Metabolic kinetics of proteoglycans by embryonic chick sternal cartilage in culture.
Explant cultures of embryonic chick sternum have been widely studied, but the kinetics of biosynthesis of proteoglycans by this tissue in culture has not been characterized. Caudal cartilaginous portions of 16-day-old embryonic chick sterna were cultured for 8 days. Histological examination showed that the fresh cartilage contained morphologically homogenous chondrocytes, which were embedded in a uniform extracellular matrix. After culture for 8 days, the histological appearance of the explant remained unchanged but the tissue increased in size with time as indicated by a progressive increase in DNA content and in the content of glycosaminoglycan and collagen. Rates of degradation and release from the tissue of proteoglycans labeled in ovo with 35S were first order during culture, as were the unlabeled proteoglycans. Proteoglycan synthesis was high during the first 2 days of culture, and this then gradually decreased from this high level during the following 2 days. Synthesis was then maintained at a constant level for the remainder of the culture period. After culture for 2 and 7 days, the proteoglycans synthesized by the explants were identical to the preexisting proteoglycans in hydrodynamic size, glycosaminoglycan chain size, and ability to form aggregates. These findings suggest that the embryonic chick sterna maintained a stable cartilage phenotype during the extended culture periods. The initial rapid rate of matrix turnover was probably attributable to an adaptation of the tissue to ex ovo culture conditions and the subsequent maintenance of cellular activities at a lower level indicated the establishment of a steady-state rate of metabolism.
The Royal Veterinary College, University of London, Royal College Street, London, NW1 0TU, United Kingdom. hongxiang.liu@ucl.ac.uk
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D000818:Animals; D002356:Cartilage / Q000033:anatomy & histology / Q000196:embryology* / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D002845:Chromatography; D003094:Collagen / Q000032:analysis; D004247:DNA / Q000032:analysis; D006025:Glycosaminoglycans / Q000032:analysis; D007700:Kinetics; D011509:Proteoglycans / Q000032:analysis / Q000737:chemistry*; D013249:Sternum / Q000033:anatomy & histology / Q000196:embryology* / Q000378:metabolism; D013997:Time Factors
D006025:Glycosaminoglycans; D011509:Proteoglycans; D003094:Collagen; D004247:DNA