Fig. 1. Alignment of protein sequences for melatonin receptors in zebrafish (Danio rerio). Please note the remarkable differences among various melatonin receptor subtypes within the red rectangles. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2. Melatonin phylogenetic trees and genome synteny of melatonin receptors in vertebrates. (Fig. 2A) The phylogenetic tree was constructed on the basis of 57 MTNR1A protein sequences (the left part), and the synteny data of mtnr1a (the right part) were presented for validation. (Fig. 2B) The phylogenetic tree was constructed on the basis of 59 MTNR1B protein sequences (the left part), and the synteny data of mtnr1b (the right part) were presented for confirmation. (Fig. 2C) The phylogenetic tree was constructed on the basis of 48 MTNR1C protein sequences (the left part), with the synteny data of mtnr1c (the right part) for validation. Numbers on the branches from left to right are bootstrap values generated in the PhyML reconstruction and the Bayesian posterior probabilities obtained by the Bayesian inference, respectively. Those bootstrap values under 60% and posterior probabilities less than 0.60 are not shown.

Fig. 3. Predicted 3D-structure comparisons of MTNR1C among zebrafish, chicken and human. (A) Zebrafish MTNR1C (blue) versus chicken (green); (B) Chicken MTNR1C (green) versus human (red); (C) Zebrafish MTNR1C (blue) versus human (red). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 4. Comparisons of gene structures of mtnr1c in representative vertebrates. Blue rectangles stand for exons, and the dark lines represent introns. The C-terminal DUF4045 domains of mtnr1c in Eutherian mammals were marked in orange. Box colored in red rose includes the species without the extended domain of mtnr1c, and box colored in yellow includes the species in Eutherian mammals with the extended domain of mtnr1c. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)