Salinity changes in the anadromous river pufferfish, Takifugu obscurus, mediate gene regulation

Abstract

This study aimed to better understand the hydromineral regulatory response of the anadromous river pufferfish, Takifugu obscurus, to salinity changes through real-time RT-PCR. After abrupt transfer from 30 or 5 psu to 5 or 30 psu, respectively, we analyzed the mRNA expression of Na⁺/K⁺ ATPase, prolactin receptor, and aquaporin from osmoregulatory organs of the river pufferfish such as gills, kidney, and intestine. Na⁺/K⁺ ATPase showed notable changes in the gills and kidney when salinity was increased. In the gills, the expression level of Na⁺/K⁺ ATPase suddenly increased within a day after abrupt transfer from 5 to 30 psu and then slightly declined within 2 days after exposure. In the kidney, Na⁺/K⁺ ATPase has shown consistently high mRNA expression after the increase in salinity. Expression levels of the prolactin receptor gene increased when environmental salinity decreased. In the intestine, gene expression of the prolactin receptor remained high, even when salinity decreased. To the contrary, there was a steady increase or decrease in mRNA expression in the kidney in response to salinity decrease or increase, respectively. As for aquaporins, aquaporin 1 was mainly expressed in the intestine and kidney, and aquaporin 3 was mainly expressed in the gills and intestine. In the gills, increased expression of aquaporin 3 was found after transfer to lower salinity and in the intestine and kidney, a decrease in salinity followed by an abrupt decrease in aquaporin 1 and aquaporin 3. Contrastingly, the expression of these genes increased in the intestine after transfer to 30 psu. Osmoregulatory genes were expressed in diverse organs, apparently to overcome an influx or exhaust of water or ions. A superior adaptation ability of the river pufferfish to a wide range of salinities is most reasonably due to active osmoregulatory processes mediated by the genes monitored here.

Transcriptional stress responses to environmental and husbandry stressors in aquaculture species

“…In pufferfish Takifugu obscurus, the expression level of Na + /K + ATPase increased after salinity increased, the prolactin receptor gene increased when environmental salinity decreased and increased expression of aquaporin was exhibited at lower salinity (Jeong et al . ); these changes in the gene expression are an effort to maintain the haemostasis and counteract the salinity changes.…”

“…It is known that Na + /K + ATPase (NKA), prolactin receptor (PLR) and aquaporin (AQP) are key factors in fulfilling the osmoregulation mechanism (Gonen & Walz 2006;Choi & An 2008;Binart et al 2010). In pufferfish Takifugu obscurus, the expression level of Na + /K + ATPase increased after salinity increased, the prolactin receptor gene increased when environmental salinity decreased and increased expression of aquaporin was exhibited at lower salinity (Jeong et al 2014); these changes in the gene expression are an effort to maintain the haemostasis and counteract the salinity changes.…”

Prolactin and teleost ionocytes: New insights into cellular and molecular targets of prolactin in vertebrate epithelia

“…Fiol et al (2009) and Chen et al (2011) subsequently established the existence of two distinct prolactin receptor genes in tilapia and zebrafish ( Danio rerio ). Expression of the two prolactin receptors in the gill is highly plastic and differentially impacted by both osmoregulatory challenges and hormone treatments (Huang et al, 2007; Pierce et al, 2008; Fiol et al, 2009; Tomy et al, 2009; Breves et al, 2010b; Rhee et al, 2010; Breves et al, 2011; Flores and Shrimpton, 2012; Breves et al, 2013; Jeong et al, 2013). For example, in vivo levels of branchial prolactin receptor a , but not prolactin receptor b are stimulated by transfer to ion-poor water and prolactin injection in zebrafish (Breves et al, 2013).…”

Harpin Hpa1 Interacts with Aquaporin PIP1;4 to Promote the Substrate Transport and Photosynthesis in Arabidopsis

“…AQPs are intramolecular channels essential for movements of H 2 O, CO 2 , and other small substrates across biomembranes 21 22 . By this role, AQPs can modulate CO 2 uptake and assimilation (photosynthesis) in plants 23 24 and regulate water relations and many other physiological processes in all living organisms 20 25 26 27 . In plants, AQPs fall into five major phylogenic families including the PIP family 28 .…”