Chemical nature of collagen in the dermis of the lamprey, Entosphenus japonicus

Does Subunit Composition Influence the Intermolecular Crosslinking of Fish Collagen? A Study with Hake and Blue Shark Skin Collagens

Acid-soluble collagens from European hake and Blue shark skin were isolated, characterized, and compared. As the structure of collagen determines its function, the final objective of this study was to investigate biochemical differences between both collagens to identify future potential applications. Chromatographic behavior revealed differences in collagen from both species. Increases of temperature and stirring time produced no effect on European hake collagen solubility in the mobile phase, resulting in the same chromatographic profiles. Conversely, the application of temperature and stirring-time increments showed a positive effect on Blue shark collagen solubility, resulting in different chromatographic profiles and observing higher molecular weight components when sample is incubated at 50 °C (15 min) after 48 h stirring. To test if the different chromatographic behavior exhibited by both collagens could be influenced by differences in subunit composition (alpha-chains), cation exchange chromatography was employed to separate collagen subunits. The electrophoretic patterns and gel permeation chromatography with light-scattering detection (GPC-LS) results of the obtained cation exchange peak fractions revealed differences regarding subunit composition between both species, influencing the crosslinking pattern. This is the first comparative study using GPC-LS to provide information of European hake and Blue shark collagen subunit composition.

Chondrogenesis of a non-collagen-based cartilage in the sea lamprey,Petromyzon marinus

Chondrogenesis of the trabeculae, non-collagen-based cartilages in prolarval stages of the sea lamprey, Petromyzon marinus, was examined by light and electron microscopy. Chondrogenesis of the trabecular cartilages in prolarval lampreys commenced with the formation of mesenchymal condensations. Two peaks in mesenchymal cell density occurred, one prior to condensation formation and a second immediately before cartilage differentiation. The possibility of inductive influences by epithelio-mesenchymal interactions on the initiation of chondrogenesis is discussed. Bilateral condensations first appeared by day 17 post fertilization ventromedial to the eyes in a band of tightly packed yolk-laden mesenchymal cells that represent neural crest derived tissue. Cartilage differentiation occurred by day 19 post fertilization and was indicated by the presence of matrix-synthesizing organelles and the first ultrastructural appearance in the extracellular matrix of lamprin, a structural protein unique to lamprey cartilage. Lamprin was initially deposited as discrete 15- to 40-nm globules. Subsequently, lamprin appeared as fibrils aggregated into branching and parallel arrays arranged in pericellular, territorial, and interterritorial zones. Lengthening of the trabecular cartilages was primarily by appositional growth at the rostral end. The timing of the appearance of trabecular cartilages in prolarval stages likely reflects the functional importance of these structures for supporting the brain as the lamprey initiates burrowing behaviour.