cDNA Characterization and Expression of Selenium-Dependent CqGPx3 Isoforms in the Crayfish Cherax quadricarinatus under High Temperature and Hypoxia

Abstract

Glutathione peroxidase 3 (GPx3) is the only extracellular selenoprotein (Sel) that enzymatically reduces H2O2 to H2O and O2. Two GPx3 (CqGPx3) cDNAs were characterized from crayfish Cherax quadricarinatus. The nerve cord CqGPx3a isoform encodes for a preprotein containing an N-terminal signal peptide of 32 amino acid residues, with the mature Sel region of 192 residues and a dispensable phosphorylation domain of 36 residues. In contrast, the pereiopods CqGPx3b codes for a precursor protein with 19 residues in the N-terminal signal peptide, then the mature 184 amino acid residues protein and finally a Pro-rich peptide of 42 residues. CqGPx3 are expressed in cerebral ganglia, pereiopods and nerve cord. CqGPx3a is expressed mainly in cerebral ganglia, antennulae and nerve cord, while CqGPx3b was detected mainly in pereiopods. CqGPx3a expression increases with high temperature and hypoxia; meanwhile, CqGPx3b is not affected. We report the presence and differential expression of GPx3 isoforms in crustacean tissues in normal conditions and under stress for high temperature and hypoxia. The two isoforms are tissue specific and condition specific, which could indicate an important role of CqGPx3a in the central nervous system and CqGPx3b in exposed tissues, both involved in different responses to environmental stressors.

Transcriptomic Changes Following Induced De-Masculinisation of Australian Red Claw Crayfish Cherax quadricarinatus

“…Glutathione peroxidase 3 ( GPx3 ), a stress-responsive antioxidant upregulated in the testis tissue, was recently characterised in C. quadricarinatus , demonstrating upregulation in response to environmental stressors such as high temperature and hypoxia [ 52 ]. GPx3 reduces oxidative stress by catalysing the reduction in intracellular hydrogen peroxide to oxygen and water [ 53 ].…”

“…GPx3 reduces oxidative stress by catalysing the reduction in intracellular hydrogen peroxide to oxygen and water [ 53 ]. Two GPx3 cDNA isoforms have been previously characterised: CqGPx3a , expressed primarily in the nervous tissue; and CqGPx3b , expressed primarily in the walking legs [ 52 ]. CqGPx3a was upregulated in response to environmental stressors while CqGPx3b was unaffected, and CqGPx3b was suggested to function as an antimicrobial peptide [ 52 ].…”

“…Two GPx3 cDNA isoforms have been previously characterised: CqGPx3a , expressed primarily in the nervous tissue; and CqGPx3b , expressed primarily in the walking legs [ 52 ]. CqGPx3a was upregulated in response to environmental stressors while CqGPx3b was unaffected, and CqGPx3b was suggested to function as an antimicrobial peptide [ 52 ]. Despite clear tissue specificity in the aforementioned study, both CqGPx3b and CqGPx3b precursors were characterised as the same upregulated transcript due to high homology.…”

Snow crab (Chionoecetes opilio) hemocytes and hepatopancreas transcriptomes: identification, validation, and application of immune-relevant biomarkers of exposure to noise

“…GPx3, a selenoprotein that catalyzes the reduction of H 2 O 2 [hydrogen peroxide, a reactive oxygen species (ROS)] to H 2 O and O 2 , is a key component of the redox system that protects cells from oxidative damage (Hernańdez-Aguirre et al, 2022). Functional annotations associated with gpx3 include "selenium binding", "oxidoreductase activity", "cellular oxidant detoxification", response to lipid hydroperoxide", and "response to oxidative stress" (Supplemental Table 2).…”

“…A mud crab hepatopancreas RNA-seq study found that gpx3 and other oxidative stress relevant transcripts (thioredoxin, thioredoxin reductase, cytochrome p450) were upregulated after air exposure, an important environmental stressor for crab aquaculture and transport (Cheng et al, 2020b). As well, crayfish (Cherax quadricarinatus) gpx3 transcripts were shown to be upregulated in nerve cord by elevated temperature and hypoxia (Hernańdez-Aguirre et al, 2022), and Zhikong scallop (Chlamys farreri) gpx3 upregulation in kidney after exposure to paralytic shellfish toxin (PST)-producing dinoflagellates may protect this organ from PSTassociated oxidative stress (Hlaing et al, 2021). While the aforementioned crustacean gpx3 expression studies showed induction following exposure to various environmental stressors (in agreement with our observation of snow crab gpx3 upregulation by chronic noise in hepatopancreas), gpx3 was found to be significantly downregulated in Chinese mitten crab (Eriocheir sinensis) gill after salinity stress (Li et al, 2014).…”