Constantina is co-leading with Dr. Yasuko Tobari (Azabu University, Japan) a project coordinated by Dr. Kazuo Okanoya (University of Tokyo and RIKEN Brain Science Institute, Japan), where oxytocin sequence and synthesis are compared in the wild White Rumped munias and the domesticated Bengalese finches. This project essentially brings together several interests of Constantina: domestication, oxytocin, and vocal learning.
Bengalese finches are the domesticated 'version' of the wild white rumped munias. Bengalese finches are less fearful, show different pigmentation in their plumage and, importantly, sing a more complex song than the white rumped munias. This has led scientists to hypothesize that the higher vocal learning complexity in Bengalese finches might have occurred as a by-product of their domestication. Since oxytocin has been highlighted in research focused on differences between domesticated and wild species, and in the context of avian vocal learning, we hypothesized that it made a great candidate for studying the neurobiology underlying these species' behavioral differences.
We sequenced the oxytocin gene (OT) from 10 wild munias and 11 Bengalese finches and identified intra-strain variability in both the untranslated and protein-coding regions of the sequence, with all the latter giving rise to synonymous mutations. Several of these changes fall in specific transcription factor-binding sites, and show either a conserved or a relaxed evolutionary trend in the avian lineage, and in vertebrates in general. Although in situ hybridization in several hypothalamic nuclei did not reveal significant differences in the number of cells expressing OT between the two strains, real-time quantitative PCR showed a significantly higher OT mRNA expression in the cerebrum of the Bengalese finches relative to munias, but a significantly lower expression in their diencephalon. Our study thus points to a brain region-specific pattern of neurochemical expression in domesticated and wild avian strains, which could be linked to domestication and the behavioral changes associated with it.
Read our study published in Genes, Brain and Behavior (Tobari*, Theofanopoulou* et al. 2021).