Mollusca

The bioaccumulation of a wide variety of organic compounds has been described in laboratory exposures of bivalves and gastropods. In addition to the data of Tables 8,9 and 13, and some 30 or more compounds described in Geyer et al. (1982), Zaroogian et al. (1985) and Hawker and Connell (1986), other xenobiotics taken up include PCP (Kobayashi et al. 1969), di-w-butyltin (Holwerda and Herwig 1986), methylmercury (Davies and Russel 1988) and trichlorfon [0-0-dimethyl- 1 -hydroxy-2,2,2-trichloroethyl)-phosphonate] (Mattson et al. 1988). The uptake and interactions of mixtures of compounds have also been examined, e.g. the uptake of napthalene by the oyster Crassostrea virginica was reduced by simultaneous presence of BaP and a PCB mixture (Fortner and Sick 1985). 

The bioaccumulation of a xenobiotic usually involves an initial high linear rate of uptake, followed by the eventual reaching of a maximal tissue equilibrium concentration (Burns and Smith 1981 Hawker and Connell 1986). In some cases clearly biphasic or multiphasic uptake have been observed, e.g. petroleum hydrocarbons (Stegeman and Teal 1973) and picric and picramic acids (Burton et al. 1984) taken up by C. virginica, which, as for depuration processes (see below), can be interpreted in terms of equilibration of the xenobiotic into multiple compartments within the organism. In other cases tissue equilibrium concentrations have not been reached after long periods of exposure, e.g. various bivalves exposed to hydrocarbons for up to 6 months (Clement et al. 1980 Widdows et al. 1982). The initial rate of uptake and equilibrium biotic concentration depends on the xenobiotic exposure concentration (Burns and Smith 1981 Hawker and Connell 1986). 

Species Xenobiotics Field site Concentration (/igg- wetwt.) Reference 

Mytilus edulls, Crassostrea virginica, Mya arenaria, Tresus capax Total PAH (3-6 ring) Oregon bays (USA) — clean — light commerce — heavy commerce 0.03-0.06 0.03-0.04 0.48-1.33 Mix (1984) 

Mytilus galloprovincialis Total PAH (2-6 ring) Thermaikos gulf (Greece) 0.08-0.09 Isoifidou et al. (1982) 

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In Mollusca, bioluminescence occurs in a great variety of organisms having distinctly different appearances, such as the classes Gastropoda (limpets, snails and sea hares), Bivalvia (clams), and Cephalopoda (squids and octopuses). All luminous molluscs currently known are marine organisms, except the New Zealand fresh water limpet Latia neritoides and the Malaysian land snail Quantula (Dyakia) striata. No information is yet available on the biochemical aspects of the Quantula luminescence. 

Girsch, S., Herring, P. J., and McCapra, F. (1976). Structure and preliminary biochemical characterization of the bioluminescent system of Ommas-trephes pteropus (Steenstrup) (Mollusca Cephalopoda). J. Mar. Biol. Ass., U.K. 56 707-722. 

Johnsen, S., Balser, E. J., Fisher, E. C., and Widder, E. A. (1999). Bioluminescence in the deep-sea cirrate octapod Strauroteuthis syrtensis Verrill (Mollusca Cephalopoda). Biol. Bull. 197 26-39. 

Phylum Mollusca Chitons, snails, clams, squids, octopi... 

Schulte-Oehlmann, U., Tilhnann, M., and Marker , B. et al. (2000). Effects of endocrine disrupters on prosobranch snails (Mollusca gastropoda) in the laboratory. Part II Triphenyltin as a xeno-androgen. Ecotoxicology 9, 399 12. 

Mollusca and Arthropoda. A variety of pharmacological actions are induced by the toxins found in molluscs (17). For example, surugatoxin is a potent mydriatic (5J), ganglion blocker (84), and a potent hypotensive agent in cats. 

Intracellular symbiosis is extremely widespread in invertebrates. For example, mutualistic symbioses with intracellular bacteria can be found in almost all animal phyla, including sponges, cnidaria, nematodes, anellids, mollusca and arthropoda. Buchner (1965) thoroughly reviews most information published on bacterial symbiosis in animals up to 1964. After this monumental work, various reviews on more specific subjects have been published (e.g. Baumann, 1998, and references therein) including some recent reviews on Wolbachia (O Neill et al., 1997 Werren, 1997). In most of these papers, the term symbiosis is apparently used with a broad meaning the intracellular bacterium is usually referred to as an endosymbiont even in the absence of data on effects on host fitness. Here only key points on intracellular symbiosis and Wolbachia will be summarized, so as to put the information available on symbiosis in filarial nematodes into a broader context. 

Wiesner L, Gunther B, Fenske C (2001) Temporal and spatial variability in the heavy-metal content of Dreissena polymorpha (Pallas) (Mollusca Bivalvia) from the Kleines Haff (northeastern Germany). Hydrobiologia 443 137-145... 

Swaileh, K.M. and D. Adelung. 1994. Levels of trace metals and effect of body size on metal content and concentration in Arctica islandica L. (Mollusca Bivalvia) from Kiel Bay, western Baltic. Mar. Pollut. Bull. 28 500-505. 

Fantin, A.M.B., A. Franchini, E. Ottaviani, and L. Benedetti. 1985. Effect of pollution on some freshwater species. II. Bioaccumulation and toxic effects of experimental lead pollution on the ganglia in Viviparus ater (Mollusca, Gastropoda). Basic Appl. Histochem. 29 377-387. 

Munzinger, A. and M.L. Guarducci. 1988. The effect of low zinc concentrations on some demographic parameters of Biomphalaria glabrata (Say), mollusca gastropoda. Aquat. Toxicol. 12 51-61. 

Willis, M. 1988. Experimental studies on the effects of zinc on Ancylus fluviatilis (Muller) (mollusca gastropoda) from the Afon Crafnant, N. Wales. Arch. Hydrobiol. 112 299-316. 

Mollusca Gastropods, Bivalves Lectins, PO, AMPs, molluscan defense molecules, fibrinogen related proteins, cytokines... 

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