Organization of the cell membrane inEuglena

Miller, Kenneth R.; Miller, G. J.

doi:10.1007/bf01279691

Cited by 29 publications

(11 citation statements)

References 10 publications

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“…4c). The striated EF fracture surface can be identified in these stripped membranes since the opposing protoplasmic face (PF) retains large granules that are artifacts of the relatively high temperature (-120*C) used for fracturing these membranes (38). In negatively stained preparations (not shown) as well as in fractured (Fig.…”

Section: Effects Of Naoh On Isolatesmentioning

confidence: 99%

The membrane skeleton of a unicellular organism consists of bridged, articulating strips.

Dubreuil¹,

Bouck²

1985

The Journal of Cell Biology

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In this paper we show that a membrane skeleton associated with the plasma membrane of the unicellular organism Euglena consists of ~40 individual S-shaped strips that overlap along their lateral margins. The region of strip overlap is occupied by a set of microtubule-associated bridges and microtubule-independent bridges. Both cell form and plasma membrane organization are dependent on the integrity of this membrane skeleton. Removal of the membrane skeleton with a low-molar base results in loss of membrane form and randomization of the paracrystalline membrane interior characteristic of untreated cells. Conversely, removal of the plasma membrane and residual cytoplasm with lithium 3,5-diiodosalicylate/Nonidet P-40 yields cell ghosts that retain the form of the original cell but consist only of the membrane skeleton. Two major polypeptides of 86 and 80 kD persist in the skeleton and two other major proteins of 68 and 39 kD are associated with the plasma membrane fraction. None of these components appears to be the same as the major polypeptides (spectrins, band 3) of the erythrocyte ghost, the other cell system in which a well-defined peripheral membrane skeleton has been identified. We suggest that the articulating strips of euglenoids are not only the basic unit of cell and surface form, but that they are also positioned to mediate or accommodate surface movements by sliding, and to permit surface replication by intussusception.Many euglenoids can undergo rapid changes in cell shape. Earlier suggestions (27) and recent evidence (57) indicate that these shape changes may be generated at the cell surface, thereby making this an especially interesting region of the motile cell. The surface of these euglenoids consists of alternating ridges and grooves that shift in orientation during cell deformation (2,4,22,28,37). The plasma membrane follows the contours of the ridges and grooves and is underlain by a closely adhering membrane skeleton. Previous studies have shown that when surfaces of Euglena are removed from other portions of the cytoplasm, they retain the native surface organization of ridges and grooves (22), although whole cell form is lost by fragmentation during isolation. At least three components of these surface isolates could in theory maintain surface and/or whole cell form: (a) The plasma membrane could dictate cell shape by a bilayer-couple mechanism (50) as resuggested for the erythrocyte (9,12,24,25,49). (b) The membrane skeleton could impose its own shape onto the plasma membrane, as proposed for the spectrin-rich membrane skeleton of the erythyrocyte (6, 23, 42, 51, reviewed in references 19 and 33). (c) The surface-associated microtubules may be responsible for whole cell shape, as previously suggested (13), although it seems unlikely that they are required for the maintenance of ridges and grooves (22).In the present study we have first examined in detail the structural organization of the ridge and groove and have found that they consist of articulating S-shaped strips joined at th...

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Section: Effects Of Naoh On Isolatesmentioning

confidence: 99%

The membrane skeleton of a unicellular organism consists of bridged, articulating strips.

Dubreuil¹,

Bouck²

1985

The Journal of Cell Biology

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“…Their appearance in thin sections suggests that the particles are inserted into the membrane lipid bilayer, and thus are probably integral membrane proteins. An array of integral membrane particles has been seen in freeze fracture studies of Euglena gracilis, another algae of the Euglenophyceae class (24,25) . The particles in that species are smaller and have a different shape than the ones seen in Distigma, but it is interesting to note that they too occur in rows that cross the surface folds at -35°.…”

Section: Components Of the Membranemicrotubule Complexmentioning

confidence: 99%

Three-dimensional structure of a membrane-microtubule complex.

Murray¹

1984

The Journal of Cell Biology

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The unicellular algae Distigma proteus contain a group of aligned microtubules associated with their cell membrane. The association is maintained in isolated membrane fragments. The membrane-microtubule complex also includes a crystalline array of membrane particles. The major peptide component of this array was identified by labeling whole cells with radioiodine. The entire complex of membrane, particles, and microtubules is sufficiently well ordered to permit reconstruction from electron micrographs by Fourier techniques. A three-dimensional model of the membrane array at a nominal resolution of 2.5 nm has been calculated. Some similarities were apparent between lattice spacings in the membrane array and in microtubules. Analysis of these lattice correlations suggests a way in which the array of membrane particles may serve as scaffolding for microtubule attachment.

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“…In general, both micro‐tubules and the proteinaceous strips of the cell cortex migrate through the canal opening and form the inner cytoskeletal lining of the canal. Within the canal, the proteinaceous strips disappear gradually near the junction between the canal and reservoir, an anatomical position that may be termed the “transition zone” (Miller and Miller 1978). The microtubules of the pellicle pass around the reservoir and are continuous with those of one of the three flagellar roots, which functions as an MTOC (Farmer and Triemer 1988; Willey and Wibel 1985).…”

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confidence: 99%

Comparative Morphology of the Euglenid Pellicle. I. Patterns of Strips and Pores

Leander

Farmer

2000

J Eukaryotic Microbiology

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In anticipation that improved knowledge of euglenid morphology will provide robust apomorphy-based definitions for clades, transmission and scanning electron microscopy were used to reveal novel morphological patterns associated with the euglenid pellicle. In some taxa, the number of pellicle strips around the cell periphery reduces as discrete whorls at the anterior and posterior ends of the cell. The number of whorls at either end varies between selected euglenid taxa but is invariant within a taxon. The pattern of strip reduction associated with these whorls is shown to have at least three evolutionarily linked states: exponential, pseudoexponential, and linear. Two general equations describe these states near the posterior end of euglenid cells. Exponential patterns of strip reduction near the anterior end are described by a third equation. In addition, several euglenid taxa were found to possess conspicuous pellicle pores. These pores are arranged in discrete rows that follow the articulation zones between adjacent strips. The number of strips between rows of pores varies between taxa and displays a series of consecutive character states that differ by a power of two. The patterns of pores may not only have phylogenetical and taxonomical value but may provide morphological markers for following strip maturation during cytoskeletal reproduction.

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Organization of the cell membrane inEuglena

Cited by 29 publications

References 10 publications

The membrane skeleton of a unicellular organism consists of bridged, articulating strips.

The membrane skeleton of a unicellular organism consists of bridged, articulating strips.

Three-dimensional structure of a membrane-microtubule complex.

Comparative Morphology of the Euglenid Pellicle. I. Patterns of Strips and Pores

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