A molluscs

Furthermore, as shown in Figure 5.28, the number of amino acid differences between two cytochrome c sequences is proportional to the phylogenetic difference between the species from which they are derived. The cytochrome c in humans and in chimpanzees is identical human and another mammalian (sheep) cytochrome c differ at 10 residues. The human cytochrome c sequence has 14 variant residues from a reptile sequence (rattlesnake), 18 from a fish (carp), 29 from a mollusc (snail), 31 from an insect (moth), and more than 40 from yeast or higher plants (cauliflower). 

Even an invertebrate animal that gives no appearance of physical activity possesses a muscle that has a capacity of the Krebs cycle that is similar to that in a muscle of a young adult human. This is the radular retractor muscle of a mollusc, the wheUc. Whelks are found on the seashore they can use their radula continually for very long periods, up to 24 hours in some cases, to rasp flesh off, for example, a fish carcass. A simple dissection of a whelk readily reveals the radular retractor muscle, easily identified by its brilliant red colour. This muscle illustrates the principle that for muscles that are physiologically essential and have to work for long periods of time, the generation of ATP must be from the oxidation of a fuel which requires mitochondria and therefore cytochromes, which is why the radular retractor muscle is red. 

A pearl is a concretion produced by a mollusc. There are a number of theories as to why a pearl forms, but it seems evident that it is, at least in part, as a reaction to some type of intruder or foreign body in the shell. 

All pearls can occur naturally, but today the majority of them are cultivated and are known as cultured pearls . Although they grow naturally inside a mollusc, their growth is instigated and controlled by human intervention. 

As already stated, a mollusc can also cover an object that is attached to the inside of its shell. This can be a natural occurrence, but is also copied to produce cultured blister pearls. A hemisphere of mother-of-peari or plastic is attached to the shell underneath the mantle, and the mollusc is left to coat the object with nacre. Usually the blister pearl will be cut away from the shell and the shell back and nucleus removed, leavir a hollow hemisphere of nacre. This is cleaned, and filled with resin or wax. The hemisphere is then backed with a new piece of policed mother-of-pearl. The result is a composite cultured blister peari. The term mab is now generic and used to describe these pearis, although, strictly speaking, it should only refer to blister pearls fix)m a single species of oyster - the black willed oyster (Figs 9.3 and 9.11). 

A shell is the calcareous outer part of a mollusc s body. Molluscs are animals living both on land and in the sea, but the shells that are used as gem material come mostly from marine or freshwater molluscs, though some land-based snails are also used. 

A mollusc s shell is formed by the mantle, which deposits an organic matrix (sometimes called conchiolin), and calcium carbonate, which forms crystals. The mollusc absorbs the chemicals necessary for this from its surroundings. 

Mab pearls are cultured blister pearls, produced against the shell of a mollusc. They are dealt with in detail in Chapter 9 (TeariO as they are used and sold as pearls (Figs 9.2 and 9.3). 

The invention of dyeing lias been attributed to the Phoenicians, probably because it is chronicled that Solomon sent to Hiram of Tyre for a man cunning to work inter alia in purple and crimson and blue. The Tyrian purple was derived from the throats of a species of murex, a molluscous animal, a single drop from each. Other dyes from animal substances include sepia derived from the black secretion of the cuttlefish, and cochineal which consists of dried female cochineal insects, discovered by the Spaniards in 1518. 

Charlet, M., Chernysh, S., Philippe, H., Hetru, C., Hoffmann, J.A., Bulet, P. Innate immunity. Isolation of several cysteine-rich antimicrobial peptides from the blood of a mollusc, Mytilus edulis. J. Biol. Chem. 1996, 271, 21808-21813... 

From the products obtained by treatment of a dilute solution of sodium alginate with an extract of the liver of abalone (a mollusc) was isolated a crystalline disaccharide which gave D-mannuronic acid on hydrolysis and showed the spectrum of an a,/3-unsaturated acid. If the assumption is made that no transglycosylation had occurred, the structure of this compound must be that of 4-0-(4-deoxy-a-L-er2/[Pg.115]

Tsujino and Sato treated a dilute solution of sodium alginate with an enzyme obtained by extraction of the liver of a mollusc (abalone). The crystalline, unsaturated disaccharide 71 was isolated in low yield. 

Shipworm Teredo spp.) a mollusc tropica) waters. b) Cribble Limnoria spp.) a crustacean cooler waters. 

Kobayashi, S., Kobayashi, J., Yazaki, R., Ueno, M. (2007). Toward the total synthesis of onchidin, a cytotoxic cyclic depsipeptide from a mollusc. Chemistry - An Asian Journal, 2, 135-144. 

Erspamer developed a very sensitive assay using the isolated rat uterus in oestrus. Vane made use of the rat-stomach fundus cut into narrow strips. The heart of a mollusc, Venus mercenaria, was also utilized by Welsh to detect minute amounts of S-HT in various biological materials (see Erspamer in ref. 4). The specificity of these bioassays should be verified systematically with S-HT antagonists like LSD or BOL since so many factors in crude-tissue extracts can also induce similar biological effects. The biological assays lost some of their value following the development of more sensitive assay techniques based on physicochemical properties of indoles and their derivatives. 

Linz, G.S., Sanduja, R., Weinhermer, A.J., Alam, M., and Martin, G.E. (1986) pHcation of COSY and homonuclear relay 2D-NMR in determining structure of a cembrane from a mollusc Planaxis sulcatus. Tetrahedron Lett., 27, 4833—4836. 

With the exception of a-conotoxin SII from Conus striatus, all a-conotoxins have the cysteine pattern, CC—C—C (Myers et al., 1993) (see Table 4). Peptides from the fish-hunting species, C geographus, C. striatus and C. magus, have the consensus core sequence CC(N/H)PACGXX(Y/F)XC and two disulfide bonds that connect Cys to Cys and Cys to Cys. Comparison with the a-conotoxins recently isolated from C. pennaceus, a mollusc-hunter, and C. imperialism a worm-hunter, indicates variations in the size of the intercysteine loops. The second loop has seven amino acid residues in a-conotoxins PnIA and PnIB from C pennaceus (Fainzilber et al., 1994), and only three residues in a-conotoxin Iml from C. imperialis (McIntosh et al., 1994), compared to five residues in the other a-conotoxins. 

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