Mesomechanics and Thermodynamics of Nanostructural Transitions in Biological Membranes Under the Action of Steroid Hormones

Electron Diffraction of Wet Biological Membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050809 ◽

1974 ◽

Vol 32 ◽

pp. 158-159

Author(s):

S.W. Hui ◽

D.F. Parsons

Keyword(s):

Electron Diffraction ◽

Data Collection ◽

Biological Membranes ◽

Small Areas ◽

Electron Diffraction Technique ◽

Electron Microscopes ◽

Collection Time ◽

Camera Length

The development of the hydration stages for electron microscopes has opened up the application of electron diffraction in the study of biological membranes. Membrane specimen can now be observed without the artifacts introduced during drying, fixation and staining. The advantages of the electron diffraction technique, such as the abilities to observe small areas and thin specimens, to image and to screen impurities, to vary the camera length, and to reduce data collection time are fully utilized. Here we report our pioneering work in this area.

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Ultrastructural Cytopiasmic Changes of Adrenal Cortex During Pregnancy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100063408 ◽

1969 ◽

Vol 27 ◽

pp. 298-299

Author(s):

T. M. Murad ◽

Karen Israel ◽

Jack C. Geer

Keyword(s):

Adrenal Gland ◽

Steroid Hormones ◽

Adrenal Cortex ◽

Lipid Droplets ◽

Plasma Cholesterol ◽

Adrenal Steroids ◽

Dynamic Changes ◽

Cortical Cells ◽

Acetyl Coenzyme A ◽

Adrenal Cortical Cells

Adrenal steroids are normally synthesized from acetyl coenzyme A via cholesterol. Cholesterol is also shown to enter the adrenal gland and to be localized in the lipid droplets of the adrenal cortical cells. Both pregnenolone and progesterone act as intermediates in the conversion of cholesterol into steroid hormones. During pregnancy an increased level of plasma cholesterol is known to be associated with an increase of the adrenal corticoid and progesterone. The present study is designed to demonstrate whether the adrenal cortical cells show any dynamic changes during pregnancy.

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Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076640 ◽

1983 ◽

Vol 41 ◽

pp. 608-609

Author(s):

Neng-Bo He ◽

S.W. Hui

Keyword(s):

Lipid Bilayers ◽

Erythrocyte Membrane ◽

Lipid Membranes ◽

Surface Film ◽

Biological Membranes ◽

Electron Microscopic Observation ◽

Electron Microscopic ◽

Black Lipid Membranes ◽

Fine Mesh ◽

Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

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Smooth endoplasmic reticulum in perfusion and immersion-fixed Leydig cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157954 ◽

1990 ◽

Vol 48 (3) ◽

pp. 82-83

Author(s):

R.T.F. Bernard ◽

R.H.M. Cross

Keyword(s):

Endoplasmic Reticulum ◽

Electron Microscope ◽

Steroid Hormones ◽

Transmission Electron Microscope ◽

Leydig Cells ◽

Smooth Endoplasmic Reticulum ◽

Random Mixture ◽

Transmission Electron

Smooth endoplasmic reticulum (SER) is involved in the biosynthesis of steroid hormones, and changes in the organisation and abundance of this organelle are regularly used as indicators of changes in the level of steroidogenesis. SER is typically arranged as a meshwork of anastomosing tubules which, with the transmission electron microscope, appear as a random mixture of cross, oblique and longitudinal sections. Less commonly the SER appears as swollen vesicles and it is generally suggested that this is an artefact caused during immersion fixation or during immersion of poorly-perfused tissue.During a previous study of the Leydig cells of a seasonally reproducing bat, in which tissue was fixed by immersion, we noted that tubular SER and vesicular SER often occured in adjacent cells and sometimes in the same cell, and that the abundance of the two types of SER changed seasonally. We came to doubt the widelyheld dogma that vesicular SER was an artefact of immersion fixation and set out to test the hypothesis that the method of fixation does not modify the ultrastructure of the SER.

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