Cloning, Functional Characterization and Response to Cadmium Stress of the Thioredoxin-like Protein 1 Gene from Phascolosoma esculenta

Abstract

Cadmium (Cd) is a heavy metal toxicant and is widely distributed in aquatic environments. It can cause excessive production of reactive oxygen species (ROS) in the organism, which in turn leads to a series of oxidative damages. Thioredoxin (Trx), a highly conserved disulfide reductase, plays an important role in maintaining the intracellular redox homeostasis in eukaryotes and prokaryotes. Phascolosoma esculenta is an edible marine worm, an invertebrate that is extensively found on the mudflats of coastal China. To explore the molecular response of Trx in mudflat organisms under Cd stress, we identified a new Trx isoform (Trx-like protein 1 gene) from P. esculenta for the first time, designated as PeTrxl. Molecular and structural characterization, as well as multiple sequence and phylogenetic tree analysis, demonstrated that PeTrxl belongs to the Trx superfamily. PeTrxl transcripts were found to be ubiquitous in all tissues, and the highest expression level occurred in the coelomic fluid. Exposure to three sublethal concentrations of Cd resulted in the upregulation and then downregulation of PeTrxl expression levels over time in coelomic fluid of P. esculenta. The significant elevation of PeTrxl expression after 12 and 24 h of Cd exposure at 6 and 96 mg/L, respectively, might reflect its important role in the resistance to Cd stress. Recombinant PeTrxl (rPeTrxl) showed prominent dose-dependent insulin-reducing and ABTS free radical-scavenging abilities. After exposure to 96 mg/L Cd for 24 h, the ROS level increased significantly in the coelomic fluid, suggesting that Cd induced oxidative stress in P. esculenta. Furthermore, the injection of rPeTrxl during Cd exposure significantly reduced the ROS in the coelomic fluid. Our data suggest that PeTrxl has significant antioxidant capacity and can protect P. esculenta from Cd-induced oxidative stress.

Integrative physiological and transcriptome analyses provide insights into the Cadmium (Cd) tolerance of a Cd accumulator: Erigeron canadensis

“…These results indicate that SOD activity is activated under low-concentration Cd stress and that POD activity mainly responds to intense Cd stress. Similar results were observed in B. juncea under a gradient of Cd treatments [ 16 ]. Generally, chloroplasts are highly vulnerable to heavy metal stress because excess heavy metals can dissolve the thylakoid membranes of chloroplasts and hamper enzyme activity for chlorophyll photosynthesis [ 47 , 53 ].…”

“…3 F), indicating that E. canadensis experienced severe damage under 1 mmol/L CdCl 2 treatment. Enhancement of POD and SOD activities is considered a defence strategy against excess ROS in plants [ 16 , 49 ]. The SOD activity increased markedly in shoots treated with different CdCl 2 solutions (Fig.…”

The Draft Genome of Chinese Endemic Species Phascolosoma esculenta (Sipuncula, Phascolosomatidae) Reveals the Phylogenetic Position of Sipuncula

“…As a burrowing organism thriving in the intertidal zone ecosystem, P. esculenta has evolved an extraordinary resilience to harsh and dynamically changing intertidal stresses (Su et al, 2010;Shen et al, 2021). Although, P. esculenta has high tolerance of abiotic stress, including temperature, salinity, and hypoxia, the molecular mechanism bolstering P. esculenta against intertidal stresses has not been thoroughly investigated (Meng et al, 2022). Hence, decoding the genome of P. esculenta will allow for a more thorough understanding of Sipuncula's ecological adaptation and phylogenetic evolution.…”

Characterization of Copper/Zinc Superoxide Dismutase Activity on Phascolosoma esculenta (Sipuncula: Phascolosomatidea) and Its Protection from Oxidative Stress Induced by Cadmium

“…The experiment was carried out in a 32 × 21 × 20 cm plastic water tank, with 12 L of continuously aerated water in each tank. According to our previous experiment, the half-lethal concentration of Cd for 96 h was 192 mg/L [ 52 ]. In this experiment, according to the 96 h LC 50 concentration gradient (0, 1/32 of 96 h LC 50 , 1/8 of 96 h LC 50 , ½ h of LC 50 ), a total of 126 P. esculenta were used.…”

“…The 5 RACE reverse transcription assay was performed using the Smart RACE cDNA amplification kit (CloneTech, USA) while the 3′ RACE reverse transcription assay was performed using the 3′-Full RACE Core Set with a PrimeScript RTase kit (Takara, China). Both assays were conducted according to our previous research [ 52 ]. The products obtained were stored at −20 °C until further analysis.…”