There are a large number of valuable substances in diatoms, such as neutral lipid and pigments. However, due to the lack of clear metabolic pathways, their applications are still limited. Recently, chemical modulators are found to be powerful tools to investigate the metabolic pathways of neutral lipids. Thus, in this study, to identify new neutral lipid accumulation effectors, we screened the natural products that we separated before in the model diatom Phaeodactylum tricornutum (P. tricornutum) by using Nile-red staining method. Two compounds, penicillide and verrucarin J which were isolated from two marine fungal strains, were identified to promote neutral lipid accumulation. However, penicillide and verrucarin J were also found to significantly inhibit the growth of P. tricornutum through specifically inhibiting the photosynthesis of P. tricornutum. Quantitative analysis results showed that penicillide and verrucarin J significantly increased total lipid and triacylglycerol (TAG) contents, which are consistent with previous Nile-red staining results. The expression of key genes such as DGAT2D, GPAT2, LPAT2, and PAP involved in TAG synthesis and unsaturated fatty acids also increased after penicillide and verrucarin J treatments. Besides, many TAG-rich plastoglobuli formed in plastids shown by increased lipid droplets in the cytosol. Finally, penicillide and verrucarin J were found to reduce the expression of synthetic genes of fucoxanthin, and consequently reduced the content of fucoxanthin, indicating that there might be crosstalk between lipid metabolism and fucoxanthin metabolism. Thus, our work exhibits two useful compounds that could be used to further study the metabolic pathways of neutral lipid and fucoxanthin, which will fulfill the promise of diatoms as low cost, high value, sustainable feedstock for high-value products such as neutral lipid and pigments.

中文翻译：

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从化学遗传学筛选中鉴定了两种海洋天然产物青霉素和verrucarin J，用于检定三角果中的中性脂质积累效应子。

硅藻中有大量有价值的物质，例如中性脂质和色素。但是，由于缺乏清晰的代谢途径，其应用仍然受到限制。最近，发现化学调节剂是研究中性脂质代谢途径的有力工具。因此，在这项研究中，为了鉴定新的中性脂质蓄积效应物，我们使用尼罗红染色方法筛选了我们先前在模型硅藻三角藻（P. tricornutum）中分离出的天然产物。从两个海洋真菌菌株中分离出两种化合物，青霉素和维鲁卡林J，可以促进中性脂质的积累。然而，还发现青霉素和维鲁卡林J通过特异性抑制P.的光合作用，显着抑制Tricornutum的生长。三角龙 定量分析结果表明，青霉素和Verrucarin J显着增加了总脂质和三酰基甘油（TAG）的含量，这与以前的尼罗红染色结果一致。青霉素和verrucarin J处理后，参与TAG合成和不饱和脂肪酸的关键基因如DGAT2D，GPAT2，LPAT2和PAP的表达也增加。此外，在质体中形成了许多富含TAG的质体球，表现为胞浆中脂质滴的增加。最后，发现青霉素和verrucarin J降低了岩藻黄质合成基因的表达，从而降低了岩藻黄质的含量，表明脂质代谢和岩藻黄质代谢之间可能存在串扰。从而，