Zhao Wei, Liu Jihua, Song Hui, Chen Bokun, Ji Hongli, Yang Xue, Li Gang
Institute of Marine Science and Technology, Shandong University, Qingdao 266237, China.
Joint Laboratory for Ocean Research and Education of Dalhousie University, Shandong University and Xiamen University, Qingdao 266237, China.
Microorganisms. 2025 Jul 12;13(7):1652. doi: 10.3390/microorganisms13071652.
The acute rise in temperature due to marine heatwaves has a strong impact on marine phytoplankton. To determine whether these effects depend on ambient temperature and cell size, we acclimated two diatom species, smaller (Hasle and Heimdal, 1970) and larger (Meunier, 1910), at low (LAT), medium (MAT) and high ambient temperatures (HAT) and examined their physiochemical and transcriptional responses to temperature rise (AT + 6 °C). The specific growth rate (µ) of smaller cells was increased by 32% due to temperature rise at LAT, but decreased by 13% at HAT, with the stimulatory and inhibitory extent being ~50% less than that of larger cells. At LAT, chlorophyll (Chl ), carotenoid (Car) and carbon (POC) contents were increased in smaller cells due to temperature rise, but were decreased in larger cells; at HAT, Chl and Car were increased in both smaller and larger cells and POC was increased in only smaller cells. At LAT, temperature rise led to a disproportionate increase in photosynthesis and dark respiration, resulting in an increase in carbon utilization efficiency (CUE) in smaller cells and a decrease in CUE in larger cells; at HAT, there was a decrease in CUE in both the smaller and larger cells, but to a lesser extent in the former than in the latter. Our results also show that smaller cells cope with the acute temperature rise mainly by strengthening their enzyme activity (e.g., the antioxidant system) and conservatively regulating their metabolism, while larger cells mainly regulate their photosynthetic and central carbon metabolism. Moreover, larger cells can outperform their smaller counterparts when the temperature rise occurs at lower ambient temperature.
海洋热浪导致的温度急剧上升对海洋浮游植物有强烈影响。为了确定这些影响是否取决于环境温度和细胞大小，我们将两种硅藻，较小的（哈斯勒和海姆达尔，1970年）和较大的（梅尼耶，1910年），在低（LAT）、中（MAT）和高环境温度（HAT）下进行驯化，并研究它们对温度上升（AT + 6°C）的理化和转录反应。较小细胞的比生长速率（µ）在LAT时因温度上升而增加了32%，但在HAT时下降了13%，其刺激和抑制程度比大细胞小约50%。在LAT时，较小细胞中叶绿素（Chl）、类胡萝卜素（Car）和碳（POC）含量因温度上升而增加，但在较大细胞中则下降；在HAT时，较小和较大细胞中的Chl和Car均增加，POC仅在较小细胞中增加。在LAT时，温度上升导致光合作用和暗呼吸不成比例地增加，导致较小细胞中碳利用效率（CUE）增加，较大细胞中CUE下降；在HAT时，较小和较大细胞中的CUE均下降，但前者的下降程度小于后者。我们的结果还表明，较小细胞应对温度急剧上升主要是通过增强其酶活性（如抗氧化系统）并保守地调节其代谢，而较大细胞主要调节其光合和中心碳代谢。此外，当在较低环境温度下发生温度上升时，较大细胞的表现优于较小细胞。
