|Budget Amount *help
¥4,800,000 (Direct Cost : ¥4,800,000)
Fiscal Year 1997 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1996 : ¥3,000,000 (Direct Cost : ¥3,000,000)
Japanese common squid, Todarodes pacificus, produces large numbers of small eggs, encapsulated in gelatinous masses 50 cm or larger in diameter. These egg masses are wrapped up in fragile gel membranes which are assumed to be secreted by nidamental glands and to serve as a physical barrier between the eggs and the surrounding seawater.
In this study, we report the biochemical characterization of egg mass membrane and its posulated precursor, nidamental gland mucin.
1. The egg mass membrane is largely composed of mucin which was isolated by solubilization with dilute alkaline treatment (0.4N NaOH,4ﾟC,3 days), followed by precipitation with 50% ethanol. The mucin comprises 14% protein and 86% neutral and amino sugars and more than 90% of the protein was accounted for Thr, Pro and He in a molar ratio of 2 : 1 : 1. This feature is very similar to that of nidamental gland mucin, suggesting that the egg mass membrane is mainly derived from nidamental gland mucin.
2. In order to investigate the structure of sugar components, the sugar chains were liberated by treatment of the mucins with anhydrous hydrazine at 80ﾟC-9h. One of the neutal sugar chains was isolated by gel filtration and analyzed by a combination of mass spectrometry and NMR spectroscopy, indicating the occurrence of a branched, tetra-saccharide containing two new components of 4-O-methylglucose and 4-O-methyl-N-acetylglucosamine.
Although little information concerning the chemical properties of mucins from marine invertebrates was available so far, this study has clearly revealed the unique properties of egg mass membrane mucin and its precursor form.