The role of estrogen-related receptors in ion regulation of medaka (Oryzias melastigma)
| Autor: | Shang-Wu Shih, 施尚武 |
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| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 Euryhaline teleosts are capable of surviving within a wide range of salinities including in freshwater (FW) and seawater (SW). Ionocytes in fish gills or embryonic skin are specialized mitochondrion-rich cells which express different ion transporters to transport ions. These cells are responsible for ion absorption and secretion to maintain ion compositions of body fluids in FW and SW, respectively. The basic regulatory model of FW and SW types of ionocytes in medaka has been proposed, but the detailed ionoregulatory mechanisms are still not explained well. Thus, discovering possible factors involved in ion regulation is an important issue and is helpful to completely understand how fishes acclimate to fluctuating environments. Estrogen-related receptors (ERRs), steroid hormone receptors, are orphan nuclear receptors, functioning as transcription factors to regulate the expression of other genes, including energy metabolism-related genes. Previous studies showed that ERRα and ERRγ regulate the expression of ion transporters in mammals, implying that ERRs might involve in ion regulation. Therefore, this study used Indian medaka (Oryzias melastigma), euryhaline teleosts, as experimental organisms to investigate the role of ERRs in ion regulation of fishes. The mRNA expression of errα, errβ1, errγ1, and errγ2 in medaka embryos and adult gills were down-regulated after transfer from FW to SW, suggesting that ERRs may play roles in acclimation to FW. Besides, the results of in situ hybridization showed the mRNA signals of errγ2 were mostly co-localized with the immunohistochemistry signals of ionocyte marker, Na+-K+ ATPase (NKA), in both embryos and adult gills in FW, indicating that most part of ERRγ2 is expressed in the ionocyte. Moreover, ERRγ2 knockdown in embryos reduced the Na+/Cl- contents and Na+ influxes of ionocytes, but did not affect the ionocyte numbers in the embryonic skin, O2 consumption rate, and NH4+ secretion rate in the embryos. Overall, the present study suggested that ERRγ2 expressed in ionocytes may participate in salt-absorption mechanisms to adapt to FW. However, how ERRγ2 regulates the salt-absorption of ionocytes is still unclear and will be further investigated in the future. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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