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H C Fertuck

Publications and source records attributed to H C Fertuck.

7 recordsLinked to original sources
PubMed1977

Resolution in electron microscope autoradiography. III. Iodine-125, the effect of heavy metal staining, and a reassessment of critical parameters.

Resolution for 125I-labeled specimens under electron microscope (EM) autoradiographic conditions was assessed experimentally. With this isotope the size of the silver halide crystal was the most important resolution-limiting factor. Heavy metal staining such as is routinely used in preparing animal tissues for EM autoradiography produced an improvement in resolution of approximately 15-20%. For a 500-1,000-A biological tissue section fixed with OsO4 and stained with uranyl acetate, we obtained resolution (half distance, HD) values of approximately 800 +/- 120 A using Ilford L4 emulsion and 500 +/- 70 A using a Kodak NTE-type emulsion. General aspects of resolution-limiting factors and comparison with 3H and 14C values are discussed.

Animals↗
PubMed1976

Quantitation of junctional and extrajunctional acetylcholine receptors by electron microscope autoradiography after 125I-alpha-bungarotoxin binding at mouse neuromuscular junctions.

The distribution and quantitation of 125I-alpha-bungarotoxin (alpha-BTX) binding sites and thus acetylcholine receptor (AChR) were determined in mouse sternomastoid muscle by electron microscope autoradiography. We found that a valid criterion for receptor saturation at the neuromuscular junction was the complete elimination of neurally evoked tetanic muscle contractions, since, when such a criterion was used for the endpoint of toxin incubation, alpha-BTX was bound to approximately 90% of total available endplate sites. When, without implying localization, the presynaptic axonal membrane was used as a convenient reference structure, the concentration of alpha-BTX relative to this membrane was determined to be 46,000 +/- 27% sites/mum2.

Acetylcholine↗
PubMed1975

In vivo recovery of muscle contraction after alpha-bungarotoxin binding.

Acetylcholine receptors were inactivated in vivo at the mouse neuromuscular junction using alpha-bungarotoxin (alpha-BTX). It was found that neurally produced muscle contraction recovered within 4-8 days (halftime similar to 3 days). Actinomycin D interfered with this recovery, but did not affect normal nerve-stimulated muscle contraction. If the response was initially eliminated by [125-I]alpha-BTX and the end plates examined by EM autoradiography, no evidence of mass internalization of bound radioactivity during recovery was seen. The fine structure of the end plates and muscle was unaltered during the post-alpha-BTX recovery period.

Acetylcholine↗
PubMed1974

Localization of acetylcholine receptor by 125I-labeled alpha-bungarotoxin binding at mouse motor endplates.

Exposed sternomastoid muscles of anaesthetized mice were bathed in (125)I-labeled alpha-bungarotoxin until all neurally evoked muscle contractions were eliminated. The distribution of label was then determined by electron microscope autoradiography. It was found that the label was localized at the top of the junctional folds, i.e., at the postjunctional membrane nearest the axon. Since the alpha-bungarotoxin had fully eliminated the physiological muscle response, these results indicate that the active acetylcholine receptor occupies a limited area of the junctional folds and is not distributed uniformly throughout this membrane. Specialized membrane densities seem to coincide with the labeled regions.

Animals↗