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- A Comparison of the Killing of Cultured Mammalian Cells Indu...A Comparison of the Killing of Cultured Mammalian Cells Induced by Decay of Incorporated Tritiated Molecules at -196°C
Biophysical Journal, Volume 8, Issue 4, 1 April 1968, Pages 445-456
H.John Burki and S. Okada
AbstractThe killing efficiency of tritium disintegrations in frozen mammalian cells labeled with tritiated uridine, histidine, and lysine was compared with the killing efficiency of incorporated tritiated thymidine. In each case, the distribution of tritium in the cells was determined by chemical fractionation as well as by radio-autography. Of all tritium disintegrations, by far the most effective were those occurring in DNA molecules within frozen cells; such incorporated tritium has a killing efficiency of 0.006. When cells were incubated with tritiated uridine for 10min to label nuclear RNA, the killing efficiency was 0.0015. When the cells were pulse labeled with tritiated uridine and permitted to grow in nonradioactive media for 10 hr before freezing in order to incorporate tritium into cytoplasmic RNA, the killing efficiency was reduced to 0.0010. The results suggest that decay of tritium in nuclear RNA is more effective than that in cytoplasmic RNA. When the cells were labeled with tritiated histidine or lysine for 30min, tritium atoms were found mainly in the acid soluble rather than in the protein fraction and the killing efficiency in each case was approximately 0.0007. The results of these suicide experiments indicate that the killing efficiency of tritium disintegrations depends on where tritium is located within the cells. Tritium disintegrations in the nucleus are more effective in killing the cell than that in cytoplasm; and tritium disintegrations on DNA in the nucleus is more effective in killing the cell than that of nuclear RNA.
Abstract | PDF (1235 kb) - On the Relative Contribution of Viscous Flow ys. Diffusional...On the Relative Contribution of Viscous Flow ys. Diffusional (Frictional) Flow to the Stationary-State Flow of Water through a "Tight" Membrane
Biophysical Journal, Volume 7, Issue 5, 1 September 1967, Pages 527-534
D.C. Mikulecky
AbstractThe practice of calculating the diffusion contribution to the total pressure-driven flow of water through a tight membrane by using the self-diffusion coefficient for tritiated water is examined by a theoretical analysis. Equations of motion for water and membrane in pressure-driven water flow and water, membrane, and tritiated water in self-diffusion of tritiated water are adapted from Bearman and Kirkwood (1958). These equations of motion are used to develop an equation for the pressure-driven flow of water. Because of the lack of specific information about the detailed structure of most membranes, as well as considerations of the need to eliminate some of the mathematical difficulties, an “equivalent capillary” model is used to find a solution to the equation of motion. The use of the equivalent capillary model and possible ambiguities in distinctions between diffusion and hydrodynamic flow are discussed
Abstract | PDF (399 kb) - A fibrillar collagen gene, Col11a1, is essential for skeleta...A fibrillar collagen gene, Col11a1, is essential for skeletal morphogenesis
Cell, Volume 80, Issue 3, 10 February 1995, Pages 423-430
Y Li, D.A Lacerda, M.L Warman, D.R Beier, H Yoshioka, Y Ninomiya, J.T Oxford, N.P Morris, K Andrikopoulos, F Ramirez, B.B Wardell, G.D Lifferth, C Teuscher, S.R Woodward, B.A Taylor, R.E Seegmiller and B.R Olsen
SummaryMice that are homozygous for the autosomal recessive chondrodysplasia () mutation die at birth with abnormalities in cartilage of limbs, ribs, mandible, and trachea. Limb bones of newborn mice are wider at the metaphyses than normal bones and only about half the normal length. By linkage analysis, the gene and the gene encoding the α1 (XI) chain of cartilage collagen XI were mapped to the same region of chromosome 3. Deletion of a cytidine residue about 570 nt downstream of the translation initiation codon in cho α1(XI) mRNA causes a reading frame shift and introduces a premature stop codon. The data demonstrate that collagen XI is essential for normal formation of cartilage collagen fibrils and the cohesive properties of cartilage. The results also suggest that the normal differentiation and spatial organization of growth plate chondrocytes is critially dependent on the presence of type XI collagen in cartilage extracellular matrix.
Summary | PDF (5608 kb) - …more
Copyright © 1964 The Biophysical Society. All rights reserved.
Biophysical Journal, Volume 4, Issue 1, 167-196, 1 January 1964
doi:10.1016/S0006-3495(64)86936-8
Biochemistry and Biosynthesis of Mucopolysaccharides
Cell Fine Structure and Biosynthesis of Intercellular Macromolecules
Keith R. Porter
Abstract
Fibroblasts active in collagen production show a rich development of the endoplasmic reticulum (ER) and an enlarged Golgi complex, both characteristic of cells engaged in protein synthesis. The relatively quiescent fibrocyte, on the other hand, is deficient in these same cytoplasmic systems. When fibroblasts (or chondroblasts) are provided with tritiated (H3) proline, the label shows, by autoradiography, incorporation first into materials (collagen) in the cisternae of the ER, transfer thence in time to the Golgi, and eventual secretion into the extracellular environment. Sulfur25 incorporation into chondroitin sulfate appears to involve only structural elements of the Golgi complex. There is increasing evidence of intimate fibroblast (or cell) involvement in the initiation and orientation of unit collagen fibrils. This question is reexamined in relation to the development of the prominent basement lamella of young adult lampreys.
