The direct measurement of temperature changes within freeze‐fracture specimens during rapid quenching in liquid coolants

Costello, M. Joseph; Corless, Joseph M.

doi:10.1111/j.1365-2818.1978.tb01151.x

Cited by 155 publications

(72 citation statements)

References 10 publications

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“…Samples containing < 50% PEG were mixed with glycerol to a final concentration of 30%. In some instances samples were frozen without cryoprotectants, employing a quick freeze apparatus (Costello & Corless, 1978) built in this laboratory. In this method, 0.1 gl of sample was placed between a 75-1am thick copper foil sandwich and rapidly quenched in liquid propane from room temperature.…”

Section: Freeze-fracture Electron Microscopymentioning

confidence: 99%

Lipid-polyethylene glycol interactions: I. Induction of fusion between liposomes

et al. 1981

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Fusion between unilamellar vesicles of both egg phosphatidylcholine and bovine phosphatidylserine was induced by polyethylene glycol. Aggregation and fusion events were monitored by electron microscopy and turbidity measurements. The threshold concentration of polyethylene glycol for aggregation and fusion is found to be independent of lipid concentration. Typically, aggregation of phosphatidylcholine vesicles starts at 2.5% (wt/wt) polyethylene glycol, but fusion is not significant until the polyethylene glycol concentration reaches 35%. Multilamellar vesicles were formed as a result of fusion.

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Section: Freeze-fracture Electron Microscopymentioning

confidence: 99%

Lipid-polyethylene glycol interactions: I. Induction of fusion between liposomes

et al. 1981

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“…For the unfixed specimens, the thin strips of outer medulla were further trimmed to a standard volume (hereafter called blocks) of about 0.25 x 0.25 x 0.5 mmL These blocks were placed on Balzers specimen holders and frozen by immersion in liquid propane (Air Products and Chemicals, Inc., Tamaqua, Pa.) using a guillotinetype device [2]. The tissue was frozen in its own "natural juices.…”

Section: Preparation Of the Tissue For Freezingmentioning

confidence: 99%

Intercellular fibrillar skeleton in the basal interdigitations of kidney tubular cells

Zampighi

Kreman

1985

J. Membrain Biol.

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The tubular cells from the thick ascending limb of the loop of Henle in rabbit kidney medulla contain in their basal-lateral surfaces a complex system of interdigitations. Within these interdigitations, the plasma membranes are separated by extracellular spaces of relatively constant width that contain a previously undescribed fibrillar system. The structural organization and distribution of this intercellular fibrillar skeleton was studied using freeze-fracture etch and then section electron microscopy. The skeleton is comprised of discrete strands with a density of 300 to 400 per micron 2 evenly distributed along the entire basal-lateral region. Each strand has the shape of a brace and it is constructed from up to eight finer filaments each having a width of about 2 nm. The filaments are tightly joined together along their shafts for about 30 nm but they separate at both ends for about 10 nm before contacting the external surface of the plasma membrane. We propose that this intercellular fibrillar skeleton is responsible for maintaining the wide (about 50 nm) and uniform plasma membrane separation along the entire length of the basal-lateral region of the tubular cells of the thick ascending limb.

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“…They were fixed with aldehydes, thoroughly washed with double distilled water, aligned in a single layer in a 'copper sandwich' holder, and frozen in liquid propane (Costello & Corless, 1978). The specimens, surrounded by a liquid nitrogen cooled shroud, were fractured at -130 0C and etched for 10 m at -100 0C in order to reveal the true external surface of muscle cells.…”

Section: Pmentioning

confidence: 99%

“…Firstly, enzymatic digestion of basal lamina and collagen removes the nerve terminals and cleans the true external membrane of material that would obscure the AChR. Secondly, the use of a monolayer of fibres in a 'copper sandwich', allows rapid freezing rates with a consequent good preservation of the non-cryoprotected tissue (Costello & Corless, 1978).…”

Section: Pmentioning

confidence: 99%

Communications

1981

The Journal of Physiology

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It has recently been suggested that the inactivation of calcium currents in molluscan neurones may depend on calcium entry, rather than membrane potential as such (Tillotson, 1979). We have studied calcium current in identified, voltageclamped neurones of the snail bathed in sodium-free saline containing 25 mm CaCl2, 10 KCl, 5 MgCl2, 5 Tris-HCl, with 75 mm TEA-Cl and 2 mM-4-aminopyridine to reduce potassium currents as much as possible.Under these conditions inward calcium currents turn offexponentially over the first 100 msec at potentials up to + 20 mV. At these potentials the currents do not inactivate completely, even during pulses up to 1 see in duration. With potentials more positive than + 20 mV the current becomes outward at the end of a 400-msec pulse. Cadmium ions (1-2 mM) completely abolished the inward current and, for potentials above +30 mV, also reduced the net outward current at the end of a 400-msec pulse, suggesting that some of this outward current was calcium-activated.The rate of decline of the calcium current was dependent on its size. When the current was reduced by reducing [Ca]o from 25 to 5 mm the decline was slowed. (For a pulse to 0 mV the time constant changed from 46 to 88 msec.) The inactivation was also studied in two-pulse experiments. A 250 msec pre-pulse of variable voltage was followed after a 100-msec interval by a test pulse to 0 mV. The inward current during the test pulse was reduced as the pre-pulse became more positive in the range -30 to + 30 mV, but then increased with further depolarization, approaching the value for no pre-pulse when the pre-pulse was + 110 to + 120 mV.This result may be interpreted in terms of calcium entry causing calcium inactivation, or alternatively in terms of the calcium entry leading to a Ca-activated potassium current instantaneously activated by depolarization during the test pulse. Such Ca-activated K currents have been shown to be voltage-dependent (Gorman & Hermann, 1979), and it might therefore be expected that such an effect would increase with increasing test pulse potential. This second explanation is less likely as the relationship between test pulse current relative to that with no pre-pulse

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The direct measurement of temperature changes within freeze‐fracture specimens during rapid quenching in liquid coolants

Cited by 155 publications

References 10 publications

Lipid-polyethylene glycol interactions: I. Induction of fusion between liposomes

Lipid-polyethylene glycol interactions: I. Induction of fusion between liposomes

Intercellular fibrillar skeleton in the basal interdigitations of kidney tubular cells

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