Project description:Background: Pantoea ananatis LMG 2665T synthesizes and utilizes acyl homoserine lactones (AHLs) for signaling. In this strain, short chain AHLs (C4 to C8) are produced by the EanI/R quorum sensing (QS) system that is involved in pathogenicity and biofilm formation. The complete set of genes regulated by the EanI/R system in P. ananatis LMG 2665T is still not fully known. In the present study, RNA-seq was used to analyze the transcriptome profiles controlled by the EanI/R system in this strain by comparing the wild type strain and its QS mutant 2665T ean∆I/R during lag and log stages. The RNA seq data was validated by RT qPCR. Results: The results showed that the EanI/R regulon in P. ananatis LMG 2665T comprised 144 genes, constituting 3.3% of the whole transcriptome under the experimental conditions in this study. The majority of genes regulated by the EanI/R system included genes for flagella assembly, bacterial chemotaxis, pyruvate metabolism, two component system, metabolic pathways, microbial metabolism and biosynthesis of secondary metabolites. Conclusions: This is the first study to identify the EanI/R QS regulon in P. ananatis LMG 2665T. Functional analysis of genes regulated the EanI/R system in LMG 2665T could help unveil genes that play a vital role in pathogenesis and survival strategies of this pathogen.
Project description:Photoperiod is a key environmental factor regulating circadian rhythm and physiology in aquatic organisms, but its effects on the immune function of the sea urchin Strongylocentrotus intermedius (S. intermedius) remain unclear. This study investigated photoperiodic regulation of immune resistance, transcriptomes, and circadian rhythm in S. intermedius, and the role of circadian clock gene Cryptochrome1 (Cry1) in immunity. The sea urchins were acclimated to four photoperiods (LL, DD, LD, DL) for one month, followed by Pseudoalteromonas sp. challenge. Bacterial load and gene expression were detected by qRT-PCR; transcriptomic analysis identified DEGs between LD-ZT0 and LD-ZT12, and Cry1 was knocked down via dsRNA for verification. LD photoperiod significantly enhanced antibacterial resistance, with the lowest bacterial load and highest expression of immune genes (SOD, CAT, TNFSF14, C3, ACP, NLRP3) at 12/24 hpi. Transcriptome analysis identified 1450 DEGs enriched in immune (innate immunity, NLRP3 inflammasome assembly) and circadian pathways. LD maintained robust 24-hour rhythms of circadian (Cry1, Cycle, Clock, Rev-erbα) and immune genes, while DL induced phase inversion and LL/DD abolished rhythms. Cry1 knockdown reduced bacterial load and upregulated NLRP3, C3, IL-17D, and TNFSF14. Collectively, LD is optimal for S. intermedius circadian rhythm and immune homeostasis, and Cry1 negatively regulates its immune response. This study provides insights into photoperiodic regulation of echinoderm immunity and support for S. intermedius aquaculture. Collectively, these findings indicate that LD photoperiod is optimal for maintaining circadian rhythm and immune homeostasis of S. intermedius, and Cry1 plays a negative regulatory role in its immune response. This study provides novel insights into the molecular mechanisms of photoperiod regulating immune function in echinoderms and theoretical support for aquaculture management of S. intermedius.