| Autor: |
Kenzo Takata, Sakaru Suzuki, Munemitsu Hoshino, Ikuo Suzuki, Atsuhiko Oohira, Koji Kimata |
| Rok vydání: |
1974 |
| Předmět: |
|
| Zdroj: |
Journal of Biological Chemistry. 249:1637-1645 |
| ISSN: |
0021-9258 |
| DOI: |
10.1016/s0021-9258(19)42927-x |
| Popis: |
Light and electron microscopic studies were made on the structures of cells (chondroblasts or chondrocytes) and matrices of developing epiphysial cartilage of 12-day-old chick embryo. Four zones composed of cells with different morphological features were characterized; Zone 1 designated small, round cells; Zone 2, flattened cells; Zone 3 and Zone 4, enlarging cells characterized by an increasing vacuolated cytoplasm. Synthetic activities of DNA, chondroitin sulfate, and collagen were investigated in the different zones by means of radioautographic techniques. The results indicated that a close relation exists between variations of the three synthetic activities and changes in the ultrastructure of cells or in the stage of cytodifferentiation. The chemical nature of the newly synthesized collagens in the different zones was examined to see if any structural heterogeneity may exist in the collagens. Exposure of each zone from the proline-labeled cartilages to 4 m guanidine hydrochloride resulted in the solubilization of more than 80% of the labeled collagen in the zones, there being little difference in the extractability of the labeled collagens among the four zones. The labeled collagens from the four zones showed little change in the degree of hydroxylation of the proline moieties. Further characterization of the collagen samples indicated that all the samples comprised two forms, one corresponding to the known α1(II) chain and the other a precursor form of the α1(II) chain. It was shown from pulse-chase experiments that the precursor form was rapidly converted to α1(II) with a reduction of molecular size: the apparent rates of this conversion increasing gradually in going from Zone 1 to Zone 4. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
