Analyses of Skin Secretions of Vipera ammodytes (Linnaeus, 1758) (Reptilia: Serpentes), with Focus on the Complex Compounds and Their Possible Role in the Chemical Communication.

Kostadin Andonov,Deyan Duhalov,Miroslav Slavchev,Borislav Naumov,Daniela Nedeltcheva-Antonova,Angel Dyugmedzhiev,Simeon Lukanov,Emiliya Vacheva,Nikola Stanchev,Yurii V Kornilev,Georgi Popgeorgiev

doi:10.3390/molecules25163622

Abstract

Snakes rely heavily on chemical cues when foraging, searching for mates, etc. Snakes’ sex attractiveness pheromones comprise mainly heavy, semi-volatile compounds such as ketones. Here we investigated the composition of skin secretions of adult Vipera ammodytes (Linnaeus, 1758) individuals. The samples were analyzed by gas chromatography/mass spectrometry and the identification of the compounds was performed using commercial mass spectral libraries and retention times. The relative concentrations of all detected compounds were tested for significant differences between (1) male vs. female live individuals, (2) shed skin vs. live individuals, and (3) pre-reproductive vs. reproductive live individuals. We detected fifty-nine compounds of which six were ketones. Two ketones (2-pentacosanone and 2-heptacosanone) were present in many of the samples and thus may have an important role in the V. ammodytes chemical communication. We did not find significant differences between the relative concentrations of the compounds between male and female individuals (only three compounds are exceptions). Significant differences were found between extracts from shed skins and live individuals and between live pre-reproductive individuals and live reproductive individuals. The results of the study suggest that chemical communication in V. ammodytes involves less compounds in comparison to the known literature data for other species.

Highlights

As a result of past evolutionary adaptations for subterranean life, snakes are generally constrained in the visual perception of their environment [1] and rely heavily on chemical cues when foraging, escaping from predators, and searching for mates [2,3,4]
The ketones we found in V. ammodytes are 5,9-undecadien-2-one, pentadecanone,6,10,14-trimethyl- (C18H36O), 2-pentacosanone (C25H50O), 2-heptacosanone (C27H54O), 6,10-dimethyl- (C13 H22 O), 2-pentadecanone,6,10,14-trimethyl- (C18 H36 O), 2-pentacosanone (C25 H50 O), 2-hentriacontanone (C31H62O) and 2-tritriacontanone (C33H66O)
We are aware that the Gas Chromatography/Mass Spectrometry (GC/MS) method might not be able to detect compounds with very high molecular mass that are even less volatile, we speculate that the complex of ketones in the V. ammodytes skin secretion is less diverse compared to well-studied species such as T. sirtalis [2]

Summary

Introduction

As a result of past evolutionary adaptations for subterranean life, snakes are generally constrained in the visual perception of their environment [1] and rely heavily on chemical cues when foraging, escaping from predators, and searching for mates [2,3,4]. In contrast to most animals that use chemical signalization produced by a discrete gland, snake pheromones are components of their integumental skin lipids [2,8]. Low temperatures and hibernation may affect the production of pheromones in snakes [12,13]. This, coupled with their specific behaviors such as secretive lifestyle, complicates the extraction of skin chemicals and pheromones, and has resulted in a few studies on the variety of skin compounds across different species. The extensive ecological plasticity of snakes, allowing them to inhabit almost all terrestrial and aquatic habitats, as well as their diverse reproductive strategies and social behaviors, strongly suggests variations in their chemical communication and pheromone composition

Methods

Results

Discussion

Conclusion