Invertebrates mollusks

Invertebrates Mollusks (e.g., mussels, Mytilus spp.) Favorable characteristics for monitoring include resistance to toxic effects, ease of sampling, and lack of mobility... 

Most aquatic invertebrates have very little capacity for metabolism this is particularly true of mollusks. Crustaceans (e.g., crabs and lobsters) appear to have greater metabolic capability than mollusks (see Livingstone and Stegeman 1998 Walker and Livingstone 1992). 

Of particular interest in the present context is that TBT can inhibit cytochrome-P450-based aromatase activity in both vertebrates and aquatic invertebrates (Morcillo et al. 2004, Oberdorster and McClellan-Green 2002). The conversion of testosterone to estradiol is catalyzed by aromatase, and so inhibition of the enzyme can, in principle, lead to an increase in cellular levels of testosterone. The significance of this is that many mollusks experience endocrine disruption when exposed to TBTs,... 

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... 

Examples of differences in the responses of wildlife organisms to EDCs include the differences in sensitivity to phthalates and bisphenols among mollusks, crustaceans, and amphibians compared to fish. In invertebrates, biological effects are observed at exposures in the ng/L to low pg/L range, compared to high pg/L for most effects in fish (reviewed in Oehtmann et al. 2008). In addition, aquatic mollusks tend to bioconcentrate and bioaccumulate pollutants to a greater level than hsh, possibly owing to poorer capabilities for metabolic detoxification (see Chapter 4, Section 4.3). 

Determinations of NO in a variety of biological systems have been made. For example, measurement of NO has been made in eyes [79-81], gastrointestinal tract [82, 83], brain tissue [47, 50, 84-87], kidney and kidney tubule fluid [88-93], rat and guinea pig isolated and intact hearts [94, 95], rat spinal cord [96], human monocyte cells [97], human endothelial cells [98], mitochondria [99, 100], rat penis corpus cavemo-sum [101], granulocytes [102], invertebrate ganglia and immunocytes [103], choroidal endothelial cells [104], cancer cells [105, 106], peripheral blood [107], human blood [108], human leukocytes [109], platelets [110-112], ears [113, 114], plants [115-118], and pteropod mollusk [119]. 

Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, F.G. Thompson, and J.D. Williams. 1988. Common and Scientific Names of Aquatic Invertebrates from the United States and Canada Mollusks. Amer. Fish. Soc. Spec. Publ.16. 227 pp. + 12 plates. Williams, A.B., L.G. Abele, D.L. Felder, H.H. Hobbs, Jr., R.B. Manning, P.A. McLaughlin, and I.P. Farfante. 1989. Common and Scientific Names of Aquatic Invertebrates from the United States and Canada Decapod Crustaceans. Amer. Fish. Soc. Spec. Publ. 17. 77 pp. + 4 plates. 

Source Higher animals, some invertebrates Higher animals, some invertebrates invertebrates Arthropods, mollusks... 

The distribution of aquatic species sensitivities to cypermethrin is typical of SPs [7] (Giddings JM (2006) Compilation and evaluation of toxicity data for synthetic pyrethroids. Unpublished report of Compliance Services International, Rochester). Crustacean and insect species (from the phylum Arthropoda) tend to be more sensitive to pyrethroids compared to other invertebrates such as worms and mollusks, and fish tend to be less sensitive than arthropods. These sensitivities are... 

Significant concentrations of cyanotoxins have been found to accumulate in the tissues of macroinvertebrates such as mollusks and crustaceans, presenting an indirect route of exposure for invertebrates, fish, and aquatic mammals at higher trophic levels (Negri and Jones 1995). In natural systems, mortality among benthic invertebrate herbivores is probably low because most bloom-forming bacteria are planktonic and only periodically come into contact with the benthos. Nevertheless, Kotak et al. (1996) determined that enhanced mortality of snails at the end of a bloom cycle in Canadian lakes was due to consumption of Microcystis cells that had formed a scum on the surface of macrophytes. Oberemm et al. (1999) found that aqueous microcystins, saxitoxins, and anatoxin-a all resulted in developmental delays in fish and salamander embryos. Interestingly, more severe malformations and enhanced mortality were observed when larvae were exposed to crude cyanobacterial extracts than to pure toxins applied at natural concentrations (Oberemm et al. 1999). 

There are 34 fundamental phyla of life 17 occur on land and 32 in the sea (including some overlaps). More chemical diversity is found among marine hfe forms. Most of these are from invertebrate organisms— sponges, tunicates, and mollusks. Some of the compounds from marine life forms are extremely potent, given that these organisms have to defend themselves from attacks in vast volumes of water that dilute the compound. 

Prialt [Fig. 6] is a synthetic copy of a toxin from the Magician s cone snail. Conus magus, a mollusk from the Indo-Pacific region. This is also one of the first pharmaceuticals that demonstrate the promise that marine life, particularly invertebrates, holds for drug developers. 

In the mollusks, only marine species are known for unusual metabolites. However, while polypropionates of marine pulmonates have de novo origin (Table 9.1), the secondary metabolites isolated from opisthobranch mollusks derive mostly from dietary cyanobacteria, seaweeds, and invertebrates. 

Brominated compounds widely occur in marine organisms, particularly seaweeds and invertebrates. Many of them play a defensive role against parasites and predators, and are incorporated by opisthobranch mollusks to this scope from the diet. Bromine is uptaken by seaweeds and invertebrates from bromide dissolved at sparingly 1 mM concentration in seawater. The process is catalyzed by haloperoxidases, which have been characterized both as structure and function (Butler 1997). 

The zebra mussel, Dreissenapolymorpha, is a most successful invertebrate invader. This Eurasian bivalve mollusk has recently entered the US, first in the Great Lakes region and then the Mississippi and Hudson rivers, where it is out of control. 

Com shell is carnivorous snail belongs to the world s largest genus of marine invertebrates (Conus) under the phylum of mollusks (Bingham et al., 2010). Com shell species are able to secrete venom, which contains com shell toxins (conotoxins) of bioactive peptides called as conopeptides (Layer and McIntosh, 2006). Different structural classes of... 

Mammals other than primates further oxidize urate by a liver enzyme, urate oxidase. The product, allantoin, is excreted. Humans and other primates, as well as birds, lack urate oxidase and hence excrete uric acid as the final product of purine catabolism. In many animals other than mammals, allantoin is metabolized further to other products that are excreted Allantoic acid (some teleost fish), urea (most fishes, amphibians, some mollusks), and ammonia (some marine invertebrates, crustaceans, etc.). This pathway of further purine breakdown is shown in figure 23.22. 

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