Expression Analysis of a Novel Oxidoreductase Glutaredoxin 2 in Black Tiger Shrimp, Penaeus monodon

Abstract

Glutaredoxin (Grx) is a glutathione-dependent oxidoreductase that is an important component of the redox system in organisms. However, there is a serious lack of sequence information and functional validation related to Grx in crustaceans. In this study, a novel Grx was identified in Penaeus monodon (PmGrx2). The full-length cDNA of PmGrx2 is 998 bp, with an open reading frame (ORF) of 441 bp, encoding 119 amino acids. Sequence alignment showed that PmGrx2 had the highest identity with Grx2 of Penaeus vannamei at 96.64% and clustered with Grx2 of other crustaceans. Quantitative real-time PCR (qRT-PCR) analysis showed that PmGrx2 was expressed in all examined tissues, with higher expression levels in the stomach and testis. PmGrx2 was continuously expressed during development and had the highest expression level in the zygote stage. Both ammonia-N stress and bacterial infection could differentially induce the expression of PmGrx2 in hepatopancreas and gills. When PmGrx2 was inhibited, the expression of antioxidant enzymes was suppressed, the degree of apoptosis increased, and the GSH content decreased with the prolongation of ammonia-N stress. Inhibition of PmGrx2 resulted in shrimp being exposed to a greater risk of oxidative damage. In addition, an SNP locus was screened on the exons of PmGrx2 that was significantly associated with an ammonia-N-stress-tolerance trait. This study suggests that PmGrx2 is involved in redox regulation and plays an important role in shrimps’ resistance to marine environmental stresses.

Oxidative Stress in Aquatic Organisms

“…Taxonomically, these papers cover freshwater fish ( Carassius auratus [ 4 ], Monopterus albus [ 5 ], Ictalurus punctatus [ 6 ], Megalobrama amblycephala [ 7 ], Micropterus salmoides [ 8 ], Lateolabrax maculatus [ 9 , 10 , 11 , 12 ], Carassius gibelio [ 13 , 14 ], Aplodinotus grunniens [ 15 ], Pangasianodon hypophthalmus [ 16 ], Danio rerio [ 17 ], and hybrid grouper [ 18 ]), marine fish ( Scophthalus maximus [ 19 ]), crustaceans ( Macrobrachium rosenbergii [ 20 , 21 , 22 ], Litopenaeus vannamei [ 23 , 24 , 25 ], Penaeus monodon [ 26 ], Scylla paramamosain [ 27 ], and Eriocheir sinensis [ 28 ]), and molluscs ( Crassostrea hongkongensis [ 29 ], Trachinotus ovatus [ 30 ], and Pacific abalone [ 31 ]). Meanwhile, these papers reveal several endogenous and exogenous factors that induce oxidative stress, such as environmental factors (water hardness [ 4 ], chronic hyperthermia [ 6 ], acute hypoxic stress [ 10 ], acute ammonia nitrogen [ 12 ], hypothermia [ 15 ], low salinity [ 23 ], and ammonia-N-stress [ 26 ]), nutritional factors (high carbohydrate levels [ 5 ], oxidized lipids [ 7 ], high-fat diet [ 12 , 20 ], and lipopolysaccharide [ 29 ...…”

“…Therapeutically, some papers have also explored some medicines or immunostimulants to resist oxidative stress, such as herbal medicine (mulberry leaf flavonoids [ 5 ], emodin [ 7 ], berberine [ 17 ], Sophora flavescens root extract [ 19 ], and tea tree oil [ 22 ]), nutritional stimulants ( Atractylodes macrocephala polysaccharide [ 9 ], taurine alleviates [ 13 ], histamine [ 16 , 18 ], vitamin E [ 20 ], β-Glucan [ 23 ], krill oil [ 24 ], and zinc [ 25 ]), antibiotics (florfenicol and ofloxacin [ 21 ]), and feeding administration (feed restriction [ 6 ]). Additionally, the full length of antioxidant genes was also cloned to analyze their functional responses to oxidative stress, such as glutaredoxin [ 26 ] and catalase [ 31 ].…”

“…Yang et al [ 25 ] revealed that organic zinc had a higher bioavailability to improve zinc homeostasis, antioxidant capacity, immune response, glycolysis and intestinal microbiota, and was therefore a more beneficial zinc resource than inorganic zinc in white shrimp ( L. vannamei Boone, 1931). Fan et al [ 26 ] identified a novel glutaredoxin (PmGrx2) in P. monodon . They cloned the full length and indicated that PmGrx2 is involved in redox regulation and plays an important role in resistance to ammonia-N-stress.…”

“…cloned to analyze their functional responses to oxidative stress, such as glutaredoxin [26] and catalase [31].…”