RC4: Time-Lapse Slide Show of Arabidopsis in 33% D2O

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

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High-voltage Electron Microscopy of astroglial cell whole mounts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143201 ◽

1986 ◽

Vol 44 ◽

pp. 316-317

Author(s):

J.N. Turner ◽

W.G. Shain ◽

V. Madelian ◽

R.A. Grassucci ◽

D.L. Forman

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Time Lapse ◽

Astroglial Cells ◽

High Voltage Electron Microscopy ◽

Rat Glioma ◽

Voltage Electron ◽

High Voltage Electron ◽

Nervous System Function ◽

Beta Adrenergic Agonist

Homogeneous cultures of astroglial cells have proved useful for studying biochemical, pharmacological, and toxicological responses of astrocytes to effectors of central nervous system function. LRM 55 astroglial cells, which were derived from a rat glioma and maintained in continuous culture, exhibit a number of astrocyte properties (1-3). Stimulation of LRM 55s and astrocytes in primary cell cultures with the beta-adrenergic agonist isoproterenol results in rapid changes of morphology. Studies with time lapse video light microscopy (VLM) and high-voltage electron microscopy (HVEM) have been correlated to changes in intracellular levels of c-AMP. This report emphasizes the HVEM results.

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Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141238 ◽

1995 ◽

Vol 53 ◽

pp. 972-973

Author(s):

R H. Selinfreund ◽

A. H. Cornell-Bell

Keyword(s):

Membrane Potential ◽

Confocal Microscopy ◽

Patch Clamp ◽

Electrical Activity ◽

Time Lapse ◽

Neuronal Firing ◽

Neuronal Membrane ◽

Pituitary Cells ◽

Patch Clamp Recording ◽

Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

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