In amphibians

There is some evidence for chemically mediated endocrine disruption in amphibians. The egg yolk protein, vitellogenin, is inducible in amphibians by exposure to DDT. " Males of the short clawed toad Xenopus laevis given 250 fig/g or 1 fig/g o,p -DDT for seven days have been shown to produce vitellogenin, although the induction was less than that achieved by treatment with 1 fig/g of either 17/1-oestradiol or diethylstilboestrol. Research has also shown that endocrine disrupting chemicals can alter sex ratios in wild populations of certain species PCB congeners and organochlorine compounds have been linked with male domination of sex ratios in polluted compared to unpolluted sites. ... 

More controversially, endocrine disruption as a consequence of exposure to the herbicide atrazine (2-chloro-4-ethylamine-6-isopropylamine-s-triazine), one of the most widely used herbicides in the world, has also been hypothesized to explain various adverse biological effects in frog populations in the United States. Exposure to atrazine in the laboratory at high concentrations, far exceeding those found in the natural environment, has been reported to induce external deformities in the anuran species Rana pipiens, Rana sylvatica, and Bufo americanus (Allran and Karasov 2001). Studies by Hayes et al. have suggested that atrazine can induce hermaphroditism in amphibians at environmentally relevant concentrations (Hayes et al. 2002 Hayes et al. 2003). Laboratory studies with atrazine also indicated the herbicide... 

These are a family of peptides which include substance P, isolated in 1931 but only sequenced in 1971. This peptide has been extensively studied since it was the first major peptide to be extracted from brain but only now are useful antagonists becoming available. Two closely related peptides were then isolated from mammalian tissues and can be added to a number of other tachykinins, many of which are found in amphibians. The name tachykinins originated from the vasoactive effects of substance P but the nomenclature has been resolved into calling the three major mammalian peptides substance P, neurokinin A (NKA) and neurokinin B (NKB) with the corresponding receptors being numbered 1 to 3. The order of potencies at the three receptors as follows ... 

Fig. 1.1 Distribution of AOS in Amphibians. All living groups possess (+) an AOS, except some tailed forms (- ) (after Colbert, 1966).

Madison D. (1977). Chemical communication in Amphibians and Reptiles. In Chemical Signals in Vertebrates 1 (Miiller-Schwarze D. and Mozell M.M., eds.). Plenum, New York, pp. 135-168. 

Sunkara, P. S., Wright, D. A., and Rao, P. N. (1979). Mitotic factors from mammalian cells induce germinal vesicle breakdown and chromosome condensation in amphibian oocytes. Proc. Natl. Acad. Sci. USA 76 2799-2802. 

The metaphase arrest in vertebrate oocytes is maintained by cytostatic factor activity (CSF Masui Markert 1971). CSF was first demonstrated in amphibian oocytes by transferring cytoplasm from metaphase II (M II)-arrested oocytes into one blastomere of a two-cell embryo. The injected blastomere was arrested in M phase while the non-injected blastomere continues to cleave (Masui Markert... 

Marin 0., Smeets W. J., Gonzalez A. (1998). Evolution of the basal ganglia in tetrapods a new perspective based on recent studies in amphibians. Trends Neurosci. 21(11), 487-94. 

Herkovits, J. and C.S. Perez-Coll. 1991. Antagonism and synergism between lead and zinc in amphibian larvae. Environ. Pollut. 69 217-221. 

Rollins-Smith, L.A. Neuroendocrine-immune system interactions in amphibians. Implications for understanding global amphibian declines. Immunologic Res., 2312 3, 273, 2001. 

The first step in a strategy for developing effective control of a pest by chemical ecology must be to determine if the species uses a chemical signaling system. If intra-specific signaling is shown to occur, the next step is to identify and synthesise the chemical agents utilized, with a view to successful application under field conditions. The most likely source of communication chemicals in amphibians is the secretions of the skin glands. 

This form of luminescence occurs sporadically in a wide range of natural organisms, such as protists (bacteria, fungi), animals, marine invertebrates and fish. It even exists naturally, albeit rarely, in plants or in amphibians, reptiles, birds, or mammals. 

TABLE 1 Occurrence of lipid-soluble alkaloids in amphibians... 

FIGURE 1 Structures of lipophilic amphibian alkaloids. Alkaloids indicated by asterisks represent structural classes that have not been detected in nature except in amphibians and, in the case of batrachotoxins, in one species of bird (9). 

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