The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,w...The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient conditions.Our results showed that the SV of T.weissflogii under different nutrient limitation conditions varied substantially.The highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/d.As the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,respectively.Notably;under conditions with limited nitrate and phosphate concentrations,the SV values of T.weissflogii significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,respectively.The change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica contents.The results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure.展开更多
The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted ...The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted during the summer of 2022 in the Changjiang River(Yangtze River) Estuary(CJE) and its adjacent waters.The settling column method was employed to measure the sinking velocity(SV) of different size fractions of phytoplankton at the surface of the sea and to analyze their environmental control mechanisms.The findings reveal significant spatial variation in phytoplankton SV(-0.55-2.41 m/d) within the CJE.High-speed sinking was predominantly observed in phosphate-depleted regions beyond the CJE front.At the same time,an upward trend was more commonly observed in the phosphate-rich regions near the CJE mouth.The SV ranges for different sizefractionated phytoplankton,including micro-(>20 μm),nano-(2-20 μm),and picophytoplankton(0.7-2 μm),were-0.50-4.74 m/d,-1.04-1.59 m/d,and-1.24-1.65 m/d,respectively.Correlation analysis revealed a significant negative correlation between SV and dissolved inorganic phosphorus(DIP),implying that the influence of DIP contributes to SV.The variations in phytoplankton alkaline phosphatase activity suggested a significant increase in SV across all size fractions in the event of phosphorus limitation.Phytoplankton communities with limited photo synthetic capacity(maximum photochemical efficience,Fv/Fm <0.3) were found to have higher SV than that of communities with strong capacity,suggesting a link between sinking and alterations in physiological conditions due to phosphate depletion.The findings from the in situ phosphate enrichment experiments confirmed a marked decrease in SV following phosphate supplementation.These findings suggest that phosphorus limitation is the primary driver of elevated SV in the CJE.This study enhances the comprehension of the potential mechanisms underlying hypoxic zone formation in the CJE,providing novel insights into how nearshore eutrophication influences organic carbon migration.展开更多
China is the largest country in eastern Asia and contains habitats that range from cold temperate to tropical rainforest.The Chinese have a long history of plant cultivation and domestication.Although most cultivated ...China is the largest country in eastern Asia and contains habitats that range from cold temperate to tropical rainforest.The Chinese have a long history of plant cultivation and domestication.Although most cultivated plants in China are native species,many are non-native plants introduced throughout Chinese history for food,medicine,horticulture or ornamental purposes(Xie et al.,2001;Axmacher and Sang,2013).The Catalogue of Alien Plants in China records a total of 14,710 alien plants(Lin and Ma,2022).Among these,some,such as corn and potato,are used as food to meet the demands of China’s large population.Non-native plants that have established populations and colonized local environments are called naturalized plants.Previous studies indicate that the number of naturalized plant species in China ranges from 861(Jiang et al.,2011)to 933(Yan et al.,2019).展开更多
为探究绵羊GDF9基因编码区多态性与繁殖性能的遗传效应,以杜泊羊、滩寒羊、杂一代、杂二代和横交一代5个绵羊群体为研究对象,利用Sequenom Mass ARRAY? SNP技术对5个绵羊群体GDF9基因的4个错义突变位点进行检测,并与产羔数进行关联分析...为探究绵羊GDF9基因编码区多态性与繁殖性能的遗传效应,以杜泊羊、滩寒羊、杂一代、杂二代和横交一代5个绵羊群体为研究对象,利用Sequenom Mass ARRAY? SNP技术对5个绵羊群体GDF9基因的4个错义突变位点进行检测,并与产羔数进行关联分析。结果显示,rs425223128、rs597009987和rs415699275位点基因型均为纯合型,rs160076408位点在5个群体中存在CC、TC、TT等3种基因型。对rs 160076408位点不同基因型与5个群体的产羔数进行关联分析,结果表明,rs160076408位点在杂一代群体中与产羔数有一定的关联性,其中TC基因型产羔数显著高于CC基因型(P<0.05)。可见,rs160076408位点适用于杂一代绵羊群体多羔性状的选育。生物信息学分析表明,绵羊GDF9蛋白理论等电点为9.08,不稳定系数为54.43,为不稳定的碱性蛋白;脂肪系数为77.31,总平均亲水性为-0.404。rs 160076408位点突变前后GDF9蛋白的二级结构类型发生了变化。蛋白质互作网络分析表明,GDF9蛋白与调控动物繁殖的相关蛋白质互作。展开更多
基金The Key R&D Program of Zhejiang under contract No.2023C03120the Science Foundation of Donghai Laboratory under contract No.DH-2022KF0215+2 种基金the National Key Research and Development Program of China under contract No.2021YFC3101702the National Programme on Global Change and Air-Sea Interaction (PhaseⅡ)—Hypoxia and Acidification Monitoring Warning Project in the Changjiang EstuaryLong-term Observation and Research Plan in the Changjiang Estuary and Adjacent East China Sea (LORCE) Project under contract No.SZ2001。
文摘The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient conditions.Our results showed that the SV of T.weissflogii under different nutrient limitation conditions varied substantially.The highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/d.As the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,respectively.Notably;under conditions with limited nitrate and phosphate concentrations,the SV values of T.weissflogii significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,respectively.The change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica contents.The results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure.
基金The National Programme on Global Change and Air-Sea Interaction (PhaseⅡ)—Hypoxia and Acidification Monitoring and Warning Project in the CE under contract No.GASI-01-CJKthe Science Foundation of Donghai Laboratory under contract No.DH-2022KF0215+3 种基金the Oceanic Interdisciplinary Program of Shanghai Jiao Tong UniversityScientific Research Fund of the Second Institute of Oceanography,MNR under contract No.SL2022ZD207the National Key R&D Program of China under contract No.2021YFC3101702the Long-term Observation and Research Plan in the Changjiang Estuary and Adjacent East China Sea (LORCE)Project under contract No.SZ2001。
文摘The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted during the summer of 2022 in the Changjiang River(Yangtze River) Estuary(CJE) and its adjacent waters.The settling column method was employed to measure the sinking velocity(SV) of different size fractions of phytoplankton at the surface of the sea and to analyze their environmental control mechanisms.The findings reveal significant spatial variation in phytoplankton SV(-0.55-2.41 m/d) within the CJE.High-speed sinking was predominantly observed in phosphate-depleted regions beyond the CJE front.At the same time,an upward trend was more commonly observed in the phosphate-rich regions near the CJE mouth.The SV ranges for different sizefractionated phytoplankton,including micro-(>20 μm),nano-(2-20 μm),and picophytoplankton(0.7-2 μm),were-0.50-4.74 m/d,-1.04-1.59 m/d,and-1.24-1.65 m/d,respectively.Correlation analysis revealed a significant negative correlation between SV and dissolved inorganic phosphorus(DIP),implying that the influence of DIP contributes to SV.The variations in phytoplankton alkaline phosphatase activity suggested a significant increase in SV across all size fractions in the event of phosphorus limitation.Phytoplankton communities with limited photo synthetic capacity(maximum photochemical efficience,Fv/Fm <0.3) were found to have higher SV than that of communities with strong capacity,suggesting a link between sinking and alterations in physiological conditions due to phosphate depletion.The findings from the in situ phosphate enrichment experiments confirmed a marked decrease in SV following phosphate supplementation.These findings suggest that phosphorus limitation is the primary driver of elevated SV in the CJE.This study enhances the comprehension of the potential mechanisms underlying hypoxic zone formation in the CJE,providing novel insights into how nearshore eutrophication influences organic carbon migration.
基金supported partly by the National Natural Science Foundation of China (31872645)Special Funds for Chief Scientist of Beijing Botanical Garden (2020-2023)。
文摘China is the largest country in eastern Asia and contains habitats that range from cold temperate to tropical rainforest.The Chinese have a long history of plant cultivation and domestication.Although most cultivated plants in China are native species,many are non-native plants introduced throughout Chinese history for food,medicine,horticulture or ornamental purposes(Xie et al.,2001;Axmacher and Sang,2013).The Catalogue of Alien Plants in China records a total of 14,710 alien plants(Lin and Ma,2022).Among these,some,such as corn and potato,are used as food to meet the demands of China’s large population.Non-native plants that have established populations and colonized local environments are called naturalized plants.Previous studies indicate that the number of naturalized plant species in China ranges from 861(Jiang et al.,2011)to 933(Yan et al.,2019).
