A possible role of chorion protease in shell membrane degradation during development of quail embryos

Abstract

In the eggs of the quail Coturnix japonica, the limiting membrane demarcates the shell membrane at the interface with the albumen and decreases in width during the hatching process. This study was done to identify agents that affect the width of this limiting membrane. Zymography tests on extracts from extraembryonic tissues, yolk sacs, or chorioallantoic membranes, or all three, showed proteolytic activities during d 4 to 10 of incubation. Localization experiments on these activities, performed on d 5 eggs, indicated that they were located in an avascular chorion. Electron microscopic analysis showed there were secretory cells specifically located in the avascular chorion. After partial purification of d 5 avascular chorion extracts using QA52 and Sephadex G-200 column chromatography, the proteolytic activity of 20 kDa was isolated. The protease showed a high level of activity toward succinyl-Gly-Pro-Leu-Gly-Pro-4-methylcoumaryl-7-amide. It had an optimal pH of 9 and digested the limiting membrane. These enzymatic activities were inhibited moderately by EDTA and strongly by leupeptin and aprotinin. It was concluded that it is the 20-kDa protease, showing collagenase-like activity produced by the avascular chorion, that affects the limiting membrane.

Characterization of a novel hatching enzyme purified from starfish Asterina pectinifera

“…3). The maximum activity pH (7.0) of the starfish hatching enzyme in this study was the same as pH 7.0 of brine shrimp and lower than those of the hatching enzyme of sea urchin (pH 8.0) (Roe and Lennarz 1990; Li and Kim 2014), A. amurensis (pH 8.0) (Li and Kim 2013), O. latipes (LCE pH 8.6; HCE pH 8.0, 8.7) (Yasumasu et al 1989a, b), S. gairdneri (pH 8.0–8.5) (Hagenmaier 1974), sea squirt (pH 8.5) (D’Aniello et al 1997), quail (pH 9.0) (Iwasawa et al 2009), but higher than pH 6.0 of the shrimp hatching enzyme (Li et al 2006). The optimal activity temperature of the starfish hatching enzyme was 40 °C (Fig.…”