Mollusks chains

PAHs can be bioconcentrated or bioaccumulated by certain aquatic invertebrates low in the food chain that lack the capacity for effective biotransformation (Walker and Livingstone 1992). Mollusks and Daphnia spp. are examples of organisms that readily bioconcentrate PAH. On the other hand, fish and other aquatic vertebrates readily biotransform PAH so, biomagnification does not extend up the food chain as it does in the case of persistent polychlorinated compounds. As noted earlier, P450-based monooxygenases are not well represented in mollusks and many other aquatic invertebrates (see Chapter 4, Section 4.2) so, this observation is not surprising. Oxidation catalyzed by P450 is the principal (perhaps the only) effective mechanism of primary metabolism of PAH. 

It appears that organisms at the top of aquatic food chains are not exposed to substantial levels of PAH in food because of the detoxifying capacity of organisms beneath them in the food chain. On the other hand, fish, birds, and aquatic mammals feeding on mollusks and other invertebrates are in a different position. Their food may contain substantial levels of PAH. Although they can achieve rapid metabolism of dietary PAH, it should be remembered that oxidative metabolism causes... 

Initially, it was suspected that the nitrophorins were insect hemoglobins. Indeed, they showed 45-48% homology with monomeric hemoglobins from insects, annelids, mollusks, nematodes, and even human 3 chains and leghemoglobin (44). However, in due time it became clear that these proteins were not globins at all, but rather, beta-barrel proteins called lipocalins (see Section III). As for the four nitrophorins, the sequences of NPl and NP4 are 90% identical, whereas those of NP2 and NP3 are 79% identical NPl and NP2, however, are only 38% identical. 

Chu, K. H., Wong, S. H., and Leung, P. S. C. (2000). Tropomyosin is the major mollusk allergen Reverse transcriptase polymerase chain reaction, expression and IgE reactivity. Mar. Biotechnol. 2,499-509. 

Maintenance of bottom fish and marine mollusk communities. Bioaccumulation in the marine food chain will not result in unacceptable tissue COPC concentrations. Measure COPC concentrations in tissue samples and compare to literature-based toxicity reference values. 

Chapters 3 and 4 investigate representatives of the invertebrate groups in the intertidal zone, the small animals. These organisms include sponges, cnidarians, worms, mollusks, crustaceans, and echinoderms. In the coastal food chain, these invertebrates feed on plants and animals and serve as food for larger organisms. Most are protected by structures such as shells or spines or by toxic chemicals. 

Sepe, N., De Petrocellis, E., Montanaro, E, Cimino, G., Di Marzo, V. (1998) Bioactive long chain N-acylethanolamines in five species of edible bivalve mollusks. Possible implications for mollusk physiology and sea food industry. Biochem. Biophys. Acta 1389, 101-111. 

Colombo, F., Cerioli, M., Colombo, M.M., Marchisio, E., Malandra, R., and Renon, P. 2002. A simple polymerase chain reaction-restricition fragment length polymorphism PCR-RFLP method for the differentiation of cephalopod mollusk families Loliginidae from Ommastrephidae, to avoid substitutions in fishery field. Food Control 13, 185-190. 

Plutonium was found to bioaccumulate in aquatic organisms, primarily at the lower end of the food chain. The bioconcentration factors (i.e., the amount of the chemical found in the organism divided by the concentration in the surrounding water over the same time period) were 1,000 for mollusks and algae, 100 for Crustacea, and 10 for fish (WHO 1983). Plutonium is concentrated in the bones of fish rather than in muscle tissues, as seen by whole fish to muscle tissue ratios of 2X10 to 5x10 or 40 1 (NCRP 1984). 

---