Botanical Institute, Karlsruhe Institute of Technology, Kaiserstr. 2, 76131 Karlsruhe, Germany.
Institute for Pulsed Power and Microwave Technology (IHM), Karlsruhe Institute of Technology, Campus Nord, 76344 Eggenstein-Leopoldshafen, Germany.
Biochim Biophys Acta Biomembr. 2017 May;1859(5):651-661. doi: 10.1016/j.bbamem.2017.01.007. Epub 2017 Jan 6.
Nanosecond pulsed electric fields (nsPEFs) have great potential for biotechnological and medical applications. However, the biological mechanisms causing the cellular responses are still far from understood. We used the unicellular green algae Chlamydomonas reinhardtii as experimental model to dissect the immediate consequences of electroporation from the developmental cellular responses evoked by nsPEFs. We observe that nsPEFs induce a short-term permeabilization of the membrane, accompanied by swelling and oxidative burst. These response are transient, but are followed, several days later, by a second wave of oxidative burst, arrested cell division, stimulated cell expansion, and the formation of an immobile palmella stage. This persistent oxidative burst can be suppressed by specific inhibitor diphenyl iodonium (DPI), but not by the unspecific antioxidant ascorbic acid (Asc). Treated with natural and artificial auxins allow to modulating the cell cycle and cell expansion, and natural auxin can suppress the spontaneous formation of palmella stages. However, when administered prior to the nsPEFs treatment, auxin cannot mitigate the elevated formation of palmella stages induced by nsPEFs. We interpret our findings in terms of a model, where nsPEFs generate a developmental signal that persists, although the other immediate responses remain transient. This signal will initiate, several days later, a developmental programme comprising halted cell cycle, stimulation of cell expansion, a persistent activation of NADPH oxidase activity causing a second wave of oxidative burst, and the irreversible initiation of palmella stages. Thus, a short transient nsPEFs treatment can initiate a stable response of cellular differentiation in Chlamydomonas reinhardtii.
纳秒脉冲电场（nsPEFs）在生物技术和医学应用方面具有巨大的潜力。然而，导致细胞反应的生物学机制仍远未被理解。我们使用单细胞绿藻莱茵衣藻作为实验模型，从 nsPEFs 引起的细胞发育反应中剖析电穿孔的直接后果。我们观察到，nsPEFs 诱导细胞膜的短期通透性增加，伴随着细胞肿胀和氧化爆发。这些反应是短暂的，但几天后会出现第二次氧化爆发，细胞分裂停止，细胞扩张，形成不可移动的棕榈状阶段。这种持续的氧化爆发可以被特异性抑制剂二苯基碘（DPI）抑制，但不能被非特异性抗氧化剂抗坏血酸（Asc）抑制。用天然和人工植物生长素处理可以调节细胞周期和细胞扩张，天然生长素可以抑制棕榈状阶段的自发形成。然而，当在 nsPEFs 处理之前给予生长素时，生长素不能减轻 nsPEFs 诱导的棕榈状阶段的升高形成。我们根据一个模型解释我们的发现，其中 nsPEFs 产生一个持续存在的发育信号，尽管其他即时反应仍然是短暂的。这个信号将在几天后启动一个包含细胞周期停止、细胞扩张刺激、NADPH 氧化酶活性持续激活导致第二次氧化爆发以及棕榈状阶段不可逆启动的发育程序。因此，短暂的 nsPEFs 处理可以在莱茵衣藻中引发细胞分化的稳定反应。
