Low incubation temperature during early development negatively affects survival and related innate immune processes in zebrafish larvae exposed to lipopolysaccharide

Low incubation temperature during early development negatively affects survival and related innate immune processes in zebrafish larvae exposed to lipopolysaccharide Overall design: Zebrafish embryos were collected from 28 °C, and divided into three temperature groups (24 °C, 28 °C, 32 °C) for incubation. At the first-feeding stage, larvae from each incubation temperature group were further split into three temperature groups in a full-factorial way for LPS challenge. In total, nine temperature groups (three incubation temperatures x three challenge temperatures) were generated. At 24 h post LPS challenge, mortality of larvae were recorded. Larvae originating from 24 °C incubation temperature group had higher mortality rate than larvae from the other two temperature groups. LPS-treated larvae from three temperature groups, incubation 24 °C x challenge 24 °C, incubation 24 °C x challenge 32 °C, and incubation 32 °C x challenge 24 °C, together with their respective control were chosen for transcriptomic analyses using mRNA sequencing. A total of 722 genes were determined differentially expressed (DEGs) by DESeq2 (adjusted p-value < 0.05) in LPS-challenged larvae compared to control, and 605 of them had a fold change greater than 1.5, including 294 DEGs (144 up-/150 down-regulated) in larvae incubated and challenged with LPS at 24 °C; 33 DEGs (20 up-/13 down-regulated) in larvae incubated at 32 °C and challenged at 24 °C; and 278 DEGs (190 up-/88 down-regulated) in larvae incubated at 24 °C and challenged at 32 °C. Larvae incubated and challenged with LPS at 24 °C had stimulated innate immune response compared to control, while they also showed down-regulated innate immune processes and genes. In larvae incubated at 32 °C and challenged at 24 °C, the innate immune processes were up-regulated in larvae exposed to LPS compared to control, and theses processes were even much stronger (with higher enrichment values) than larvae from incubation and challenge temperature of 24 °C. In larvae incubated at 24 °C and challenged with LPS at 32 °C, limited innate immune response were up-regulated, and additional hypoxia and oxidative processes were observed. Genes annexin A2a, S100 calcium binding protein A10b, and lymphocyte antigen-6, epidermis were identified as promising candidates for LPS recognition and signal transduction.

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Zhang Q, Kopp M, Babiak I, Fernandes JMO