It has recently been shown that Southern Ocean phytoplankton species have evolved to optimize their light-harvesting potential without increasing the high iron-requiring proteins used for photosynthesis. We measured molecular and physiological responses of phytoplankton cultures under a combination of iron and light conditions. While iron-replete cultures mostly increased biovolume, photochemical efficiency (F_v/F_m) and the relative abundance of photosystem II (PSII) and Cytochrome b₆f protein compared to iron-limited cultures, light also regulated cellular chlorophyll a content and played a role in controlling PSII protein abundance. Investment of protein resources into the carbon fixing enzyme Ribulose 1,5-bisphosphate carboxylase oxygenase (Rubisco) was species-specific, but increased growth rates correlated with increased investment into Rubisco for all species. Our results suggest that Proboscia inermis uses a divergent molecular strategy to compete for nutrients, light, and CO₂ in the Southern Ocean.

中文翻译：

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光限制和铁限制的南大洋浮游植物的不同生理和分子反应

最近的研究表明，南大洋浮游植物物种已经进化以优化其光捕获潜力，而不会增加用于光合作用的高铁需求蛋白质。我们测量了铁和光照条件下浮游植物培养物的分子和生理反应。虽然与铁限制培养相比，富含铁的培养物主要增加了生物量、光化学效率 ( F _v / F _m ) 以及光系统 II (PSII) 和细胞色素b ₆ f蛋白的相对丰度，但光也调节了细胞叶绿素a含量并在控制 PSII 蛋白丰度中发挥作用。将蛋白质资源投资于固碳酶核酮糖 1,5-二磷酸羧化酶加氧酶 (Rubisco) 是物种特异性的，但增长速度的增加与所有物种对 Rubisco 的投资增加相关。我们的研究结果表明，Proboscia inermis使用不同的分子策略来竞争南大洋中的营养、光和 CO ₂。