Shaowu Li

Trancriptome profiles of Amur sturgeon spleen in response to Yersinia ruckeri infection

ABSTRACT Yersinia ruckeri (YR) is the causative agent of yersiniosis which has caused significant economic losses in fish culture worldwide, including in Amur sturgeon (Acipenser schrenckii) culture. To better understand the mechanism of the immune responses to YR in Amur sturgeon, the transcriptomic profiles of the spleens from YR‐infected and non‐infected groups were obtained using RNA‐seq techniques. The de novo assemblies yielded totally 145 670 unigenes from the two libraries. The total numbers of transcripts in YR‐infected and non‐infected groups were from 110 893 to 147 336, with the mean length varying from 560 to 631 (N50: from 882 to 1083). GO analysis revealed that 10 038 unigenes were categorized into 26 biological processes subcategories, 17 cellular components subcategories and 19 molecular functions subcategories. A total of 59 487 unigenes were annotated in the KEGG pathway and 20 pathways were related to the immune system. 1465 differently expressed genes (DEGs) were identified, including 377 up‐regulated genes and 1088 down‐regulated genes. 125 DEGs were found to be related to immune responses of Amur sturgeon and further divided into 16 immune‐related KEGG pathways, including antigen processing and presentation, complement and coagulation cascades, T cell receptor signaling pathway, B cell receptor signaling pathway, NOD‐like receptor signaling pathway, chemokine signaling pathway, etc. Eight of the DEGs were further validated by qRT‐PCR. Altogether, the results obtained in this study will provide insight into the immune response of Amur sturgeon against Y. ruckeri infection. HighlightsTranscriptome of Amur sturgeon infected with Yersinia ruckeri was analyzed.Totally 145 670 unigenes were yielded by de novo assembly.Totally 1465 DGEs were identified under Y. ruckeri challenge.125 DEGs were divided into 16 immune‐related KEGG pathways.Eight of DEGs were chosen for further validation using qRT‐PCR.

Effects of different cytokines on immune responses of rainbow trout in a virus DNA vaccination model

Seven rainbow trout cytokine genes (interleukin (IL)-2, IL-8, IL-15, IL-17, IL-1β, intracellular interferon (iIFN) 1a, and IFN-γ2) were evaluated for their adjuvant effects on a DNA vaccine, called pG, containing the glycoprotein gene of infectious hematopoietic necrosis virus (IHNV). Distinct DNA constructs in expression plasmid pcDNA3.1 encoding a cytokine gene were generated. Immunofluorescence assays in rainbow trout gonadal cells demonstrated successful protein expression from all these constructs. Subsequently, fish were immunized with pG alone or together with a cytokine expression plasmid. Results showed that each cytokine plasmids at an appropriate dose showed notable effects on immune gene expression. IL-17 and IFN-γ2 can enhance early specific IgM response. All cytokines, except IL-8, can benefit initial neutralizing antibody (NAb) titers. At 35 days post immunization (dpi), NAb titers of fish immunized with pG and IL-2, iIFN1a, or IFN-γ2 plasmids remained at high levels (1:160). NAb titers of fish immunized with pG alone decreased to 1:40. IL-8 or IL-1β can enhance antigen-specific proliferative T-cell responses at 14 dpi. At 28 dpi, coinjection of pG with IL-2, IL-8, IL-15, or IL-17 plasmids induced considerably stronger lymphocyte proliferation than that with injection of pG alone. All cytokine plasmids delivered with pG plasmid enhanced protection of trout against IHNV-mediated mortality. These results indicate that the type and dose of trout cytokine genes injected into fish affect quality of immune response to DNA vaccination.

Rule of accumulation of enrofloxacin in Acipenser baerii and drug-induced damage to the tissues.

Enrofloxacin (ENX) has been widely used in the prevention and control of bacterial diseases in sturgeon aquaculture due to its characteristics of wide antibacterial spectrum, strong antibacterial activity, less toxicity and fewer side effects, rapid action, extensive in vivo distribution, and little cross-resistance with other antibiotics. However, the spinal abnormality was found in Acipenser baerii soon after ENX administration, which resulted an “S”-shaped curvature of the spine and retarded fish growth. It was still not clear whether ENX could cause spinal abnormality in sturgeons by now. The aim of this work was to determine the accumulation rule and toxicity of ENX to A. baerii when used at a high dose and/or unusually long durations. Here, ENX was orally given to A. baerii for 3–5 d continuously at the dosage of 0, 20, 40, and 80 mg/kg once daily, respectively. The accumulation of ENX in blood, liver, kidney, and cartilage was detected after withdrawal, and the tissues were made into sections for morphological examination. The results showed that the levels of ENX increased in the four tissues with the increase of dose and duration, and the ENX level in serum was far lower than that in other tissues. At 240 h, ENX levels in the four tissues decreased significantly. The histology indicated that the liver, kidney, and cartilage began to show structural damages at 5 d after withdrawal of 40 mg/kg ENX. The damage was aggravated at 3–5 d after withdrawal of 80 mg/kg ENX. At 240 h, the damaged tissues showed signs of recovery. These results suggested that ENX should be no more than 40 mg/kg and that exposure time should not be greater than 5 d to prevent liver, kidney, and cartilage damage. More attention should be paid to the impact of ENX on the occurrence and development of chondrocytes in juvenile A. baerii and the potential damage to the cartilage.

Identification and analysis of differentially expressed microRNAs in rainbow trout (Oncorhynchus mykiss) responding to infectious hematopoietic necrosis virus infection

ABSTRACT MicroRNAs (miRNAs) are a class of regulators essential for numerous biological processes. Infectious hematopoietic necrosis virus (IHNV) is one of the most important viral pathogens in salmon and trout. In this study, the miRNA expression profiles of rainbow trout upon IHNV infection were explored. In total, 392 known miRNAs and 936 novel miRNAs were identified. Twelve known and 13 novel miRNAs were differentially expressed between infected and uninfected fish. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that certain miRNA target genes were associated with biological regulation, the immune system, and signal transduction. In addition, over‐ and suppressed expression of miR‐146a‐3p, miR‐155–5p, miR‐216a‐5p, and miR‐499b‐5p could respectively increase and decrease viral gene expression in cells and viral titers. MiR‐146a‐3p and miR‐216a‐5p inhibited the expression of type‐I IFN and the Mx1 gene induced by IHNV. These results provide preliminary insights into the IHNV–host interactions mediated by miRNAs. HIGHLIGHTSMiRNA responses to IHNV infection were identified in rainbow trout by sequencing.12 known and 13 novel miRNAs were differentially expressed during IHNV infection.Several differentially expressed miRNAs were predicted to be involved in immunity.MiR‐146a‐3p, 155–5p, 216a‐5p and 499b‐5p were positive for IHNV replication.MiR‐146a‐3p and 216a‐5p inhibited IHNV induced type I IFN and Mx1 expression.

Histological Studies of the Effects of Aeromonas salmonicida on the Tissues in Brachymystax lenok

Shaowu Li1, Gefeng Xu2, Di Wang1, Zhenbo Mou1 and Tongyan Lu1* 1Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, PR China 2College of Animal Science and Technology, Northeast Agricultural University, Harbin, PR China *Corresponding author: Tongyan Lu, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, PR China, Tel: +86-451-84604803, E-mail: lutongyan@hotmail.com