Phenotypic plasticity in gene expression and physiological response in red drum Sciaenops ocellatus exposed to a long-term freshwater environment

Abstract

Red drum (Sciaenops ocellatus) is a euryhaline fish commonly found in the Gulf of Mexico and along the Atlantic coast of North America. Because of high commercial demand and its euryhaline characteristics, aquaculture of this species has diversified from marine to low-salinity aquaculture systems. In recent years, interest in the feasibility of producing red drum in inland freshwater systems has grown and this prompted us to investigate its osmoregulatory capacity after rearing for 8 months in a freshwater aquaculture system. We compared the activities of several genes and enzymes involved in the osmoregulatory process in freshwater-acclimatized (FW) and seawater (SW) red drum. The gene expression profiles were variable: the expression of genes encoding Na/K-ATPase (NKA) and the cystic fibrosis transmembrane regulator (CFTR) was slightly higher in SW than FW fish, while phosphoenolpyruvate carboxykinase (PEPCK) and the glucocorticoid receptor messenger RNA (mRNA) levels were higher in FW red drum. The total plasma K concentration was 60.3% lower, and gill NKA activity was 63.5% lower in FW than in SW fish. PEPCK activity was twofold higher in FW than in SW red drum. Similarly, liver glycogen was 60% higher in FW fish. In summary, both gene expression and the enzyme activity data support the phenotypic plasticity of red drum and suggest that the limited capacity for ion homeostasis observed, in particular the low plasma K concentration, was due to the composition of freshwater and does not necessarily reflect a physiological inability to osmoregulate.

Growth and survival of juvenile red drum, Sciaenops ocellatus, acclimated to freshwater at three different stocking densities in a partial recirculation system

“…The growth of juveniles has been reported for salinity conditions of 11 ppt in RAS growout tanks (Pfeiffer & Wills, ). Similarly, it has been reported that acclimated red drum cultivated for long periods have undergone phenotypic plasticity and physiological changes at a salinity of 0 ppt (Gullian‐Klanian, ; Gullian‐Klanian, Zapata‐Pérez, & Vela‐Magaña, ). Therefore, the aim of this article is to present biological and technological indicators of an inland culture of S. ocellatus in a freshwater semirecirculation system, without the addition of ions or chemical elements for a long‐term culture period.…”

Adaptive divergence and underlying mechanisms in response to salinity gradients between two Crassostrea oysters revealed by phenotypic and transcriptomic analyses

“…Our observations between species were reasonable in contrast to the transcriptomic variation of populations within Crassostrea virginica , where two reef‐source populations showed a greater environment effect than genetic effect on gene expression differences in response to different salinity environments (Eierman & Hare, 2016). Furthermore, transporters (especially SLCs), taurine metabolism pathway, and pyruvate metabolism pathway enriched in the salinity‐correlated module were in response to salinity gradients, which were supported by those of previous studies (SLCs: Boyle et al, 2015; Choi et al, 2003; Hoglund et al, 2011; Hui et al, 2014; Jiang et al, 2020; Kurita et al, 2008; Li et al, 2021; Menchini & Chaudhry, 2019; Nakajima et al, 2013; Wang et al, 2015; Wang et al, 2020; Wu et al, 2021; Zhou et al, 2018; Taurine: Meng et al, 2013; Wu et al, 2021; Pyruvate: Derakhshani et al, 2020; Gullian et al, 2018; Wang, Li, et al, 2017). These salinity‐responsive pathways also exhibited divergent responses between two oyster species for their enrichment of DEG sets for the species effect and in species‐correlated modules, emphasizing the role of these mechanisms in the formation of divergence in salinity adaptation between the two species.…”