Lung-fish

Table 4.1 presents a classification of fishes derived from Nelson (1994) in order to indicate the taxonomic position of the species studied. This classification puts the fishes in an order that reflects their postulated evolutionary relationship, ranging from the most ancient splits in vertebrate evolution, Chondrichthyes (sharks, rays), Sarcopterygii (Lung-fish, Coelacanths and Tetrapods) and Actinopterygii (ray-finned fishes), to the most recent teleost orders, Pleuronectiformes (flounders) and Tetraodontiformes (puffers). 

Fig. 182. Urea formation by the glycine-allantoin cycle in lung fish...

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. 

Routes of entry - fish and mammals share two potential routes of entry, namely oral and percutaneous. Mammals also absorb xenobiotics via the lungs while gill absorption is possible in fish. 

Inorganic arsenic salts are also present in pesticides, herbicides, fungicides, paints, and tobacco plants. If transmitted to water, they accumulate in fish, mollusks, crustaceans, and algae (Johansen et ah, 2000). Transformed into organic salts, they reach the gastrointestinal tract via food and are delivered to liver, spleen, kidneys, and lungs. Arsenic is deposited in skin, nails, and hair. 

Zinc is an important trace element required for all healthy plants and animals. Zinc is found in proteins, such as meats, fish, eggs, and milk. About 10 to 15 miUigrams of zinc is required per day, and it may be taken as a dietary supplement. Zinc helps the blood in our bodies move the waste gas—carbon dioxide—to the lungs and helps prevent macular degeneration (loss of vision). 

Murphy, R., Mourtzakis, M., Chu, Q., Baracos, V., Reiman, T., and Mazurak, V. (2011). Nutritional intervention with fish oil provides a benefit over standard of care for weight and skeletal muscle mass in patients with nonsmall cell lung cancer receiving chemotherapy. Cancer 117,1775-1782. 

Squalene 287 Fish liver oils Yeast lipids and higher >2.0 Colon, Lung [30,37,46,89]... 

A microsomal O -methyltransI erase that methylates a number of alkyl-, methoxy-, and halophenols has been described from rabbit liver and lungs. These methylations are inhibited by SKF-525, A-ethyl-maleimide and /->-chloromercuribenzoate. A hydroxyin-dole O-methyItransferase, which methylates A -acetyl-serotonin to melatonin and, to a lesser extent, other 5-hydroxyindoles and 5,6-dihydroxyindoles, has been described from the pineal gland of mammals, birds, reptiles, amphibians, and fish. 

Liver and adipose tissue are the major storage compartments for CACs. Ratios between liver and adipose tissue distribution are species dependent and follow the order rodents > birds > humans > fish.30 In marine mammals this ratio is determined by their relatively large adipose tissue compartment, with large storage capacities. CAC metabolites may bind to specific target proteins, e.g. in blood, kidney or lung. 

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