Project description:Recently, amphioxus has served as a model for studying the origin and evolution of vertebrate immunity. However, little is known about how microRNAs (miRNAs) are involved in the immune defense in amphioxus. In this article, we identified the amphioxus miRNAs in the acute-phase response to Lipopolysaccharide (LPS). First, we determined the time point for the peak of immune response in amphioxus after LPS challenge by evaluating the expression of TLR4 and NF-κb(v-rel) which were commonly used immune response indicators. Then we performed miRNA microarray analysis on gill samples collected at the time point to select the differentially expressed miRNAs. Finally, we used real-time quantitative PCR to detect the expression patterns of amphioxus miRNAs under effective LPS challenge during the time course. The microarray data revealed that the miRNA expression file was significantly changed after LPS stimulation. The changes of the most upregulated and most downregualted miRNAs in gills of the amphioxus following challenge with LPS revealed a temporal induction kinetic. Our current study will provide valuable information to take an insight into molecular mechanism of innate immune and the evolution of the miRNA family.