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Adenosine deaminases acting on tRNAs (ADATs) are involved in the formation of inosine in tRNAs, and they are members of the adenosine deaminase acting on RNA (ADAR) family of RNA editing enzymes. In this study, we analyzed and characterized two ADAT genes, AdADAT2 and AdADAT3, from Dabry's sturgeon (Acipenser dabryanus). The full‐length cDNAs of AdADAT2 and AdADAT3 were 1704 and 1402 bp, respectively, and they encoded putative proteins of 188 amino acids and 355 amino acids, respectively. AdADAT2 and AdADAT3 genes contain six exons and two exons, respectively. The deduced amino acid sequences exhibit signature features of three residues (generally, one histidine and two cysteines) embedded in three characteristic motifs (motif Ⅰ, Ⅱ, and Ⅲ). AdADAT2 and AdADAT3 mRNAs were expressed ubiquitously in the tissues of healthy A. dabryanus, with elevated levels in the intestine, middle kidney, head kidney, and spleen. In response to polyinosine‐polycytidylic acid (poly I:C), the AdADAT2 mRNA level was significantly upregulated at 6 h post‐stimulation (hps), but the AdADAT3 mRNA level was prominently downregulated at 6 hps. The different responses of the two genes to poly I:C indicate that they have different defense mechanisms against viruses. [ABSTRACT FROM AUTHOR]

Mx and Viperin are important interferon‐stimulated genes that mediate the antiviral immune response. In this study, we cloned the Mx and viperin genes from Dabry's sturgeon (Acipenser dabryanus). The Mx cDNA sequence contained an open reading frame (ORF) of 1,449 nucleotides, encoding a putative protein of 392 aa, which is significantly shorter than other animal Mx proteins. Although the similarity and identity were low between sturgeon Mx and other animal Mx proteins, sturgeon Mx contains the conserved tripartite GTP binding motif and a dynamin family signature. The sturgeon Mx gene contains eight exons split by seven introns. The sturgeon viperin cDNA sequence contained an ORF of 1,047 bp encoding a putative protein of 349 aa, which is relatively well conserved among species. Sturgeon viperin proteins show 82% similarity with those of Xiphophorus maculatus platyfish and Poecilia formosa Amazon molly. The sturgeon viperin gene has a six exon/five intron structure with the same size of second, third, fourth, and fifth exons between different species. The expression of Mx and viperin was detectable in all tissues examined, with the highest expression in skin for Mx and in peripheral blood for viperin. After mock infection using polyinosine‐polycytidylic acid, Mx and viperin showed significantly upregulated expression in primary spleen leukocytes from 3 hr to 72 hr. Lipopolysaccharide could also induce their expression. These results suggested Mx and Viperin could play a vital antiviral role in the innate immune system of Dabry's sturgeon. [ABSTRACT FROM AUTHOR]

Dabry's sturgeon (Acipenser dabryanus) represents an ancient Actinopterygian lineage that are termed "living fossils". Many diseases have been found in Dabry's sturgeon. In the present study, genes encoding interleukin (IL)‐16 and IL‐17D in Dabry's sturgeon were identified by RNA‐sequencing. Phylogenetic tree analysis suggested that they clustered together with the corresponding pro‐IL‐16 proteins and IL‐17D proteins from other fish. Sequence analysis revealed that IL‐17D protein was more conserved than pro‐IL‐16. Dabry's sturgeon pro‐IL‐16 contains four putative PDZ domains and do not include signal peptides, while IL‐17D only possesses signal peptides (1–25 aa). The expression patterns of IL‐16 and IL‐17D genes were investigated in Dabry's sturgeon to reveal their functions in disease. The expression level of IL‐16 showed no significant changes in embryos; however, the high expression level of IL‐17D at 0–14 hpf (hours post fertilization) implied the existence of maternal expression in the oocyte and an association with embryonic development. Tissue distribution analysis revealed that IL‐16 and IL‐17D proteins have potential functions in immune and non‐immune tissue compartments. IL‐16 and IL‐17D had different fold changes in primary spleen leukocytes after polyinosinic:polycytidylic acid (poly I:C) and lipopolysaccharide (LPS) administration, which suggested that IL‐16 has a stronger antiviral capability compared with its antibacterial response, and IL‐17D has a stronger antibacterial capability compared with its antiviral response. IL‐16 showed an earlier response to virus compared with IL‐17D, and IL‐17D showed earlier and shorter response to bacteria compared with IL‐16. Our findings suggested the roles of IL‐16 and IL‐17D in Dabry's sturgeon, and provided the theoretical basis for the prevention and control of diseases of Dabry's sturgeon. [ABSTRACT FROM AUTHOR]

TRIM proteins are a group of highly conserved proteins that participate in a variety of biological processes in innate immunity. However, the roles of the Acipenseridae trim genes in the anti‐bacterial immune response remained uncertain. In the present study, the Dabry's sturgeon (Acipenser dabryanus) TRIM2, TRIM8, and TRIM59 protein sequences were found to be similar to Chicken (Gallus gallus), with identities 92.8%, 89.1%, and 79.4%, respectively. Meanwhile, the TRIM23, TRIM37, and TRIM82 proteins shared 95.8%, 81.7%, and 78.1% similarity with Zebrafish (Danio rerio) homologs, respectively. Sequence alignment indicated that these six adTRIMs contained incomplete domains at their N‐termini, including a RING‐finger domain and one or two B‐boxes domains. The six adtrim genes were constitutively expressed in immune related tissues, such as the head kidney, and were also expressed in non‐immune related tissues, like the blood, brain, muscle, and liver. After challenge with Aeromonas hydrophila, the expression levels of adtrims changed during the early stage of infection. Stimulation by A. hydrophila upregulated the expression levels of adtrim8 and adtrim59 in the spleen and caudal kidney, while the expression of adtrim82 in the spleen and caudal kidney was inhibited at 12 hr post‐infection. A. hydrophila challenge led to significant upregulation of adtrim2 and downregulation of adtrim23 in the spleen. In addition, adtrim37 was only weakly affected by A. hydrophila stimulation. These results suggested that adtrims were related to the immune response to bacterial infection, which provides the fundamental basis for protecting Dabry's sturgeon against pathogen attack. [ABSTRACT FROM AUTHOR]