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Wang H, Chen F, Mi T, Liu Q, Yu Z, Zhen Y. Responses of Marine Diatom Skeletonema marinoi to Nutrient Deficiency: Programmed Cell Death. Appl Environ Microbiol 2020; 86:e02460-19. [PMID: 31757826 PMCID: PMC6974647 DOI: 10.1128/aem.02460-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 11/15/2019] [Indexed: 11/20/2022] Open
Abstract
Diatoms are important phytoplankton and contribute greatly to the primary productivity of marine ecosystems. Despite the ecological significance of diatoms and the importance of programmed cell death (PCD) in the fluctuation of diatom populations, little is known about the molecular mechanisms of PCD triggered by different nutrient stresses. Here we describe the physiological, morphological, biochemical, and molecular changes in response to low levels of nutrients in the ubiquitous diatom Skeletonema marinoi The levels of gene expression involved in oxidation resistance and PCD strongly increased upon nitrogen (N) or phosphorus (P) starvation. The enzymatic activity of caspase 3-like protein also increased. Differences in mRNA levels and protein activities were observed between the low-N and low-P treatments, suggesting that PCD could have a differential response to different nutrient stresses. When cultures were replete with N or P, the growth inhibition stopped. Meanwhile, the enzymatic activity of caspase 3-like protein and the number of cells with damaged membranes decreased. These results suggest that PCD is an important cell fate decision mechanism in the marine diatom S. marinoi Our results provide important insight into how diatoms adjust phenotypic and genotypic features of their cell-regulated death programs when stressed by nutrient limitations. Overall, this study could allow us to better understand the molecular mechanism behind the formation and termination of diatom blooms in the marine environment.IMPORTANCE Our study showed how the ubiquitous diatom S. marinoi responded to different nutrient limitations with PCD in terms of physiological, morphological, biochemical, and molecular characteristics. Some PCD-related genes (PDCD4, GOX, and HSP90) induced by N deficiency were relatively upregulated compared to those induced by P deficiency. In contrast, the expression of the TSG101 gene in S. marinoi showed a clear and constant increase during P limitation compared to N limitation. These findings suggest that PCD is a complex mechanism involving several different proteins. The systematic mRNA level investigations provide new insight into understanding the oxidative stress- and cell death-related functional genes of diatoms involved in the response to nutrient fluctuations (N or P stress) in the marine environment.
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Affiliation(s)
- Hualong Wang
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, USA
| | - Feng Chen
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, USA
| | - Tiezhu Mi
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, China
| | - Qian Liu
- College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Zhigang Yu
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Chemical Theory and Technology, Ministry of Education, Qingdao, China
| | - Yu Zhen
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao, China
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, China
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