Kuzdzal-Fick Jennie J, Chen Lin, Balázsi Gábor
Department of Systems Biology The University of Texas MD Anderson Cancer Center Houston Texas.
Department of Biology and Biochemistry University of Houston Houston Texas.
Ecol Evol. 2019 Jul 9;9(15):8509-8523. doi: 10.1002/ece3.5322. eCollection 2019 Aug.
Multicellular organisms appeared on Earth through several independent major evolutionary transitions. Are such transitions reversible? Addressing this fundamental question entails understanding the benefits and costs of multicellularity versus unicellularity. For example, some wild yeast strains form multicellular clumps, which might be beneficial in stressful conditions, but this has been untested. Here, we show that unicellular yeast evolve from clump-forming ancestors by propagating samples from suspension after larger clumps have settled. Unicellular yeast strains differed from their clumping ancestors mainly by mutations in the (Antagonist of Mitotic exit Network) gene. Ancestral yeast clumps were more resistant to freeze/thaw, hydrogen peroxide, and ethanol stressors than their unicellular counterparts, but they grew slower without stress. These findings suggest disadvantages and benefits to multicellularity and unicellularity that may have impacted the emergence of multicellular life forms.
多细胞生物通过几次独立的重大进化转变出现在地球上。这些转变是可逆的吗？要回答这个基本问题，需要了解多细胞性与单细胞性的利弊。例如，一些野生酵母菌株会形成多细胞团块，这在压力条件下可能是有益的，但这一点尚未得到验证。在这里，我们表明单细胞酵母是通过在较大的团块沉降后从悬浮液中传代样本，从形成团块的祖先进化而来的。单细胞酵母菌株与其形成团块的祖先的主要区别在于（有丝分裂退出网络拮抗剂）基因的突变。祖先酵母团块比其单细胞对应物对冻融、过氧化氢和乙醇应激源更具抗性，但在没有压力的情况下生长较慢。这些发现表明了多细胞性和单细胞性的缺点和优点，可能影响了多细胞生命形式的出现。
