Shukla Arvind Kumar, Johnson Kory, Giniger Edward
National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bldg 35, Rm 1C 1002, Bethesda, MD 20892, USA.
iScience. 2021 Jun 8;24(7):102703. doi: 10.1016/j.isci.2021.102703. eCollection 2021 Jul 23.
Lifespan is limited both by intrinsic decline in vigor with age and by accumulation of external insults. There exists a general picture of the deficits of aging, one that is reflected in a pattern of age-correlated changes in gene expression conserved across species. Here, however, by comparing gene expression profiling of raised either conventionally, or free of bacteria, we show that ∼70% of these conserved, age-associated changes in gene expression fail to occur in germ-free flies. Among the processes that fail to show time-dependent change under germ-free conditions are two aging features that are observed across phylogeny, declining expression of stress response genes and increasing expression of innate immune genes. These comprise adaptive strategies the organism uses to respond to bacteria, rather than being inevitable components of age-dependent decline. Changes in other processes are independent of the microbiome and can serve as autonomous markers of aging of the individual.
寿命受到年龄增长导致的内在活力下降以及外部损伤积累的双重限制。衰老存在一些普遍的缺陷特征，这些特征反映在跨物种保守的与年龄相关的基因表达变化模式中。然而，通过比较常规饲养或无菌饲养的果蝇的基因表达谱，我们发现这些保守的、与年龄相关的基因表达变化中约70%在无菌果蝇中并未出现。在无菌条件下未能显示出时间依赖性变化的过程中，有两个衰老特征在整个系统发育中都能观察到，即应激反应基因表达下降和先天免疫基因表达增加。这些是生物体用于应对细菌的适应性策略，而非年龄依赖性衰退的必然组成部分。其他过程的变化与微生物组无关，可作为个体衰老的自主标志物。
