NATURAL AMINO-ACIDS AS EFFECTIVE STIMULI, CAUSING CHEMORECEPTORALLY DIRECTED BEHAVIOR IN ANURAN TADPOLES

The behavioral reactions of tadpoles of four anuran species, inhabitin g Moscow Region (Rana temporaria L., R. lessonae Cam., Bufo bufo, and Pelobates fuscus Laur.), on solutions of natural L-amino-acids of diff erent concentrations. It was shown that none of the tadpoles respond t o solutions of most amino-acids with concentrations less than 10(-2) m ole/l. Sequences of relative efficiency of amino-acids as chemical sti muli, inducing Feeding behavior. These sequences display interspecific differences, however, positively correlate in different amino-acid co ntent during pairwise comparison of species. For tadpoles of later dev elopmental stages asparagine, glutamine, and lysine are good feeding b ehavior stimuli; proline is little or not effective. A reaction of avo idance of arginine, more pronounced in earlier developmental stages wa s observed in Bufo bufo tadpoles. The sensitivity of different age tad poles to alanine, valine, glutamine, lysine, ornithine, and proline wa s studied by registering behavioral responses at different development al stages. nt earlier stages sensitivity is rather high (up to 10(-4) mole/l in R. temporaria tadpoles), and subsequently decreases in ontho genesis to an average Level of 10(-4) mole/l. Tadpoles of different sp ecies, but similar developmental stages were found to differ in their sensitivity to amino-acids. Experiments with olfactory deprivation of P. fuscus tadpoles showed amino-acid sensitivity to be connected with olfaction, whereas behavioral responses to amino-acid solutions with c oncentrations 10(-2) mole/l may be connected with any exterochemorecep tion system.