Living coccolithophores(LCs)are regarded as a group of calcifiers and play important roles in global carbon cycle.This study used microscopic observations of LCs in the western Pacific Ocean to investigate their commu...Living coccolithophores(LCs)are regarded as a group of calcifiers and play important roles in global carbon cycle.This study used microscopic observations of LCs in the western Pacific Ocean to investigate their community structure and biodiversity,especially to test whether local physical traits(mesoscale eddies)could explain their biogeographic distributions during autumn of 2017.The coccolithophore calcite inventory based on carbon-volume transformation was estimated in this study.A total of 28 taxa of coccospheres and 19 types of coccoliths were identified from 161 samples.Gephyrocapsa oceanica was the most predominant species in all the coccolithophore community,followed by Florisphaera profunda,Emiliania huxleyi,Umbilicosphaera sibogae,Gladiolithusflabellatus and Umbellosphaera tenuis.The abundance of coccospheres and coccoliths ranged from 0 to 26.8×10^(3)cells/L and from 0 to 138.5×10^(3)coccoliths/L,averaged at 4.2×10^(3)cells/L and 10.9×10^(3)coccoliths/L,respectively.This study indicated that coccolithophore community in the survey area can be clustered into four groups.Three ecological niches of coccolithophores were characterized by their vertical profiles and multivariate statistical analysis.Coccolithophore abundance and species composition were remarkably different among warm-eddy region,G.oceanica dominated warm-eddy region,while F.profunda dominated warm-eddy and none-eddy region.The average values of estimated particulate inorganic carbon,particulate organic carbon were0.197μg/L and 0.140μg/L,respectively.The current field study widened the dataset of coccolithophores in western Pacific Ocean.展开更多
N2 fixation rates(NFR,in terms of N)in the northern South China Sea(nSCS)and the East China Sea(ECS)were measured using the acetylene reduction assay in summer and winter,2009.NFR of the surface water ranged from 1.14...N2 fixation rates(NFR,in terms of N)in the northern South China Sea(nSCS)and the East China Sea(ECS)were measured using the acetylene reduction assay in summer and winter,2009.NFR of the surface water ranged from 1.14 nmol/(L·d)to 10.40 nmol/(L·d)(average at(4.89±3.46)nmol/(L·d),n=11)in summer and 0.74 nmol/(L·d)to 29.45 nmol/(L·d)(average at(7.81±8.50)nmol/(L·d),n=15)in winter.Significant spatio-temporal heterogeneity emerged in our study:the anticyclonic eddies(AE)(P<0.01)and the Kuroshio Current(KC)(P<0.05)performed significantly higher NFR than that in the cyclonic eddies or no-eddy area(CEONE),indicating NFR was profoundly influenced by the physical process of the Kuroshio and mesoscale eddies.The depth-integrated N2 fixation rates(INF,in terms of N)ranged from 52.4μmol/(m2·d)to 905.2μmol/(m2·d)(average at(428.9±305.5)μmol/(m2·d),n=15)in the winter.The contribution of surface NFR to primary production(PP)ranged from 1.7%to 18.5%in the summer,and the mean contribution of INF to new primary production(NPP)in the nSCS and ECS were estimated to be 11.0%and 36.7%in the winter.The contribution of INF to NPP(3.0%–93.9%)also decreased from oligotrophic sea toward the eutrophic waters affected by runoffs or the CEONE.Furthermore,we observed higher contributions compared to previous studies,revealing the vital roles of nitrogen fixation in sustaining the carbon pump of the nSCS and ECS.展开更多
The hypothesis that eukaryotes originated from within the domain Archaea has been strongly supported by recent phylogenomic analyses placing Heimdallarchaeota-Wukongarchaeota branch from the Asgard superphylum as the ...The hypothesis that eukaryotes originated from within the domain Archaea has been strongly supported by recent phylogenomic analyses placing Heimdallarchaeota-Wukongarchaeota branch from the Asgard superphylum as the closest known archaeal sister-group to eukaryotes. However, our understanding is still limited in terms of the relationship between eukaryotes and archaea, as well as the evolution and ecological functions of the Asgard archaea. Here, we describe three previously unknown phylum-level Asgard archaeal lineages, tentatively named Sigyn-, Freyr-and Njordarchaeota. Additional members in Wukongarchaeota and Baldrarchaeota from distinct environments are also reported here, further expanding their ecological roles and metabolic capacities. Comprehensive phylogenomic analyses further supported the origin of eukaryotes within Asgard archaea and a new lineage Njordarchaeota was supposed as the known closest branch with the eukaryotic nuclear host lineage. Metabolic reconstruction suggests that Njordarchaeota may have a heterotrophic lifestyle with capability of peptides and amino acids utilization, while Sigynarchaeota and Freyrarchaeota also have the potentials to fix inorganic carbon via the Wood-Ljungdahl pathway and degrade organic matters. Additionally, the Ack/Pta pathway for homoacetogenesis and de novo anaerobic cobalamin biosynthesis pathway were found in Freyrarchaeota and Wukongrarchaeota,respectively. Some previously unidentified eukaryotic signature proteins for intracellular membrane trafficking system, and the homologue of mu/sigma subunit of adaptor protein complex, were identified in Freyrarchaeota. This study expands the Asgard superphylum, sheds new light on the evolution of eukaryotes and improves our understanding of ecological functions of the Asgard archaea.展开更多
基金The National Natural Science Foundation of China under contract Nos 41876134,41676112,41276124the University Innovation Team Training Program for Tianjin under contract No.TD12-5003+1 种基金the Tianjin 131 Innovation Team Program under contract No.20180314the Changjiang Scholar Program of Chinese Ministry of Education under contract No.T2014253。
文摘Living coccolithophores(LCs)are regarded as a group of calcifiers and play important roles in global carbon cycle.This study used microscopic observations of LCs in the western Pacific Ocean to investigate their community structure and biodiversity,especially to test whether local physical traits(mesoscale eddies)could explain their biogeographic distributions during autumn of 2017.The coccolithophore calcite inventory based on carbon-volume transformation was estimated in this study.A total of 28 taxa of coccospheres and 19 types of coccoliths were identified from 161 samples.Gephyrocapsa oceanica was the most predominant species in all the coccolithophore community,followed by Florisphaera profunda,Emiliania huxleyi,Umbilicosphaera sibogae,Gladiolithusflabellatus and Umbellosphaera tenuis.The abundance of coccospheres and coccoliths ranged from 0 to 26.8×10^(3)cells/L and from 0 to 138.5×10^(3)coccoliths/L,averaged at 4.2×10^(3)cells/L and 10.9×10^(3)coccoliths/L,respectively.This study indicated that coccolithophore community in the survey area can be clustered into four groups.Three ecological niches of coccolithophores were characterized by their vertical profiles and multivariate statistical analysis.Coccolithophore abundance and species composition were remarkably different among warm-eddy region,G.oceanica dominated warm-eddy region,while F.profunda dominated warm-eddy and none-eddy region.The average values of estimated particulate inorganic carbon,particulate organic carbon were0.197μg/L and 0.140μg/L,respectively.The current field study widened the dataset of coccolithophores in western Pacific Ocean.
基金The National Natural Science Foundation of China under contract Nos 41876134 and 41406155the University Innovation Team Training Program for Tianjin under contract No.TD12-5003+3 种基金the Tianjin 131 Innovation Team Program under contract No.20180314the Changjiang Scholar Program of Chinese Ministry of Education to Jun Sun under contract No.T2014253the Tianjin Municipal Education Commission Research Program under contract No.2017KJ012the Open Fund of Tianjin Key Laboratory of Marine Resources and Chemistry under contract Nos 201506 and 201801
文摘N2 fixation rates(NFR,in terms of N)in the northern South China Sea(nSCS)and the East China Sea(ECS)were measured using the acetylene reduction assay in summer and winter,2009.NFR of the surface water ranged from 1.14 nmol/(L·d)to 10.40 nmol/(L·d)(average at(4.89±3.46)nmol/(L·d),n=11)in summer and 0.74 nmol/(L·d)to 29.45 nmol/(L·d)(average at(7.81±8.50)nmol/(L·d),n=15)in winter.Significant spatio-temporal heterogeneity emerged in our study:the anticyclonic eddies(AE)(P<0.01)and the Kuroshio Current(KC)(P<0.05)performed significantly higher NFR than that in the cyclonic eddies or no-eddy area(CEONE),indicating NFR was profoundly influenced by the physical process of the Kuroshio and mesoscale eddies.The depth-integrated N2 fixation rates(INF,in terms of N)ranged from 52.4μmol/(m2·d)to 905.2μmol/(m2·d)(average at(428.9±305.5)μmol/(m2·d),n=15)in the winter.The contribution of surface NFR to primary production(PP)ranged from 1.7%to 18.5%in the summer,and the mean contribution of INF to new primary production(NPP)in the nSCS and ECS were estimated to be 11.0%and 36.7%in the winter.The contribution of INF to NPP(3.0%–93.9%)also decreased from oligotrophic sea toward the eutrophic waters affected by runoffs or the CEONE.Furthermore,we observed higher contributions compared to previous studies,revealing the vital roles of nitrogen fixation in sustaining the carbon pump of the nSCS and ECS.
基金supported by the National Natural Science Foundation of China (91751205, 41921006, 41902313, 92051116)the China Ocean Mineral Resources R&D Association (COMRA) project (DY135-B2-12)+1 种基金the National Key Research and Development Project of China (2018YFC0310803)the Senior User Project of RV KEXUE (KEXUE2019GZ06)
文摘The hypothesis that eukaryotes originated from within the domain Archaea has been strongly supported by recent phylogenomic analyses placing Heimdallarchaeota-Wukongarchaeota branch from the Asgard superphylum as the closest known archaeal sister-group to eukaryotes. However, our understanding is still limited in terms of the relationship between eukaryotes and archaea, as well as the evolution and ecological functions of the Asgard archaea. Here, we describe three previously unknown phylum-level Asgard archaeal lineages, tentatively named Sigyn-, Freyr-and Njordarchaeota. Additional members in Wukongarchaeota and Baldrarchaeota from distinct environments are also reported here, further expanding their ecological roles and metabolic capacities. Comprehensive phylogenomic analyses further supported the origin of eukaryotes within Asgard archaea and a new lineage Njordarchaeota was supposed as the known closest branch with the eukaryotic nuclear host lineage. Metabolic reconstruction suggests that Njordarchaeota may have a heterotrophic lifestyle with capability of peptides and amino acids utilization, while Sigynarchaeota and Freyrarchaeota also have the potentials to fix inorganic carbon via the Wood-Ljungdahl pathway and degrade organic matters. Additionally, the Ack/Pta pathway for homoacetogenesis and de novo anaerobic cobalamin biosynthesis pathway were found in Freyrarchaeota and Wukongrarchaeota,respectively. Some previously unidentified eukaryotic signature proteins for intracellular membrane trafficking system, and the homologue of mu/sigma subunit of adaptor protein complex, were identified in Freyrarchaeota. This study expands the Asgard superphylum, sheds new light on the evolution of eukaryotes and improves our understanding of ecological functions of the Asgard archaea.