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At least 73 records · Page 4Linked to original sources
PubMed2001

Mass mortality of the Japanese pearl oyster Pinctada fucata martensii in relation to water temperature, chlorophyll a and phytoplankton composition.

Mass mortalities of the Japanese pearl oyster Pinctada fucata martensii have widely occurred in western Japan since 1994. The causes of these mass mortalities are at present not thoroughly understood. In this study, we investigated oyster survival in relation to some environmental factors such as water temperature, concentration of chlorophyll a and density or composition of phytoplankton. The examined mass mortality occurred from September to December 1998, and the color on the adductor muscle of the oysters was red-brown, suggesting an infectious disease. Oysters that became moribund during the experiment lost weight, while the weight of unaffected oysters increased. The cell density of Nitzschia spp., an inedible algae for the oyster, in Uchiumi Bay increased before and during the mass mortality event. From the results of our study, we hypothesize that P. fucata martensii was weakened by starvation because of the dominance of inedible food and then contracted an infectious disease that resulted in mortality.

Animals↗
PubMed2002

Detection of marine birnavirus in the Japanese pearl oyster Pinctada fucata and seawater from different depths.

This study examines the seasonal changes of marine birnavirus (MABV) in seawater and the Japanese pearl oyster Pinctada fucata reared at different depths (2 and 15 m). Oysters and seawater were collected in 1998, and a 2-step PCR was carried out to detect MABV. Virus isolation was performed on the PCR-positive samples in the oyster. The detection rate of the MABV genome in the oyster was low during June, but increased after July at both 2 and 15 m depths. MABV was not isolated until after September, when isolation rates of 10 to 28.6% were recorded. The results suggest that growth of MABV in the oyster is similar at 2 and 15 m depth. In contrast, the MABV genome in seawater was present through the year at 15 m depth, but was not detected in summer at 2 m. This suggests that the virus is destroyed by UV and/or other factors at 2 m in summer, but is stable in deeper waters.

Animals↗
PubMed2002

Receptors for recombinant feline interferon-omega in hemocytes of the Japanese pearl oyster Pinctada fucata martensii.

In a previous study we determined that administration of recombinant feline interferon-omega (rFeIFN-omega) could protect Japanese pearl oysters Pinctada fucata martensii from akoya-virus infection. Our results suggested that rFeIFN-omega enhanced the potential of agranulocytes to phagocytize necrotic cells and to produce collagen fibers that repair the lesions caused by the akoya-virus. In the present study, using an indirect immunofluorescence technique with an anti-rFeIFN-omega rabbit serum, we examined whether hemocytes bear receptors that bind rFeIFN-omega. rFeIFN-omega receptors were present on agranulocytes and bound rFeIFN-omega, and appeared as green fluorescent spots in the cytoplasm under a fluorescent microscope. Around 56% of agranulocytes in Japanese pearl oysters bore the rFeIFN-omega receptors.

Animals↗
PubMed2001

Microbiological quality of the bivalve Pinctada imbricata commercialized in Cumaná, Venezuela.

The habitual consumption of oysters in the city of Cumaná, Venezuela, is made in poor sanitary conditions, therefore a study was carried out to determine the sanitary quality of the product. For this, 120 samples of oyster Pinctada imbricata were collected directly from: a) Fishing boats (unhandled samples) and b) after being shucked by the salesman (handled samples). Unhandled samples showed the following MPN/g: Faecal coliforms < 3 - 2.2 x 10, Aeromonas sp. < 3 - 1.1 x 10(3), Staphylococcus aureus < 3 - 7.5 x 10; Clostridium perfringens < 3 - 9.3 x 10); cfu/g Enterobacteriaceae 3 - 4.1 x 10(2); total aerobes 2.9 x 10(2) - 6.9 x 10(5); 6% of S. aureus were coagulase positive. Values of MPN/g of handled samples were higher: Faecal coliforms 4 - 4.6 x 10(2); E. coli 9 - 2.1 x 10(2), Aeromonas 3 - 4.6 x 10(2), S. aureus 2.3 x 10 - 4.6 x 10(2), C. perfringens < 3 - 2.8 x 10(2), and cfu/g counts of Enterobacteriaceae 5.4 x 10 - 6.5 x 10(6), total aerobes 30 - 2.8 x 10(5); 25% of S. aureus were coagulase positive. Salmonella sp. was detected in two of the handled samples. These results suggest contamination in growth areas of bivalve and during the collecting operation, which is increased by handling of the product by the salesman.

Analysis of Variance↗
PubMed2003

The water-soluble matrix fraction from the nacre of Pinctada maxima produces earlier mineralization of MC3T3-E1 mouse pre-osteoblasts.

Nacre or mother of pearl is a calcified structure that forms the lustrous inner layer of some shells. We studied the biological activity of the water-soluble matrix (WSM) extracted from powdered nacre from the shell of the pearl oyster, Pinctada maxima, on the MC3T3-E1 pre-osteoblast cell line from mouse calvaria. This cell line has the ability to differentiate into osteoblasts and to mineralize in the presence of beta-glycerophosphate and ascorbic acid. Cell proliferation and alkaline phosphatase activity were measured as markers of osteoblast differentiation, and mineralization was analyzed. These studies revealed that WSM stimulates osteoblast differentiation and mineralization by day 6 instead of the 21-day period required for cells grown in normal mineralizing media. We compared the activity of WSM with that of dexamethasone on this cell line. WSM can inhibit alkaline phosphatase (ALP) activity and the activity of dexamethasone on MC3T3-E1 cells. This study shows that nacre WSM could speed up the differentiation and mineralization of this cell line more effectively than dexamethasone.

3T3 Cells↗
PubMed1993

[Presence of gregarine (Protozoa sporozoa) parasite of black-lipped pearl oysters Pinctada margaritifera (L.,1758) (Mollusca bivalvia) in French Polynesia].

High death rates have been recorded in populations of Pinctada margaritifera (natural or reared stocks) in atolls in the Tuamotu Archipelago (French Polynesia). An histological study of the oysters from the concerned areas revealed the occurrence of a protist of which ultrastructural features correspond to those of Gregarinea. It is still premature to establish a link between the presence of the Gregarine and recent deaths of pearl oysters.

Animals↗
PubMed2006

Effects of cryopreservation methods on post-thaw motility of spermatozoa from the Japanese pearl oyster, Pinctada fucata martensii.

In order to develop cryopreservation techniques for Japanese pearl oyster spermatozoa, the effects of various cryopreservation conditions on post-thaw motility were examined. Spermatozoa cryopreserved with 10% methanol (MET), dimethylformamide or dimethylacetamide plus 90% diluent comprising 80% seawater and 20% fetal bovine serum (FBS) showed higher percentages of post-thaw motility than those cryopreserved with 10% dimethylsulfoxide or glycerol. When spermatozoa were cryopreserved with various concentrations (0-20%) of MET and 100-80% diluent, 10% MET showed the highest percentages of post-thaw motility. When spermatozoa were cryopreserved with 10% MET and 90% diluent comprising various concentrations (0-100%) of FBS or Ringer solution mixed with seawater, the percentages of post-thaw motility peaked at 20% FBS or Ringer solution, and were significantly higher for 20% FBS than for 20% Ringer solution. The percentages of post-thaw motility increased with increasing dilution ratios from 2.5- to 50-fold. Spermatozoa cooled to -50 degrees C and then immersed in liquid nitrogen (LN) showed higher post-thaw motility than those cooled to -30 degrees C or -40 degrees C. When spermatozoa were cryopreserved to -50 degrees C at various cooling rates by changing the sample height above the LN surface, the post-thaw motilities of spermatozoa cooled at 10 cm (cooling rate: -21.3 degrees C/min) and 12.5 cm (-15.6 degrees C/min) from the LN surface were higher than those at 5, 7.5 or 15 cm. These results indicate that 10% MET plus 90% diluent comprising 80% seawater and 20% FBS is a suitable extender for cryopreservation of Japanese pearl oyster spermatozoa and that samples should be cooled to -50 degrees C at a cooling rate between -15 and -20 degrees C/min for efficient storage.

Animals↗
PubMed2004

Quantification of in situ nutrient and heavy metal remediation by a small pearl oyster (Pinctada imbricata) farm at Port Stephens, Australia.

The use of pearl oysters has recently been proposed as an environmental remediation tool in coastal ecosystems. This study quantified the nitrogen, phosphorus and heavy metal content of the tissue and shell of pearl oysters harvested from a small pearl oyster farm at Port Stephens, Australia. Each tonne of pearl oyster material harvested resulted in approximately 703 g metals, 7452 g nitrogen, and 545 g phosphorus being removed from the waters of Port Stephens. Increasing current farm production of 9.8 tyr(-1) to 499 tyr(-1) would balance current nitrogen loads entering Port Stephens from a small Sewage Treatment Plant (STP) located on its southern shores. Furthermore, manipulation of harvest dates to coincide with oyster condition would likely remove substantially greater quantities of nutrients. This study demonstrates that pearl aquaculture may be used to assist in the removal of pollutants from coastal waters while producing a commercially profitable commodity.

Animals↗
PubMed2003

Arsenic compounds accumulated in pearl oyster Pinctada fucata.

We investigated the water-soluble arsenic compounds present in the soft tissues of both the pearl-free and the pearl-containing pearl oysters. After dividing the soft tissue into five parts, i.e., adductor muscle, foot, mantle, viscera and gill, each part was analyzed by high-performance liquid chromatography-inductively coupled plasma mass spectrometry for the arsenic compounds accumulated in it. Arsenic concentration of each tissue part ranged from 22.1 to 45.7 microg g(-1) of dry tissue in the pearl-free pearl oyster and from 27.4 to 50.4 microg g(-1) of dry tissue in the pearl-containing pearl oyster. On the grounds of the present evidence the major water-soluble arsenic compound accumulated in each part was identified as arsenobetaine without exception in both types of pearl oysters (94.3-99.7% in the pearl-free pearl oyster and 87.2-99.7% in the pearl-containing pearl oyster). Trace or small amounts of arsenic compounds including tetramethylarsonium ion and arsenocholine were also detected in some parts. The levels of these minor arsenicals were a little higher in pearl-free pearl oyster than in the pearl-containing pearl oyster. This study confirms the hygienic safety of the soft tissues of both the pearl-free and the pearl-containing pearl oysters, as food.

Animals↗
PubMed2002

Soluble silk-like organic matrix in the nacreous layer of the bivalve Pinctada maxima.

Nacre organic matrix has been conventionally classified as both 'water-soluble' and 'water-insoluble', based on its solubility in aqueous solutions after decalcification with acid or EDTA. Some characteristics (aspartic acid-rich, silk-fibroin-like content) were specifically attributed to either one or the other. The comparative study on the technique of extraction (extraction with water alone vs. demineralization with EDTA) presented here, seems to reveal that this generally accepted classification may need to be reconsidered. Actually, the nondecalcified soluble organic matrix, extracted in ultra-pure water, displays many of the characteristics of what until now has been called 'insoluble matrix'. We present the results obtained on this extract and on a conventional EDTA-soluble matrix, with various characterization methods: fractionation by size-exclusion and anion-exchange HPLC, amino acid analysis, glycosaminoglycan and calcium quantification, SDS/PAGE and FTIR spectroscopy. We propose that the model for the interlamellar matrix sheets of nacre given by Nakahara [In: Biomineralization and Biological Metal Accumulation, Westbroek, P. & deJong, E.W., eds, (1983) pp. 225-230. Reidel, Dordrecht, Holland] and Weiner and Traub [Phil. Trans. R. Soc. Lond. B (1984) 304, 425-434] may no longer be valid. The most recent model, proposed by Levi-Kalisman et al. [J. Struct. Biol. (2001) 135, 8-17], seemed to be more in accordance with our findings.

Amino Acids↗
PubMed2000

[Electroporation of sperm to introduce foreign DNA into the genome of Pinctada maxima (Jameson)].

Gene transfer was investigated in marine molluscs via electroporated sperm. Sperm of P. maxima (J.) was incubated with linear "all-fish" growth hormone gene (pCAgcGH and pCAgcGHc) for 30 min. Then, mature eggs were in-vitro fertilized with the sperm cells treated with electroporation at 10 kV and 2(7) pulses of six cycles. DNA was extracted from spat and analyzed by PCR and southern blot. The results indicated that the foreign DNA had been transferred into the genome of experimental molluscs. The transgenetic ration was 5.6%, 20% and 50% when 2 micrograms/mL, 6 micrograms/mL and 18 micrograms/mL of foreign DNA was used, respectively. It is suggested that the transferred efficiency is correlated with the amount of the foreign DNA.

Animals↗