Transcriptomic analysis of brine shrimp Artemia franciscana across a wide range of salinities.

Brine shrimp Artemia franciscana, a commercially important species, can thrive in a wide range of salinities and is commonly found in hypersaline lakes and solar salterns. Transcriptome analysis can enhance the understanding of the adaptative mechanisms of brine shrimp in aquaculture. RNA sequencing (RNAseq) data was generated from A. franciscana adults that were salt-adapted for 2-4 weeks at five salinities: 35, 50, 100, 150, and 230 psu. Long-read isoform sequencing (IsoSeq) data was used to construct a high-quality transcriptome assembly. Also, the gene expression patterns in A. franciscana adults were examined. Notably, the transcriptional response of A. franciscana's acclimation to intermediate salinities (50-150 psu) displayed frequently and differentially U-shaped or inverted U-shaped expression patterns. In addition, the types of genes showing two nonmonotonic expression patterns were distinct from each other. The coordinated shifts in gene expression suggest different homeostatic strategies of A. franciscana at specific salinities; such strategies may enhance population fitness at extreme salinities. Our study should promote a scientific concept for the gene expression patterns of A. franciscana along a broad salinity gradient, and a variety of salinity and prey should be monitored for testing the gene expression pattern of this important aquaculture species.