Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export
Programmed cell death in the marine cyanobacterium Trichodesmium mediates carbon and nitrogen export
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DOI：
10.1038/ismej.2013.121
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发表时间：
2013-12-01
期刊：
影响因子：
11
通讯作者：
Berman-Frank, Ilana
中科院分区：
文献类型：
--
作者：
Bar-Zeev, Edo;Avishay, Itamar;Berman-Frank, Ilana
向深海输出的碳(C)和氮(N)的程度取决于将初级产品输送到深海的生物泵的效率，从而阻止其在上层光区再循环。固氮菌（重氮营养型）Trichodesmium spp.通过在营养匮乏的热带和亚热带地区形成广泛的水华，对海洋C和N循环有重要贡献。这些大规模的花通常在形成几天后就会消失，但细胞机制以及相关的C和N输出过程的大小尚不清楚。在这里，我们使用一个定制的2米高的水柱来模拟自然水华，并专门测试和量化木霉菌的程序性细胞死亡（PCD）是否在机制上调节了C和n的垂直通量增加。我们的研究结果表明，木霉菌水华的极快发展和PCD诱导的突然死亡（2-3天内）导致透明外聚合物的排泄大大增加，以及颗粒有机物的大量向下脉冲。我们的研究结果将自催化PCD和水华崩塌与定量C和N输出通量联系起来，表明PCD可能对海洋生物泵效率有影响。
The extent of carbon (C) and nitrogen (N) export to the deep ocean depends upon the efficacy of the biological pump that transports primary production to depth, thereby preventing its recycling in the upper photic zone. The dinitrogen-fixing (diazotrophic) Trichodesmium spp. contributes significantly to oceanic C and N cycling by forming extensive blooms in nutrient-poor tropical and subtropical regions. These massive blooms generally collapse several days after forming, but the cellular mechanism responsible, along with the magnitude of associated C and N export processes, are as yet unknown. Here, we used a custom-made, 2-m high water column to simulate a natural bloom and to specifically test and quantify whether the programmed cell death (PCD) of Trichodesmium mechanistically regulates increased vertical flux of C and N. Our findings demonstrate that extremely rapid development and abrupt, PCD-induced demise (within 2-3 days) of Trichodesmium blooms lead to greatly elevated excretions of transparent exopolymers and a massive downward pulse of particulate organic matter. Our results mechanistically link autocatalytic PCD and bloom collapse to quantitative C and N export fluxes, suggesting that PCD may have an impact on the biological pump efficiency in the oceans.