Extracellular matrix synthesis by skeletal muscle in culture. Proteins and effect of enzyme degradation

Extracellular matrix proteins produced by a mouse skeletal muscle cell line, G8-1, were isolated and characterized. Cultures were incubated with [35S]methionine or [3H]glycine and [3H]proline, and the labeled, substrate-attached proteins were obtained after cellular proteins were extracted by deoxycholate in neutral salt. The labeled matrix was analyzed by gel electrophoresis and fluorography before and after enzymatic digestion. Of the nine major bands present in the matrix, four were identified. Fibronectin and collagen were detected on the bases of their relative mobilities, differential labeling with 3H-versus 35S-labeled amino acids and their solubilization by protease free collagenase. High molecular weight material which was present in the matrix was also sensitive to collagenase and probably included cross-linked collagen and laminin. Proteins co-migrating with actin and myosin were also present in the extracellular matrix. These results are novel in that they demonstrate that the skeletal muscle phenotype, not contaminated with fibroblastic elements, is able to synthesize basal lamina-type macromolecules and incorporate them into an insoluble, extracellular matrix. Since this cell line is able to form functional synaptic contacts with neuronal cells, the influence of nerve on basal lamina production by muscle in vitro is possible.     

Epidemiological observations on contagious equine metritis in Kentucky, 1978.

Contagious equine metritis, introduced by importation of 2 comtaminated stallions from France, affected 54 Thoroughbred brood mares during the 1978 breeding season in Kentucky. The infection was diagnosed bacteriologically and by the use of a complement fixation test. Although lateral spread to stallions, and probably to a few mares, occurred through human agency in the breeding sheds of 2 stud farms, control measures instituted early in the epidemic confined the disease to brood mares bred by stallion on only these farms.     

The histone demethylase KDM5 is required for synaptic structure and function at the Drosophila neuromuscular junction

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