Contents lists available at ScienceDirect General and Comparative Endocrinology journal homepage: www.elsevier.com/locate/ygcen Expression profles of types 2 and 3 iodothyronine deiodinase genes in relation to vitellogenesis in a tropical damselfsh, Chrysiptera cyanea Sung-Pyo Hur a , Angka Mahardini b , Yuki Takeuchi c,d , Satoshi Imamura b , Nina Wambiji b , Dinda Rizky b , Shingo Udagawa b , Se-Jae Kim a , Akihiro Takemura c, ⁎ a Department of Biology, Jeju National University, 102 Jejudahakro, Ara-1 Dong, Jeju-si, Jeju 63243, Republic of Korea b Graduate School of Engineering and Science, University of the Ryukyus, Nishihara 903-0213, Japan c Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan d Okinawa Institute of Science and Technology Graduate University, 1919-1, Onna, Okinawa 904-0495, Japan ARTICLEINFO Keywords: Damselfsh In situ hybridization Iodothyronine deiodinase qPCR Triiodothyronine Vitellogenesis ABSTRACT Thyroid hormone (TH) is involved in regulating the reproduction of vertebrates. Its physiological action in the target tissues is due to the conversion of TH by iodothyronine deiodinases. In this study, we aimed to clone and characterize type 2 (sdDio2) and type 3 (sdDio3) of the sapphire devil Chrysiptera cyanea, a tropical damselfsh that undergoes active reproduction under long-day conditions, and to study the involvement of THs in the ovarian development of this species. When the cDNAs of sdDio2 and sdDio3 were partially cloned, they had deduced amino acid sequences of lengths 271 and 267, respectively, both of which were characterized by one selenocysteine residue. Real-time quantitative PCR (qPCR) revealed that both genes are highly expressed in the whole brain, and sdDio2 and sdDio3 are highly transcribed in the liver and ovary, respectively. In situ hy- bridization analyses showed positive signals of sdDio2 and sdDio3 transcripts in the hypothalamic area of the brain. Little change in mRNA abundance of sdDio2 and sdDio3 in the brain was observed during the vitellogenic phases. It is assumed that simultaneous activation and inactivation of THs occur in this area because oral ad- ministration of triiodothyronine (T3), but not of thyroxine (T4), upregulated mRNA abundance of both genes in the brain. The transcript levels of sdDio2 in the liver and sdDio3 in the ovary increased as vitellogenesis pro- gressed, suggesting that, through the metabolism of THs, sdDio2 and sdDio3 play a role in vitellogenin synthesis in the liver and yolk accumulation/E2 synthesis in the ovary. Taken together, these results suggest that io- dothyronine deiodinases act as a driver for vitellogenesis in tropical damselfsh by conversion of THs in certain peripheral tissues. 1. Introduction The thyroid hormones (THs) thyroxine (T4) and triiodothyronine (T3) play important roles in regulating physiological processes such as growth, morphogenesis, osmoregulation, and reproduction in teleost fsh (Cyr and Eales, 1996; Habibi et al., 2012). The synthesis of TH in thyroid follicles is centrally controlled by the hypothalamic–pituitar- y–thyroid (HPT) endocrine axis, which comprises thyrotropin-releasing hormone (TRH) in the hypothalamus and thyrotropin (TSH) in the pi- tuitary (Blanton and Specker, 2007). Furthermore, specifc actions of THs in target tissues are due to the activation and inactivation of in- tercellular deiodination by iodothyronine deiodinases (Habibi et al., 2012; Jarque and Piña, 2014), and consequent conversion from T4 to T3, a biologically active form of TH, and its specifc binding to thyroid hormone receptors (Nelson and Habibi, 2009). To date, three io- dothyronine deiodinases, type I (Dio1), type II (Dio2), and type III (Dio3), have been identifed in vertebrates (Jarque and Piña, 2014; St Germain and Galton, 1997). Among these, Dio2 and Dio3 are involved in the catalytic activity of outer- and inner-ring deiodination, and mediate the conversion from T4 to T3 and from T3 to 3,3′-diiodothyr- onine (T2), an inactive metabolite, respectively (Habibi et al., 2012). Thus, it is likely that the intercellular activity of these iodothyronine deiodinases ensures TH action in the target tissues (Cicatiello et al., 2018). It has been reported that T4 treatment accelerates the vitellogenesis of guppy Poecilia reticulata (Lam and Loy, 1985). In vitro experiments revealed that co-treatment of gonadotropin with T3 enhanced estradiol- 17ß (E2) production from the vitellogenic oocytes of rainbow trout https://doi.org/10.1016/j.ygcen.2019.113264 Received 3 June 2019; Received in revised form 21 August 2019; Accepted 26 August 2019 ⁎ Corresponding author. E-mail address: takemura@sci.u-ryukyu.ac.jp (A. Takemura). General and Comparative Endocrinology 285 (2020) 113264 Available online 27 August 2019 0016-6480/ © 2019 Elsevier Inc. All rights reserved. T