Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA.
Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA.
Plant J. 2022 Aug;111(4):995-1014. doi: 10.1111/tpj.15867. Epub 2022 Jul 11.
Even subtle modifications in growth conditions elicit acclimation responses affecting the molecular and elemental makeup of organisms, both in the laboratory and in natural habitats. We systematically explored the effect of temperature, pH, nutrient availability, culture density, and access to CO and O in laboratory-grown algal cultures on growth rate, the ionome, and the ability to accumulate Fe. We found algal cells accumulate Fe in alkaline conditions, even more so when excess Fe is present, coinciding with a reduced growth rate. Using a combination of Fe-specific dyes, X-ray fluorescence microscopy, and NanoSIMS, we show that the alkaline-accumulated Fe was intracellularly sequestered into acidocalcisomes, which are localized towards the periphery of the cells. At high photon flux densities, Zn and Ca specifically over-accumulate, while Zn alone accumulates at low temperatures. The impact of aeration was probed by reducing shaking speeds and changing vessel fill levels; the former increased the Cu quota of cultures, the latter resulted in a reduction in P, Ca, and Mn at low fill levels. Trace element quotas were also affected in the stationary phase, where specifically Fe, Cu, and Zn accumulate. Cu accumulation here depends inversely on the Fe concentration of the medium. Individual laboratory strains accumulate Ca, P, and Cu to different levels. All together, we identified a set of specific changes to growth rate, elemental composition, and the capacity to store Fe in response to subtle differences in culturing conditions of Chlamydomonas, affecting experimental reproducibility. Accordingly, we recommend that these variables be recorded and reported as associated metadata.
即使是生长条件的微小变化也会引发适应反应，影响生物体的分子和元素组成，无论是在实验室还是在自然栖息地。我们系统地研究了温度、pH 值、养分供应、培养密度以及 CO 和 O 的可及性对实验室培养藻类的生长速度、离子组和积累 Fe 的能力的影响。我们发现藻类细胞在碱性条件下积累 Fe，当存在过量 Fe 时更是如此，同时生长速度降低。我们使用 Fe 特异性染料、X 射线荧光显微镜和 NanoSIMS 的组合，表明碱性积累的 Fe 被细胞内隔离到液泡小体中，这些液泡小体位于细胞的外围。在高光量子通量密度下，Zn 和 Ca 特别过度积累，而 Zn 仅在低温下积累。通过降低搅拌速度和改变容器填充水平来探测通气的影响；前者增加了培养物的 Cu 配额，后者导致低填充水平下 P、Ca 和 Mn 的减少。在静止阶段，痕量元素配额也会受到影响，特别是 Fe、Cu 和 Zn 会积累。这里的 Cu 积累与培养基中 Fe 浓度呈反比。个别实验室菌株对 Ca、P 和 Cu 的积累水平不同。总之，我们确定了一组特定的变化，包括生长速度、元素组成以及在应对小球藻培养条件的微小差异时储存 Fe 的能力，这会影响实验的可重复性。因此，我们建议记录并报告这些变量作为相关元数据。
