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- Toll-like receptor evolution: does temperature matter?Publication . Sousa, Carmen; Fernandes, Stefan A.; Cardoso, João; Wang, Ying; Zhai, Wanying; Guerreiro, Pedro; Chen, Liangbiao; Canario, A.V.M.; Power, DeborahToll-like receptors (TLRs) recognize conserved pathogen-associated molecular patterns (PAMPs) and are an ancient and well-conserved group of pattern recognition receptors (PRRs). The isolation of the Antarctic continent and its unique teleost fish and microbiota prompted the present investigation into Tlr evolution. Gene homologues of tlr members in teleosts from temperate regions were present in the genome of Antarctic Nototheniidae and the non-Antarctic sister lineage Bovichtidae. Overall, in Nototheniidae apart from D. mawsoni, no major tlr gene family expansion or contraction occurred. Instead, lineage and species-specific changes in the ectodomain and LRR of Tlrs occurred, particularly in the Tlr11 superfamily that is well represented in fish. Positive selective pressure and associated sequence modifications in the TLR ectodomain and within the leucine-rich repeats (LRR), important for pathogen recognition, occurred in Tlr5, Tlr8, Tlr13, Tlr21, Tlr22, and Tlr23 presumably associated with the unique Antarctic microbiota. Exposure to lipopolysaccharide (Escherichia coli O111:B4) Gram negative bacteria did not modify tlr gene expression in N. rossii head-kidney or anterior intestine, although increased water temperature (+4 degrees C) had a significant effect.
- Transcriptomic down-regulation of immune system components in barrier and hematopoietic tissues after lipopolysaccharide injection in antarctic notothenia coriicepsPublication . Sousa, Carmen; Power, Deborah; Guerreiro, Pedro M; Louro, Bruno; Chen, Liangbiao; Canario, AdelinoThe environmental conditions and isolation in the Antarctic have driven the evolution of a unique biodiversity at a macro to microorganism scale. Here, we investigated the possible adaptation of the teleost Notothenia coriiceps immune system to the cold environment and unique microbial community of the Southern Ocean. The fish immune system was stimulated through an intraperitoneal injection of lipopolysaccharide (LPS 0111:B4 from E. coli) and the tissue transcriptomic response and plasma biochemistry were analyzed 7 days later and compared to a sham injected control. Gene transcription in the head-kidney, intestine and skin was significantly modified by LPS, although tissues showed different responsiveness, with the duodenum most modified and the skin the least modified. The most modified processes in head-kidney, duodenum and skin were related to cell metabolism (up-regulated) and the immune system (comprising 30% of differentially expressed genes). The immune processes identified were mostly down-regulated, particularly interleukins and pattern recognition receptors (PRRs), nucleotide-binding oligomerization domain-like receptors and mannose receptors, unlike the toll-like receptors response commonly described in other teleost fish. The modified transcriptional response was not mirrored by a modified systemic response, as the circulating levels of enzymes of innate immunity, lysozyme and antiproteases, were not significantly different from the untreated and sham control fish. In conclusion, while the N. coriiceps immune system shares many features with other teleosts there are also some specificities. Further studies should better characterize the PRRs and their role in Antarctic teleosts, as well as the importance of the LPS source and its consequences for immune activation in teleosts.