厦门大学焦念志课题组近日取得一项新成果。他们的最新研究提出了高核酸和低核酸原核生物对资源利用率下降的适应策略，以及原生动物的选择性捕食。该研究于2024年4月26日发表于国际一流学术期刊《中国科学：地球科学》杂志上。

据了解，原核生物在全球海洋生物地球化学循环中起着重要作用。然而，生态上不同的亚群(即高核酸(HNA)和低核酸(LNA)细胞)的丰度和代谢活性，及其调节因子如何随着海洋环境条件的变化而变化，目前尚不清楚。

该团队通过在大容量(11.7万L)宏观环境中进行73天的孵育实验，深入研究了HNA和LNA原核亚群对资源可用性下降和原生动物选择性捕食的动态响应，以促进群落水平的探索。研究发现，当宏观环境资源充足时，HNA亚群的代谢活性高于LNA亚群，但随着资源越来越稀缺，HNA亚群的下降速度比LNA亚群快，导致LNA细胞对原核活性的贡献稳步增加。

同时，随着宏观生态系统资源的有限，原生动物的捕食偏好从海航亚群转向LNA亚群，LNA亚群对宏观生态系统碳流的贡献增加。这些发现强调了LNA细胞在资源有限环境中的弹性，阐明了在不断变化的资源条件下，原生动物选择性捕食在平衡不同原核生物亚群中的关键作用，并展示了在不同环境背景下，原生动物和原核生物之间复杂的适应性相互作用。

附：英文原文

Title: Adaptive strategies of high and low nucleic acid prokaryotes in response to declining resource availability and selective grazing by protozoa

Author: Chen HU, Liuqian YU, Xiaowei CHEN, Jihua LIU, Yao ZHANG, John BATT, Xilin XIAO, Qiang SHI, Rui ZHANG, Tingwei LUO, Nianzhi JIAO, Dapeng XU

Issue&Volume: 2024/04/26

Abstract: Prokaryotes play a fundamental role in global ocean biogeochemical cycles. However, how the abundance and metabolic activity of ecologically distinct subgroups (i.e., high nucleic acid (HNA) and low nucleic acid (LNA) cells), and their regulating factors, change in response to changing marine environmental conditions remains poorly understood. Here, we delved into the time-evolving dynamic responses of the HNA and LNA prokaryotic subgroups to declining resource availability and selective grazing by protozoa by conducting a 73-day incubation experiment in a large-volume (117,000L) macrocosm that facilitates community-level exploration. We found that the metabolic activity of the HNA subgroup was higher than that of the LNA subgroup when the macrocosm was resource replete but that the HNA subgroup declined more rapidly than the LNA subgroup as the resources became increasingly scarce, leading to a steadily increasing contribution of LNA cells to prokaryotic activity. Meanwhile, as resources in the macrocosm became limited, protozoan grazing preference shifted from the HNA to the LNA subgroup and the contributions of the LNA subgroup to the carbon flow within the macrocosm increased. The findings highlight the resilience of LNA cells in resource-limited environments, illuminate the critical role of selective grazing by protozoa in balancing distinct prokaryotic subgroups under changing resource conditions, and demonstrate the complex and adaptive interactions between protozoa and prokaryotes across diverse environmental contexts.

DOI: 10.1007/s11430-023-1326-2

Source: https://www.sciengine.com/10.1007/s11430-023-1326-2