# Transcriptomic Analysis Reveals Sex-Biased Gene Expression in Duck Turbinate Tissue

## TL;DR

This study finds sex differences in gene activity in duck smell-related tissue, suggesting males and females process smells differently at the molecular level.

## Contribution

The study identifies sex-biased gene expression patterns and key receptor genes in duck olfactory tissue, offering new insights into sex-specific sensory processing.

## Key findings

- 1906 genes showed sex-biased expression in duck turbinate tissue.
- Sex differences were linked to neuronal signaling and tissue organization rather than odor detection.
- TACR2 and DRD4 were highlighted as key receptor genes with potential roles in modulating smell signals.

## Abstract

Smell helps ducks find food and choose mates, and males and females may rely on smell in different ways, but the genes behind these differences are poorly understood. In this study, we compared gene activity in the smell-sensing tissue of male and female Tianfu Nonghua Mottled Ducks. Overall gene activity patterns clearly differed between sexes, yet genes that directly detect odor molecules showed little difference. Many sex-biased genes were linked to how nerve cells communicate, how cells attach to each other, and how the supporting structure around cells is organized, suggesting that sex differences may be driven more by how smell information is processed than by odor detection itself. We also identified two key receptor genes—tachykinin receptor 2 and dopamine receptor D4—which encode proteins that respond to chemical signals in the nervous system and may influence how smell-related signals are modulated. These findings provide practical starting points for future studies of duck behavior and physiology and may ultimately support improved breeding and management strategies.

Olfaction is crucial for ducks, influencing essential behaviors such as foraging and mating. However, the molecular basis of sex-associated variation in duck olfactory tissues remains poorly understood. Here, we performed bulk RNA-seq on turbinate tissue from male and female Tianfu Nonghua Mottled Ducks (Anas platyrhynchos domesticus Linnaeus, 1758; Anatidae) to characterize sex-biased transcriptional programs. Our results suggest strong global transcriptomic separation between males and females, with 1906 differentially expressed genes (DEGs) identified. These DEGs were enriched in pathways related to neuronal signaling, cell adhesion, and extracellular matrix organization, suggesting coordinated sex-associated differences in signaling and tissue-organization programs. While olfactory receptor (OR) and trace amine-associated receptor (TAAR) genes showed limited sex-biased expression in bulk tissue, two neuromodulatory GPCRs, TACR2 and DRD4, were prioritized as hub genes within sex-biased co-expression networks. Notably, both genes also showed relatively high expression in turbinate tissue and neuroendocrine centers in an integrated multi-tissue transcriptomic dataset, nominating them as candidate targets for future functional and cell-type-resolved investigations. Overall, our study provides a descriptive molecular profile of sex-biased transcription in duck turbinate tissue, laying a foundation for follow-up studies and potential applications in poultry breeding and management.