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Molecular cloning and characterization of two ARNT (ARNT‐1 and ARNT‐2) genes in Atlantic croaker and their expression during coexposure to hypoxia and PCB77
Author(s) -
Rahman Md Saydur,
Thomas Peter
Publication year - 2019
Publication title -
environmental toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.813
H-Index - 77
eISSN - 1522-7278
pISSN - 1520-4081
DOI - 10.1002/tox.22670
Subject(s) - aryl hydrocarbon receptor nuclear translocator , biology , aryl hydrocarbon receptor , gene , hypoxia (environmental) , messenger rna , microbiology and biotechnology , medicine , endocrinology , biochemistry , transcription factor , chemistry , oxygen , organic chemistry
Aryl hydrocarbon receptor nuclear translocator (ARNT) is an important transcriptions factor that binds/coactivates drug‐metabolizing genes in vertebrates. In this study, we report the cloning and characterization of two ARNT (ARNT‐1 and ARNT‐2) genes and their mRNA and protein expression in liver tissues of Atlantic croaker after co‐exposure to hypoxia and 3,3′,4,4′‐tetrachlorobiphenyl (PCB77). The full‐length croaker ARNT‐1 and ARNT‐2 genes encode proteins of 537 and 530 amino acids, respectively, and are highly homologous to ARNT‐1 and ARNT‐2 genes of other vertebrates. ARNT mRNAs are ubiquitously expressed in all tissues. Hypoxia (dissolved oxygen: 1.7 mg/L) exposure (1‐4 weeks) did not affect hepatic ARNTs mRNA levels. Dietary PCB77 treatment (2 and 8 μg/g body weight/day for 4 weeks) caused marked increases in ARNTs mRNA and protein levels in normoxic fish. However, coexposure to hypoxia and PCB77 for 4 weeks significantly blunted the increase in ARNTs mRNA and protein levels in response to PCB77 exposure. These results suggest that ARNT activity and functions induced by exposure to PCB aryl hydrocarbon receptor (AhR) agonists could be compromised in croaker inhabiting hypoxic coastal regions.