The first gene-encoded amphibian neurotoxin

Area of Science:

• Biochemistry
• Toxicology
• Amphibian Biology

Background:

• Gene-encoded neurotoxins are known in various vertebrates.
• Amphibians were not previously known to possess gene-encoded neurotoxins.

Purpose of the Study:

• To identify and characterize novel neurotoxins from amphibian skin secretions.
• To investigate the functional properties and ecological role of a newly discovered amphibian toxin.

Main Methods:

• Purification and characterization of a neurotoxin peptide (anntoxin) from Hyla annectans skin secretions.
• Inhibition assays to determine the effect of anntoxin on tetrodotoxin-sensitive voltage-gated sodium channels and trypsin.
• Tissue distribution analysis of anntoxin in H. annectans.

Main Results:

• A novel 60-residue neurotoxin peptide, anntoxin, was identified.
• Anntoxin inhibited tetrodotoxin-sensitive voltage-gated sodium channels (IC50 ≈ 3.4 μM) and trypsin (Ki = 0.025 μM).
• The highest concentration of anntoxin was found in the skin, suggesting a defensive role.

Conclusions:

• Anntoxin is the first identified gene-encoded neurotoxin in amphibians.
• Anntoxin's properties suggest a role in defense against predators and possibly prey acquisition for H. annectans.
• The toxin's distribution and function offer insights into the ecological adaptation of arboreal amphibians.