Showing papers on "Oyster published in 1968"

Effect of Steroid on Oyster-III

Abstract: The effect of estradiol-17β on the tissue distribution of PAS-positive substance digestable by saliva-treatment, namely, glycogen was studied using the Japanese common oysters during sexual maturation. The experiment was carried out indoors. In oysters which were kept in sea water containing low concentrations of estradiol-17β (total steroid applied, 4 μg and less/oyster), sexual maturation proceeded normally without sex reversal and an acceleration of glycogenolysis by this steroid was found in females. However, no such effect was seen in the experimental groups treated with high concentrations (10 μg and over/oyster) except at a level of 1, 000-4, 000 μg/oyster. These results indicate that the concentration of steroid applied is of special importance for the appearance of such an effect. The decrease in the glycogen amount which was observed in the 1, 000-4, 000 μg group should be considered to be qualitatively different from that occurring in the 4 μg and less group, because of the high frequency of mortality which is most likely due to serious pathological changes in the digestive diverticula. The present study together with the previous one1) strongly suggests that the acceleration of glycogenolysis by estradiol-17β may occur in female C. gigas provided that sexual maturation proceeds normally without sex reversal.

Bacteriophage Clearance in the Oyster (Crassostrea virginica)

Abstract: Since relatively few quantitative immunological studies had been conducted with invertebrates, this study was designed to learn more about the immune potential of the oyster, a molluscan representative Experiments measured the primary and secondary clearance rates of T2 coliphage in the oyster The fate of phage injected intracardially or intramuscularly was traced by measuring serum and tissue fluid plaque-forming unit levels at various times postinjection Phage-neutralizing activity was also measured Although circulating T2-neutralizing antibody was not induced in the oyster, secondary injections of T2 were cleared more rapidly than primary injections The difference in clearance rates between primary and secondary groups was not as pronounced in the oyster as in the lemon shark, an animal capable of producing high levels of serum antibody to T2

Incidence of Clostridium botulinum type E in salmon and other marine fish in the Pacific Northwest.

Abstract: Salmon, sole, cod, oysters, clams, and crabs from ocean waters along the coast of Oregon and Washington were examined for the presence of Clostridium botulinum type E The organism was detected by identification of the type E toxin in enrichment cultures of the viscera of individual fish Of 369 salmon specimens, 48 yielded cultures containing toxin lethal to mice, and almost half of the toxic cultures were shown to contain botulinal toxin, chiefly type E Eighteen of 113 sole and cod specimens, 4 of 22 Dungeness crab specimens, 5 of 16 oyster specimens, and 27 of 115 clam specimens gave rise to cultures containing botulinal toxin which was usually type E, although types A and B were occasionally encountered

The Occurrence and Retention of Dimethyl-β-Propiothetin in Some Filter-Feeding Organisms

Abstract: Determinations of dimethyl-β-propiothetin (DMPT) levels are reported for 10 filter-feeding organisms, 1 browsing mollusc, 1 carnivorous mollusc, and 1 crustacean. Mature oysters, scallops, and the pteropod Limacina helicina showed high (ca. 0.1 mg/g) DMPT levels, mussels showed generally lower levels, and quahogs and a tunicate showed negligible amounts of DMPT. The periwinkle accumulated DMPT only when feeding on an alga rich in DMPT. Retention of DMPT over prolonged periods was studied in the oyster and in mussels.Seasonal variations, year-to-year variations, and variations with locations were studied for oysters and to a limited extent for mussels. The findings are discussed in terms of food availability and feeding habits and indicate that together with tocopherol it may be possible to correlate DMPT levels with the availability of phytoplankters in the food intake or some species. It is suggested that phagocytes may be responsible for prolonged retention of DMPT in oysters.

Fertilization and Completion of Meiosis in Spawned Eggs of the American Oyster, Crassostrea Virginica Gmelin

Abstract: SUMMARYMeiosis and fertilization in spawned eggs of the American oyster, Crassostrea virginica, are of the normal type found in the large majority of the metazoa and higher plants. Various deviations from the regular sequence of these events were not infrequent, however, in oyster eggs examined in this study. Meiosis and fertilization can be cytogenetically followed critically in these eggs, which, consequently, offer many opportunities for experimental manipulation of the genetic material.

Method of growing oysters

Abstract: 1,268,086. Oyster culture. LONG ISLAND OYSTER FARMS Inc. 15 Aug., 1969 [30 Aug., 1968], No. 40983/69. Heading A1A. A method of growing seed molluscs especially oysters comprises setting the mollusc larvae onto particulate material of 100 to 3000 interim size. The material is preferably oyster shell with a particle size in the range 300 to 600 micron. The particulate material is placed in racks 16 with nylon mesh bottoms. The racks are placed in a tank 10 supplied with centrifuged sea water to which nutrients are added. Antibiotics may be added to the water to destroy harmful bacteria. The water is circulated by a pump, operated by forcing high pressure air through tube 19 which forces water up through tube 17 and through outlet 18 over the racks 16. The seed oysters may be sized by sieving at various stages in their growth.

Studies Accumulation of Heavy Metals in Aquatic Organisms-II

Abstract: Former studies on “green oyster” were all done on the samples which had abnormally accumulated copper and zinc in aquatic environment. We have no information on the accumulating process of cpper and zinc in normal oysters which were transplanted to the water area producing green oyster. In the previous paper, the author reported the evident difference between the contents of copper in oysters collected at southern coast of Nobeoka Bay (S-group) and the adjacent waters to north of Nobeoka Bay (N-group). The oysters collected at the former were all regraded as green oyster. Therefore, normal oysters at Urashiro Bay (one of N-group) were transplanted to Akamizu Inlet (one of S-group), where we examined the variation of copper and zinc accumulation in the meat of oysters. The variation of accumulated quantity of copper and zinc in oysters during 125 days from July to November in 1965 is reported in this paper. The technical terms concerned with the accumulation used in this paper is defined as follows: 1) Normal accumulation indicated the phenomenon of the increase and decrease of heavy metals in organisms which the metabolism of heavy metals at normal physiological condition bring on. 2) Abnormal accumulation indicates the phenomenon of the increase of heavy metals in organisms brought by the influence of abnormal environmental factors. 3) Moreover, abnormal accumulation shows continual increase of heavy metals in organisms by abnormal accumulating phenomenon, therefore, the quatity of Absolute abnormal accumulation is calculated by subtracting the quantity of normal accumulation from the quantity of abnormal accumulation. In this paper, the normal accumulation refers to the copper and zinc accumulation in oysters at Urashiro Bay, the control field, and the abnormal accumulation refers to the copper and zinc accumulation in oysters at Akamizu Inlet, the test field. The quantity of absolute abnormal accumulation is calculated by subtracting the normal accumulation of copper and zinc at Urashiro Bay from the abnormal accumulation of copper and zinc at Akamizu Inlet. The normal oysters were transplanted to the water area of green oyster, and the variation of accumulative quantity of copper and zinc in the meat of oysters, and the influence of normal accumulation upon the abnormal accumulation, were discussed, and we obtained following results: 1) The quantity of copper in abnormal accumulation increases in the exponential function type, log Y=1.4399+0.0069X, and that of zinc indicates sigmoid type (Fig. 1, 2, 3). 2) The critical points (Fig. 4) are remarked on the variation of quantity of absolute abnormal accumulation of copper and zinc. The regression lines are straight over and under of the points. It appears that the normal accumulation has influence upon the variation of quantity of absolute abnormal accumulation of copper and zinc. 3) It is clear that the absorption and accumulation of copper and zinc are not done in same mechanism in oysters, that each of these metals has its peculiarity in the metabolism of oysters, and that the ratio of zinc to copper in oysters becomes smaller in the process of abnormal accumulation of copper and zinc.

The control of radioactive pollution in a north sea oyster fishery

Abstract: 1. The radiological situation in the Blackwater estuary is reviewed. 2. Some data are produced to contrast the behaviour of particulate and soluble nuclides in this estuarine environment and it is demonstrated that65Zn,60Co and55Fe probably reach the oysters on fine silt particles. 3. The conclusion of the pre-operational assessment is confirmed, that oysters are the critical material and65Zn is the critical radionuclide. 4. At present, oysters are the only material in which measurable concentrations of activity exist throughout the estuary. 5. The maximum dose-rates experienced by exceptional oyster consumers are less than 0.2% of the I.C.R.P. permissible Dose Limits for members of the public. 6. A system is developed to relate oyster contamination, and consequently discharge rate of radioactivity, to any distance from the power station outfall.

Chemical composition of oysters from São Paulo and Paraná, Brazil

Abstract: During the years 1966/67 a comparative study of the chemical composition of oysters was performed on protein, water, ash, trimethylamine oxide, trimethylamine, crude glycogen, iron (Fe+ + +) , calcium, magnesium, total and inorganic phosphorus, with oysters coming from the lagoon regions of the State of Sao Paulo, namely Cananeia and Bertioga Channel (Santos), and from the State of Parana. The oyster discussed here is the species found on mangrove tree stilt roots. It was determined as Ostrea arborea Chemnitz, by Dr. Hugo de Souza Lopes, Museu Nacional do Rio de Janeiro. Other zoologists have placed the present species in the genus Crassostrea. Appraisal of the analytical results of the oysters was made taking into consideration the reproductive cycle and the meteorological conditions of the three regions under study. A seasonal variation was observed regarding fat, crude glycogen, dry matter and energy content when related to fresh and dry matter, and of protein when expressed in relation to dry matter. The seasonal variation are related to the reproductive cycle of oysters and is probably influenced by water temperature variations which depend on the solar radiation incidence, and also by phytoplankton abundance. We endeavoured to determine the season when distinct phases of the oyster reproductive cycle occurs, fattening, ripening, gonadal and sexual products discharge, for each one of the three regions studied, as well as the most favorable time of the year for comsumption (winter and spring). This paper shows that oysters are a complementary source of food and income, that their production must be managed for an optimum return to the population inhabiting the lagoon regions of Brazil southern coast.

Laboratory hatching and rearing of Pacific coast clams and oysters. Annual Report. July 1, 1967 - June 30, 1968

Abstract: "The Pacific Coast oyster industry is dependent upon imported oyster seed from Japan. Inconsistent quantity and quality of the imported seed is limiting growth and expansion of the oyster industry while the demand for marketable oysters is increasing. The development of oyster hatcheries on the Pacific Coast could provide the oyster industry with a continuous supply of seed needed for increased production. Controlled hatchery conditions would also provide better quality oyster seed production through selective breeding. The main objectives of the first year were to develop spawning and setting techniques for Pacific Coast molluscs." (from the Introduction)

[The paralytic poisonous component in cultivated oyster at Miyazu Bay, Kyoto prefecture].

Abstract: In February 1962, in Miyazu city of Kyoto Prefecture, a food poisoning event occurred which closely resembled globefish poisoning. According to Dr. Hobo's epidemiological investigation a conclusion was reached that the food directly connected with the poisoning was the oyster which had been cultivated in Miyazu Bay.An experiment was conducted to clarify the cause of this poisoning and the following results were obtained.1) The poisonous component of the oysters was soluble in water.2) This component was found in abundance in the internal organs, and the potency was lost by boiling in alkali.3) The purified poison which was extracted with methanol and a purified method performed with ion exchange resine, charcoal and cellite had lethal doses of aproximately 1.2μg for 20g mouse parentally administered.4) The poison was slightly different from the paralytic shellfish poison of mussel and Akasaragai as well as that of the globefish.