Some essential amino acids modulate lifespan; the effect of non-essential amino acids, such as tyrosine (Tyr), is less clear. In a recent study, Kosakamoto et al. examine the contribution of Tyr to Drosophila melanogaster physiology.

Using a synthetic diet, the researchers established that Tyr deprivation prolonged lifespan and negatively affected reproductive functions. However, higher dietary amino acid levels or loss of reproductive capacity, which is a nutrient-consuming process, abolished the effects of Tyr restriction on physiology, suggesting that Tyr may become limiting only when flies have a high demand for amino acids and a low supply. Mechanistically, Kosakamoto et al. showed that Tyr deprivation decreased internal Tyr levels and activated the transcription factor ATF4 through an unclear pathway, yet removing ATF4 was not enough to eliminate the increase in lifespan caused by the lack of Tyr.

一些必需氨基酸调节寿命;非必需氨基酸，如酪氨酸 （Tyr） 的作用不太清楚。在最近的一项研究中，Kosakamoto 等人研究了 Tyr 对黑腹果蝇生理学的贡献。

使用合成饮食，研究人员确定 Tyr 剥夺会延长寿命并对生殖功能产生负面影响。然而，较高的膳食氨基酸水平或生殖能力的丧失（这是一个消耗营养的过程）消除了 Tyr 限制对生理的影响，这表明只有当果蝇对氨基酸的需求量高而供应量低时，Tyr 才会受到限制。从机制上讲，Kosakamoto 等人表明，Tyr 剥夺降低了内部 Tyr 水平并通过不明确的途径激活了转录因子 ATF4，但去除 ATF4 不足以消除因缺乏 Tyr 而导致的寿命增加。