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The giant honeycomb oyster Hyotissa hyotis occurs at a high density in the shallow subtidal rocky bottom of Jeju Island off the south coast of Korea, where the sea surface temperature ranges from 14[degrees]C to 25[degrees]C seasonally. Unlike other oysters, H. hyotis has an extraordinarily large adductor muscle (AM) that accounts for more than 40% of the total tissue weight. This study analyzed the proximate composition, amino acids, and fatty acids of the AM of H. hyotis in Jeju Island to evaluate the nutritional potential. For the analyses, oysters were grouped based on their reproductive condition as prespawning (May-August), spawning (September-November), and postspawning (December-April). The AM contained a high level of protein (54.7%-69.4%) followed by carbohydrate (16.0%-25.3%) and lipid (4.5%-9.9%) throughout the year, indicating that the AM is enriched with protein. The total amino acids (TAA) in the AM ranged from 9.4 to 12.9 g/100 g dry weight annually, and essential amino acids accounted for up to 36.7% of the TAA. Like other marine bivalves, the AM contained a high level of taurine, which accounted for 26.5%-28.5% of the total free amino acids. The AM also included high levels of essential fatty acids, such as palmitic acid, docosahexaenoic acid, and eicosapentaenoic acid, as these fatty acids accounted for 35.9%-37.0% of the total fatty acids. The AM of prespawning oysters collected during May and August contained comparatively higher total proteins and carbohydrates. Results suggested that, like scallops and pen shells, the AM of the giant honeycomb oyster is highly suitable as seafood, and H. hyotis should be considered as a species of high potential for future aquaculture efforts. KEY WORDS: honeycomb oyster, Hyotissa hyotis, adductor muscle, proximate composition, amino acid profile, fatty acid profile, spawning, INTRODUCTION The giant honeycomb oyster Hyotissa hyotis (Linnaeus, 1758) is distributed widely on the subtidal hard bottom of shallow tropical or subtropical waters from the Indo-Pacific to the eastern Pacific [...]

A polyclonal antibody specific to an egg protein of Suminoe oyster Crassostrea ariakensis was previously developed in our laboratory to assess the reproductive life cycle of the oyster. The present study was undertaken to investigate vitellin of C. ariakensis (CAVt). Vitellin is an essential component of egg proteins in marine invertebrates as it provides energy and nutrients to the embryo and larvae. CAVt was purified from eggs of the oyster using ammonium sulfate precipitation followed by affinity chromatography with Concanavalin A-agarose. Native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate PAGE showed that CAVt is a high molecular weight [532 kiloDaltons (kDa)] protein, with multiple subunits. Similar to other vitellin proteins, it is a phospholipoglycoprotein composed of phospholipids (12.06%), carbohydrates (mannose, 10.08% or glucose, 9.84%), and alkali-labile phosphates (4.16%). Affinity chromatography, enzyme-linked immunosorbent aasay (ELISA) and western blot analysis revealed that CAVt is only present in the ovary, and two subunits of CAVt (72 and 35 kDa) are believed to be incorporated from the hemolymph into the oocyte. The antibody specific to CAVt (anti-CAVt), raised in rabbit, strongly cross reacted with the egg proteins of oyster species and scallops, suggesting that the antigenic epitopes are highly conserved among species. Our results suggest that the anti-CAVt antibody can be used to develop a tool similar to ELISA or western blotting for investigation of the effect of microorganisms on reproduction as well as the effect of chemicals on the endocrine system in C. ariakensis. [ABSTRACT FROM AUTHOR]

The subtropical brooding oyster Ostrea (= Striostrea ) circumpicta (Pilsbry, 1904) occurs at high density in the shallow, subtidal, rocky bottom in Jeju Island, off the south coast of Korea, where the sea surface temperature and salinity varies annually from 13 to 25°C and 30 to 33 ppt, respectively. In this study, the annual gametogenesis and early larval development of O. circumpicta was examined, using histology and scanning electron microscopy (SEM). Histology indicated that the females and males initiated gonial mitosis in September, shortly after sexual resting in August. In December, ripe eggs first appeared in the follicles, and most of the females exhibited fully mature oocytes in May, as the water temperature reached 17 to 18°C. Spawning females were dominant in June and July, when the trochophore and strait- hinged veliger larvae were also identified in the branchial chambers, their size ranging from 111 to 130 μm and 135-205 μm in diameter, respectively. The veliger larvae in the brooding chamber exhibited a well- developed velum and digestive tract, suggesting that the larvae are engaged in feeding in the branchial chamber. Unlike other marine bivalves in temperate coastal ecosystems, O. circumpicta has a long period of gonad maturation and a short resting phase. It has been believed that such a long period of reproductive maturation is associated with a low level of food in the environment and the comparatively large size of the oocytes, which may require a relatively longer time to accumulate necessary nutrients to produce large eggs in a food-poor environment.

The oyster ovarian parasite Marteilioides chungmuensis has been reported from Korea and Japan, damaging the oyster industries. Recently, Marteilioides-like organisms have been identified in other commercially important marine bivalves. In this study, we surveyed Marteilioides infection in the Manila clam Ruditapes philippinarum, Suminoe oyster Crassostrea ariakensis, and Pacific oyster Crassostrea gigas, using histology and Marteilioides-specific small subunit (SSU) rDNA PCR. The SSU rDNA sequence of M. chungmuensis (1716 bp) isolated from C. gigas in Tongyoung bay was 99.9% similar to that of M. chungmuensis reported in Japan. Inclusions of multi-nucleated bodies in the oocytes, typical of Marteilioides infection, were identified for the first time in Suminoe oysters. The SSU rDNA sequence of a Marteilioides-like organism isolated from Suminoe oysters was 99.9% similar to that of M. chungmuensis. Marteilioides sp. was also observed from 7 Manila clams of 1840 individuals examined, and the DNA sequences of which were 98.2% similar to the known sequence of M. chungmuensis. Unlike Marteilioides infection of Pacific oysters, no remarkable pathological symptoms, such as large multiple lumps on the mantle, were observed in infected Suminoe oysters or Manila clams. Distribution of the infected Manila clams, Suminoe oysters and Pacific oysters was limited to small bays on the south coast, suggesting that the southern coast is the enzootic area of Marteilioides infection., (Copyright © 2013 Elsevier Inc. All rights reserved.)