The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed th...The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed that this transition coincided with the increase in the atmospheric oxygen level that was key to the evolution of life.Even though ancient redox conditions can be inferred from the composition of sedimentary iron mineral species,this method is not necessarily applicable to all rocks.In the Earth system,the cycling of iron is of considerable interest owing to its sensitivity to redox conditions.Information regarding the paleo-oceanic iron cycle is revealed in the iron isotopic composition of ironbearing minerals.Unfortunately,only limited iron isotopic data exists for Ediacaran-to Cambrianperiod oceans.To circumvent this deficiency,we drilled a fossiliferous Ediacaran to Early Cambrian sedimentary succession in the Three Gorges region,South China.We analyzed the iron isotope ratios(δ^(56/54)Fe)of pyrite grains in the drill cores using laser ablation multi collector inductively coupled plasma mass spectrometry.The results demonstrate large variations inδ^(56/54)Fe,from-1.6 to 1.6‰,and positive iron isotope ratios are observed in many successions.The presence of positiveδ^(56/54)Fe in pyrite indicates that the ferrous iron in the seawater was partially oxidized,suggesting that seawater at Three Gorges was ferruginous during the Ediacaran and Early Cambrian periods.However,aggregated pyrite grains in organic carbon-rich black shales at Member 4 of the Doushantuo Formation and the base of the Shuijingtuo Formation yield near-zeroδ^(56/54)Fe values;this suggests that the ocean was transiently dominated by sulfidic conditions during these periods.Notably negativeδ^(56/54)Fe values,lower than-1‰,can be interpreted as a signature of DIR.The DIR also might contribute in part to the re-mineralization of organic matter during the largest negative carbon isotope anomaly in the Ediacaran.展开更多
We calculate level densities for ^56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction. The results of calculations show that the step structure observed experimentally has been supported by mic...We calculate level densities for ^56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction. The results of calculations show that the step structure observed experimentally has been supported by microscopic theory, Also the S-shaped energy and entropy as function of temperature have been obtained in theoretical calculations. Structures in the curves are interpreted as fingerprints of breaking Cooper pairs and quenching of pairing correlations.展开更多
Decidual natural killer （dNK） cells are believed to be critical for maintaining maternal/fetal tolerance and regulating placental vascular remodeling based upon their abundance and unique phenotype during early preg...Decidual natural killer （dNK） cells are believed to be critical for maintaining maternal/fetal tolerance and regulating placental vascular remodeling based upon their abundance and unique phenotype during early pregnancy. However, the mechanism for how the dNK cells play such important roles in successful pregnancy remains undefined. Here, we identified a subtype of dNK cells characterized as having a CD3-CD56^brightCD25^＋ phenotype. We found that CD56^brightCD25^＋ NK cells preferentially localize to the maternal/fetal interface during early human pregnancy. CD25^＋ dNK cells account for approximately 75% of CD25-expressing decidual immune cells （DICs）. However, less than 5% of CD25-positive peripheral blood mononuclear cells are CD25^＋ NK cells. Furthermore, CD25^＋ and CD25^- dNK cells exhibit distinct phenotypes： CD25^＋ dNK cells display a more activated phenotype and greater cytokine-secreting capacity. Interestingly, coculture of peripheral NK （pNK） cells with primary trophoblasts upregulates the percentage of CD25-expressing pNK cells, resulting in increased expression of activation markers and cytokine production by pNK cells. In addition, we demonstrated that the CXCL12/CXCR4 axis is crucial for the recruitment of CD25^＋ dNK cells and contributes to the accumulation of CD3^-CD56^brightCD25^＋ dNK cells at the maternal/fetal interface. Thus, our data reveal that the crosstalk between trophoblasts and pNK cells leads to the accumulation of CD3^-CD56^brightCD25^＋ dNK cells, which exert a regulating effect at the maternal/fetal interface.展开更多
基金supported by JSPS grants(Nos.24840021,18740318,23340152,25610148) from the Ministry of Education, Culture, Sports, Science and Technology, Japan
文摘The Ediacaran-Cambrian transition is characterized by numerous events such as the emergence of large multi-cellular metazoans and surface environmental disturbances.Based on geological evidence,it has been proposed that this transition coincided with the increase in the atmospheric oxygen level that was key to the evolution of life.Even though ancient redox conditions can be inferred from the composition of sedimentary iron mineral species,this method is not necessarily applicable to all rocks.In the Earth system,the cycling of iron is of considerable interest owing to its sensitivity to redox conditions.Information regarding the paleo-oceanic iron cycle is revealed in the iron isotopic composition of ironbearing minerals.Unfortunately,only limited iron isotopic data exists for Ediacaran-to Cambrianperiod oceans.To circumvent this deficiency,we drilled a fossiliferous Ediacaran to Early Cambrian sedimentary succession in the Three Gorges region,South China.We analyzed the iron isotope ratios(δ^(56/54)Fe)of pyrite grains in the drill cores using laser ablation multi collector inductively coupled plasma mass spectrometry.The results demonstrate large variations inδ^(56/54)Fe,from-1.6 to 1.6‰,and positive iron isotope ratios are observed in many successions.The presence of positiveδ^(56/54)Fe in pyrite indicates that the ferrous iron in the seawater was partially oxidized,suggesting that seawater at Three Gorges was ferruginous during the Ediacaran and Early Cambrian periods.However,aggregated pyrite grains in organic carbon-rich black shales at Member 4 of the Doushantuo Formation and the base of the Shuijingtuo Formation yield near-zeroδ^(56/54)Fe values;this suggests that the ocean was transiently dominated by sulfidic conditions during these periods.Notably negativeδ^(56/54)Fe values,lower than-1‰,can be interpreted as a signature of DIR.The DIR also might contribute in part to the re-mineralization of organic matter during the largest negative carbon isotope anomaly in the Ediacaran.
文摘We calculate level densities for ^56,57 Fe nuclei using BCS hamiltonian with inclusion of pairing interaction. The results of calculations show that the step structure observed experimentally has been supported by microscopic theory, Also the S-shaped energy and entropy as function of temperature have been obtained in theoretical calculations. Structures in the curves are interpreted as fingerprints of breaking Cooper pairs and quenching of pairing correlations.
基金This work was supported by the Key Project of Shanghai Basic Research from Shanghai Municipal Science and Technology Commission （STCSM） （12JC1401600 to DJL）, the Key Project of Shanghai Municipal Education Commission （MECSM） （14ZZ013 to MRD） and the Nature Science Foundation from National Nature Science Foundation of China （NSFC） （NSFC31270969 to DJL NSFC81070537, NSFC31171437 and NSFC81370770 to MRD+1 种基金 NSFC31300751 to HLP NSFC81370730 to QF）.
文摘Decidual natural killer （dNK） cells are believed to be critical for maintaining maternal/fetal tolerance and regulating placental vascular remodeling based upon their abundance and unique phenotype during early pregnancy. However, the mechanism for how the dNK cells play such important roles in successful pregnancy remains undefined. Here, we identified a subtype of dNK cells characterized as having a CD3-CD56^brightCD25^＋ phenotype. We found that CD56^brightCD25^＋ NK cells preferentially localize to the maternal/fetal interface during early human pregnancy. CD25^＋ dNK cells account for approximately 75% of CD25-expressing decidual immune cells （DICs）. However, less than 5% of CD25-positive peripheral blood mononuclear cells are CD25^＋ NK cells. Furthermore, CD25^＋ and CD25^- dNK cells exhibit distinct phenotypes： CD25^＋ dNK cells display a more activated phenotype and greater cytokine-secreting capacity. Interestingly, coculture of peripheral NK （pNK） cells with primary trophoblasts upregulates the percentage of CD25-expressing pNK cells, resulting in increased expression of activation markers and cytokine production by pNK cells. In addition, we demonstrated that the CXCL12/CXCR4 axis is crucial for the recruitment of CD25^＋ dNK cells and contributes to the accumulation of CD3^-CD56^brightCD25^＋ dNK cells at the maternal/fetal interface. Thus, our data reveal that the crosstalk between trophoblasts and pNK cells leads to the accumulation of CD3^-CD56^brightCD25^＋ dNK cells, which exert a regulating effect at the maternal/fetal interface.
