Transcriptome profiles of the hepatopancreas of the Chinese swamp shrimp (Neocaridina denticulata) under different diurnal rhythms

Diurnal rhythm affects many physiological functions in crustaceans.To study its effects on physiological functions in Neocaridina denticulata, a small shrimp with high ornamental value, we analyzed its hepatopancreatic transcriptome under the daily rhythm using high-throughput sequencing.Hepatopancreas were collected from the shrimps at four time points (06:00, 12:00, 18:00, and 24:00) within a 24-h period.Interestingly, numerous circadianrelated unigenes were annotated, including Per, Tim, Clk, Cyc, Cry, and 5-HT.We used the whole genes identified at each time point as a group and performed pairwise comparative analysis to screen for differentially expressed genes under the daily rhythm.The largest number of differentially expressed genes (DEGs) (983) was identified between 12:00 and 18:00.The Gene Ontology functional enrichment analysis of DEGs indicated that the sugar and chitin metabolism processes in N. denticulata were impacted by its daily rhythm; the Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that the DEGs were mainly enriched in the 'phototransduction-fly' and 'thermogenesis' pathways.To the best of our knowledge, this is the first comparative transcriptome analysis of the hepatopancreas of N. denticulata under daily rhythms; our findings will provide molecular genetic evidence for the study of diurnal rhythms in shrimps.Thus, our study will be useful for future neurophysiology studies using environmental stimuli or overcoming environmental stress.