Unravelling the characterization of hypoxia‐inducible factor‐1α ( HIF‐1α ) and antioxidant enzymes in clam Cyclina sinensis in response to hypoxia

Abstract

Aquatic hypoxia has negative or detrimental effects on clams. To cope with hypoxia stress, a complex series of physiological and biochemical strategies can be employed in clams. Hypoxia‐inducible factor‐1α (HIF‐1α) and antioxidant enzymes are commonly found in aquatic animals as an adaptation against hypoxia. In the present study, we cloned the HIF‐1α sequence in clam Cyclina sinensis, and it consists of 2654 base pairs (bp) carrying a single open‐reading frame that encompasses 2235 bp of the coding region. The predicted C. sinensis HIF‐1α protein (744 amino acids) has the conserved HLH‐PAS domain, which contained one N‐terminal basic helix–loop–helix (bHLH) domain and two Per‐ARNT‐Sim A/B (PAS) domains, followed by PAS‐associated C‐terminal (PAC) domain. HIF‐1α is expressed predominantly in gills. Exposed to hypoxia, the transcript level of HIF‐1α was significantly up‐regulated in response to hypoxia, and then, the transcript level declined continuously with the time elapsed. The antioxidant enzymes (SOD, CAT and GSH‐PX) in gills were increased initially and then decreased after acute hypoxia exposure. Our study indicates that the HIF‐1α gene and antioxidant enzymes may play an important role in cope with acute hypoxia exposure.

Effect of chronic ammonia nitrogen stress on the SOD activity and interferon-induced transmembrane protein 1 expression in the clam Cyclina sinensis

“…Six clams were dissected and various tissues collected, which were then frozen in liquid nitrogen for RNA extraction (Ni et al, 2022).…”

“…Seven hundred and twenty selected clams were randomly stored in six concrete tanks (200 L water) at a density of 120 clams per tank, with three replicates for each treatment. According to the 96-h median lethal concentration (LC 50 -96 h) TAN for C. sinensis (Ni et al, 2022), the TAN level in the experimental group was set at 8.07 mg/L. To achieve the designed level of TAN, a stock solution of NH 4 Cl (1.0 g/L) was used.…”

“…The CDS sequence of the IFITM1 gene was derived from the clam whole-genome sequencing complementary DNA (cDNA) library (Wei et al, 2020). To clone the full-length cDNAs, rapid amplification of cDNA ends PCR (RACE-PCR) was conducted (Ni et al, 2022). The primers required for IFITM1 gene cloning are shown in Table 1.…”

“…The ExPASy ProtParam program was utilized to predict the molecular weight and isoelectric points of the IFITM1 protein. According to a previous report, multiple sequence alignments were generated and a phylogenetic tree was constructed (Ni et al, 2022).…”

“…The clam grows fast, tastes delicious, and has great market demand (Ge et al, 2021;Liao et al, 2022). The clam is highly adaptable to ammonia nitrogen (Ni et al, 2022). However, when the accumulation of ammonia nitrogen reaches the threshold level, this can have serious effects on the clam, including oxidative stress and poor immune response (Ni et al, 2021;Ge et al, 2022a).…”