Meeting Abstract

P3.13A  Thursday, Jan. 6  Comparative Peptide Profiles of Sympatric Anurans Hyla versicolor (Hylidae) and Lithobates clamitans (Ranidae): An Anti-predator Hypothesis BONGE, Samuel*; JACKSON, Ken W.; LUTTERSCHMIDT, William I.; Sam Houston State University; University of Oklahoma Health Science Center; Sam Houston State University bonge@shsu.edu

Researchers (Brodie and Formanowicz 1981) observed significant differences in mortality rate between the eastern gray treefrog (Hyla versicolor) and the heterospecific bronze frog (Lithobates clamitans) and suggested that the skin secretions produced by H. versicolor may serve as an antipredatory defense mechanism. To investigate how these Hylid skin secretions may serve to influence such differences in observed mortality rate (0 vs. 95%), we collected Hyla versicolor skin secretions stimulated by norepinephrine injection. Peptidomic analysis was conducted using reverse phase HPLC, MALDI-TOF and electrospray mass spectrometry. Edman degradation was then used to characterize target peptides. The secretions produced by H. versicolor lead to the discovery of a novel 58 amino acid toxin. This peptide is analogous in structure to the first and recently described gene encoded neurotoxin (anntoxin) found in the secretions of the Assam treefrog (Hyla annectans). Our novel peptide reported here is similar to anntoxin in that it has highly conserved trypsin inhibitory regions ₁₃KGSGS_T₁₉ and four cystine residues forming two disulfide bonds. Both of these structural components indicate that the peptide is similar in homology to the Kunitz family of toxins found in the venom of snakes (dendrotoxins) and cone snails (conotoxins). Data from mass spectrometry analysis illustrates that this novel toxin is the most abundant molecule produced within Hyla versicolor secretions, and may be the cause for the observed difference in palatability between H. versicolor and L. clamitans.