Showing papers on "Oyster published in 1970"

Survival of Virus in Chilled, Frozen, and Processed Oysters

Abstract: Samples of whole and shucked Pacific and Olympia oysters, contaminated with 10(4)-plaque-forming units (PFU) of poliovirus Lsc-2ab per ml, were held refrigerated at two temperatures, 5 and - 17.5 C. To study the survival of virus in the oysters under these conditions, samples were assayed for virus content at weekly intervals for as long as 12 weeks. Results indicated that poliovirus would survive in refrigerated oysters for a period varying from 30 to 90 days, depending upon temperature. The survival rate varied from 10 to 13%. To study the extent of the hazard presented by oysters contaminated with virus, samples of whole and shucked Pacific oysters contaminated with 10(4) PFU of poliovirus Lsc-2ab per ml were heat processed in four ways: by stewing, frying, baking, and steaming. Results indicated that virus in oysters withstood these methods of processing. The survival rate varied from 7 to 10% and appeared dependent upon the processing method used. Heat penetration studies showed that the internal temperature in the oyster was not sufficient to inactivate all of the virus present. These results suggest that not only fresh but also refrigerated and cooked oysters can serve as vectors for the dissemination of virus disease if the shellfish are harvested from a polluted area.

Cystic Fibrosis: Characterization of the Inhibitor to Ciliary Action in Oyster Gills

Abstract: The inhibitor to oyster ciliary activity was isolated from serumof cystic fibrosis patients and heterozygotes.The inhibitinig protein fraction wast a cation as judged by electrophoresis; it had a molecuer weight of 125,000 to 200,000 as judged by gel filtration; antd oil diethylaminoethyl-cellulose chromatography it eluted with the immunoglobulin G fraction. The analogous fraction in normal individuals did not inhibit oyster cillary activity.

Optimization of oyster (Pleurotus ostreatus) mushroom cultivation using locally available substrates and materials in Debre Berhan, Ethiopia

Abstract: Article history: Received on: 12/11/2014 Revised on: 07/12/2014 Accepted on: 26/12/2014 Available online: 27/02/2015 Techniques to grow oyster mushrooms from culture to harvest were evaluated using locally available materials. Oyster was successfully grown in Potato Dextrose Agar (PDA). Spawn for Pleurotus ostreatus was prepared from sorghum and wheat without showing significance preference on them. Wheat straw, barley straw, sinar straw, waste paper, and gabi wastes were used as substrates; waste paper and gabi wastes alone or in mixture with saw dust yielded more oyster than wheat straw, barley straw, sinar straw. Substrates were reused and the yield was slower when it is compared to original substrates and they were found contaminated during pasteurization. Effects of pore size, temperature, and relative humidity on growth of mushrooms were evaluated. Pin hole size, high temperature (25C) and high relative humidity were optimal for oyster growth. This temperature is optimal for spawn running both in cultivation and spawn production.

Zinc Enzymes in Crassostrea virginica

Abstract: Nearly all the zinc in oysters is bound, either to soluble high-molecular weight proteins or to structural cellular components such as cell membranes Oyster alkaline phosphatase is a zinc metalloenzyme, as indicated by in vitro inhibition studies with various metal-binding agents Dialysis of soluble tissue extracts at pH 7–9 removes up to 96% of the total zinc without effect on alkaline phosphatase If alkaline phosphatase is considered representative of the metabolic functions of zinc in oysters, most of the zinc accumulated by oysters must be superfluous to the animal's requirements

The Effects of Freezing on the Survival of Salmonella and E. coli in Pacific Oysters

Abstract: SUMMARY: A mixed inoculum of Salmonella derby or S typhimurium and Escherichia coli I was injected into the intestinal region of Pacific oysters (Crassostrea gigas) which were then frozen by four methods Frozen oysters were stored at O°F, and survival of the inoculated bacteria was determined over a period of two weeks In separate experiments, inoculated oysters were homogenized and then stored, unfrozen, at 32°F and −30°F (frozen) Routinely, bacterial counts and pH readings were taken of all samples during the course of experiments Both species of Salmonella proved to be highly sensitive to freezing, regardless of the freezing method, and showed a survival of 1% or less after 48 hr E coli proved less sensitive, showing a wide and capricious variability of survival during the first week of storage, with survival ranging from 10 to 30% Generally, however, most samples showed a decline comparable to that of salmonellae after two weeks’storage Because of the fluctuation in E coli counts after freezing, it is difficult to correlate the numbers of E colt in frozen shellfish with the count in unfrozen shellfish Therefore, it would be inappropriate to apply coliform standards for fresh oysters to the frozen product In separate studies using inoculated oyster homogenates held at 32° and −30°F for 168 hr, a higher survival rate of E coli and salmonellae was noted in samples held at −30°F However, since results obtained were based solely on bacterial counts, it is not possible to say with certainty that these results indicate a protective effect by oyster homogenates against the adverse effects of freezing Significantly, the results of these experiments did not agree with results obtained with whole oysters, thus indicating the inadvisability of attempting to apply results of homogenate studies to the whole oyster

Method for growing oysters

Abstract: A method of growing oysters on annular rings by first placing and vertically suspending the rings on a horizontal support in an oyster seed growing marine habitat, than suspending the rings horizontally on support lines in a vertical stack where the oysters grow to maturity.

Effects of Light on Spat Settlement of the American Oyster (Crassostrea virginica)

Abstract: Comparing numbers of spat obtained in opaque tanks with those from transparent tanks where time of illumination was varied, indicated that setting of mature larvae of Crassostrea virginica Gmelin is encouraged by darkness and partially inhibited by light.

Gaping Oysters by Shock Wave Energy

Abstract: A preliminary study showed that oysters (Crassostrea virginica) may be gaped for mechanical shucking by use of shock wave energy. Among the devices available for producing shock wave energy, the General Electric Electrohydraulic System and the PAR Air Gun were examined. Results indicate that as much as 87% of the total number of oysters subjected to treatment can be gaped at a rate of about one oyster per second.

Method and package for storing and shipping oyster larvae

Abstract: Method and package for storing marine larvae, such as oyster larvae, by taking marine larvae at or near the state of metamorphosis and reducing the marine larvae to a temperature substantially below the larval growing temperature to avert metamorphosis for a period of time, and thereafter raising the temperature of the marine larvae to cause metamorphosis to commence.

Studies on the assimilation of l,l,l-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT) byCrassostrea virginica Gmelin.

Abstract: The gills of the oyster are probably the primary entry site of DDT. The gut may be a DDT entry site also, but is of secondary importance. Further, mantle uptake of DDT has not been demonstrated. Hence, DDT found in the mantle is probably deposited there by the circulatory system after uptake across the gills. On the basis of the rapid rate of pesticide elimination from oyster tissue, the value of the oyster as an environmental integrator is questionable.

Oyster setting method and apparatus

Abstract: Oyster shells are fed in bulk from a storage hopper and allowed to free-fall into a setting tank containing liquid and freeswimming oyster larvae. The shells land on their convex side on a moving open-mesh conveyer. The conveyer transports the shells through the liquid and out of the tank. As the shells are passed through the liquid the larvae set on the convex undersides. As the shells leave the setting tanks with the larvae attached they are utilized in open-mesh bags and then placed in a recovery tank for a few days until suitably conditioned for transporting and placing in natural oyster beds.

Method of growing oysters

Abstract: Apparatus for growing oysters in sea water comprising a member mounted in sea water so that it is above the bottom level of the sea water at all times and below the top surface of the sea water for a substantial period of each 24 hours A plurality of seed oysters are provided and a cement other than that excreted by the oyster seed secures the oyster seed to the member The oysters are arranged in a predetermined pattern and are spaced in such a manner that the oysters can grow to a substantially larger size on the member without deforming each other In the method, a member is positioned in the sea water so that it is disposed above the bottom level of the sea water and for a substantial period of time of each 24 hours, below the top surface of the sea water Seed oysters are secured to the member using an adhesive and the oysters are arranged in a predetermined pattern and are spaced in such a manner so that they can grow to a substantially larger size without deforming each other

Food consumption and growth of the larvae of the Pacific oyster (Crassostrea gigas)

Abstract: approved: The food consumption and growth of Pacific oyster larvae were studied in three experiments making use of a constant flow apparatus. The apparatus maintained a continuous flow of various densities of algae through test chambers containing different numbers of larvae in a factorial design. Three additional experiments were conducted in which a flow of algae was not used. These standing water experiments were conducted to study the effects of temperature, larval size, and algal density on the food consumption rate of oyster larvae. Dichromate wet oxidations were conducted on samples of oyster larvae to establish the relationship between shell length and caloric content of the larvae. These data were used to estimate the total caloric content of test populations of larvae. The constant flow experiments showed that larval growth rates increased as the density of algae flowing into the test chambers increased up to an optimum density. Subsequent increases in algal inflow density caused the larval growth rate to decline. Larval food consumption in the three standing water experiments was measured as cells consumed per larva per hour and as an instantaneous coefficient of food consumption called grazing rate. Grazing rate is essentially a measure of the proportion of the algal population that is removed by the larvae. The standing water experiments showed that larval food con sumption increased rapidly with increases in temperature from 10°C to 24°C. Grazing rate more than doubled with each increase of 5°C. In other experiments, the grazing rate of Pacific oyster larvae was found to increase exponentially with increases in larval shell length and linearly with increases in the caloric content per larva. A'third experiment showed that larval grazing rate was inversely related to algal density (i. e. , grazing rate declined with increased algal density). The number of algal cells consumed per larva per hour, on the other hand, was found to be directly related to the algal density. The possible application of a constant flow feeding system to an oyster hatchery is discussed. Food Consumption and Growth of the Larvae of the Pacific Oyster (Crassostrea gigas) by Robert Edward Malouf

A predator-prey relationship. sea stars-bivalves. the chemical basis of the response of asterias vulgaris to crassostrea virginica. a bioassay, its applications and the partial purification of an active extract.

Abstract: : The chemical basis of the predator/prey relationship, sea stars/bivalves, was examined. Under controlled conditions in a flow-tank, Asterias vulgaris senses intact oysters (Crassostrea virginica) upstream at distances of at least 120 cm. and shows a positive chemotaxis. It responds similarly to aqueous extracts of oyster tissue at concentrations as low as a few parts per billion. The threshold sensitivity of Asterias vulgaris and Asterias forbesi for an oyster extract was compared. It was measured also for A. vulgaris relative to other bivalves. Contamination of the testing tank with particulate suspensions and oil dispersions at concentrations of less than 10 10 mg/liter is sufficient to decrease the response to oyster extract and to lower the threshold sensitivity of the sea stars. A reliable, repeatable method was developed for the partial purification of the oyster extract. Infrared spectroscopy indicates that the major functional groups are -OH, -NH and -COOH. It is probable that the activity is centered in a number of polar, low molecular weight compounds. They are heat stable at 100C, stable to acid, and not hydrolyzable. (Author)

The microbial ecology of sulfur transformations in oyster pond, woods hole, massachusetts

Abstract: III. MATERIALS AND M E T H O D S ...................................52 A. Sampling Locations ................................ 52 B. Sampling Methods .................................. 52 C. Physical Factors ..................................52 1. Water Temperature ........................... 52 2. Transparency....................................53 D. Chemical Analyses of the W a t e r ............... . . 5 3 1. p H ............................... 53 2. Sali n i t y ........................................ 53 3. Dissolved Oxygen .............................. 54 4. S u l f i d e ........................................ 55 5. Thiosulfate and Polythionates .............. 55 6. S u l f u r ...........................................57 7. S u l f i t e ........................................ 58 8. S u l f a t e ........................................ 58 9. Inorganic Phosphorus and Nitrogen .......... 59 a. P h o s p h a t e ................................. 59 b. N i t r i t e ....................................60 c. N i t r a t e ....................................61 d. A m m o n i u m ....................................62 10. Total Inorganic Carbon ....................... 64 E. Analyses of S e d i m e n t s ............................. 64 1. Dry Weight and Ash W e i g h t ....................64 2. Chloride ......................... . . . . . . 65 3. Water Soluble Sulfides ......... 65 4. Acid Soluble S u l f i d e s ........................ 65

STUDIES ON THE OYSTER DISEASES 1. Pathogenetic Investigation

Abstract: The present paper deals with mortality and pathogenetic investigation of the oysters Crassostrea gigas cultured by tile coventional bamboo and hanging method in Kimhae and Koje-Do in 1969. The results of the investigation may be summarized as follows: 1. Mortality of the oysters by the bamboo method in Kimhae was in June, In July, in August and in September, respectively, 2. Mortality of the oysters cultured by the hanging method in Koje-Do was in June, in July, in October, in November and in December, respectively 3. The diseased oysters had severe inflammation, necrosis and multiple abscess in the epithelia of stomach, mid-gut, digestive tubules, blood vessels and gonads, mucous membrane and surrounding tissue. 4. From August gram negative bacteria were found in the nodules of connective tissue and multiple abscess of the diseased oysters. Particularly the connective tissue of the diseased oysters contained more bacteria than epithelia. 5. Since the bacteria are less abundant in the region of digenerated tissue, mortality of the oysters is not caused only by the infectious bacteria but seems that is also caused by other environmental factors such as extreme temperatures and salinities.

Contamination of Oysters by Pesticides

Abstract: The oyster concerned was the American or Eastern oyster, specifically Crassostrea virginica; the study area was near Barataria Bay and approximately forty miles south of New Orleans. The sample collection was conducted on approximately a bimonthly basis from October 1968 through May 1969. The interaction of dieldrin and endrin with the bottom sediment was evaluated in order to try to determine if the sediment could be a source of pesticides for the oysters. The influence of organic matter in the sediment as well as the pH and salinity were evaluated.

Flat oyster cultivation in galicia

Abstract: 1. Spanish industrial firms and scientific institutions are interested in cultivating the oyster,Ostrea edulis L., for commercial and scientific purposes. Even though bays in Galicia (Northwest Spain) appear to be well suited for oyster cultivation, success has been rather limited thus far. 2. The local natural beds ofOstrea edulis are largely exhausted for several years. The Galician oyster cultivation is, therefore, at present limited to the import of middle sized oysters (mainly from Brittany) and their fattening during the favourable season, i.e. March to November, in suitable natural habitats. 3. Sufficient rates of reproduction of the fattened oysters are difficult to attain because (a) the oysters are attached to vertically arranged ropes and hence not stimulated to spawn simultaneously (large vertical gradient at critical temperature which stimulates spawning), (b) settling oyster larvae are not sufficiently attracted due to the absence of suitable natural and artificial substrates. 4. Experiments are presently being carried out employing traditional larvae collectors (tiles) and laboratory-raised oyster spat fed on phytoplankton cultures and amylaceous products. 5. Low salinities in winter, lack of oxygen in summer and adverse qualities of the natural substratum increase the mortality. Under present circumstances, fattening of middle-sized oysters appears to be still the most satisfactory method with regard to commercial view points.

Pasteurization of Pacific Oysters by Radiation: Post-Mortem Changes in Nucleotides During Storage at 0-2°C

Abstract: SUMMARY: The concentration of nucleotides was lower in the adductor muscle of the oyster (1.64 μmoles/g) than in the remaining dark tissues of the oyster (2.75 μmoles/g). The concentration was less in the whole oyster meats (2.87 μmoles/g) than is usually found in fish muscle, or other marine invertebrates. In addition to the adenine nucleotides and inosine monophosphate, uridine triphosphate, guanosine triphosphate, guanosine diphosphate, guanosine monophosphate and guanosine diphosphate-mannose were found in the fresh oysters. Samples collected in summer had greater concentrations of nucleotides than similar winter samples. lnosine monophosphate formed rapidly from adenosine triphosphate during storage at 0°–2°C, while the turnover rate of inosine monophosphate was slow and reflected low 5′-nucleotidase activity. Hypoxanthine, inosine, guanosine, guanine and uracil were formed during ice storage. The nucleotide breakdown in oysters was not changed by 2 mrads of radiation dose. Total nucleosides and free bases increased during storage of both unirradiated and irradiated samples. During the latter part of the storage period the concentrations of nucleosides and free bases were considerably greater in the irradiated samples. This difference probably is due to the utilization of these compounds by bacteria in the un-irradiated samples. After 15 days of storage bacteria had increased to more than 10’organisms per g, while the counts for irradiated samples were very low (less than 103 per g).

Occurrence ofVibrio parahaemolyticus andRelated Hemolytic Vibrios inMarine Environments of

Abstract: whereas watersamples werequite variable. Samples ofthePacific oyster(Crassostrea gigas), obtained on aregular basis for26months fromasingle environment, showed a close correlation between total numbers ofmesophilic vibrios andtheoverlying watertemperature; theseasonal counts ofoysters ranged fromless than10togreater than100,000 per g.Ecological implications andpossible pathogenicity ofthese vibrios are discussed.