Invertebrate and

Environmental Considerations. The phosphate flame retardants, plasticizers, and functional fluids have come under intense environmental scmtiny. Results pubUshed to date on acute toxicity to aquatic algae, invertebrates, and fish indicate substantial differences between the various aryl phosphates (159—162). The EPA has summarized this data as well as the apparent need for additional testing (147). 

DDT is slowly converted in vivo by reductive dechlorination to DDD and by further dechlorinations to 4,4 -dichlorodiphenylacetic acid [83-05-6] (DDA), the predominant excretory metaboUte. Anaerobically, it may form 4,4 -dichlorodiphenyiacetonitrile [20968-04-1] (DDCN). However, most DDT that enters the environment is sequestered as DDE, which is ubiquitously present in the body Hpids of invertebrate and vertebrate animals. In humans. 

In addition to reproductive effects, fish exposed to endocrine disrupters may have a decreased response to stress or decreased growth and metabolism which can affect their ability to survive, or to defend themselves against predators. All of these factors can affect the ability of the species to survive and to reproduce itself in sufficient numbers to maintain the stocks on which our commercial and sport fisheries are based. Not all fish species will be equally susceptible to the effects of endocrine disrupters. Selective sensitivity to such effects, especially those affecting reproduction, may well lead to major changes in the flora and fauna of some of our major aquatic ecosystems as the balance between fish, mammals, invertebrates and plants, and between predators and prey, is destabilised... 

K. J. Maeek, K. S. Buxton, S. S. Sauter, S. Gnilka and J. W. Dean, Chronic Toxicity of Atrazine to Selected Aquatic Invertebrates and Pishes, Environmental Researeh Laboratory, US Environmental Proteetion Ageney, Deluth, MN, 1976, EPA 600/3-76-047. 

MMP genes show a highly conserved modular structure. They were first detected in vertebrates (1962), and human beings, but have since been found in invertebrates and plants as well. The MMP family... 

In contemporary societies replete with various industries and automobiles, NO (NO, N02, and N03) has been recognized to be one of the important factors responsible for air pollution. Only two decades ago, NO was found to be an essential molecule that regulates cellular/molecular functions in mammals. NO is also enzymatically synthesized in nonmammals, invertebrates, and yeasts. Therefore, the origin of NO may date back to the birth of life arising from single cell organisms living around 3-billion years ago. 

Nonmuscle/smooth muscle myosins-Il are structurally similar to striated muscle myosin-II, but they have slower rates of ATP hydrolysis than do their striated muscle counterparts. Nonmuscle/smooth muscle myosin-II is also regulated differently than striated muscle myosin-II. Nonmuscle myosin-II is divided into the invertebrate and vertebrate branches (Cheney et al., 1993). This group is ubiquitous because it is present in most lower organisms, such as slime molds, amoeba, sea urchins, etc., and in virtually all mammalian nonmuscle cells. Smooth muscle myosin-II is also somewhat heterogeneous in that at least three separate forms of smooth muscle heavy chains, with molecular weights of 196,000, 200,000, and 204,000 have been identified (Kawamoto and Adelstein, 1987). The physiological properties of these separate myosin heavy chains are not yet known. 

Sediment Analysis. Sediment is the most chemically and biologically active component of the aquatic environment. Benthic invertebrate and microbial life concentrate in the sediment, a natural sink for precipitated metal forms, and an excellent sorbent for many metal species. TTie extent to which potentially toxic trace element forms bind to sediment is determined by the sediment s binding intensity and capacity and various solution parameters, as well as the concentration and nature of the metal forms of interest. Under some conditions sediment analyses can readily indicate sources of discharged trace elements. 

Lamed ST, Dairy T, Robinson C (2007) Invertebrate and microbial reponses to inundation in an ephemeral river reach in New Zealand effects of preceding dry periods. Aquat Sci 69 554-567... 

Monomethyltirf. Acute toxicity studies were identified for monomethyltin for algae, invertebrates, and fish. Chronic NOECs were available for algae and invertebrates. A chronic NOEC of 0.007 mg/1 for monomethyltin chloride in Scenedesmus subspica-tus was the lowest reported result. Since there were no long-term test results available for fish, it was necessary to apply an uncertainty factor of 50 to the critical study. 

Dioctyltirv. Acute toxicity studies were identified for dioctyltin for invertebrates and fish. Chronic NOECs were available for algae and invertebrates. 

The major routes of uptake of xenobiotics by animals and plants are discussed in Chapter 4, Section 4.1. With animals, there is an important distinction between terrestrial species, on the one hand, and aquatic invertebrates and fish on the other. The latter readily absorb many xenobiotics directly from ambient water or sediment across permeable respiratory surfaces (e.g., gills). Some amphibia (e.g., frogs) readily absorb such compounds across permeable skin. By contrast, many aquatic vertebrates, such as whales and seabirds, absorb little by this route. In lung-breathing organisms, direct absorption from water across exposed respiratory membranes is not an important route of uptake. 

There have been a nnmber of estimates of bioconcentration factors for total PCBs in aqnatic species following long-term exposure to PCB mixtures (EHC 140). Values for both invertebrates and hsh have been extremely variable, ranging from values below 1 to many thonsands. Bioaccnmnlation factors for birds and mammals for different Aroclors have indicated only limited degrees of bioaccumulation from food, for example, 6.6 and 14.8 for the whole carcasses of big brown bats Eptesicus fuscus) and white pelican (Pelecanus erythrorhynchos), respectively (see Environmental Health Criteria 140). 

Mechanistic studies have shown that TBT and certain other forms of trialkyltin have two distinct modes of toxic action in vertebrates. On the one hand they act as inhibitors of oxidative phosphorylation in mitochondria (Aldridge and Street 1964). Inhibition is associated with repression of ATP synthesis, disturbance of ion transport across the mitochondrial membrane, and swelling of the membrane. Oxidative phosphorylation is a vital process in animals and plants, and so trialkyltin compounds act as wide-ranging biocides. Another mode of action involves the inhibition of forms of cytochrome P450, which was referred to earlier in connection with metabolism. This has been demonstrated in mammals, aquatic invertebrates and fish (Morcillo et al. 2004, Oberdorster 2002). TBTO has been shown to inhibit P450 activity in cells from various tissues of mammals, including liver, kidney, and small intestine mucosa, both in vivo and in vitro (Rosenberg and Drummond 1983, Environmental Health Criteria 116). 

As noted earlier, OPs are known to be highly toxic to aquatic invertebrates and to fish. This has been demonstrated in field studies. For example, malathion applied to watercress beds caused lethal intoxication of the freshwater shrimp Gammarus pulex located downstream (Crane et al. 1995). Kills of marine invertebrates have been reported following the application of OPs. Accidental release of OPs into rivers, lakes, and bays has sometimes caused large-scale fish kills (see Environmental Health Criteria 63). 

Protozoa and Porifera. The pharmacology and toxicology of the dinoflagellate toxins which act upon the voltage- and time-dependent sodium channel found in nerves of vertebrates and invertebrates, and the skeletal muscle of vertebrates, are discussed in other chapters in this volume. 

Machado, G. et al.. Chemical defense in harvestmen (Arachnida, Opiliones) do benzoquinone secretions deter invertebrate and vertebrate predators J. Chem. EcoL, 31, 2519, 2005. 

Mason RP, Laporte J, Andres S. 2000. Factors controlling the bioaccumulation of mercury, methyhnercury, arsenic, selenium, and cadmium by freshwater invertebrates and fish. Arch Environ Contam Toxicol 38 283-297. 

C. Holmstrom and S. Kjelleberg, The effect of external biological factors on settlement of marine invertebrate and new antifouling technology. Biofouling, 1994, 8, 147. 

Biogenic amines are decarboxylated derivatives of tyrosine and tryptophan that are found in animals from simple invertebrates to mammals. These compounds are found in neural tissue, where they function as neurotransmitters, and in non-neural tissues, where they have a variety of functions. The enzymes involved in biogenic amine synthesis and many receptors for these compounds have been isolated from both invertebrate and vertebrate sources. In all cases, the individual proteins that effect biogenic amine metabolism and function show striking similarity between species, indicating that these are ancient and well-conserved pathways. 

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