Research Update:Ostrea gigas and extract.

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   Phytochemical info of Ostrea gigas.

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 Definition:Ostrea gigas are majorly composed of
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   Research Update:Ostrea gigas and extract.

  Ostreae Testa prevent ovariectomy-induced bone loss in mice by osteoblast activations.:J Ethnopharmacol. 2007 Dec 3;114(3):400-5. Epub 2007 Aug 19.

 AIM OF THE STUDY: The anti-osteoporotic effect of heated powder of Ostreae Testa (hPOT), a powder of oyster shell-Ostrea gigas Thumb (Ostrediae) was observed in vitro and in vivo. MATERIALS AND METHODS: The effects on proliferation and alkaline phosphatase activity of primary osteoblasts, bone nodule formation, pit formation of osteoclasts and osteoclastogenesis were observed in vitro, and to observe the in vivo efficacy hPOT was orally administered once a day for 28 days to bilateral ovariectomy-induced osteoporosis mice at 125, 250 and 500mg/kg (of body weight). RESULTS: Although hPOT did not influence the pit formation and the number of multinucleated osteoclast-like cells, osteoclastogenesis, it enhanced the proliferation of primary osteoblasts, differentiation (ALP activity) and bone nodule formation of osteoblast in vitro. The estrogen-deficient osteoporotic changes were dramatically prevented by hPOT treatment except for osteoclasts/bone perimeter. CONCLUSIONS: In conclusion, hPOT prevents OVX-induced osteoporosis through osteoblasts activation effects.

  Cloning of cDNAs and hybridization analysis of lysozymes from two oyster species, Crassostrea gigas and Ostrea edulis.:Comp Biochem Physiol B Biochem Mol Biol. 2006 Nov-Dec;145(3-4):325-30. Epub 2006 Aug 17.

 In bivalve molluscs including oysters, lysozymes play an important role in the host defense mechanisms against invading microbes. However, it remains unclear in which sites/cells the lysozyme genes are expressed and which subsequently produced the enzyme. This study cloned lysozyme cDNAs from the digestive organs of Pacific oyster Crassostrea gigas and European flat oyster Ostrea edulis. Both complete sequences of two oysters' lysozymes were composed of 137 amino acids. Two translated proteins present a high content in cysteine residues. Phylogenetic analyses showed that these oysters' lysozymes clustered with the invertebrate-type lysozymes of other bivalve species. In the Pacific oyster, lysozyme mRNA was expressed in all tissues except for those of the adductor muscle. In situ hybridization analyses revealed that lysozyme mRNA was expressed strongly in basophil cells in the digestive gland tubule of C. gigas, but not in digestive cells. Results indicated that the basophil cells of the oyster digestive gland are the sites of lysozyme synthesis.

  Species identification of Crassostrea and Ostrea oysters by polymerase chain reaction amplification of the 5S rRNA gene.:J AOAC Int. 2006 Jan-Feb;89(1):144-8.Cross I, Rebordinos L, Diaz E.Universide C¨¢diz, Facultad de Ciencias Mar y Ambientales, Laboratorio de Gen¨¦tica, Poligono del Rio San Pedro, 11510 Puerto Real, C¨¢diz, Spain.

 A specific multiplex polymerase chain reaction (PCR) was developed for the identification of Crassostrea angulata, C. gigas, Ostrea edulis, and O. stentina oyster species. Universal primers were used for the amplification of complete repetition units of 5S rDNA in each of the 4 species. The alignment of the obtained sequences was the basis for the specific design of species-specific primers (ED1, ED2, ST1, ST2, CR1, and CR2) located in the nontranscribed spacer regions. The different sizes of the species-specific amplicons, separated by agarose gel electrophoresis, allowed identification of Crassostrea and Ostrea species. A multiplex PCR with a set of the 6 designed primers showed that they did not interfere with each other and bound specifically to the DNA target. This genetic marker can be very useful for traceability of the species, application in the management of oyster cultures, and conservation of the genetic resources of the species.

  Restriction enzyme digestion chromosome banding in Crassostrea and Ostrea species: comparative karyological analysis within Ostreidae.:Genome. 2004 Oct;47(5):781-8.Leit?o A, Chaves R, Santos S, Guedes-Pinto H, Boudry P.Laboratoire de G¨¦n¨¦tique et Pathologie, Station de l'Institut pour la Recherche et l'Exploitation de la Mer (IFREMER), 17390 La Tremblade, France.

 Reliable banding techniques are a major necessity for genetic research in oysters. In this study, we carried out the cytogenetic characterization of four oyster species (family Ostreidae) using restriction endonuclease treatments. Chromosomes were treated with three different restriction enzymes, stained with Giemsa, and examined for banding patterns. The following species were studied: Crassostrea gigas (2n = 20; total number of bands with ApaI, 74; HaeIII, 61; PstI, 76), Crassostrea angulata (2n = 20; ApaI, 62; HaeIII, 61; PstI, 55) (subfamily Crassostreinae), Ostrea edulis (2n = 20; ApaI, 82; HaeIII, 59; PstI, 66), and Ostrea conchaphila (2n = 20; ApaI, 68; HaeIII, 62; PstI, 69) (subfamily Ostreinae). Treatment of samples with ApaI, HaeIII, and PstI produced specific banding patterns, which demonstrates the potential of these enzymes for chromosome banding in oysters. This is of special interest, since it has been recently shown in mammalian chromosomes that restriction enzyme banding is compatible with fluorescence in situ hybridization. This study therefore provides a fundamental step in genome mapping of oysters, since chromosome banding with restriction enzymes facilitates physical gene mapping in these important aquaculture species. The analysis of the banded karyotypes revealed a greater similarity within the genera of Crassostrea and Ostrea than between them.

  Estimates of trace metal bioavailability to humans ingesting contaminated oysters.:Food Chem Toxicol. 2004 Nov;42(11):1893-902.Bragigand V, Berthet B, Amiard JC, Rainbow PS.Service d'Ecotoxicologie, CNRS/GDR1117, SMAB, ISOMer, 2 rue de la Houssini¨¨re, BP 92208, 44322 Nantes Cedex 3, France.

 Oysters, as very popular food items in France, are subject to rules concerning the maximum acceptable contents of trace metals in foods. The food standards for the quantities of metals permitted are always based on total metal concentrations, and not on the metal concentrations that are potentially bioavailable to the consumer (man). In order to estimate the percentages of accumulated trace metals (i.e. Ag, Cd, Cu and Zn) that are potentially bioavailable during consumption, we have used a simple chemical digestion simulation on the insoluble fraction of oysters. These quantities have been added to the soluble fraction, assuming that metals in this fraction are completely bioavailable. Our experiments were conducted on oysters Crassostrea gigas sampled from five sites on the French Atlantic coast and on oysters Ostrea edulis sampled from Restronguet Creek in the United Kingdom. These sites are characterised by various degrees of metal contamination. This study has allowed us to gain a better estimate of the real concentrations of metals bioavailable to the consumer. Only a part of the total metal present is bioavailable: 36-68% for silver, 44-75% for cadmium, 26-80% for copper and 50-80% for zinc. These new estimates have the potential to contribute to any re-evaluation of the food standards for metals.


  Hsp70 expression in thermally stressed Ostrea edulis, a commercially important oyster in Europe.:Cell Stress Chaperones. 2002 Jul;7(3):250-7.Piano A, Asirelli C, Caselli F, Fabbri E.Interdepartment Centre for Environmental Science Research, University of Bologna, via Tombesi dall'Ova 55, 48100 Ravenna, Italy.

 Synthesis of heat shock proteins (Hsps) in response to elevated temperatures and other denaturing agents is a common feature of prokaryotic and eukaryotic cells. The heat-induced expression of Hsp70 family members in the gills and mantle of Ostrea edulis, a highly valued fisheries resource inhabiting primarily estuarine environments, has been studied. O edulis is exposed to a variety of natural and anthropogenic stresses in the environment. Two isoforms of about 72 kDa and 77 kDa were constitutively present in unstressed organisms, reflecting the housekeeping function performed by these proteins under normal circumstances. Their expression in animals undergoing thermal stress was highly variable, and on the average, little change occurred under different experimental conditions. A third isoform of about 69 kDa was induced in both tissues after exposure to > or = 32 degrees C; its synthesis was detected within 4 hours of poststress recovery at 15 degrees C, reaching the maximum expression after 24 hours in the gills and after 48 hours in the mantle and declining thereafter. Hsp69 expression was low at 38 degrees C, a temperature lethal for about 50% of the individuals tested. Densitometric analysis of Western blots revealed that Hsp69 was mostly responsible for the significant heat-induced overexpression of Hsp70s in O edulis. Comparison with heat shock responses in tissues of Crassostrea gigas indicated a similar pattern of Hsp70 expression. In this organism, however, Hsp69 was induced after exposure to > or = 38 degrees C. We conclude that tissue expression of Hsp69 in O edulis, and possibly other bivalves, is an early sign of thermal stress; determining whether these changes also correlate with other major environmental stresses is the goal of ongoing studies.

  Xenobiotic-induced immunomodulation in the European flat oyster, Ostrea edulis.:Mar Environ Res. 2002 Sep-Dec;54(3-5):585-9.Auffret M, Mujdzic N, Corporeau C, Moraga D.LEMAR-UMR 6539, Institut Universitaire Europ¨¦en de la Mer, Universit¨¦ de Bretagne Occidentale, Plouzan¨¦, France. michel.auffret@univ-brest.fr

 The presence of chemical contaminants in marine coastal waters is a major subject of concern since many molecules are potentially immunotoxic, even at low concentration. During the last decade, studies in sentinel species, such as the blue mussel, Mytilus edulis, or the Pacific oyster, Crassostrea gigas, have revealed that immunosuppressive responses can be related to xenobiotic exposure, in the laboratory and in the field. In the present study, European flat oysters were experimentally exposed to heavy metals, to investigate possible alterations of their immune function. Several hematological and functional parameters of hemocytes were measured by flow cytometry, a technique allowing rapid, sensitive, cell-by-cell measurements in large cell populations. Results reveal a depression of phagocytosis and several subcellular, physiological changes in oysters exposed to cadmium alone or to cadmium and copper, suggesting an overall alteration of the phagocytic function.

  Kinetics of metal elimination in oysters from a contaminated estuary.:Comp Biochem Physiol C Toxicol Pharmacol. 2002 Mar;131(3):281-93.Geffard A, Amiard JC, Amiard-Triquet C.Service d'Ecotoxicologie, CNRS GDR 1117, ISOMer, SMAB, 2, rue de la Houssini¨¨re, BP 92208, 44322 Nantes Cedex 3, France.

 In oysters Crassostrea gigas translocated from a metal-enriched estuary (Gironde, France) to a comparatively clean site, the Bay of Bourgneuf (France), Cd, Cu and Zn concentrations were determined monthly in the whole soft tissues, or in different fractions (cytosolic or insoluble) of gills and digestive glands. In all cases, the concentrations of all of the three metals decreased logarithmically and half-lives were always shortest for Cd (86-251 days). After 4 months, the Cd concentration had become not significantly different from the threshold considered safe for human consumption (1 mg kg(-1) wet wt.). In the digestive gland, half-lives were similar in cytosolic and insoluble fractions. In contrast, in the gills, elimination patterns differed markedly between these fractions. The long half-lives calculated for divalent metals in the insoluble fraction of the gills (1505 and 3010 days for Zn and Cu, respectively) is possibly due to a fossilization of metals in intracellular membrane-bound inclusions as shown previously in Ostrea edulis. It is interesting to underline that elimination is fastest for cytosolic metals compared to the insoluble fraction.

  Detection of oyster herpesvirus DNA and proteins in asymptomatic Crassostrea gigas adults.:Virus Res. 2002 Mar 20;84(1-2):151-60.Arzul I, Renault T, Th¨¦bault A, G¨¦rard A.IFREMER, Laboratoire de G¨¦n¨¦tique et Pathologie, 17390 La Tremblade, France.

 Since 1972, several herpes-like virus infections have been reported among different bivalve species around the world. Most of these reports involved larvae or juveniles presenting high mortalities. Two case reports of herpes-like viruses concerned adult oysters, Crassostrea virginica in USA and Ostrea angasi in Australia. Molecular techniques including PCR and in situ hybridization (ISH) have been recently developed to detect the oyster herpesvirus genome. In the present study, 30 Pacific oyster, Crassostrea gigas, adults have been analyzed using three different techniques: PCR, ISH and immunochemistry, in order to detect herpesviruses in asymptomatic individuals. PCR and ISH allowed detection of oyster herpesvirus DNA in 93.3 and 86.6%, respectively, of analyzed oysters while polyclonal antibodies allowed detection of viral proteins in 76.6% of analyzed adult oysters. These results suggest that oyster herpesvirus infects adult oysters with high prevalence and that the virus may persist in its host after primary infection. The detection of viral DNA and viral proteins in the gonad of several individuals supports the hypothesis of a possible vertical transmission of the infection. Lastly, concordance among the three techniques used in this study is discussed.

  Ultrastructure of Mikrocytos mackini, the cause of Denman Island disease in oysters Crassostrea spp. and Ostrea spp. in British Columbia, Canada.:Dis Aquat Organ. 2001 Aug 2;45(3):215-27.Hine PM, Bower SM, Meyer GR, Cochennec-Laureau N, Berthe FC.Laboratoire de G¨¦n¨¦tique et Pathologie, IFREMER, La Tremblade, France. hinem@maf.govt.nz

 An ultrastructural study was carried out on Mikrocytos mackini, the cause of Denman Island disease in Pacific oysters Crassostrea gigas in western Canada. Three forms were identified, quiescent cells (QC), vesicular cells (VC) and endosomal cells (EC). QC occurred in the vesicular connective tissue (VCT), haemocytes (hyalinocytes), adductor and heart myocytes, and extracellularly. They had a central round to ovoid nucleus, < 7 cisternae of inactive nuclear membrane-bound Golgi, few vesicles and lysosome-like bodies. VC were rarely extracellular and usually occurred in adductor and heart myocytes, in close association with host cell mitochondria. The contents of the host cell mitochondria appeared to pass through a tubular extension into the cytoplasm of the parasite. Cytoplasmic vesicles resembled the tubular structure in appearance and size. EC occurred in the VCT, in haemocytes and extracellularly. They had a dilated nuclear membrane, sometimes containing a looped membranous structure that appeared to derive from the nucleus, and pass into the cytoplasm. A well-developed anastomosing endoplasmic reticulum connected the nuclear and plasma membranes, and endosomes were present in the cytoplasm. QC and EC cells were frequently observed tightly against, or between, the nuclear membranes of the host cell. Few organelles occurred in all forms of M. mackini, especially QC. The lack of organelles found in most eukaryotic cells, including mitochondria or their equivalents, may be due to obligate parasitism and the utilization of host cell organelles reducing the need for parasite organelles. Alternatively, perhaps M. mackini is a primitive eukaryote. Although phylogenetic affinities could not be determined, it is not a haplosporidian. A developmental cycle is proposed from these findings.


  Enzymatic activities in European flat oyster, Ostrea edulis, and pacific oyster, Crassostrea gigas, hemolymph.:J Invertebr Pathol. 2000 Oct;76(3):155-63.Xue Q, Renault T.Laboratoire de G¨¦n¨¦tique et Pathologie, IFREMER, La Tremblade, 17390, France.

 Enzymatic activities in the hemolymph of healthy and Bonamia-infected Ostrea edulis and Crassostrea gigas were studied with a commercial kit for the detection of 19 enzymes: 15 and 16 enzymes, respectively, were detected in the hemolymph of O. edulis and C. gigas and 10 of them showed relatively high activity levels. Most of them existed in both the cell-free fraction of the hemolymph and in the hemocytes. The cell-free hemolymph fraction of Bonamia ostreae-infected European flat oysters showed an elevated enzymatic activity level compared with that of healthy individuals. C. gigas hemocytes possessed higher enzymatic activity levels than O. edulis hemocytes. Differences in enzymatic activities existed in granulocytes and hyalinocytes in both oyster species. The enzyme release from oyster hemocytes seemed to be selective. The infection by B. ostreae induced enzymatic activity variations in European flat oysters. Higher enzyme levels within hemocytes may contribute partly to the natural resistance of C. gigas to the infection by B. ostreae.

  Discrimination between closely related Pacific oyster species (Crassostrea) via mitochondrial DNA sequences coding for large subunit rRNA.:Mol Mar Biol Biotechnol. 1993 Jun;2(3):129-36.Banks MA, Hedgecock D, Waters C.Bodega Marine Laboratory, University of Califor¨½ia at Davis, Bodega Bay 94923.

 Mitochondrial DNA sequence variation was characterized for the large subunit rRNA-coding gene (16SrDNA) in two closely related Pacific oyster species (Crassostrea gigas and C. sikamea) and an out group, the Olympia oyster (Ostrea lurida). Although each species was shown to have a single, fixed haplotype for the DNA sequence under study, 7 nucleotide differences were found between C. gigas and C. sikamea, and these two species differed from the O. lurida haplotype at 62 and 60 nucleotide sites, respectively. Nucleotide differences for the two Crassostrea species showed a notable transition bias (85.7%) in contrast to the marginal transversion bias (54.5%) in nucleotide differences between Crassostrea haplotypes and the more distantly related O. lurida. Conservation of primary sequence in all three oyster species as well as other published 16SrDNA sequences was noted for regions with apparent functional significance. We developed DNA sequence-specific discrimination techniques and employed sequence-specific PCR primers, dot-blot hybridization, and restriction digests as alternate techniques for rapid diagnosis of Crassostrea oyster larvae.

  Physico-chemical analysis of Ostreas gigas Thumberg from Xinghua.:Zhongguo Zhong Yao Za Zhi. 1990 Dec;15(12):711-3, 763-4. Chinese.Zhang H, Kang C, Zhou B.Yangzhou Manicipal Institute for Drug Control, Jiangsu.

 This paper presents a comparative physico-chemical analysis of the ancient Ostrea gigas with the medical Ostrea gigas concha, and shows that the protein and amino acid contents in the former are obviously lower than those in the latter, but for the contents of trace elements Mn, Fe, Ni and Pb (with the exception of As), the former appears higher than the latter.

  Analysis of Ostrea gigas Thunberg from Xinhua, Jiangsu.:Zhongguo Zhong Yao Za Zhi. 1989 Nov;14(11):650-2, 701. Chinese.Zhang HB, Zhou BY.

 This paper compares the ultramicrostructure, infrared spectrum and Meigen reaction of the ancient Ostrea gigas shell from Xinhua County, Jiangsu Province, with those of fresh Ostrea gigas shell from Fujian Province. It was shown that the histomorphology of the ancient Ostrea gigas shell is the same as that of the fresh one and both shells are composed of calcite.

  The structure and distribution of ceramide aminoethylphosphonates in the oyster (Ostrea gigas).:Biochim Biophys Acta. 1975 Jun 23;388(3):353-60. Matsubara T.

 1. Ceramide aminoethylphosphonate was isolated from the adductor, gills, mantle and viscera of oysters. 2. After drastic acid hydrolysis of the lipid, aminoethylphosphonic acid was the only water-soluble carbon-phosphorous compound detected. 3. The main fatty acids of ceramide aminoethylphosphonates were hexadecanoic acid (77-90%) and 2-hydroxy hexadecanoic acid (13-15%). 4. Hexadeca-4-sphingenine, octadeca-4-sphingenine and octadeca-4,8-sphingadienine were identified as the major long chain base components. However, the ratio of the three bases was characteristic for each tissue; the adductor muscle contains primarily hexadeca-4-sphingenine, and the viscera, octadeca-4,8-sphingadienine. The gills and mantle contain the three bases in approximately equal concentration. 5. The main molecular species in the adductor muscle was hexadecanoyl-hexadeca-4-sphingenyl 2-aminoethylphosphonate, while in the viscera hexade-canoyl-octadeca-4,8-sphingenyl 2-aminoethylphosphonate predominated.


  A new adenosyl-alkaloid from Ostrea rivularis.:Nat Prod Res. 2006 Jan;20(1):79-83.Ouyang MA.Department of Bio-engineering and Technology, Huaqiao University, Quanzhou, Fujian 362011, China. maouyang@hqu.edu.cn

 A new adenosyl-alkaloid, ostrerine A, has been isolated along with an amino acid, tryptophan and a ribonucleoside, 2'-deoxythymidine from the Quanzhou marine mollusk, Ostrea rivularis, and the structures were elucidated by 1D and 2D NMR experiments, including (1)H-(1)H COSY, TOCSY, NOESY, HMQC, and HMBC methods.

  Seasonal distribution of bromophenols in selected Hong Kong seafood.:J Agric Food Chem. 2003 Nov 5;51(23):6752-60.Chung HY, Joyce Ma WC, Kim JS. Department of Biology, Food and Nutritional Sciences Programme, and Food Science Laboratory, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.

 Selected seafood including rabbitfish (Siganus canaliculatus), brown-spotted grouper (Epinephelus areolatus), clam (Tapes philippinarum), oyster (Ostrea rivularis), shrimp (Penaeus japonicus), and crab (Charybdis feriatus), commonly found in the Hong Kong wet market, was monitored for their distribution and seasonal variations of their bromophenol contents. Specifically, 2-bromophenol (1). 4-bromophenol (2). 2,4-dibromophenol (3). 2,6-dibromophenol (4). and 2,4,6-tribromophenol (5). were monitored due to their flavor impact to seafood. All samples of marine origin contained bromophenols throughout a year. Crab had the highest concentration of total bromophenol content throughout the season. Concentrations of compounds 1, 4, and 5 in the local seafood were generally higher than that found in the literature values to provide characteristic flavor, but lower than that required to cause off-flavor. Variations of the flavor impact of bromophenols in seafood during a season could be better shown by their flavor values. Distribution and seasonal variations of bromophenol content in seafood coincided well with the seasonal growth cycle of the bromophenol synthesizing seaweeds, e.g. brown algae, in the region suggesting the abundant source of bromophenols in the environment might have a high impact on the quantity of bromophenols found in seafood.

  Molecular phylogenetics of cupped oysters based on partial 28S rRNA gene sequences.:Mol Phylogenet Evol. 1994 Sep;3(3):221-9.Littlewood DT.Department of Palaeontology, Natural History Museum, London, England.

 Partial sequences of 28S-like rDNA were amplified using PCR and sequenced for eight species of oyster and one species of mussel. Phylogenetic relationships among seven species of Crassostreinid oyster were inferred from aligned sequences by parsimony and maximum-likelihood methods. Of the 315 sites that varied, 90 were phylogenetically informative in parsimony analysis. Inference by maximum parsimony (MP) is consistent with maximum-likelihood (ML) analysis for the major lineages, yielding a tree with the topology (Mytilus edulis (Ostrea edulis ((Crassostrea rivularis (C. belcheri, C. gigas))(C. virginica, C. rhizophorae, Saccostrea cuccullata, S. commercialis)))). MP and ML analyses resolved the systematic relationships of the Saccostrea and Atlantic Crassostrea differently such that a polytomy linking these four taxa is preferred with the data available. Molecular data support a later divergence of the tropical Pacific Saccostrea from a common ancestor of the Atlantic Crassostrea species. Molecular data from domains D1, D2, and partial D3 of the 28S rDNA supply sufficient phylogenetic information to determine systematic relationships among the extant oyster taxa, from the major species groups to the family level, thus providing valuable characters that are able to supplement the paucity of morphological characters so far recognized.

  Effects of oyster extract on the reproductive function of zinc-deficient mice: bioavailability of zinc contained in oyster extract.:Congenit Anom (Kyoto). 2003 Dec;43(4):271-9.

 Zinc is a vital nutrient in the normal reproductive function and embryonic development of mammals, and it is well known that oyster extract contains significant amounts of zinc. The effects of oyster extract on reproductive function, such as embryonic development, serum levels of zinc and sperm maturation were examined in zinc-deficient mice. Zinc deficiency in dams during pregnancy induced a decrease in the successful pregnancy rate, maternal weight gain, the number of live fetuses and fetal body weight. Zinc deficiency for 12 weeks in male mice induced a decrease in body weight, testis weight and sperm count in the epididymis. However, reproductive failure, embryonic defects and decreased sperm motility in zinc-deficient mice were improved by supplementation with oyster extract. Some nutrients contained in oyster extract, such as taurine and glycogen, may be related to the recovery of reproductive function. There were significantly lower serum concentrations of zinc in dams fed a zinc-deficient diet. However, the serum zinc concentration was normal in the oyster extract-supplemented group. No difference in the concentration of serum zinc was observed between the oyster extract- and zinc carbonate-supplemented groups. From these findings, it is suggested that oyster extract is a useful supplement that can prevent reproductive defects from zinc deficiency, and the bioavailability of zinc may be identical to zinc carbonate.

  Protective effect of Crassostrea gigas extract on audiogenic seizures in magnesium deficient mice.:Biomed Pharmacother. 1998;52(4):162-5.Bac P, Pages N, Dhalluin S, Tapiero H.Department of Cellular and Molecular Pharmacology, CNRS URA 1218, Universit¨¦ de Paris--Facult¨¦ de Pharmacie, Chatenay-Malabry, France.

 Audiogenic seizures associated with loss of weight, prostration, piloerection, palpebral ptosis and motor deficiency were induced after sound stimulation of determined frequency and amplitude in magnesium-deficient DBA/2 mice. These symptoms were maintained when standard diet conditions (1700 ppm Mg2+) were restored. In contrast, mice were protected from audiogenic seizure in a dose related manner when Crassostrea gigas extract (JCOE) were added to the diet for 10 consecutive days. Although a rational explanation for this protective effect has not yet been determined, it is assumed that it might be due to a chelating complex formed between Mg2+ and taurine, which enhance the uptake of Mg2+.


  Free radical-scavenging activity of Crassostera gigas extract.:Biomed Pharmacother. 1997;51(8):328-32.

 In the present study, we evaluate the free radical-scavenging activity of Crassostera gigas extract, a powder extracted from Crassostera gigas by a spin-trapping method using electron paramagnetic resonance (EPR), and also estimate the protective effect against gastric mucosal cell injury induced by hydrogen peroxide. The EPR study demonstrated that Crassostera gigas extract directly scavenged superoxide radical as well as hydroxyl radical in a concentration-dependent manner. After exposure to hydrogen peroxide for 4 h in Hank's balanced buffered solution, cell viability of rat gastric mucosal cells (RGM-1) was measured by modified MTT assay. Hydrogen peroxide-induced injury was not reversed by 1-h preincubation with 100 to 1,000 micrograms/mL JCOE solution which has high reactivity to hydroxyl radicals, indicating that the active ingredients, including taurine of Crassostera gigas extract on scavenging action of hydroxyl radical, did not penetrate cell membranes easily. Twenty-four hour pretreatment with the JCOE solution significantly reversed the decrease in cell viability induced by hydrogen peroxide, indicating the possibility that Crassostera gigas extract solution may stimulate the endogenous eliminating system against hydrogen peroxide.

  Increased glutathione expression in cells induced by Crassostera gigas extract.:Biomed Pharmacother. 1996;50(3-4):149-53.Tapiero H, Tew KD.Facult¨¦ de Pharmacie, Universit¨¦ de Paris, Chatenay Malabry, France.

 The amino-acid composition of Crassostera gigas extract powder is high in glutamic acid and taurine. In order to study whether these components present in Crassostera gigas extract could be contributory factors in enhancing cellular glutathione-stimulating hormone (GSH) and glutathione S-transferase (GST), HL60 cells were exposed to increasing concentrations of Crassostera gigas extract. Statistically significant increases in GSH occurred at extract concentrations of 0.05 and 0.1% with no significant change in GST activity. Because of the high taurine levels measured in the extract, the effects of micromolar taurine supplementation of the medium were studied. A modest, but not statistically significant increase in both GSH levels and GST activity was measured. We therefore conclude that while the taurine present in JCOE could be a contributory factor in enhancing GSH and GST, it was not the only stimulus.

  Determination of an arsenosugar in oyster extracts by liquid chromatography-electrospray mass spectrometry and liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic fluorescence spectrometry.:Analyst. 2002 Jan;127(1):60-5.S¨¢nchez-Rodas D, Geiszinger A, G¨®mez-Ariza JL, Francesconi KA.Departamento de Qu¨ªmica y Ciencia de los Materiales, Escuela Polit¨¦cnica Superior, Universidad de Huelva, Spain. rodas@uhu.es

 HPLC-UV-HG-AFS analysis of aqueous extracts of oysters (Crassostrea gigas) taken from the southwestern Atlantic coast of Spain showed the presence of arsenite, arsenate, dimethylarsinic acid and an unidentified arsenic peak. Subsequent analysis of the oyster samples by LC-electrospray MS and comparison with four standard dimethylarsinoylribosides (arsenosugars), showed that the previously unidentified peak was an arsenosugar (arsenosugar 2). When the arsenosugar in the oyster was quantified using the two detection methods and external calibration with standard arsenosugar, there was a large discrepancy between the two sets of results. The LC-MS analysis was strongly affected by the sample matrix and gave concentrations 50% lower than those obtained by AFS detection. When the method of standard addition was applied to the LC-MS analysis, the results were comparable to the AFS data. The matrix effects were eliminated by subjecting the extract to a clean-up procedure with anion-exchange and gel permeation preparative chromatography before the LC-MS analysis. The arsenosugars gave a small signal without photo-oxidation when they were analysed by HPLC-HG-AFS. Possibly this resulted from partial decomposition of the arsenosugar to dimethylarsinic acid under the acidic conditions employed in the hydride generation step.

  Aroma extracts from oyster Crassostrea gigas: comparison of two extraction methods.:J Agric Food Chem. 2002 Jan 16;50(2):299-304.Pennarun AL, Prost C, Demaimay M.Laboratoire de Biochimie Alimentaire et Industrielle, Ecole Nationale des Ing¨¦nieurs des Techniques Agro-Alimentaire, Rue de la G¨¦raudi¨¨re, B.P. 82225, 44322 Nantes Cedex 3, France. pennarun@enitiaa-nantes.fr

 The study of the aroma of oysters is of great economic interest in France because it enables their organoleptic quality to be verified. The aim of this study is to optimize the extraction methods of the volatile compounds of oysters Crassostrea gigas in order to obtain an extract with an odor as close as possible to that of the original oysters'. Oyster aroma is rarely studied, and its sensory profile has not been investigated to date. Two extraction methods were studied: vacuum hydrodistillation carried out at 20 degrees C with noncrushed oyster using ultrapure water and dynamic headspace carried out using noncrushed oyster during a 30 min purge. They were compared with regard to their sensory characteristics by a panel of seven judges, all trained in seafood aroma recognition. This study has shown that vacuum hydrodistillation is the better method to obtain an extract closest in aroma to the oyster reference.

  The antioxidant effects of Crassostrea gigas extract in human volunteers.:In Vivo. 1998 May-Jun;12(3):305-9.Tapiero H, Gat¨¦ L, Dhalluin S, Nguyen Ba G, Soupramanien V, Kouyate J, Tew KD.Department of Pharmacology, CNRS-URA 1218, Faculty of Pharmacy, Chatenay Malabry, France. Haim.Tapiero@cep.u-psud.fr

 Since several in vitro and animal studies of an extract from Crassostrea gigas (JCOE) have demonstrated its antioxidant properties and other interesting effects, a preliminary human trial was carried out. Seven healthy male volunteers aged 23-37 received orally 3 x 2 capsules of JCOE per day for 8 days. On days 0, 1, 4, 8 and 15 (7 days after completion of the schedule) blood samples were drawn and the antioxidant potential of serum was tested. A statistically significant increase in the buffering effects of serum against hemoglobin (Hb) and lactate dehydrogenase (LDH) release from red blood cells treated with the free radical generator azobis amidino propane (AAPH) was found following JCOE treatment. At 8 days, the oxidative effects were reduced by > 90% of the pretreatment values. In these same individuals, serum levels of reduced glutathione were increased by an average of 1.5-fold over the time course of treatment. It is concluded that in normal human volunteers, JCOE capsules provide an orally available formula for enhancing the antioxidant capacity of blood serum. While the extract is known to contain some direct acting antioxidant components, at least a portion of the protective effect is facilitated by enhancement of GSH biosynthesis.


  Impact of dietary supplement of Crassostrea gigas extract on glutathione levels and glutathione S-transferase activity in rat tissues.:In Vivo. 1998 May-Jun;12(3):299-303.Gat¨¦ L, Schultz M, Walsh E, Dhalluin S, Nguyen Ba G, Tapiero H, Tew KD.Department of Pharmacology, CNRS-URA 1218, Faculty of Pharmacy, Chatenay Malabry, France.

 Male Sprague Dawley rats received various amounts of extract of Crassostrea gigas by gavage every day for 2 weeks or one month. At these times, groups of animals were sacrificed and samples of major organs analyzed for levels of glutathione (GSH) and glutathione S-transferase (GST) activities. Following the two week protocol, GSH levels were significantly increased in the mucosa of the large intestine; at one month the small intestine and spleen were elevated. GST activity increased in liver under both schedules and at one month, activity was also elevated in kidney and small intestine. Since the Crassostrea gigas extract contains high levels of a variety of important amino acids, it is concluded that biologically available peptides are taken up in target organs and stimulate GSH metabolism. Enhanced levels of GSH and associated enzymes may contribute to a more effective detoxification phenotype, thus providing enhanced chemoprotective capacity.

  Study on neurotoxic shellfish poisoning involving the oyster, Crassostrea gigas, in New Zealand.:Toxicon. 1996 Sep;34(9):1050-3.

 Lipid-soluble polyether marine toxins were isolated from 80% methanol extract of oysters, Crassostrea gigas, harvested in 1993 at Tiki Road, Coromandel Peninsula, New Zealand, by chromatography on columns of LH-20 and ODS (C18), followed by reversed-phase high-performance liquid chromatography. They were identified as known brevetoxins, PbTx-2 and 3. PbTx-3 was also isolated from oysters collected at Rangaunu Harbour in February 1994 and June 1995, followed by the above procedures.


  Scientific References:

  1.Research Update:Ostrea gigas and extract.