Metabolic Profiling Reveals That the Olfactory Cues in the Duck Uropygial Gland Potentially Act as Sex Pheromones

Abstract

The exchange of information between animals is crucial for maintaining social relations, individual survival, and reproduction, etc. The uropygial gland is a particular secretion gland found in birds. We speculated that uropygial gland secretions might act as a chemical signal responsible for sexual communication. We employed non-targeted metabolomic technology through liquid chromatography and mass spectrometry (LC-MS) to identifying duck uropygial gland secretions. We observed 11,311 and 14,321 chemical substances in the uropygial gland secretion for positive and negative ion modes, respectively. Based on their relative contents, principal component analysis (PCA) showed that gender significantly affects the metabolite composition of the duck uropygial gland. A total of 3831 and 4510 differential metabolites were further identified between the two sexes at the positive and negative ion modes, respectively. Of them, 139 differential metabolites were finally annotated. Among the 80 differential metabolites that reached an extremely significant difference (p < 0.01), we identified 24 volatile substances. Moreover, we further demonstrated that five kinds of volatile substances are highly repeatable in all testing ducks, including picolinic acid, 3-Hydroxypicolinic acid, indoleacetaldehyde, 3-hydroxymethylglutaric acid, and 3-methyl-2-oxovaleric acid. All these substances are significantly higher in males than in females, and their functions are involved in the reproduction processes of birds. Our data implied that these volatile substances act as sex pheromones and may be crucial olfactory clues for mate selection between birds. Our findings laid the foundation for future research on whether uropygial gland secretion can affect ducks’ reproduction and production.

Non-targeted metabolomics aids in sex pheromone identification: a proof-of-concept study with the triangulate cobweb spider, Steatoda triangulosa

“…Non -targeted metabolomics as a pheromone research tool seems to have been used in only a recent single study 50 . Liu et al 50 hypothesized that the uropygial gland of ducks secretes chemicals that mediate sexual communication.…”

“…Non -targeted metabolomics as a pheromone research tool seems to have been used in only a recent single study 50 . Liu et al 50 hypothesized that the uropygial gland of ducks secretes chemicals that mediate sexual communication. Using LC–MS and principal component analyses, the authors found numerous metabolites in gland secretions, and noticed a gender-bias in metabolite secretions.…”

“…However, there is now emerging evidence that metabolomics may be able—to some extent—to assume the analytical role of antennal bio-detectors in pheromone research. Non -targeted metabolomics was effectively applied to help select candidate pheromone components of ducks 50 and spiders this study , both groups lacking antennae or equivalently effective bio-detectors for pheromone tracing. As a result, there is incentive now to apply non -targeted metabolomics for pheromone research in marine and terrestrial mammals, fish, birds, reptiles and amphibians, or even in signaling studies within and among plants.…”