The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i>
Mercury (Hg) poses high toxicity to organisms including algae. Studies showed that the growth and photosynthesis of green algae such as <i>Chlorella</i> are vulnerable to Hg stress. However, the differences between the activities and tolerance of photosystem I and II (PSI and PSII) of gr...
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MDPI AG
2022-08-01
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| Series: | Toxics |
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| Online Access: | https://www.mdpi.com/2305-6304/10/8/455 |
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| author | Shuzhi Wang Jia Duo Rehemanjiang Wufuer Wenfeng Li Xiangliang Pan |
| author_facet | Shuzhi Wang Jia Duo Rehemanjiang Wufuer Wenfeng Li Xiangliang Pan |
| author_sort | Shuzhi Wang |
| collection | DOAJ |
| description | Mercury (Hg) poses high toxicity to organisms including algae. Studies showed that the growth and photosynthesis of green algae such as <i>Chlorella</i> are vulnerable to Hg stress. However, the differences between the activities and tolerance of photosystem I and II (PSI and PSII) of green microalgae under Hg exposure are still little known. Responses of quantum yields and electron transport rates (ETRs) of PSI and PSII of <i>Chlorella</i> <i>pyrenoidosa</i> to 0.05–1 mg/L Hg<sup>2+</sup> were simultaneously measured for the first time by using the Dual-PAM-100 system. The photosystems were isolated to analyze the characteristics of toxicity of Hg during the binding process. The inhibition of Hg<sup>2+</sup> on growth and photosystems was found. PSII was more seriously affected by Hg<sup>2+</sup> than PSI. After Hg<sup>2+</sup> exposure, the photochemical quantum yield of PSII [Y(II)] decreased with the increase in non-photochemical fluorescence quenching [Y(NO) and Y(NPQ)]. The toxic effects of Hg on the photochemical quantum yield and ETR in PSI were lower than those of PSII. The stimulation of cyclic electron yield (CEF) was essential for the stability and protection of PSI under Hg stress and played an important role in the induction of non-photochemical quenching (NPQ). The results showed a strong combination ability of Hg ions and photosystem particles. The number of the binding sites (n) of Hg on PSII was more than that of PSI, which may explain the different toxicity of Hg on PSII and PSI. |
| first_indexed | 2024-03-09T03:46:01Z |
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| language | English |
| last_indexed | 2024-03-09T03:46:01Z |
| publishDate | 2022-08-01 |
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| record_format | Article |
| series | Toxics |
| spelling | doaj.art-f2d356648b08461888195a7729abb0532023-12-03T14:34:56ZengMDPI AGToxics2305-63042022-08-0110845510.3390/toxics10080455The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i>Shuzhi Wang0Jia Duo1Rehemanjiang Wufuer2Wenfeng Li3Xiangliang Pan4National Engineering Technology Research Center for Desert-Oasis Ecological Construction, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi 830011, ChinaNational Engineering Technology Research Center for Desert-Oasis Ecological Construction, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi 830011, ChinaNational Engineering Technology Research Center for Desert-Oasis Ecological Construction, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi 830011, ChinaNational Engineering Technology Research Center for Desert-Oasis Ecological Construction, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, 818 South Beijing Road, Urumqi 830011, ChinaXinjiang Key Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, ChinaMercury (Hg) poses high toxicity to organisms including algae. Studies showed that the growth and photosynthesis of green algae such as <i>Chlorella</i> are vulnerable to Hg stress. However, the differences between the activities and tolerance of photosystem I and II (PSI and PSII) of green microalgae under Hg exposure are still little known. Responses of quantum yields and electron transport rates (ETRs) of PSI and PSII of <i>Chlorella</i> <i>pyrenoidosa</i> to 0.05–1 mg/L Hg<sup>2+</sup> were simultaneously measured for the first time by using the Dual-PAM-100 system. The photosystems were isolated to analyze the characteristics of toxicity of Hg during the binding process. The inhibition of Hg<sup>2+</sup> on growth and photosystems was found. PSII was more seriously affected by Hg<sup>2+</sup> than PSI. After Hg<sup>2+</sup> exposure, the photochemical quantum yield of PSII [Y(II)] decreased with the increase in non-photochemical fluorescence quenching [Y(NO) and Y(NPQ)]. The toxic effects of Hg on the photochemical quantum yield and ETR in PSI were lower than those of PSII. The stimulation of cyclic electron yield (CEF) was essential for the stability and protection of PSI under Hg stress and played an important role in the induction of non-photochemical quenching (NPQ). The results showed a strong combination ability of Hg ions and photosystem particles. The number of the binding sites (n) of Hg on PSII was more than that of PSI, which may explain the different toxicity of Hg on PSII and PSI.https://www.mdpi.com/2305-6304/10/8/455mercurybinding abilitychlorophyll <i>a</i> fluorescenceP700<sup>+</sup> absorbance changequantum yieldelectron transport rate |
| spellingShingle | Shuzhi Wang Jia Duo Rehemanjiang Wufuer Wenfeng Li Xiangliang Pan The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i> Toxics mercury binding ability chlorophyll <i>a</i> fluorescence P700<sup>+</sup> absorbance change quantum yield electron transport rate |
| title | The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i> |
| title_full | The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i> |
| title_fullStr | The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i> |
| title_full_unstemmed | The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i> |
| title_short | The Binding Ability of Mercury (Hg) to Photosystem I and II Explained the Difference in Its Toxicity on the Two Photosystems of <i>Chlorella pyrenoidosa</i> |
| title_sort | binding ability of mercury hg to photosystem i and ii explained the difference in its toxicity on the two photosystems of i chlorella pyrenoidosa i |
| topic | mercury binding ability chlorophyll <i>a</i> fluorescence P700<sup>+</sup> absorbance change quantum yield electron transport rate |
| url | https://www.mdpi.com/2305-6304/10/8/455 |
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