Pristionchus属线虫在实验室环境下通常以E. coil OP50作为食物，在这种情况下其外分泌液中能够检测到SASC、DASC、NPAR、PASC和UBAS五大类信息素。然而，真实生态环境中线虫是以混合的菌群作为食物来源，在如此复杂环境下线虫如何调控信息素的代谢和分泌过程一直不清楚。本论文通过用不同的细菌食物刺激Pristionchus属线虫后，首次开创性地发现在某些微生物环境下，线虫可以根据它们的微生物环境而选择地分泌特定种类的信息素，我们将这种首次发现的生物学现象命名为PHON。本课题发现了许多令人惊讶的结果：（1）天然野生菌株多为有益菌株，能够使Pristionchus属线虫分泌的信息素含量产生差异。（2）当线虫暴露于混合致病菌株时，会选择性地分泌特定类别的信息素，且在整个线虫包括C. elegans中都是保守存在的。线虫可能通过不同信息素种类的组合向其他线虫传递营养条件或是毒力因子程度的信息。（3）在线虫信息素稳态分泌表型（PHON）筛查中，一类未知信息素能够被选择性地分泌，经二级质谱裂解和核磁共振确定为人字形结构的三聚体信息素。（4）Ppa-UAR-1蛋白的同源物UAR-3参与调控三聚体信息素tasc#1的生物合成。这些重要发现颠覆了过去20年所累积的对线虫信息素的理解，开创出一个全新的线虫生物学研究领域。

Pristionchus nematodes usually feed on E. coil OP50 in the standard laboratory, in which case five classes of pheromones including SASC, DASC, NPAR, PASC and UBAS can be detected from their exometabolomes. However, in natural environments, nematodes use a mixed bacterial milieu as their food sources. How nematodes regulate pheromone metabolism and control their excretion in such a complex environment is completely unknown to us. By stimulating Pristionchus nematodes with different bacterial diets, we discovered that worms were able to selectively excrete their pheromones according to the specific microbial surroundings, such a novel phenotype was termed as PHON. In total, we found a number of surprising results: (1) Natural wild bacterial strains were mostly beneficial food sources for worms, which resulted in only quantitative but qualitative difference of nematodes produced pheromones. (2) When exposed to a mixture of pathogenic strains, nematodes selectively secreted some specific class(es) of pheromones, which was widely conserved throughout the nematode phylum including C. elegans. Nematodes might messenger nutritional conditions or toxicities to other nematodes through different combinations of pheromones. (3) While investigating the mechanisms of PHON, a class of unknown pheromones could be selectively secreted, they were finally characterized as trimeric ascarosides through using a combination of LC-MS/MS and NMR techniques. (4) UAR-3, a homologue protein of Ppa-UAR-1, is involved in regulating the biosynthesis of the trimeric pheromone tasc#1. These studies completely changed or even subverted our understanding on nematode pheromones, and will undoubtedly create many lines of research in the near future, which will also definitely lead to a new direction of pheromone research.