Gómez José M G
Museo de la Naturaleza de Cantabria 39509, Plaza Don Pedro Ygareda, Carrejo, Cantabria, Spain.
Curr Aging Sci. 2010 Dec;3(3):198-218.
Bacteria were traditionally thought to have a symmetrical binary fission without a clear distinction between soma and germ-line, being thus considered as immortal biological entities. Yet it has been recently described that bacteria also undergo replicative aging (RA). That is, they exhibit finite replicative abilities under good conditions to growth. The apparently initial indistinguishability of sibling cells after cytokinesis is broken. After division, the daughter cell that inherits the "old" pole present in the "mother cell" progressively exhibits a decline in its proliferative capacity with increasing cell pole age. This is a clear hallmark and phenotypic manifestation of a bona fide RA phenomenon in toto. While the exact molecular mechanism(s) underlying to this lost of replicative potential are not yet fully understood, the "old pole cell" is considered as an aging parent that in a repeatedly manner is able to produce rejuvenated offspring which inherit a resetting of the biological clock. On the order hand, bacteria exhibit in addition to this "mandatory" RA the dubbed conditional senescence (CS). CS is defined as a decline in cellular viability observed in arrested-growing bacteria populations, a phenomenon apparently not related to RA under growing active conditions. To understand bacterial aging, it is necessary to put it within the sociality-multicellularity framework. This is a new conceptual paradigm that expresses the natural reality of the bacterial world. From this more ecological perspective these bacterial aging phenomena probably should represent an insurance/bethedging anticipative survival strategy. This is underpinned in a self-generation of an appropriate level of populational phenotypic diversity. That is, bacterial aging could be considered a communitarian adaptive response to cope with different environmental stresses and threats. I have highlighted the necessity to construct an integrative conceptual framework to achieve a unified view of bacteria aging to answer this fundamental question: what are the reasons of bacterial aging?
传统上认为细菌具有对称的二分裂，体细胞和生殖系之间没有明显区别，因此被视为不朽的生物实体。然而，最近有描述称细菌也会经历复制性衰老（RA）。也就是说，它们在良好的生长条件下表现出有限的复制能力。胞质分裂后姐妹细胞最初明显的不可区分性被打破。分裂后，继承“母细胞”中“旧”极的子细胞随着细胞极年龄的增加，其增殖能力逐渐下降。这是真正的RA现象的一个明显标志和表型表现。虽然导致这种复制潜力丧失的确切分子机制尚未完全了解，但“旧极细胞”被视为一个衰老的亲本，它能够反复产生恢复活力的后代，这些后代继承了生物钟的重置。另一方面，细菌除了这种“强制性”RA外，还表现出所谓的条件性衰老（CS）。CS被定义为在生长停滞的细菌群体中观察到的细胞活力下降，这一现象显然与活跃生长条件下的RA无关。为了理解细菌衰老，有必要将其置于社会性-多细胞性框架内。这是一个表达细菌世界自然现实的新的概念范式。从这个更生态的角度来看，这些细菌衰老现象可能代表了一种保险/套期保值的预期生存策略。这体现在适当水平的群体表型多样性的自我产生中。也就是说，细菌衰老可以被认为是一种群体适应性反应，以应对不同的环境压力和威胁。我强调了构建一个综合概念框架以实现对细菌衰老的统一观点的必要性，以回答这个基本问题：细菌衰老的原因是什么？
