Oil from hake (Merluccius merluccius): Characterization, antioxidant activity, wound healing and anti-inflammatory effects.

The aim of this work was to evaluate some biological properties of hake head oil (HHO) as well its lipid composition. The fatty acid profiles showed a dominance of unsaturated fatty acids overtaking 55% of the total fatty acids. Omega-3 polyunsaturated fatty acid profiles exhibited a dominance of EPA (eicosapentaenoic acid) (3.96%) and DHA (docosahexaenoic acid) (25.39%). The antioxidant activity was determined through two different assays: DPPH scavenging activity and ß-carotene bleaching by linoleic acid assay. Eighteen mice were excised on their back and divided into 3 groups, treated with sterile saline, commercial healing cream and HHO, respectively. The wound closure rate, the hydroxyproline contents and the histopathology evolution in skin tissue were elaborated. Also, the anti-inflammatory activity was studied by carrageenan-induced mouse paw edema. Mice were divided into 3 groups treated respectively with sterile saline, anti inflammatory drug reference and HHO. The anti-inflammatory evaluation of HHO in mice exhibited an important inhibition of carrageenan-induced hind paws edema, as confirmed by the histological analysis, the superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) level. HHO displayed a significant wound healing effect probably due to the anti-inflammatory and antioxidant activities of its EPA and DHA contents. The overall results proved that HHO might be favorable drugs who exert a great therapeutic potential wound healing and anti-inflammatory effects in animal model.

Cloning and expression analysis of interferon regulatory factor 7 in the Pacific cod, Gadus macrocephalus.

Interferon regulatory factor 7 (IRF7) plays an important role in regulating the response of type I interferon (IFN) to viral infection. To understand the mechanisms underlying immune reactions in the Pacific cod, Gadus macrocephalus, the gene encoding G. macrocephalus IRF7 was cloned and characterized. The cDNA of G. macrocephalus IRF7 was also cloned and sequenced. A cDNA sequence of 2032 bp was assembled using polymerase chain reaction (PCR) products. It contains an open reading frame of 1323 bp in length, which encoded a 440-amino acid polypeptide that comprised a DNA-binding domain (DBD), an IRF association domain (IAD), and a serine-rich domain (SRD). In the DBD, the tryptophan cluster consisted of only four tryptophans, which is a unique characteristic in fish IRF7. The mRNA of IRF7 was detected in various tissues, including in the spleen, thymus, kidney, intestine, and gills, using relative quantification PCR (R-qPCR). Dynamic expression of IRF7 was observed in larvae throughout post-hatching (ph) development, with the highest level detected at day of ph (dph) 25. Response to immune stimulation was examined by challenging larvae with polyriboinosinic polyribocytidylic acid (pIC) to mimic viral infection and elicit an immune reaction. R-qPCR revealed that the expression of IRF7 significantly increased in pIC-treated groups relative to that in the control groups, in a time-dependent manner, with peak responses at 48 and 72 h after pIC-treatment. These results show that IRF7 is expressed in various tissues of adult fish and larvae and is sensitive to viral infection, suggesting that it plays a role in antiviral immune defense in G. macrocephalus.

Transcriptomic analysis and biomarkers (Rag1 and Igµ) for probing the immune system development in Pacific cod, Gadus macrocephalus.

Mortality (>90%) is a big concern in larval rearing facilities of Pacific cod, Gadus macrocephalus, limiting its culture presently still in the experimental stages. Understanding the immune system development of G. macrocephalus is crucial to optimize the aquaculture of this species, to improve the use of economic resources and to avoid abuse of antibiotics. For the transcriptome analysis, using an Illumina sequencing platform, 61,775,698 raw reads were acquired. After a de novo assembly, 77,561 unigenes were obtained. We have classified functionally these transcripts by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). 27 genes mainly related to hematopoietic or lymphoid organ development and somatic diversification of immune receptors have been reported for the first time in Pacific cod, and 14 Ig heavy chain (µ chain) locuses were assembled using Trinity. Based on our previous achievement, we have chosen Rag1 and Igµ as immune system development biomarkers. Full length cDNA of Rag1 and Igµ as biomarkers were obtained respectively using RACE PCR. Concerning Rag1, the deduced amino acid of Rag1 and protein immunodetection revealed a Rag1 isoform of 69 kDa, significantly different from other fish orthologs, such as Oncorhynchus mykiss (121 kDa). Phylogenetic analysis reveals a unique immune system for the Gadus genre, not exclusive for Atlantic cod, among vertebrates. Meanwhile, full length cDNA of Igµ included an ORF of 1710 bp and the deduced amino acid was composed of a leader peptide, a variable domain, CH1, CH2, Hinge, CH3, CH4 and C-terminus, which was in accordance with most teleost. Absolute quantification PCR revealed that significant expression of Rag1 appeared earlier than Igµ, 61 and 95 dph compared to 95 dph, respectively. Here we report the first transcriptomic analysis of G. macrocephalus as the starting point for genetic research on immune system development towards improving the Pacific cod aquaculture.

Characterization of susceptibility and carrier status of burbot, Lota lota (L.), to IHNV, IPNV, Flavobacterium psychrophilum, Aeromonas salmonicida and Renibacterium salmoninarum.

In this study, susceptibility and potential carrier status of burbot, Lota lota, were assessed for five important fish pathogens. Burbot demonstrated susceptibility and elevated mortality following challenge with infectious haematopoietic necrosis virus (IHNV) by immersion and to Aeromonas salmonicida by intraperitoneal (i.p.) injection. IHNV persisted in fish for at least 28 days, whereas A. salmonicida was not re-isolated beyond 17 days post-challenge. In contrast, burbot appeared refractory to Flavobacterium psychrophilum following intramuscular (i.m.) injection and to infectious pancreatic necrosis virus (IPNV) by immersion. However, i.p injection of IPNV resulted in re-isolation of virus from fish for the duration of the 28 day challenge. Renibacterium salmoninarum appeared to induce an asymptomatic carrier state in burbot following i.p. injection, but overt manifestation of disease was not apparent. Viable bacteria persisted in fish for at least 41 days, and bacterial DNA isolated by diagnostic polymerase chain reaction was detected from burbot kidney tissue 90 days after initial exposure. This study is the first to investigate susceptibility of burbot to selected fish pathogens, and this information will aid in efforts to culture and manage this species.