Characterization of p53 From the Marine Crab Portunus trituberculatus and Its Functions Under Low Salinity Conditions.

Xianyun Ren,Ping Liu,Yao Xu,Jianjian Lv,Jian Li,Lei Wang,Qiong Wang

doi:10.3389/fphys.2021.724693

Abstract

Portunus trituberculatus, or the swimming crab, is tolerant of reduced salinity; however, the molecular mechanism of this tolerance is not clear. Cells can be damaged by hyperosmotic salinity. The protein p53, sometimes referred to as “the guardian of the genome,” displays versatile and important functions under changing environmental conditions. Herein, the P. trituberculatus p53 gene (designated as Ptp53) was cloned and studied. The full-length Ptp53 cDNA comprised 1,544bp, with a 1,314bp open reading frame, which encodes a putative polypeptide of 437 amino acids. Quantitative real-time reverse transcription PCR assays revealed ubiquitous expression of Ptp53 in all tissues examined, with the gills showing the highest expression level. Extensive apoptosis was detected under low salinity conditions using terminal deoxynucleotidyl transferase nick-end-labeling staining. Oxidative stress was induced under low salinity conditions, consequently leading to apoptosis. Low salinity stress caused significant upregulation of Ptp53 mRNA and protein levels in the gills. Moreover, compared with that in the control group, the mortality of Ptp53-silenced crabs under low salinity stress was enhanced significantly. Taken together, our findings suggest that Ptp53, via regulation of apoptosis and antioxidant defense, played important functions in the low salinity stress response of the swimming crab.

Highlights

Salinity is one of the most important environmental factors affecting the distribution and physiological activities of aquatic organisms (Huang et al, 2019)
The Ptp53 cDNA sequence comprises 1,544 bp, containing an Open reading frame (ORF) of 1,314 bp that encodes a putative protein of 437 amino acids (GenBank Accession No MH155954)
The phylogenetic tree showed that p53 of P. trituberculatus is classified with p53 proteins from vanabin-containing prawns, and the kinship is recent relative to other invertebrates (Supplementary Figure S3)

Summary

Introduction

Salinity is one of the most important environmental factors affecting the distribution and physiological activities of aquatic organisms (Huang et al, 2019). Organisms often experience stress resulting from changes in environmental salinity, there are differences among species. The ion regulation mechanisms of freshwater and marine species have been studied extensively, for example, low salinity induced mRNA expression levels of Na+-K+-ATPase, V-type. Changes in cell contact with the outside environment and ion transport depend on the external osmotic pressure, which is affected to the greatest extent by changes in salinity. The gills experience direct exposure to the external aqueous environment and comprise the main site at which ion movement is balanced between gain and loss; the gills are the main site of apoptosis during salinity adaptation in aquatic animals (McNamara and Faria, 2012)

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