Salamander Skin Toxins, With Special Reference To 

 Necturus lewisi 



Ronald A. Brandon 



Department of Zoology, 



Southern Illinois University at Carbondale, 



Carbondale, Illinois 62901 



AND 



James E. Huheey 



Department of Chemistry, 



University of Maryland, College Park, Maryland 20742 



ABSTRACT. — Crude aqueous extracts of skin from two specimens of 

 Necturus lewisi were found to cause strong symptoms of toxinosis in 

 bioassay mice when injected intraperitoneally. The symptoms resembled 

 those caused by injections of pseudotritontoxin and skin extracts from 

 a variety of other salamanders, but only one bioassay mouse died. In 

 comparison to the effects of injected skin extracts of other salamanders 

 on bioassay mice, the skin of N. lewisi is moderately active in causing 

 distress but relatively less lethal. Effects of per os administration on 

 potential natural predators remain to be tested. 



INTRODUCTION 



The skins of most amphibians — lacking hair, feathers, epidermal 

 scales, dermal armor, or significant keratinization — are relatively thin, 

 heavily glandular, covered with a mucoid coat, and serve as the major 

 physiological interface through which ions, respiratory gases, and water 

 are exchanged with the environment (Whitear 1977). This sort of moist 

 integument in an environment rich in bacteria, fungi, and yeasts is par- 

 ticularly susceptible to invasion by microorganisms and to major physi- 

 ological disruption if the protective mucoid coat is damaged. In addi- 

 tion to containing many physiologically active regulatory chemicals, the 

 skin is bathed in mucus and other glandular products that may contain 

 a variety of chemical materials — proteins, peptides, steroids, alkaloids, 

 and simple biogenic amines (Cei et al. 1967, 1968; Daly et al. 1977; Daly 

 and Heatwole 1966; Erspamer et al. 1962, 1964; Habermehl 1974; Jaussi 

 and Kunz 1978; Flier et al. 1980; Mensah-Dwumah and Daly 1978; 

 Endean et al. 1975). Some of these chemicals have an antimicrobial 

 function (Habermehl 1975; Habermehl and Preusser 1969, 1970; Preusser 

 et al. 1975). Others may function as stress- warning markers (Hedberg 

 1981). In many species the chemicals have adaptive significance in rend- 

 ering the animals noxious or toxic to predators, or provide tastes and 

 smells that predators associate with noxious or toxic effects (Brandon 



Brimleyana No. 10:75-82. February 1985. 75 



