The dynamic response to hypo‐osmotic stress reveals distinct stages of freshwater acclimation by a euryhaline diatom
The dynamic response to hypo‐osmotic stress reveals distinct stages of freshwater acclimation by a euryhaline diatom
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对低渗透压胁迫的动态响应揭示了广盐硅藻适应淡水的不同阶段
DOI：
10.1111/mec.16703
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发表时间：
2023
影响因子：
4.9
通讯作者：
Lewis, Jeffrey A.
中科院分区：
文献类型：
--
作者：
Downey, Kala M.;Judy, Kathryn J.;Pinseel, Eveline;Alverson, Andrew J.;Lewis, Jeffrey A.
分隔海洋和淡水环境的盐度梯度是一个主要的生态鸿沟，大多数生物适应新盐度环境的机制知之甚少。硅藻是一种海洋微藻的祖先，在淡水中反复定居和多样化。Cyclotella crypticais是一种广盐性硅藻，在从完全淡水到完全海洋的盐度范围内发现，从而为理解减轻和适应低盐度的基因组机制提供了一个强大的系统。为了了解硅藻如何缓解急性低渗胁迫，我们突然将C. cryptica从海水转移到淡水，并在前10小时内进行转录分析。淡水休克显著重塑了转录组，约50%的基因组在至少一个时间点差异表达。峰值反应发生在1小时内，与强烈的阻遏基因参与细胞生长和渗透压的生产，并强烈诱导特定的胁迫防御基因。转录本在4-10小时内基本恢复到基线水平，此后不久恢复生长，表明基因表达动态可能有助于预测驯化。此外，与对C. cryptica长达数月的适应淡水的转录组学研究相比，暴露于急性应激与完全适应条件的细胞中差异表达的基因和过程之间几乎没有重叠。总而言之，这项研究强调了时间分辨转录组学的力量，揭示了细胞如何动态响应急性环境变化的基本见解，并为硅藻如何缓解自然盐度波动并成功地在全球淡水栖息地多样化提供了新的见解。
The salinity gradient separating marine and freshwater environments is a major ecological divide, and the mechanisms by which most organisms adapt to new salinity environments are poorly understood. Diatoms are a lineage of ancestrally marine microalgae that have repeatedly colonized and diversified in freshwaters.Cyclotella crypticais a euryhaline diatom found in salinities ranging from fully freshwater to fully marine, thus providing a powerful system for understanding the genomic mechanisms for mitigating and acclimating to low salinity. To understand how diatoms mitigate acute hypo‐osmotic stress, we abruptly shiftedC. crypticafrom seawater to freshwater and performed transcriptional profiling during the first 10 h. Freshwater shock dramatically remodelled the transcriptome, with ~50% of the genome differentially expressed in at least one time point. The peak response occurred within 1 h, with strong repression of genes involved in cell growth and osmolyte production, and strong induction of specific stress defence genes. Transcripts largely returned to baseline levels within 4–10 h, with growth resuming shortly thereafter, suggesting that gene expression dynamics may be useful for predicting acclimation. Moreover, comparison to a transcriptomics study ofC. crypticafollowing months‐long acclimation to freshwater revealed little overlap between the genes and processes differentially expressed in cells exposed to acute stress versus fully acclimated conditions. Altogether, this study highlights the power of time‐resolved transcriptomics to reveal fundamental insights into how cells dynamically respond to an acute environmental shift and provides new insights into how diatoms mitigate natural salinity fluctuations and have successfully diversified across freshwater habitats worldwide.