Fig 1.
PTE reduced fat storage and lipid droplet size.
(a) Fat storage indicated by Nile Red staining of fixed late L4 N2 worms treated with different concentrations of PTE. The anterior is in left and the posterior is in the right (Representative sample of around 50 worms totally observed in three biological replicates for each PTE treatment). Scale bar is 50 μm. (b) Relative TAG (triacylglycerol) content in total lipids (triacylglycerol+phospholipids, % TAG/TL) determined by TLC/GC. TAG content was significantly decreased at 0.05 g/ml concentration of PTE (**: P<0.01, *: P<0.05). Data were the mean ± SEM of four independent biological replicates. (c) Quantitation of the lipid droplet size. Lipid droplet size was correspondingly decreased with the increased concentrations of PTE (**: P<0.01, ***: P<0.001). Data were the mean ± SEM of 10 worms. (d) Distribution of lipid droplets. PTE gradually increased the percentage of small size lipid droplets (0–1 um in diameter), but decreased the percentage of large size lipid droplets (>1um in diameter). Data were the mean ± SEM of 10 worms.
Fig 2.
PTE modified the level of fatty acid compositions.
PTE significantly decreased the levels of oleic acid (C18:1n-9) and linolenic acid (C18:2), but increased the level of stearic acid (C18:0) (a), decreased the ratio of C18:1n-9/C18:0 (b), changed the levels of oleic acid (C18:1n-9) (c) as well as the ratio of C18:1n-9/C18:0 only in triglycerides (d). Data were presented as mean ± SEM of four independent biological replicates. (*: P<0.05, **: P<0.01, ***: P<0.001).
Fig 3.
PTE down-regulated the expression of SBP-1 and SCD.
(a) PTE did not affect the expression of FAT-6::GFP (around 60 worms totally observed in three biological replicates), but gradually decreased the fluorescent intensity of FAT-7::GFP and SBP-1::GFP (> 80% worms showed consistent reduction of expression, around 60 worms totally observed in three biological replicates). Scale bar is 20 μm. (b) Relative expression levels of sbp-1, fat-5, fat-6, and fat-7 measured by QPCR were significantly decreased with the increased concentrations of PTE. Data were the mean ± SEM of three independent biological replicates. (*: P<0.05, **: P<0.01, ***: P<0.001). (c) Relative expression levels of pod-2 and fasn-1 measured by QPCR. Data were the mean ± SEM of three independent biological replicates. (d) Fat storage indicated by Nile Red staining of fixation was gradually decreased in N2 worms, but not in sbp-1 and fat-6;fat-7 worms with the increased concentrations of PTE. The anterior is in left and the posterior is in the right. Scale bar is 10 μm. (e) Lipid droplet size was significantly decreased in N2 worms, but not in sbp-1 and fat-6;fat-7 worms, with the increased concentrations of PTE. Data were the mean ± SEM of 6 worms. (**: P<0.01, ***: P<0.001). (f) % of TAG/TL of fat-6;fat-7 and sbp-1 mutants treated with PTE. Data were the mean ± SEM of four independent biological replicates. (g) PTE significantly decreased the fat content of KQ377 worms. Data were the mean ± SEM of four independent biological replicates.
Fig 4.
(a) The pumping rate of pharynx was gradually decreased with the increased concentrations of PTE. Data were the mean ± SEM of 12 worms. (*: P<0.05, **: P<0.01). (b) PTE inhibited the uptake of E. coli food indicated by GFP intensity (∼80% worms showed consistent reduction of expression, around 50 worms totally observed in three biological replicates). Anterior is in left, posterior is in right. Scale bar is 50 um.
Fig 5.
PTE affected growth, brood size, and lifespan.
(a) Mean of daily laid progeny (n = 20 worms for each treatment). (b) Mean of progeny (n = 20 worms for each treatment). (c) Growth rate, n = 442, 560, 496, and 620 worms for 0 g/ml, 0.0125 g/ml, 0.025 g/ml,0.05 g/ml, respectively. (d) Lifespan, n = 189, 287, 303, and 266 worms for 0 g/ml, 0.0125 g/ml, 0.025 g/ml,0.05 g/ml, respectively.
Fig 6.
A model of Pu-erh tea reducing fat storage.
Pu-erh tea down-regulates the pumping rate, food uptake, as well as the expression of SBP-1 and SCD that reduces the conversion of stearic acid (C18:0) to oleic acid (C18:n-9), eventually reduces the fat accumulation in C. elegans. Green arrow indicated reduction. Dashed arrow indicated unclear relationship.