Effects of ammonia nitrogen on gill mitochondria in clam Ruditapes philippinarum

Abstract

Ammonia nitrogen exposure has been found to significantly increase the early apoptosis rates of gill cells, affect the contents of ATP and disturb expressions of calcium-related genes in clam Ruditapes philippinarum. Mitochondria are the centers for energy production, initiation of apoptosis and calcium signal regulation. It is hypothesized that gill mitochondrion is a target organelle for the ammonia nitrogen. Thus, ATP metabolism together with ATP-consuming functions would be interfered by ammonia exposure. In the present study, mitochondrial transmembrane potential (MTP), ATPase activities, gill functions in clearance and respiration, and histological changes were detected to characterize the effects of ammonia to the gill mitochondria in clam R. philippinarum. Results indicated that ammonia exposure led to significant decreases in MTP, Ca 2+ -ATPase activity and clearance rates. However, different concentrations of ammonia nitrogen induced different variations on H + , K + -ATPase activity and respiration rates. Histological observation revealed that subacute exposure of ammonia damaged the microstructure of gill tissues. Therefore, ammonia exposure dramatically damaged the normal structure and function of mitochondria, resulting in irreversible damage in energy formation and supply. In addition, it affected Ca 2+ and K + metabolism and inhibited food intake and respiration in clam R. philippinarum.

Toxic Effects on Bioaccumulation, Hematological Parameters, Oxidative Stress, Immune Responses and Tissue Structure in Fish Exposed to Ammonia Nitrogen: A Review

“…Furthermore, non-ionic ammonia has good lipid solubility. It can easily diffuse into fish through cell membranes, causing damage to important organs, including gill tissue, resulting in respiratory difficulties and reduced feeding rate of fish, and inhibiting their growth and development [ 8 ]. The non-ionic ammonia which enters the fish directly affects the metabolism of enzymes, causing disorders of enzyme metabolism and reducing immunity, stimulating a series of toxic reactions in fish, such as excitement and convulsions until they die of exhaustion [ 9 , 10 ].…”

Combined analysis of mRNA–miRNA reveals the regulatory roles of miRNAs in the metabolism of clam Cyclina sinensis hepatopancreas during acute ammonia nitrogen stress

“…RNA-seq technique, which refers to the sum of all RNA that can be transcribed under the same environment conditions, including mRNA and miRNA can reflect the gene expression of a specific tissue of a species during a certain state (Li et al, 2017;Yang et al, 2019). RNAseq technique has been applied to reveal the response mechanism to ammonia stress in aquatic animals, including Asian clam Corbicula fluminea (Cong et al, 2018), mud crab (Scylla paramamosain) (Cheng et al, 2019), banana shrimp Fenneropenaeus merguiensis (Wang et al, 2017) and so on. These results provided valuable information to reveal the mechanism of ammonia nitrogen exposure in immune response and oxidative stress.…”

Genome-Wide Characterization and Analysis of Expression of the Histone Gene Family in Razor Clam, Sinonovacula constricta

“…Among six organs/tissues, most histone genes were predominantly expressed in the gill and hepatopancreas compared to other organs/tissues. Notably, the gill and hepatopancreas play critical roles in maintaining homeostasis and immune defense [55,56]. In this regard, the histone genes highly expressed in gill and hepatopancreas may be required not only for the packaging of DNA into chromatin, but also for cell homeostasis and immune response.…”