Soh Jung Won, Hotic Sijana, Arking Robert
Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
Mech Ageing Dev. 2007 Nov-Dec;128(11-12):581-93. doi: 10.1016/j.mad.2007.08.004. Epub 2007 Aug 17.
We tested the effects of dietary restriction (DR) on the standard w(1118) strain as well as on our previously described Ra and La strains and their reciprocal isogenic 'cybrid' lines containing heterologous nuclear-mitochondrial combinations. The w(1118) and Ra strains, but neither the La strains nor their 'cybrid' derivatives, are DR-inducible. The Ra and La animals are more robust than the w(1118) animals, and the Ra strain shows an upward shift in its DR threshold. The non-inducibility of the La strain suggests that it expresses a constituitive version of the inducible DR phenotype of its predecessor Ra strain. The difference in mitochondrial efficiency observed between the Ra and La mitochondria (Ross, 2000) has real effects on longevity in the adults: the presence of the more efficient La mitochondria enhances the longevity of an otherwise Ra animal; while the maximum longevity inherent in the La nuclear information cannot be fully expressed in the presence of the Ra mitochondria. Despite the absence of any demographic mathematical parameters robustly and uniquely associated with extended longevity, there are some common trends in that longer lived cohorts have a longer period of low and often constant early life mortality rates (comprising the "health span"), leading to a delayed onset of senescence as noted by the late life increase in age-specific mortality rates (comprising the "senescence span"). There is a genetic basis to this phenotype, but the context-dependence of the demographic data suggests that there is not likely to be only one mechanism or pathway involved in the DR response. In addition, the presence of live yeast had systemic strain specific effects such that it increased longevity in the w(1118) animals but decreased it in the Ra and derived lines. Higher density (4-10x) foods yielded a decreased longevity in all strains at the highest level, showing that malnutrition occurs at both low and high caloric levels.
我们测试了饮食限制（DR）对标准w(1118)品系以及我们之前描述的Ra和La品系及其包含异源核 - 线粒体组合的相互同基因“胞质杂种”品系的影响。w(1118)和Ra品系可被DR诱导，而La品系及其“胞质杂种”衍生物则不能。Ra和La品系的动物比w(1118)品系的动物更强壮，并且Ra品系的DR阈值有向上的偏移。La品系的不可诱导性表明它表达了其前身Ra品系可诱导的DR表型的组成型版本。在Ra和La线粒体之间观察到的线粒体效率差异（Ross，2000）对成年动物的寿命有实际影响：更高效的La线粒体的存在可提高原本为Ra品系动物的寿命；而在存在Ra线粒体的情况下，La核信息所固有的最大寿命无法完全表达。尽管没有任何人口统计学数学参数与延长的寿命有稳健且唯一的确切关联，但存在一些共同趋势，即寿命较长的群体在早期有较长时间的低且通常恒定的死亡率（构成“健康期”），导致衰老延迟，这表现为后期年龄特异性死亡率的增加（构成“衰老期”）。这种表型有遗传基础，但人口统计学数据的背景依赖性表明，DR反应不太可能只涉及一种机制或途径。此外，活酵母的存在具有系统的品系特异性效应，即它增加了w(1118)品系动物的寿命，但降低了Ra品系及其衍生品系的寿命。高密度（4 - 10倍）食物在最高水平时会降低所有品系的寿命，表明营养不良在低热量和高热量水平下都会发生。
