Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i>
Exacerbating deoxygenation is extensively affecting marine organisms, with no exception for phytoplankton. To probe these effects, we comparably explored the growth, cell compositions, photosynthesis, and transcriptome of a diatom <i>Thalassiosira pseudonana</i> under a matrix of <i&g...
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MDPI AG
2021-12-01
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| Series: | Microorganisms |
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| Online Access: | https://www.mdpi.com/2076-2607/9/12/2541 |
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| author | Bokun Chen Jihua Liu Ge Xu Gang Li |
| author_facet | Bokun Chen Jihua Liu Ge Xu Gang Li |
| author_sort | Bokun Chen |
| collection | DOAJ |
| description | Exacerbating deoxygenation is extensively affecting marine organisms, with no exception for phytoplankton. To probe these effects, we comparably explored the growth, cell compositions, photosynthesis, and transcriptome of a diatom <i>Thalassiosira pseudonana</i> under a matrix of <i>p</i>O<sub>2</sub> levels and Light:Dark cycles at an optimal growth light. The growth rate (μ) of <i>T. pseudonana</i> under a 8:16 L:D cycle was enhanced by 34% by low <i>p</i>O<sub>2</sub> but reduced by 22% by hypoxia. Under a 16:8 L:D cycle, however, the μ decreased with decreasing <i>p</i>O<sub>2</sub> level. The cellular Chl <i>a</i> content decreased with decreasing <i>p</i>O<sub>2</sub> under a 8:16 L:D cycle, whereas the protein content decreased under a 16:8 L:D cycle. The prolonged photoperiod reduced the Chl <i>a</i> but enhanced the protein contents. The lowered <i>p</i>O<sub>2</sub> reduced the maximal PSII photochemical quantum yield (F<sub>V</sub>/F<sub>M</sub>), photosynthetic oxygen evolution rate (Pn), and respiration rate (Rd) under the 8:16 or 16:8 L:D cycles. Cellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were higher under low <i>p</i>O<sub>2</sub> than ambient <i>p</i>O<sub>2</sub> or hypoxia. Moreover, the prolonged photoperiod reduced the F<sub>V</sub>/F<sub>M</sub> and Pn among all three <i>p</i>O<sub>2</sub> levels but enhanced the Rd, MDA, and SOD activity. Transcriptome data showed that most of 26 differentially expressed genes (DEGs) that mainly relate to photosynthesis, respiration, and metabolism were down-regulated by hypoxia, with varying expression degrees between the 8:16 and 16:8 L:D cycles. In addition, our results demonstrated that the positive or negative effect of lowering <i>p</i>O<sub>2</sub> upon the growth of diatoms depends on the <i>p</i>O<sub>2</sub> level and is mediated by the photoperiod. |
| first_indexed | 2024-03-10T03:31:24Z |
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| id | doaj.art-8530dd95fc494611bc8c62332f65903e |
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| language | English |
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| spelling | doaj.art-8530dd95fc494611bc8c62332f65903e2023-11-23T09:39:33ZengMDPI AGMicroorganisms2076-26072021-12-01912254110.3390/microorganisms9122541Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i>Bokun Chen0Jihua Liu1Ge Xu2Gang Li3Institute of Marine Science and Technology, Shandong University, Qingdao 266237, ChinaInstitute of Marine Science and Technology, Shandong University, Qingdao 266237, ChinaInstitute of Marine Science and Technology, Shandong University, Qingdao 266237, ChinaKey Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510530, ChinaExacerbating deoxygenation is extensively affecting marine organisms, with no exception for phytoplankton. To probe these effects, we comparably explored the growth, cell compositions, photosynthesis, and transcriptome of a diatom <i>Thalassiosira pseudonana</i> under a matrix of <i>p</i>O<sub>2</sub> levels and Light:Dark cycles at an optimal growth light. The growth rate (μ) of <i>T. pseudonana</i> under a 8:16 L:D cycle was enhanced by 34% by low <i>p</i>O<sub>2</sub> but reduced by 22% by hypoxia. Under a 16:8 L:D cycle, however, the μ decreased with decreasing <i>p</i>O<sub>2</sub> level. The cellular Chl <i>a</i> content decreased with decreasing <i>p</i>O<sub>2</sub> under a 8:16 L:D cycle, whereas the protein content decreased under a 16:8 L:D cycle. The prolonged photoperiod reduced the Chl <i>a</i> but enhanced the protein contents. The lowered <i>p</i>O<sub>2</sub> reduced the maximal PSII photochemical quantum yield (F<sub>V</sub>/F<sub>M</sub>), photosynthetic oxygen evolution rate (Pn), and respiration rate (Rd) under the 8:16 or 16:8 L:D cycles. Cellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were higher under low <i>p</i>O<sub>2</sub> than ambient <i>p</i>O<sub>2</sub> or hypoxia. Moreover, the prolonged photoperiod reduced the F<sub>V</sub>/F<sub>M</sub> and Pn among all three <i>p</i>O<sub>2</sub> levels but enhanced the Rd, MDA, and SOD activity. Transcriptome data showed that most of 26 differentially expressed genes (DEGs) that mainly relate to photosynthesis, respiration, and metabolism were down-regulated by hypoxia, with varying expression degrees between the 8:16 and 16:8 L:D cycles. In addition, our results demonstrated that the positive or negative effect of lowering <i>p</i>O<sub>2</sub> upon the growth of diatoms depends on the <i>p</i>O<sub>2</sub> level and is mediated by the photoperiod.https://www.mdpi.com/2076-2607/9/12/2541low <i>p</i>O<sub>2</sub>photoperiodphotosynthesisrespirationcell compositions<i>Thalassiosira pseudonana</i> |
| spellingShingle | Bokun Chen Jihua Liu Ge Xu Gang Li Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i> Microorganisms low <i>p</i>O<sub>2</sub> photoperiod photosynthesis respiration cell compositions <i>Thalassiosira pseudonana</i> |
| title | Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i> |
| title_full | Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i> |
| title_fullStr | Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i> |
| title_full_unstemmed | Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i> |
| title_short | Lowering <i>p</i>O<sub>2</sub> Interacts with Photoperiod to Alter Physiological Performance of the Coastal Diatom <i>Thalassiosira pseudonana</i> |
| title_sort | lowering i p i o sub 2 sub interacts with photoperiod to alter physiological performance of the coastal diatom i thalassiosira pseudonana i |
| topic | low <i>p</i>O<sub>2</sub> photoperiod photosynthesis respiration cell compositions <i>Thalassiosira pseudonana</i> |
| url | https://www.mdpi.com/2076-2607/9/12/2541 |
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