Effects Of Chlorella Vulgaris And Haematococcus Pluvialis On Growth,physiological Biochemistry And Transcriptomic Analysis Of Juvenile Epinephelus Lanceolatus♂×epinephelus Fuscoguttatus♀

Algae is a natural feed additive which plays an important role in improving the immune activity and antioxidant activity of fish.Chlorella Vulgaris belongs to the Chlorella genus of Chlorophyta,which has the functions of antioxidant,immune-enhancing and antiviral infection.Haematococcus pluvialis,a genus of Chlorophyta,has the highest astaxanthin content in nature.H.pluvialis is currently recognized as the best biological source of astaxanthin at present.The present study was performed to evaluate the effect of dietary incorporation of C.Vulgaris and H.pluvialis on the growth and immune status of E.lanceolatus ♂ × E.fuscoguttatus♀.720 fish were randomly divided into 3 groups:（a）a control group fed on a basal diet only（DZ group）,（b）a second group fed on a diet containing C.Vulgaris 10%,（Chl group）and（c）a third group fed on a diet containing H.pluvialis 10%（Hap group）.At15 days and 60 days of rearing,the growth,antioxidant enzymes,histopathological changes and the transcriptome of mesonephros were determined.The results are as follows:1.Dietary supplemented with 10% C.Vulgaris can increase the activities of SOD,GSH-PX and CAT of juvenile E.lanceolatus♂×E.fuscoguttatus♀.The activities of SOD,GSH-PX and AKP were increased and the activities of CAT were decreased by adding 10%H.pluvialis.The two algae had no significant effect on weight gain rate,specific growth rate,hepatosomatic index and spleensomatic index of grouper.2.Through the transcriptome sequencing of the middle kidney of E.lanceolatus♂×E.fuscoguttatus♀,a total of 115.01 Gb Clean Reads were obtained.The total number of bases in each sample ranged from 5.88 to 7.54 G,and the GC content ranged from 43.29% to48.62%.A total of 95.78% of the reads showed a quality score of Q20,and 90.42% showed a quality score of Q30.the clean merged using Trinity revealed a total of 103,230 Unigenes,with a total length of 119,515,719 bp and an average length of 1,157.76 bp.3.At 15 days,there were 4,086 DEGs between the DZ group and Chl group,which1663 genes were upregulated and 2423 genes were downregulated.At 60 days,there were2911 DEGs DZ group and Chl group,which 1625 genes were upregulated and 1286 genes were downregulated.There were 259 common DEGs between the two groups both at 15 days and 60 days.Through KEGG enrichment analysis,it was found that C.Vulgaris regulated lipid metabolism by up-regulating CPT1,PGAR and other genes at day 15,and improve body immunity by down-regulating immune gene IL-1β at day 60.4.At 15 days,there were 3641 DEGs between the DZ group and Hap group,which1356 genes were upregulated and 2285 genes were downregulated.At 60 days,there were11383 DEGs between the DZ group and Hap group,which 5597 genes were upregulated and 5786 genes were downregulated.There were 1,239 common DEGs between the two groups both at 15 days and 60 days.KEGG enrichment analysis showed that the H.pluvialis regulated the B cell immunity by up-regulating CD22 at 15 d.At 60 days,H.pluvialis inhibited the synthesis of proinflammatory factors by down regulating the expression of immune genes TLR2 and TLR5,so as to improve the body’s immunity.