How does the snakehead Channa argus survive in air? The combined roles of the suprabranchial chamber and physiological regulations during aerial respiration

Expression changes of non-specific cytotoxic cell receptor (NCCRP1) and proliferation and migration of NCCs post-Nocardia seriolae infection in Northern Snakehead

Non-specific cytotoxic cells (NCCs) are essential to the cytotoxic cell-mediated immune response in teleost. The fish non-specific cytotoxic cell receptor protein 1 (NCCRP1) plays an important role as a membrane protein in the recognition of target cells and the activation of NCC. However, the roles of fish NCCs during pathogen infection require comprehensive studies. In this study, the coding sequence of northern snakehead (Channa argus) nccrp1 (Canccrp1) was cloned. Canccrp1 contains an open reading frame of 690 bp, encoding a peptide of 229 amino acids with a conserved F-box-associated domain (FBA) and proline-rich motifs (PRMs). Transcriptional expression analysis revealed that the constitutive expression of Canccrp1 was higher in the immune-related organs, such as liver, kidneys, and spleen. Moreover, mRNA and protein expression of Canccrp1 gradually increased in the spleen at 1-6 days post infection (dpi) with Nocardia seriolae, in addition to reaching peak expression in both the kidneys and liver at 2 dpi. A polyclonal antibody prepared against recombinant CaNCCRP1 effectively labeled NCCs in peripheral blood and different tissues. Then, immunofluorescence (IF) staining showed that the number of NCCs was significantly increased and showed a scattered distribution in the early stages of N. seriolae infection (2 and 4 dpi) before the forming of granulomas. At the late stages of N. seriolae infection (6 dpi), more NCCs migrated to preexisting granulomas, showing significant coaccumulation with N. seriolae. All these results clearly indicate the expression changes of CaNCCRP1, and the number and localization changes of NCCs post-N. seriolae infection, implying potential roles for fish NCCs in the antimicrobial infection process in fish.

Channa argus BMH from Baima Hu Lake: sequencing and phylogenetic analysis of the mitochondrial genome

Northern snakehead, Channa argus, is a commercially important food fish species in China. In the present study, the complete mitochondrial genome of C.argus from the Baima Hu Lake was characterized. It is 16,558 bp in length, consist of 22 tRNA genes, 13 PCD genes, 2 rRNA genes, and 1 D-loop region. The overall base composition of the C. argus mitogenome is 27.26% A, 24.21% T, 31.58% C and 16.95% G, exhibits a similar AT bias (51.47%) feature to other vertebrate mitogenomes. The phylogenetic analysis showed that C. argus clustered in genus Channa. The present resultes provide useful information to population genetics and conservation biology studies of Channa fishes.