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D J Hulmes

Publications and source records attributed to D J Hulmes.

At least 55 records · Page 3Linked to original sources
PubMed1984

Embryonic chick cartilage collagens. Differences in the low-Mr species present in sternal cartilage and tibiotarsal articular cartilage.

The collagenous polypeptides present in embryonic chick sternal and tibiotarsal cartilages have been solubilised by digestion with pepsin and separated by salt fractionation. Type II collagen, 1 alpha 2 alpha 3 alpha collagen, and two polypeptides (apparent molecular mass 150 and 42 kDa), which were reducible to a number of smaller peptides, were extracted from both tissues. However, also present in the peptic digests of tibiotarsal cartilages was a major non-reducible highly-soluble polypeptide of 45 kDa. This short-chain collagen is apparently identical to the pepsinized product of G collagen (Mr 59 000), a major low-Mr procollagen-like species previously detected in chick chondrocyte cultures.

Amino Acids↗
PubMed1983

On the state of aggregation of newly secreted procollagen.

Procollagen and partially processed procollagen from cultures of primary chicken embryo tendon cells appeared as segment-long-spacing (SLS)-like aggregates when drops of medium were negatively stained and examined by electron microscopy. Similar aggregates were obtained after negative staining of medium partially purified by gel filtration and also after staining thin sections of fixed, dehydrated, and embedded pellets formed by prolonged ultracentrifugation of whole culture medium. In contrast to results from electron microscopy, analysis by velocity density gradient sedimentation or sedimentation equilibrium indicated the exclusive presence of procollagen or partially processed procollagen monomers in solution. These contradictory data can be reconciled if procollagen exists in monomeric form when greatly diluted (as in culture medium), and in specific aggregated form (SLS) at high concentration. We believe that cells in vivo secrete procollagen in high, local concentration packaged in the SLS form. We propose that such zero-D arrayed packages are the precursors of native collagen fibrils.

Animals↗
PubMed1981

Electron microscopy shows periodic structure in collagen fibril cross sections.

X-ray diffraction was used to monitor the effects of electron microscope fixation, staining, and embedding procedures on the preservation of the three-dimensional crystalline order in collagen fibrils of rat tail tendon. A procedure is described in which the characteristic 3.8-nm lateral spacing is preserved, with increased contrast, in the diffraction pattern of the embedded fiber. This spacing is correlated with the separation between the tangentially oriented equally spaced lines of density observed in electron microscope ultrathin fibril cross sections of the same material. Optical diffraction of electron micrographs gives an objective measure of the periodicity and suggests that the fibril is composed of concentrically oriented crystalline domains. These observations, when combined with a recent interpretation of the native x-ray diffraction data [Hulmes, D. J. S. & Miller, A. (1979) Nature (London) 282, 878-880] suggest a tentative model for the three-dimensional structure of collagen fibrils.

Animals↗
PubMed1979

Procollagen segment-long-spacing crystallites: their role in collagen fibrillogenesis.

Naturally occurring segment-long-spacing crystallites of procollagen collagen have been found in the culture medium of fibroblasts from chick embryo tendon, human skin, and dermatosparaxic calf skin; in whole-mount preparations of cultured human skin fibroblasts; in homogenates of lathyritic chick embryo tendon, cartilage, and cornea; and in a partially purified preparation of procollagen. Bundles of similar aggregates occurred within secretory vacuoles of collagen-synthesizing fibroblasts and chondrocytes. These observations suggest that fibroblasts and chondrocytes secrete procollagen assemblies that are stable in the extracellular environment. We propose that subsequent enzymatic processing is accompanied by direct incorporation of such structures into the assembling fibril, which then may be considered as an n X 67 nm staggered array of segment-long-spacing crystallites.

Animals↗
PubMed1978

Low angle X-ray diffraction studies on stained rat tail tendons.

Low angle X-ray diffraction patterns of rat tail tendons with heavy metal stains added were examined to help clarify the effects of fixation and staining on collagen fibrils. Fixing and staining of rat tail tendon fibers gives an X-ray pattern with an intensified 3.8 nm row and the preservation of most equatorial features found in the native pattern. The presence of the native pattern features suggests the value of fixation in preserving native structure before staining. Staining of rat tail tendon fibers without prior fixation led to the disappearance of the native equatorial features and the appearance of a new broad row line corresponding to a spacing of around 10.0--17.5 nm. This observation suggests that some alteration has taken place in the native structure and may be related to electron microscopic observations of units of 10.0--20.0 nm in collagen fibrils under some disruptive or developmental conditions.

Animals↗