Pearl oyster

Katano, S., Oki, T., Matsuo, Y., Yoshihira, K., Nara, Y., Miki, T., Matsui, T., and Matsumoto, K. (2003). Antihypertensive effect of alkaline protease hydrolysate of the pearl oyster Pinctada fucata martencii separation and identification of angiotensin-I converting enzyme inhibitory peptides. Nippon Suisan Gakk. 69, 975-980. 

Suetsuna, K. (2002). Identification of antihypertensive peptides from peptic digest of the short-necked clam tapes philippinarum and the pearl oyster pinctada fucata martensii. 

Isoenzymes III and VII have a more specialized distribution. Carbonic anhydrase III is abundant in adipocytes which use bicarbonate in fatty acid synthesis.7 Isoenzyme V is present in the mitochondrial matrix and is also abundant in both adipocytes and liver.7 8 Isoenzyme IV is a larger membrane-associated form, while VI is secreted into the saliva.10 Carbonic anhydrase has also been identified in E. coli.,11 in a methanobacterium,12 and in green plants.13 133 A 60-kDa carbonic anhydrase called nacrein is found in the organic matrix of the nacreous layer of the pearl oyster, the layer that forms aragonite (orthorhombic calcium carbonate) in the shell and in pearls.14... 

From the pearl oyster Pinctada martensii, a glycosylceramide was isolated in which —80% of the fatty acids are comprised of a-hydroxy acids, and the main, long-chain base is CI9 , sphingosine.127... 

It is well known that well-ordered (3-chitin (a polysaccharide) associated with a less ordered protein in the (3-sheet conformation is the main component of nacreous organic matrix in shell. The amino acid sequence of such proteins is very similar to those of silk fibroins. Indeed, the amino acid sequence of a major protein from the nacreous shell layer of the pearl oyster resembles that of spidroin (Sudo et al., 1997 Weiner and Traub, 1980). The question of whether silk-like proteins play an important role in shell formation is raised. When Falini et al. (1996) did the experiment with the proteins from the shell, they assembled a substrate in vitro that contained (3-chitin and natural silk fibroin and concluded that the silk fibroin may influence ion diffusion or the accessibility to the chi tin surface or both. Furthermore, cryo-TEM study of the structure of the Atrina shell nacreous organic matrix without dehydration... 

It is also possible to divide the groups into marine and freshwater pearls. The molluscs that produce these two types of pearls are termed marine pearl oysters and freshwater mussels. 

The white-, silver- or golden-lipped pearl oyster, Pinctada maxima, is the largest pearl producing 03rster, and can measure up to 30... 

Tlie black-lipped pearl oyster, Pimtada margarm a, is a little smaller, and measures fiom 15 to 25 centimetres across. It, too, has silvery nacre inside the shell, becoming silvery gr at the edges, which are surrounded on the lip of the shell by a black border that resembles enamel. The oyster lives in the Indian Ocean and the western and central Pacific, eq>ecially around French Polynesia. It is used to produce the fiunous Tahitian black pearis, which are nucleated cultured pearls. The nacre secreted by these pearl oysters is naturally coloured and varies om li t gr to black, with iridescent hints of green, purple, pink and blue. The pearls rai in size from 10 to 18 millimetres in diameter. 

The Akoya pearl oyster, Pmctada Jucata moitenm, is again smaller, measuring 8 to 10 centimetres across. It has silvery nacre inside the shell. Akoyas are used in Japan to produce their world- mous nucleated cultured pearls, and are now also being used in China and other parts of the Far East. The cultured pearls produced by these oysters vary in size fiom 2 to 10 millimetres in diameter, and are white to cream in colour. 

The black-winged pearl oyster, Puna penguin has silvery nacre, a wide black lip and a narrow wir shape where the shell hinges. It... 

The above are the most common marine pearl oysters that are farmed today. There are many more varieties, not all of which are cultivated. The following are of historic interest. 

The La Paz pearl oyster, Pinctada mazadanica, lives in the eastern Pacific, especially around Central America. It gives white to grey pearls and was probably the source of the famous La Peregrina natural pearl (see Past and present uses section). 

The Atlantic pearl oyster, Pinctada imbricata, at between 5 and 7 centimetres across, is a relatively small oyster. It was the source of the first natural pearls that were traded from Venezuela. It is not farmed. 

The Ceylon pearl oyster, Pinctada radiata, is historically an important oyster as it is the species that gave the natural pearls that were fished around the Arabian Gulf, the Red Sea, and the Indian Ocean. 

The European pearl oyster, Margaritifera margaritifera, is of historic interest as it was the source of most of the European freshwater natural pearls. It was native to Europe and parts of North... 

Cirdte pearls are nucleated cultured pearls from marine pearl oysters. The round to oval pearls display indented rings around the middle of the pearl. It is not known eatacdy why this patterning occurs. Two possible theories are that the mantle tissue was twisted when inserted into the oyster, or that the pearl turned firequendy while it was growit. ... 

Some spedes of oyster for example the South Sea pearl oyster, can be nudeated a second time, immediately after the first pearl has been remored, by inserting a new bead into the pearl sac already there. Akoyas can only be nudeated once. 

Marine pearl oysters that are umed ate all nudeated with a bead and a piece of mantle tissue. Freshwater mussels that ate farmed are implanted with mantle tissue grafts only. In some areas the oysters and mussels to be used are bred and cultivated until they reach maturity and can be implanted. In other areas oysters are cau t in the wild to be cultivated. 

Pearl oysters are dealt with in greater detail in Chapter 9 ( Pearl ), as the shells have a great influence on the pearls they produce. Nowadays they are regarded as less important than the pearls, though originally the pearls were regarded as a by-product of shell harvesting. 

The tetramethylarsonium ion 53, arsenobetain 54, and arsenocholine 55 were detected in the soft tissues of both the pearl-free and the pearl-containing pearl oysters Pincdata fucata [162]. More than 20 years ago, arsenic-containing sugars 56 and 58 have been isolated from the kidney of the giant clam, Tridacna maxima [163]. Water-soluble arsenic species were determined in the kidney of the Tridacna derasa [164]. A total of fifteen organoarsenic species were identified, and 13 of these possessed... 

Pteriatoxin A and a 1 1 mixture of the stereoisomeric pteriatoxins B and C have been isolated from the pearl oyster Pteriapenguin from Japan [36]. Although Pteria species are widely distributed, these toxins have not, as yet, been reported in any other parts of the world. Their origin is unknown. 

Negri, A.P., Bunter, A., Jones, B. and Llewellyn, L. Effects of the bloom-forming alga Trichodesmium erythraeum on the pearl oyster Pinctada maxima. Aquaculture, 232(1 ), 91, 2003. 

CHOI Y H and chang y j (2003) The influence of cooling rate, developmental stage, and the addition of sugar on the cryopreservation of larvae of the pearl oyster Pinctada fucata martensii. Cryobiology, 46,190-193. 

ALAGAESWAMI K, DHARMARAJ S, CHELLAM A and VELAYUDHAN T S (1989) Larval and juvenile rearing of black-lip pearl oyster, Pinctada margaritifera (Linnaeus). Aquaculture, 76,43-56. 

EHTESHAMI F, CHRISTIANUS A, RAMESHI H, HARMIN S A and SAAD C R (2011) The effects of dietary supplements of polyunsaturated fatty acid on pearl oyster, Pinctada margaritifera L., gonad composition and reproductive output. Aquaculture Research, 42, 613-622. 

ZHAO B, ZHANG s and QIAN p-Y (2003) Larval settlement of the silver- or goldlip pearl oyster Pinctada maxima (Jameson) in response to natural biofihns and chemical cues. Aquaculture 220, 883-901. 

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