 individuals has been assessed. The overall incidence of left-handedness was 7.78%. The incidence of left-handedness was not related to the method of measurement, or the length or number of response items included in inventories. Study populations with lower response rates and smaller study populations showed some evidence of higher incidences of left-handedness, presumably due to response biasses. There was no evidence that the incidence of left-handedness was related to the year of publication of studies; however the incidence of left-handedness was lower in older subjects and in those from earlier birth cohorts, the two effects not being statistically distinguishable.Information was available from 64 study populations concerning the incidence of left-handedness in males and females; overall 8.52% of males were left-handed compared with 6.69% of females, the male incidence being 27.4% higher than that in females. Although there was some suggestion that the sex difference was greater in larger studies, and in studies whose main purpose was not the study of handedness, these differences were not significant. It is concluded that the size of the sex difference is unrelated to any of the moderator variables we have studied.It was not possible to carry out a meta-analysis of degree of handedness due to wide-spread differences in the method of reporting of degree of handedness.We recommend that future studies of handedness should, as a minimum, use one of three standard methods of assessment, so that comparison of studies is facilitated. Note: This manuscript was originally prepared in 1993 but due to problems at a major journal, described briefly, was never eventually published. It has however been cited on a number of occasions, and has been available at https://www.ucl.ac.uk/medical-education/publications/unpublished-manuscripts/meta-analysis-of-handedness . A major meta-analysis of handedness in 2019 by another author has now been submitted which cites this manuscript, and therefore it needs to be available in a more archivable format.

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