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Peroxiredoxin (Prx) family members play a critical role in host defense against oxidative stress, and are also involved in immune responses following microbial infection. In the present study, we firstly cloned the cDNA of Peroxiredoxin 5 from Procambarus clarkii (denoted as PcPrx5) and investigated its immune functions towards LPS and Poly I:C exposure. The PcPrx5 cDNA was composed of 564 bp and consisting of 187 amino acid residues which included Prx5-like subfamily domain, AHP1 domain and Redoxin domain. The recombinant protein was expressed in Escherichia coli (Transetta DE3), and anti-Prx5 antibodies were prepared. Tissue specific expression analysis showed that PcPrx5 was ubiquitously expressed in all examined tissues. Further, its mRNA transcript was greatest in hepatopancrease, haemocyte followed by gut and stomach, and was weak in muscle. The LPS and Poly I:C exposure could both significantly up-regulate the transcript level of PcPrx5, however the expression trends were different following LPS and Poly I: C treatments. Further, we investigated the antioxidant role of recombinant PcPrx5 protein in vitro by mixed-function oxidase assay; the results demonstrated a dose-dependent inhibition of DNA damage by PcPrx5. Our results implicate PcPrx5 as an important defense against microbial pathogens and oxidants in P. clarkii., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The RNA-sequencing followed by de novo assembly generated 61,912 unigene sequences of P. clarkii hepatopancreas. Comparison of gene expression between LPS challenged and PBS control samples revealed 2552 differentially expressed genes (DEGs). Of these sequences, 1162 DEGs were differentially up-regulated and 1360 DEGs differentially down-regulated. The DEGs were then annotated against gene ontology (GO) database and Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Some immune-related pathways such as PPAR signaling pathway, lysosome, Chemical carcinogenesis, Peroxisome were predicted by canonical pathways analysis. The reliability of transcriptome data was validated by quantitative real time polymerase chain reaction (qRT-PCR) for the selected genes. The data presented here shed light into antibacterial immune responses of crayfish. In addition, these results suggest that transcriptomic data provides valuable sequence resource for immune-related gene identification and helps to understand P. clarkii immune functions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)