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In this study, a laboratory of genetics and physiology 2 gene ( lgp2) from common carp Cyprinus carpio was isolated and characterized. The full-length complementary (c)DNA of lgp2 was 3061 bp and encoded a polypeptide of 680 amino acids, with an estimated molecular mass of 77 341·2 Da and a predicted isoelectric point of 6·53. The predicted protein included four main overlapping structural domains: a conserved restriction domain of bacterial type III restriction enzyme, a DEAD- DEAH box helicase domain, a helicase super family C-terminal domain and a regulatory domain. Real-time quantitative polymerase chain reaction ( PCR) showed widespread expression of lgp2, mitochondrial antiviral signalling protein ( mavs) and interferon transcription factor 3 ( irf3) in tissues of nine organs. lgp2, mavs and irf3 expression levels were significantly induced in all examined organs by infection with koi herpesvirus ( KHV). lgp2, mavs and irf3 messenger (m)RNA levels were significantly up-regulated in vivo after KHV infection, and lgp2 transcripts were also significantly enhanced in vitro after stimulation with synthetic, double-stranded RNA polyinosinic polycytidylic [poly(I:C)]. These findings suggest that lgp2 is an inducible protein involved in the innate immune defence against KHV in C. carpio. These results provide the basis for further research into the role and mechanisms of lgp2 in fishes. [ABSTRACT FROM AUTHOR]

Actin is a highly conserved protein that is found in all eukaryotic cells, and has been widely used as an internal control gene in gene expression studies. In this study, we cloned an actin gene (named Ecβ-actin) from Exopalaemon carinicauda and determined its expression levels. The full-length cDNA of Ecβ-actin was 1335 bp long, comprising a 1131-bp ORF encoding 376 amino acids, a 65-bp 5'-UTR, and a 139-bp 3'-UTR with a poly(A) tail. The A + T content was approximately 79% in the 3'-UTR of the Ecβ-actin mRNA. The 3'-UTR contained two repeats of the AUUUA motif. The putative protein Ecβ-actin showed high identity (97-99%) with other actins from various species. Phylogenetic analysis revealed that Ecβ-actin belongs to Crustacea, although it formed a singleton sub-branch that was located a short distance from crabs and other shrimp species. Ecβ- actin expression was detected in the hepatopancreas, ovary, muscle, gill, stomach, and hemocytes, and was strongly expressed in the hemocytes and ovary of E. carinicauda. Ecβ-actin mRNA expression varied during ovarian development, with high levels observed at stages I and V. Therefore, caution should be taken when using the Ecβ-actin gene as an endogenous control gene.