Figure 2: Changes in the profiles of the brain-pituitary-thyroid hormones and the N-methyl-D-aspartate receptor essential subunit NR1 in juvenile chum salmon during downstream migration.
From: Involvement of hormones in olfactory imprinting and homing in chum salmon
Fish were sampled at the Chitose Hatchery (Site A) at four time points (January (A1), February (A2), March (A3) and April (A4)), and following release into the Chitose River at the second bridge of the Chitose (Site B), the Chitose River in Kamaka Ward (Site C), the confluence of the Chitose and Yubari Rivers (Site D), the mouth of the Ishikari River (Site E), and Ishikari Bay (F). The gene expression ratios of thyrotropin-releasing hormone, TRHa and TRHb in the whole brain, TSHβ in the upper-head, and NR1 in the whole brain, were normalized to the reference gene (β-actin), and the expression levels were compared using the relative Ct (ΔΔCT) method. The contents of thyroxine (T4) and triiodothyronine (T3) in the lower jaw are expressed in μg/dl/lower jaw weight and ng/dl/lower jaw weight, respectively. Data are presented as the means ± SEM (N = 10–15). Different letters represent significant differences using the Tukey-Kramer multiple comparison test (TRHa, TRHb, TSHβ, NR1, and T3) and Scheffe’s F test (T4) (p < 0.05). The horizontal bar indicates the locations passed during juvenile downstream migration to the bay.
