Vertebrates marine

Neurotoxins present in sea snake venoms are summarized. All sea snake venoms are extremely toxic, with low LD5Q values. Most sea snake neurotoxins consist of only 60-62 amino acid residues with 4 disulOde bonds, while some consist of 70 amino acids with 5 disulfide bonds. The origin of toxicity is due to the attachment of 2 neurotoxin molecules to 2 a subunits of an acetylcholine receptor that is composed of a2 6 subunits. The complete structure of several of the sea snake neurotoxins have been worked out. Through chemical modification studies the invariant tryptophan and tyrosine residues of post-synaptic neurotoxins were shown to be of a critical nature to the toxicity function of the molecule. Lysine and arginine are also believed to be important. Other marine vertebrate venoms are not well known. 

There are many venomous marine vertebrates in the seas, notably sea snakes and fishes. Venoms of sea snakes have been studied much more thoroughly than fish venoms. In this chapter, sea snake venom is described in greater detail than fish venoms simply because there is much more scientific information available. 

Since sea snake venoms are discussed here, it is appropriate to review other vertebrate venoms also. Unfortunately, very few investigations have been done on the venoms of other marine vertebrates. It is known that some fish secrete venoms from their spines. The fishes known to have venoms are the scorpion fish (family Scorpaenidae), weever fish (family Trachinidae), catfish (order Siluriformes there are 31 families), stargazers (family Uranoscopidae), toad fish (family Batrachoidi-dae), and stingrays (suborder Myliobatoidea). 

From this brief review of marine vertebrate venoms, it is obvious that very few biochemical investigations have been done. The technology to study marine vertebrate venom components is available. There are simply not enough scientists interested enough to enter the field. The first task is to isolate the toxic principles and identify the amino acid sequences. Pharmacological investigation should be done on the purified toxic principle and not on the crude venom, which is a mixture of many proteins and nonproteins. 

Eisler, R. 1984. Trace metal changes associated with age of marine vertebrates. Biol. Trace Element Res. 6 165-180. 

In muscle of Weddell seals (Leptonychotes weddelli), copper is positively correlated with iron (Szefer et al. 1994). In general, concentrations of copper in all tissues of all marine vertebrates examined are positively correlated with concentrations of iron (Eisler 1984). 

Eisler, R. 1984. Trace metal changes associated with age of marine vertebrates. Biol. Trace Elem. Res. 6 165-180. Eisler, R. 1989. Molybdenum hazards to fish, wildlife, and invertebrates a synoptic review. U.S. Fish Wildl. Serv. Biol. Rep. 85 (1.19). 61 pp. 

Marine vertebrates, including fishes and elasmobranchs, have low zinc concentrations in tissues (i.e., 6 to 400 mg/kg DW) when compared to marine plants and invertebrates (Eisler 1980, 1981, 1984). Highest concentrations in muscle of marine fishes (20.1 to 25.0 mg/kg FW) were recorded in northern anchovy (Engraulis mordax) and Atlantic menhaden (Brevoortia tyrannus NAS 1979). 

Thompson, D.R. 1990. Metal levels in marine vertebrates. Pages 143-182 in R.W. Furness, and P.S. Rainbow (eds.). Heavy Metals in the Marine Environment. CRC Press, Boca Raton, FL. 

MARINE VERTEBRATES Grey mullet, Chelon labrosus 500 LC50 (85 h) 11... 

Moreover, butyltin accumulation in other marine vertebrates indicated greater accumulation in various organs [280,282,295,306]. 

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