Molecular and physiological responses in the ammonia transport pathways in clam Cyclina sinensis exposed to chronic ammonia nitrogen

Qian Ni; Xiafei Liang; Shengyi Yang; Hongxing Ge; Zhiguo Dong

Aquaculture Reports (Apr 2024)

Molecular and physiological responses in the ammonia transport pathways in clam Cyclina sinensis exposed to chronic ammonia nitrogen

Qian Ni,
Xiafei Liang,
Shengyi Yang,
Hongxing Ge,
Zhiguo Dong

Affiliations

Qian Ni: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China
Xiafei Liang: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China
Shengyi Yang: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China
Hongxing Ge: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China; Jiangsu Marine Resources Development Institute, Jiangsu Province 222005, China; Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong 266071, China; Corresponding authors at: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China.
Zhiguo Dong: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China; Jiangsu Marine Resources Development Institute, Jiangsu Province 222005, China; Jiangsu Key Laboratory of Marine Biotechnolog, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China; Corresponding authors at: Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang, Jiangsu Province 222005, China.

Journal volume & issue: Vol. 35
p. 101952

Abstract

Read online

The clam Cyclina sinensis is characterized by good ammonia resistance. With the purpose of gaining knowledge about its ammonia resistance, we assessed the mRNA expression levels of Rhesus glucoprotein b (CsRhbg), the activities of key enzymes in the ammonia transport pathways (glutamine synthetase, GS; glutamic acid dehydrogenase, GDH) in the gill and hepatopancreas and the gill histopathological section (HE staining) of the clam exposed to total ammonia nitrogen (TAN) (6.58 mg/L) for 768 h (32d). Results revealed that the full-length cDNA sequence of CsRhbg was 1777 bp in length. The CsRhbg was highly conserved in the same genus, and the protein encoded by CsRhbg contains 10 transmembrane structures (TMHs) and one signal peptide. Exposed to ammonia nitrogen, the expression level of CsRhbg mRNA climbed sharply at 3 h post-exposure, and then it decreased and fluctuated from 192 h to 768 h. The activity of GSase in the clam exposed to ammonia nitrogen increased in the first 24 h, and reached the highest value at 96 h, and then fluctuated. The activity of GDH rose sharply and reached the highest value at 3 h, and then fluctuated. With the increase of exposure time, histological alterations in the gill became more and more clear in the disappearance of the epithelial cell boundaries. The results suggest that exposure to ammonia nitrogen can activate CsRhbg gene expression, and elevate the GSase and GDH activity in the gill of the clam as the ammonia detoxiﬁcation strategy to reduce the harm of ammonia. However, prolonged exposure to ammonia nitrogen can result in the down-regulation of CsRhbg gene, dysfunction of key enzymes in the ammonia transport pathways, and damage to the structure of epithelial cells or the cellular structure in the gill of the clam. Therefore, this work will help to reveal the ammonia detoxiﬁcation strategy in bivalves exposed to chronic ammonia nitrogen.

Published in Aquaculture Reports

ISSN: 2352-5134 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Agriculture: Aquaculture. Fisheries. Angling
Website: http://www.journals.elsevier.com/aquaculture-reports/

About the journal

Abstract

Keywords