Fig. 6

Injection of L. plantarum induces a shift from lipid storage to phospholipid synthesis and decreases total cholesterols. A Heatmap showing that most of the metabolites involved in phospholipid synthesis were increased. Hemolymph samples were collected from sixth-instar larvae at 24 h post-L. plantarum (LP) or -PBS injection. Variable importance in projection (VIP) scores for a metabolite represent the contribution of that metabolite to the difference between the two groups. The larger the score, the greater the difference between the two groups. B LDs were detected in the fat bodies of sixth-instar larvae at 24 h post-L. plantarum or -PBS injection. Nile red staining was used for detection. Scale bar = 20 μm. C LD diameter and fluorescence intensity were significantly lower in fat bodies of L. plantarum-injected larvae than that of PBS-injected controls. D The levels of TAGs and total cholesterols were significantly lower in L. plantarum-injected samples than that of controls. E Expression profiles of genes encoding enzymes involved in the synthesis of cholesterol esters, lipids, or phospholipids. Fat bodies were collected from L. plantarum-injected or PBS-injected larvae. ACAT, Acyl-CoA cholesterol acyltransferase (XM_021333888); PAP, PA phosphatase (XM_021327456); DGAT, Acyl-CoA diacylglycerol acyltransferase (XM_021328346); CDS, CDP-DG synthase (XM_049847014); PGSA, PG-P synthase (XM_021335307); PSS, PS synthase (XM_049835809). F Pathways for the synthesis of cholesterol esters, lipids, and phospholipids. LD, lipid droplet; PA, phosphatidic acid; DAG, diacylglycerol; TAG, triacylglycerol; CDP-DG, cytidine diphosphate-diacylglycerol; PG-P, phosphatidyl-glycerophosphate; PS, phosphatidylserine. Statistical differences were analyzed using Student’s t test (*p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001)