Project description:Lepeophtheirus salmonis (sea lice) and bacterial co-infection threatens wild and farmed Atlantic salmon performance and welfare. The present microarray-based study examined the dorsal skin transcriptome response to formalin-killed Aeromonas salmonicida bacterin (ASAL) in pre-adult sea lice-infected and non-infected Atlantic salmon to fill the existing knowledge gap and aid in developing anti-co-infection strategies. To this aim, sea lice-infected and non-infected salmon were intraperitoneally injected with either phosphate-buffered saline (PBS) or ASAL (i.e., 4 injection/infection groups: PBS/no lice, PBS/lice, ASAL/no lice, and ASAL/lice). The analysis of the dorsal skin transcriptome data [Significance Analysis of Microarrays (5% FDR)] identified 345 up-regulated and 2,189 down-regulated DEPs in the comparison PBS/lice vs. PBS/no lice, and 82 up-regulated and 3 down-regulated DEPs in the comparison ASAL/lice vs. ASAL/no lice. The comparison ASAL/lice vs. PBS/lice identified 272 up-regulated and 11 down-regulated DEPs, whereas ASAL/no lice vs. PBS/no lice revealed 27 up-regulated DEPs. The skin transcriptome differences between the co-stimulated salmon (i.e., ASAL/lice) and PBS/no lice salmon accounted for 1,878 up-regulated and 3,120 down-regulated DEPs.
Project description:Proteins from Mortierella elongata/Candidatus Glomeribacter sp. symbiotic system were extracted, trypsine digested and identified with LC-MS/MS analysis.
Project description:This experiment constitutes an expression profiling approach to identify genes differentially regulated during the symbiotic interaction between the model legume Medicago truncatula and the nitrogen-fixing bacterium Sinorhizobium meliloti. Macro- and microarrays containing 6144 probes were generated on the basis of three cDNA libraries dedicated to the study of root symbiotic interactions. The experiment performed on wild-type and symbiotic mutant material led to the identification of genes either up- or down-regulated at different stages of the nodulation process.
Project description:The ability of Bradyrhizobium japonicum and B. elkanii strains to utilize alkane and aromatic sulfonates as sole sources of sulfur for growth was investigated. All of the strains tested were able to utilize alkane sulfonates, but not aromatic sulfonates for growth. Whole-genome transcriptional profiling was used to assess B. japonicum USDA 110 genes involved in growth on alkane sulfonates, as compared to growth on sulfate and cysteine. Two sets of genes, bll7007 to bll7011 and bll6449 to 6456 were highly expressed during growth with sulfate and sulfonates. These genes were predicted to encode alkanesulfonate monooxygenases and ABC transporter components. Reverse transcription-PCR (RT-PCR) analyses showed that these genes were organized in two operon-like structures and expressed as polycistronic messages. The sulfonate monooxygenase encoded by bll7010 (ssuD) complemented an E. coli mutant defective in utilization of sulfonates. The expression of many genes that were induced during growth on cysteine and taurine were under the control of the FixLJ-FixK2-FixK1 symbiotic nitrogen fixation cascade, indicating there is a novel linkage between sulfur metabolism and nitrogen fixation. Taken together, results of this study indicate that Bradyrhizobium sp. strains are metabolically diverse and likely use organosulfur compounds for growth and survival, and for legume nodulation and nitrogen fixation in soil systems.
Project description:Background: Salmonid species have followed markedly divergent evolutionary trajectories in their interactions with sea lice. While sea lice parasitism poses significant economic, environmental, and animal welfare challenges for Atlantic salmon (Salmo salar) aquaculture, coho salmon (Oncorhynchus kisutch) exhibit near-complete resistance to sea lice, achieved through a potent epithelial hyperplasia response leading to rapid louse detachment. The molecular mechanisms underlying these divergent responses to sea lice are unknown. Results: We characterised the cellular and molecular responses of Atlantic salmon and coho salmon to sea lice using single-nuclei RNA sequencing. Juvenile fish were exposed to copepodid sea lice (Lepeophtheirus salmonis), and lice-attached pelvic fin and skin samples were collected 12h, 24h, 36h, 48h, and 60h after exposure, along with control samples. Comparative analysis of control and treatment samples revealed an immune and wound-healing response that was common to both species, but attenuated in Atlantic salmon, potentially reflecting greater sea louse immunomodulation. Our results revealed unique but complementary roles of three layers of keratinocytes in the epithelial hyperplasia response leading to rapid sea lice rejection in coho salmon. Our results suggest that basal keratinocytes direct the expansion and mobility of intermediate and, especially, superficial keratinocytes, which eventually encapsulate the parasite. Conclusions: Our results highlight the key role of keratinocytes in coho salmon’s sea lice resistance, and the diverged biological response of the two salmonid host species when interacting with this parasite. This study has identified key pathways and candidate genes that could be manipulated using various biotechnological solutions to improve Atlantic salmon sea lice resistance.
Project description:The marine bacterium Vibrio fischeri requires flagellar motility to undergo symbiotic initiation with its host, the Hawaiian bobtail squid Euprymna scolopes. We sought to identify the genes activated by the sigma54-dependent flagellar master regulator, FlrA, in V. fischeri, thereby determining the flagellar regulon in this model symbiont.