Biochemical indices, gene expression, and SNPs associated with salinity adaptation in juvenile chum salmon (Oncorhynchus keta) as determined by comparative transcriptome analysis

Peilun Li; Wei Liu; Wanqiao Lu; Jilong Wang

doi:10.7717/peerj.13585

Biochemical indices, gene expression, and SNPs associated with salinity adaptation in juvenile chum salmon (Oncorhynchus keta) as determined by comparative transcriptome analysis

PeerJ. 2022 Sep 12:10:e13585. doi: 10.7717/peerj.13585. eCollection 2022.

Authors

Peilun Li^{1

2}, Wei Liu^{1

2}, Wanqiao Lu^{1

2}, Jilong Wang^{1

2}

Affiliations

¹ Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China.
² Key Open Laboratory of Cold Water Fish Germplasm Resources and Breeding of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Harbin, China.

Abstract

Chum salmon (Oncorhynchus keta) migrate from freshwater to saltwater, and incur developmental, physiological and molecular adaptations as the salinity changes. The molecular regulation for salinity adaptation in chum salmon is currently not well defined. In this study, 1-g salmon were cultured under 0 (control group, D0), 8‰ (D8), 16‰ (D16), and 24‰ (D24) salinity conditions for 42 days. Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase activities in the gill first increased and then decreased in response to higher salinity environments where D8 exhibited the highest Na⁺/K⁺ATPase and Ca²⁺/Mg²⁺-ATPase activity and D24 exhibited the lowest. Alkaline phosphatase (AKP) activity was elevated in all salinity treatment groups relative to controls, while no significant difference in acid phosphatase (ACP) activity was observed across treatment groups. De novo transcriptome sequencing in the D0 and D24 groups using RNA-Seq analysis identified 187,836 unigenes, of which 2,143 were differentially expressed in response to environmental salinity (71 up-regulated and 2,072 down-regulated). A total of 56,020 putative single nucleotide polymorphisms (SNPs) were also identified. The growth, development, osmoregulation and maturation factors of N-methyl-D-aspartate receptors (nmdas) expressed in memory formation, as well as insulin-like growth factor 1 (igf-1) and igf-binding proteins (igfbps) were further investigated using targeted qRT-PCR. The lowest expression of all these genes occurred in the low salinity environments (D8 or D16), while their highest expression occurred in the high salinity environments (D24). These results provide preliminary insight into salinity adaptation in chum salmon and a foundation for the development of marker-assisted breeding for this species.

Keywords: Biochemical indices; Chum salmon; Differential expressed genes; Salinity; Transcriptomics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adenosine Triphosphatases / genetics
Animals
Gene Expression Profiling
Oncorhynchus keta* / genetics
Polymorphism, Single Nucleotide / genetics
Salinity*
Transcriptome

Substances

Adenosine Triphosphatases

Grants and funding

This work was funded by the Financial support from Natural Science Foundation of Heilongjiang Province of China (YQ2019C034), the Fundamental Research Business Expenses of Central Public Welfare Research Institutions (HSY201712Q), the Basic Scientific Research Fund Project of the China Academy of Fishery Sciences (2020TD07) and the Special Financial Funds of Species Resources Conservation project of the Ministry of Agriculture and Rural Affairs of China (2130135). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.