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Escherichia coli is the major expression host for the production of homogeneous protein samples for structural studies. The introduction of high-throughput technologies in the last decade has further revitalized E. coli expression, with rapid assessment of different expression strategies and successful production of an ever-increasing number of proteins. In addition, miniaturization of biophysical characterizations should soon help choosing expression strategies based on quantitative and qualitative observations. Since many proteins form larger assemblies in vivo, dedicated co-expression systems for E. coli are now addressing the reconstitution of protein complexes. Yet, co-expression approaches show an increasing experimental combinatorial intricacy when considering larger complexes. The current combination of high-throughput and co-expression technologies paves the way, however, for tackling larger and more complex macromolecular assemblies., (Copyright © 2013. Published by Elsevier Ltd.)

The purpose of this study was to determine the effect of Haversian remodeling on the tensile properties of human cortical bone by testing specimens containing, as far a possible, a single type of bone tissue. Fifty-one specimens were prepared from sixteen fresh tibias, removed at autopsy. Age range was 19-35. Regions were selected so that the specimens would consist almost exclusively of either primary bone or Haversian bone. The ultimate tensile strength, ultimate strain and Young's modulus of elasticity were determined at a loading rate of 0.05 mm s-1. The primary bone specimens were found to have a significantly higher ultimate tensile strength and modulus of elasticity than those formed of Haversian bone.