Transcriptome Response Of Charybdis Japonica Exposed To Temperature And Salinity Stresses

Global warming has become the current research hotspot and it is thought to cause a direct influence on the temperature of the marine ecosystem.Additionally,global warming also has an indirect effect for the ocean salinity and further widespread effects on the survival of species.It is still worth noting that the physiological activity of crabs are generally considered more sensitive to ocean temperature and salinity change because they lack certain efficient regulators.The RNA sequencing(RNA-seq)technique can be used to analyze the differentially expressed genes and the molecular basis of organisms under environmental stress.As a eurythermy and euryhaline species,Charybdis japonica was provided a research source for this study.We determine the transcriptome changes of C.japonica exposed to acute temperature and salinity change.These results can provide basic data to further evaluate how climate change has contributed to C.japonica.Gills samples were extracted from exposed to 12?,20? and 28?,and all samples were then applied to the transcriptome sequencing.After filtering,a total of 69.22 Gb clean reads were obtained from all samples.We used the Trinity package on the de novo assembled remaining clean reads and 90,973 transcripts were produced,with an N50 of 2,450 bp and a mean length of 1,440.24 bp.The redundancy sequences were removed and 52,972 Unigenes were obtained,with an N50 of 1,775 bp and a mean length of 1,080.23 bp.Of all annotated Unigenes,8,503,10,436,13,494,15,676,11,742,17,795 and 18,466 Unigenes had significant matches with sequences in the GO,KEGG,KOG,Pfam,Swissprot,eggnog and NR databases,respectively.Additionally,we obtained 12,125 CDS and 12,854 SSRs.Compared with control group,401 and 33 up-expressed Unigenes were obtained in the high and low-temperature group,respectively,147 and 57 down-expressed Unigenes were obtained in the high and low-temperature group,respectively.Compared with the low-temperature group,527 up-and 196 down-expressed Unigenes were obtained in the high-temperature group,respectively.Furthermore,we conducted a GO term and KEGG pathway enrichment analysis for differently expressed Unigenes.Results showed that the gene function of differently expressed Unigenes was associated with the cell,cell part,membrane,membrane part,binding,catalytic activity,metabolic process,and cellular process.Compared with control group,up-expressed Unigenes of the high-temperature group were significantly enriched in the protein processing in the endoplasmic reticulum pathway,down-expressed Unigenes of low-temperature group were significantly enriched in the insect hormone biosynthesis pathway.Compared with low-temperature group,up-expressed Unigenes of high-temperature group were significantly enriched in the ribosome and protein processing in endoplasmic reticulum pathways.This is the case because heat shock proteins were expressed when C.japonica exposed to high temperature.Heat shock proteins can prevent the aggregation and misfolded proteins,thereby reducing the damage of C.japonica.The biological process of C.japonica was always disordered due to low temperature and therefore hormone regulation was activated.Gills samples were extracted from exposed to 15‰,25‰ and 35‰,and all samples were then applied to the transcriptome sequencing.After filtering,a total of 68.90 Gb clean reads were obtained from all samples.We used the Trinity package on the de novo assembled remaining clean reads and 73,169 transcripts were produced,with an N50 of 2,502 bp and a mean length of 1,504.58 bp.The redundancy sequences were removed and 41,058 Unigenes were obtained,with an N50 of 2,033 bp and a mean length of 1,179.39 bp.Of all annotated Unigenes,6,992,7,834,8,453,11,626,13,907,9,901,16,189 and 16,262 Unigenes had significant matches with sequences in the GO,KEGG,KOG,Pfam,Swissprot,eggnog and NR databases,respectively.Additionally,we obtained 26,853 CDS and 12,190 SSRs.Compared with control group,73 and 2,362 up-expressed Unigenes were obtained in the high and low salinity group,respectively,131 and 3,030 down-expressed Unigenes were obtained in the high and low salinity group,respectively.Compared with low salinity group,1,681 up-and 1,566 down-expressed Unigenes were obtained in the high salinity group,respectively.Furthermore,we conducted a GO term and KEGG pathway enrichment analysis for differently expressed Unigenes.Results showed that the gene function of differently expressed Unigenes was associated with cell part,membrane,catalytic activity,and metabolic process.Compared with control group,up-expressed Unigenes of high salinity group were significantly enriched in the biosynthesis of amino acids pathways,up-expressed Unigenes of low salinity group were significantly enriched in the pathways associated with genetic information.Additionally,down-expressed Unigenes of low salinity group were significantly enriched in the Hippo signaling pathway,Notch signaling pathway,and apoptosis pathways.However,compared with the low salinity group,these pathways were significantly up-regulated in the high salinity group.This is the case because crustaceans living in the fluctuation of salinity usually adapt to the fluctuation of salinity by non-isosmotic extracellular regulation and isosmotic intracellular regulation.Additionally,low salinity may affect the cell proliferation,growth and reproductive behaviors of C.japonica.