Transcriptomic Profiling of the Adaptive and Innate Immune Responses of Atlantic Salmon to Renibacterium salmoninarum Infection

Indexación: Scopus.Bacterial Kidney Disease (BKD), which is caused by a Gram-positive, intracellular bacterial pathogen (Renibacterium salmoninarum), affects salmonids including Atlantic salmon (Salmo salar). However, the transcriptome response of Atlantic salmon to BKD remained unknown before the current study. We used a 44K salmonid microarray platform to characterise the global gene expression response of Atlantic salmon to BKD. Fish (~54 g) were injected with a dose of R. salmoninarum (H-2 strain, 2 × 108 CFU per fish) or sterile medium (control), and then head kidney samples were collected at 13 days post-infection/injection (dpi). Firstly, infection levels of individuals were determined through quantifying the R. salmoninarum level by RNA-based TaqMan qPCR assays. Thereafter, based on the qPCR results for infection level, fish (n = 5) that showed no (control), higher (H-BKD), or lower (L-BKD) infection level at 13 dpi were subjected to microarray analyses. We identified 6,766 and 7,729 differentially expressed probes in the H-BKD and L-BKD groups, respectively. There were 357 probes responsive to the infection level (H-BKD vs. L-BKD). Several adaptive and innate immune processes were dysregulated in R. salmoninarum-infected Atlantic salmon. Adaptive immune pathways associated with lymphocyte differentiation and activation (e.g., lymphocyte chemotaxis, T-cell activation, and immunoglobulin secretion), as well as antigen-presenting cell functions, were shown to be differentially regulated in response to BKD. The infection level-responsive transcripts were related to several mechanisms such as the JAK-STAT signalling pathway, B-cell differentiation and interleukin-1 responses. Sixty-five microarray-identified transcripts were subjected to qPCR validation, and they showed the same fold-change direction as microarray results. The qPCR-validated transcripts studied herein play putative roles in various immune processes including pathogen recognition (e.g., tlr5), antibacterial activity (e.g., hamp and camp), regulation of immune responses (e.g., tnfrsf11b and socs1), T-/B-cell differentiation (e.g., ccl4, irf1 and ccr5), T-cell functions (e.g., rnf144a, il13ra1b and tnfrsf6b), and antigen-presenting cell functions (e.g., fcgr1). The present study revealed diverse immune mechanisms dysregulated by R. salmoninarum in Atlantic salmon, and enhanced the current understanding of Atlantic salmon response to BKD. The identified biomarker genes can be used for future studies on improving the resistance of Atlantic salmon to BKD. © Copyright © 2020 Eslamloo, Caballero-Solares, Inkpen, Emam, Kumar, Bouniot, Avendaño-Herrera, Jakob and Rise.https://www.frontiersin.org/articles/10.3389/fimmu.2020.567838/ful

Structural and mechanical properties of TiB 2 and TiC prepared by self-propagating high-temperature synthesis/dynamic compaction

Titanium-diboride and titanium-carbide compacts with diameters of 100 mm and thicknesses of 25 mm were fabricated by self-propagating high-temperature synthesis/dynamic compaction (SHS/DC) of the elemental powders. Under the best conditions, the densities were greater than 99% and 96.8% of the theoretical densities for TiB 2 and TiC, respectively. The microhardness, compressive strength, and elastic modulus of the TiB 2 prepared by the SHS/DC method were comparable to reported values for hot-pressed TiB 2 . While the microhardness and elastic modulus of the TiC compacts were comparable to those for hotpressed TiC, the compressive strength was lower due to extensive cracks in the compacts. The TiB 2 prepared using a low-purity boron powder (1–5% carbon impurity) compacted to higher densities and had less cracking than that prepared using a high-purity boron powder (0.2% carbon). This result could have an impact on the cost of producing TiB 2 /TiC structural components by the SHS/DC process.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44732/1/10853_2005_Article_BF01162518.pd

Effects of dietary administration of Bacillus probiotics on the non-specific immune responses of tinfoil barb, Barbonymus schwanenfeldii (Actinopterygii: Cypriniformes: Cyprinidae)

Background. Probiotics are known as immunostimulants as well as growth and survival promoters in fish, but despite the plethora of studies on the effect of probiotics on the fish non-specific immune responses, very few information is available for ornemental fish. Thus, this study was carried out to investigate the effects of short-term dietary administration of Bacillus probiotics (B. subtilis and B. licheniformis) on the immune responses of tinfoil barb, Barbonymus schwanenfeldii (Bleeker, 1854). Materials and methods. Three experimental diets were prepared by supplementing the diets with different concentrations of probiotics including 0 (Control), 1 × 104 (T1) and 1 × 13306 (T2) CFU · g–1 diet. Tinfoil barb weighing 16.20 ± 0.13 g were fed with the different diets for 15 days. At the end of the experiment, blood samples were collected in order to estimate the hematological (total protein, albumin, and globulin) and immune (total antiprotease, plasma peroxidase, and bactericidal activities ) parameters. Results. The plasma total protein, albumin, and globulin of fish were not affected by dietary probiotics. A six-fold increase in the plasma total antiprotease activity of fish fed 1 × 106 CFU · g–1 diet was observed. Moreover, the plasma peroxidase and bactericidal activities of fish significantly increased in T2 treatment compared to control. On the other hand, plasma natural haemolytic complement and lysozyme activities did not significantly vary between diets although the highest level of these parameters was observed in the probiotic treatments. Conclusion. This study showed the ability of dietary probiotics to enhance some innate immune responses of tinfoil barb especially after a 2-week administration of 1 × 106 CFU · g–1 diet (T2). Further study should focus on the effect of this dietary bacterial concentration on the fish response to bacterial and parasitical challenges in order to test its potential protective effect against the common pathogens of tinfoil barb