Equilibrium mechanical properties of two noncollagenous cartilages in the sea lamprey, Petromyzon marinus.

摘要

In contrast to all other vertebrate cartilages, the major extracellular matrix protein of lamprey cartilage is not collagen. Instead, the majority of cartilaginous elements in the lamprey (e.g., cranial and annular cartilages) contain a noncollagenous protein (lamprin) with sequence similarities to mammalian and avian elastins. The branchial and pericardial cartilages also possess noncollagenous, elastin-like extracellular matrix proteins, but these demonstrate different amino acid compositions from lamprin. Thus, lamprey possess a unique family of noncollagenous structural proteins, the significance of which is not completely understood. The purpose of this study was to quantify the equilibrium mechanical properties of adult lamprey annular and pericardial cartilages in order to relate them to age, morphology, and biochemistry. A custom-built uniaxial testing apparatus was used to quantify the equilibrium stress-relaxation behavior of pericardial cartilages tested in tension and annular cartilages tested in compression. Stress-relaxation data and cartilage specimen dimensions were used in the calculation of moduli (stiffnesses) and Poisson's ratios. In addition, light and electron microscopy were used to characterize cartilage morphology before and after testing. (Abstract shortened by UMI.)