Molecular characterization and expressional affirmation of the beta proteasome subunit cluster in rock bream immune defense

Network-based integration of omics, physiological and environmental data in real-world Elbe estuarine Zander

Coastal and estuarine environments are under endogenic and exogenic pressures jeopardizing survival and diversity of inhabiting biota. Information of possible synergistic effects of multiple (a)biotic stressors and holobiont interaction are largely missing in estuaries like the Elbe but are of importance to estimate unforeseen effects on animals' physiology. Here, we seek to leverage host-transcriptional RNA-seq and gill mucus microbial 16S rRNA metabarcoding data coupled with physiological and abiotic measurements in a network analysis approach to decipher the impact of multiple stressors on the health of juvenile Sander lucioperca along one of the largest European estuaries. We find mesohaline areas characterized by gill tissue specific transcriptional responses matching osmosensing and tissue remodeling. Liver transcriptomes instead emphasized that zander from highly turbid areas were undergoing starvation which was supported by compromised body condition. Potential pathogenic bacteria, including Shewanella, Acinetobacter, Aeromonas and Chryseobacterium, dominated the gill microbiome along the freshwater transition and oxygen minimum zone. Their occurrence coincided with a strong adaptive and innate transcriptional immune response in host gill and enhanced energy demand in liver tissue supporting their potential pathogenicity. Taken together, we show physiological responses of a fish species and its microbiome to abiotic factors whose impact is expected to increase with consequences of climate change. We further present a method for the close-meshed detection of the main stressors and bacterial species with disease potential in a highly productive ecosystem.

Proteasome subunit beta type-8 from sevenband grouper negatively regulates cytokine responses by interfering NF-κB signaling upon nervous necrosis viral infection

During viral infection, proper regulation of immune signaling is essential to ensure successful clearance of virus. Immunoproteasome is constitutively expressed and gets induced during viral infection by interferon signaling and contributes to regulate proinflammatory cytokine production and activation of the NF-κB pathway. In this study, we identified Hs-PSMB8, a member of the proteasome β-subunits (PSMB) family, as a negative regulator of NF-κB responses during NNV infection. The transient expression of Hs-PSMB8 delayed the appearance of cytopathic effect (CPE) and showed a higher viral load. The Hs-PSMB8 interacted with NNV which was confirmed using immunocolocalization and co-IP. Overexpression of Hs-PSMB8 diminished virus induced activation of the NF-κB promoters and downregulated the activation of IL-1β, TNFα, IL6, IL8, IFNγ expression upon NNV infection. Collectively, our results demonstrate that PSMB8 is an important regulator of NF-κB signaling during NNV infection in sevenband grouper.

Effects of the sulfated polysaccharide ulvan from Ulva ohnoi on the modulation of the immune response in Senegalese sole (Solea senegalensis)

Sulfated polysaccharides derived from green seaweeds exhibit many beneficial biological activities and have great potential to be used as nutraceutical in aquaculture. In this work, we evaluated the effects of the sulfated polysaccharide ulvan from Ulva ohnoi on Senegalese sole (Solea senegalensis) juveniles at the transcriptomic level. Cytotoxicity assay performed in liver primary cell cultures from sole determined that the different ulvan concentrations assayed did not impair cell viability. Juveniles were intraperitoneally (IP) injected with ulvan (0.5 mg/fish) followed by a challenge with Photobacterium damselae subsp. piscicida (Phdp) at 7 days. RNASeq analyses at 2 days post injection (dpi) revealed that 402 transcripts were differentially expressed in liver between ulvan IP injected and control groups before the challenge. Genes related to bacterial and antiviral defence, complement system, chemokines, proteasomes and antigen presentation were upregulated in ulvan treated groups. A detailed expression analysis of sixteen genes related to innate and adaptive immune system was performed in two systemic tissues: liver and spleen. Ulvan injection provoked the upregulation of tlr22 and a transient inflammatory response was initiated in both liver and spleen at 2 dpi. As consequence, expression of acute phase proteins, antimicrobial peptides and complement genes was induced. Moreover, expression of mhcI, mhcII, psmb10 and bcl6 was also induced 2 dpi. At 2 dpi with Phdp, inflammatory cytokines and genes related to bacterial and antiviral defense, iron metabolism, complement system and antigen presentation were differentially modulated in survival juveniles previously IP injected with ulvan. Moreover, mortality was retarded in ulvan treated juveniles. These results provide new evidence about the role of ulvan as a bioactive compound with immunomodulatory activity in Senegalese sole as well as its possible use as vaccine adjuvant against Phdp. This is the first published study that evaluates the transcriptomic response of Senegalese sole IP injected with ulvan.

Major Histocompatibility Complex (MHC) Genes and Disease Resistance in Fish

Fascinating about classical major histocompatibility complex (MHC) molecules is their polymorphism. The present study is a review and discussion of the fish MHC situation. The basic pattern of MHC variation in fish is similar to mammals, with MHC class I versus class II, and polymorphic classical versus nonpolymorphic nonclassical. However, in many or all teleost fishes, important differences with mammalian or human MHC were observed: (1) The allelic/haplotype diversification levels of classical MHC class I tend to be much higher than in mammals and involve structural positions within but also outside the peptide binding groove; (2) Teleost fish classical MHC class I and class II loci are not linked. The present article summarizes previous studies that performed quantitative trait loci (QTL) analysis for mapping differences in teleost fish disease resistance, and discusses them from MHC point of view. Overall, those QTL studies suggest the possible importance of genomic regions including classical MHC class II and nonclassical MHC class I genes, whereas similar observations were not made for the genomic regions with the highly diversified classical MHC class I alleles. It must be concluded that despite decades of knowing MHC polymorphism in jawed vertebrate species including fish, firm conclusions (as opposed to appealing hypotheses) on the reasons for MHC polymorphism cannot be made, and that the types of polymorphism observed in fish may not be explained by disease-resistance models alone.

Overgrazing induces alterations in the hepatic proteome of sheep (Ovis aries): an iTRAQ-based quantitative proteomic analysis

Background

The degradation of the steppe of Inner Mongolia, due to overgrazing, has resulted in ecosystem damage as well as extensive reductions in sheep production. The growth performance of sheep is greatly reduced because of overgrazing, which triggers massive economic losses every year. The liver is an essential organ that has very important roles in multiple functions, such as nutrient metabolism, immunity and others, which are closely related to animal growth. However, to our knowledge, no detailed studies have evaluated hepatic metabolism adaption in sheep due to overgrazing. The molecular mechanisms that underlie these effects remain unclear.

Methods

In the present study, our group applied isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic analysis to investigate changes in the protein profiles of sheep hepatic tissues when nutrition was reduced due to overgrazing (12.0 sheep/ha), with the goal of characterizing the molecular mechanisms of hepatic metabolism adaption in sheep in an overgrazing condition.

Results

The body weight daily gain of sheep was greatly decreased due to overgrazing. Overall, 41 proteins were found to be differentially abundant in the hepatic tissue between a light grazing group and an overgrazing group. Most of the differentially expressed proteins identified are involved in protein metabolism, transcriptional and translational regulation, and immune response. In particular, the altered abundance of kynureninase (KYNU) and HAL (histidine ammonia-lyase) involved in protein metabolic function, integrated with the changes of serum levels of blood urea nitrogen (BUN) and glucose (GLU), suggest that overgrazing triggers a shift in energy resources from carbohydrates to proteins, causing poorer nitrogen utilization efficiency. Altogether, these results suggest that the reductions in animal growth induced by overgrazing are associated with liver proteomic changes, especially the proteins involved in nitrogen compounds metabolism and immunity.

Conclusions

This provides new information that can be used for nutritional supplementation to improve the growth performance of sheep in an overgrazing condition.

Electronic supplementary material

The online version of this article (doi:10.1186/s12953-016-0111-z) contains supplementary material, which is available to authorized users.

Uncommon functional properties of the first piscine 26S proteasome from the Antarctic notothenioid Trematomus bernacchii

The antioxidant defense mechanisms have a great impact on the life of Antarctic organisms. The present study could represent the first evidence of a direct involvement of the 26S proteasome in the antioxidant defense systems of fish adapted to cold.

Protein homoeostasis is a fundamental process allowing the preservation of functional proteins and it has a great impact on the life of the Antarctic organisms. However, the effect of low temperatures on protein turnover is poorly understood and the cold-adaptation of the degradation machinery remains an unresolved issue. As the 26S proteasome represents the main proteolytic system devoted to the controlled degradation of intracellular proteins, the purpose of the present study was to investigate the functions of this complex in the notothenioid Trematomus bernacchii, in order to better understand its role in the physiology of Antarctic fish. To this aim, we purified and characterized the 26S proteasome from T. bernacchii and isolated the cDNAs codifying seven of the 14 subunits belonging to the proteasome 20S core particle. Results provided evidences of the high resistance of the piscine 26S proteasome to oxidative agents and of its ‘uncommon’ ability to efficiently hydrolyse oxidized bovine serum albumin (BSA), suggesting that this enzymatic complex could play a key role in the antioxidant defense systems in fish inhabiting permanently cold marine environments. These unique properties were also reflected by the 3D model analysis, which revealed a higher structural stability of the piscine complex respect to the murine template. Finally, a comparative analysis, performed in a variety of tissues collected from T. bernacchii and the temperate fish Dicentrarchus labrax, showed a lower protein retention in the cold-adapted fish, possibly due to a better efficiency of its degradation machinery.