Abstract
The effects of various salinities on growth, feeding and the mRNA expression of related genes in Liza haematocheilus were investigated. Fish were maintained at four salinities for 30 days to analyse the specific growth rate (SGR), the feeding rates (FR) of L. haematocheilus, and the mRNA expression of Na+/K+-ATPase (NKA) and Hsp 90 were measured at 0, 5, 10, 20 and 30 d, respectively. The results showed that the SGR of L. haematocheilus at 14 psu group was higher than the 2 and 42 psu group significantly; the FR of L. haematocheilus at 14 psu group was the highest and the 2 psu group was the lowest at 20 or 30 day; the NKA mRNA abundances in L. haematocheilus were increased significantly in the 2, 14 and 42 psu groups at 5 day (P < 0.05), and the lowest level emerged in the control group (28 psu), the same relationship was observed for Hsp 90 but the change scopes were smaller. The results indicate that the increased expression of NKA and Hsp 90 mRNA in L. haematocheilus is a part of the molecular responses to the osmotic stress of changes in salinity.
Highlights
Euryhaline teleosts present the capacity to tolerate the different environmental salinities by using efficient osmoregulatory mechanisms to maintain homeostasis [1]
The euryhaline killfish Fundulus heteroclitus often move between SW and FW environments and NKA expression increased whether fish were transferred from brackish water (BW) to SW or FW [20]
feeding rates (FR) was calculated using the formula: FR = V×(D0-Dt) /nt, where V was the volume of the seawater, D0 was the density of Artemia nauplius before the experiment, Dt was the density of Artemia nauplius after the experiment, n was the number of fishes in each group, t was time during the feeding
Summary
Euryhaline teleosts present the capacity to tolerate the different environmental salinities by using efficient osmoregulatory mechanisms to maintain homeostasis [1]. Fish in an isotonic medium had the lowest standard metabolic rates and fish must impose energetic regulatory costs for active ion transport if environmental salinities are differ from the internal osmotic concentration [2,3]. NKA mRNA expression increased when the European sea bass Dicentrarchus labrax were transferred from 15 psu to 50 psu or FW [19]. The euryhaline killfish Fundulus heteroclitus often move between SW and FW environments and NKA expression increased whether fish were transferred from BW to SW or FW [20]. Previous studies have reported that the relationship between Hsp 90 mRNA expression and environmental salinities in some species [22]
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