The terminus of the Middle America Trench has been traditionally represented as an arc, concave towards the continent. Tres Marías Islands are located at the terminus of the Middle America Trench in western Mexic...The terminus of the Middle America Trench has been traditionally represented as an arc, concave towards the continent. Tres Marías Islands are located at the terminus of the Middle America Trench in western Mexico, and their location is not only intriguing but also a key to the re-construction of the position of Baja California peninsula before separation from the North America plate. Previous re-constructions suggested various places around the location of Tres Marías Islands for the position of the tip of the peninsula, and several converge to a position that invades the area occupied by the islands, offering no explanation for the overlap. Before peninsular separation from North America, the Guadalupe trench followed a smooth curve;recreating the position of this paleo-trench yields a baseline for fixing the position of the peninsula, as well as the original position of the Tres Marías Islands fragment. A new tectonic view of the structure of the Middle America Trench terminus is proposed, replacing the traditional arc representation with a series of en echelon blocks, the northernmost terminates at the Tres Marías Escarpment. The long sides of the blocks correspond to previously identified geological faults in the Bahía de Banderas region, while their offshore continuation is supported by topographic observations. As a test of this model I show the corresponding re-construction of the position of Baja California prior to separation from the North America plate and the positional evolution of the peninsula and the Tres Marías fragment from Chron 4n.2 (7.90 Ma) to Chron 3n.4 (5.12 Ma).展开更多
The E3 ubiquitin ligase,carboxyl terminus of heat shock protein 70(Hsp70)interacting protein(CHIP),also functions as a co-chaperone and plays a crucial role in the protein quality control system.In this study,we aimed...The E3 ubiquitin ligase,carboxyl terminus of heat shock protein 70(Hsp70)interacting protein(CHIP),also functions as a co-chaperone and plays a crucial role in the protein quality control system.In this study,we aimed to investigate the neuroprotective effect of overexpressed CHIP on Alzheimer’s disease.We used an adeno-associated virus vector that can cross the blood-brain barrier to mediate CHIP overexpression in APP/PS1 mouse brain.CHIP overexpression significantly ameliorated the performance of APP/PS1 mice in the Morris water maze and nest building tests,reduced amyloid-βplaques,and decreased the expression of both amyloid-βand phosphorylated tau.CHIP also alleviated the concentration of microglia and astrocytes around plaques.In APP/PS1 mice of a younger age,CHIP overexpression promoted an increase in ADAM10 expression and inhibitedβ-site APP cleaving enzyme 1,insulin degrading enzyme,and neprilysin expression.Levels of HSP70 and HSP40,which have functional relevance to CHIP,were also increased.Single nuclei transcriptome sequencing in the hippocampus of CHIP overexpressed mice showed that the lysosomal pathway and oligodendrocyte-related biological processes were up-regulated,which may also reflect a potential mechanism for the neuroprotective effect of CHIP.Our research shows that CHIP effectively reduces the behavior and pathological manifestations of APP/PS1 mice.Indeed,overexpression of CHIP could be a beneficial approach for the treatment of Alzheimer’s disease.展开更多
Glacier response patterns at the catchment scale are highly heterogeneous and defined by a complex interplay of various dynamics and surface factors.Previous studies have explained heterogeneous responses in qualitati...Glacier response patterns at the catchment scale are highly heterogeneous and defined by a complex interplay of various dynamics and surface factors.Previous studies have explained heterogeneous responses in qualitative ways but quantitative assessment is lacking yet where an intrazone homogeneous climate assumption can be valid.Hence,in the current study,the reason for heterogeneous mass balance has been explained in quantitative methods using a multiple linear regression model in the Sikkim Himalayan region.At first,the topographical parameters are selected from previously published studies,then the most significant topographical and geomorphological parameters are selected with backward stepwise subset selection methods.Finally,the contributions of selected parameters are calculated by least square methods.The results show that,the magnitude of mass balance lies between-0.003±0.24 to-1.029±0.24 m.w.e.a^(-1) between 2000 and 2020 in the Sikkim Himalaya region.Also,the study shows that,out of the terminus type of the glacier,glacier area,debris cover,ice-mixed debris,slope,aspect,mean elevation,and snout elevation of the glaciers,only the terminus type and mean elevation of the glacier are significantly altering the glacier mass balance in the Sikkim Himalayan region.Mathematically,the mass loss is approximately 0.40 m.w.e.a^(-1) higher in the lake-terminating glaciers compared to the land-terminating glaciers in the same elevation zone.On the other hand,a thousand meters mean elevation drop is associated with 0.179 m.w.e.a-1of mass loss despite the terminus type of the glaciers.In the current study,the model using the terminus type of the glaciers and the mean elevation of the glaciers explains 76% of fluctuation of mass balance in the Sikkim Himalayan region.展开更多
Topography plays an important role in determining the glacier changes.However,topography has often been oversimplified in the studies of the glacier changes.No systematic studies have been conducted to evaluate the re...Topography plays an important role in determining the glacier changes.However,topography has often been oversimplified in the studies of the glacier changes.No systematic studies have been conducted to evaluate the relationship between the glacier changes and topographic features.The present study provided a detailed insight into the changes in the two branches(east branch and west branch)of Urumqi Glacier No.1 in the Chinese Tianshan Mountains since 1993 and systematically discussed the effect of topography on the glacier parameters.This study analyzed comprehensive recently observed data(from 1992/1993 to 2018/2019),including mass balance,ice thickness,surface elevation,ice velocity,terminus,and area,and then determined the differences in the changes of the two branches and explored the effect of topography on the glacier changes.We also applied a topographic solar radiation model to analyze the influence of topography on the incoming shortwave radiation(SW_(in))across the entire glacier,focusing on the difference in the SW_(in) between the two branches.The glacier mass balance of the east branch was more negative than that of the west branch from 1992/1993 to 2018/2019,and this was mainly attributed to the lower average altitude of the east branch.Compared with the west branch,the decrease rate of the ice velocity was lower in the east branch owing to its relatively increased slope.The narrow shape of the west branch and its southeast aspect in the earlier period resulted in a larger glacier terminus retreat of the west branch.The spatial variability of the SW_(in) across the glacier surface became much larger as altitude increased.The SW_(in) received by the east branch was slightly larger than that received by the west branch,and the northern aspect could receive more SW_(in),leading to glacier melting.In the future,the difference of the glacier changes between the two branches will continue to exist due to their topographic differences.This work is fundamental to understanding how topographic features affect the glacier changes,and provides information for building different types of relationship between the glacier area and ice volume to promote further studies on the basin-scale glacier classification.展开更多
Numerous strategies for linking desired chemical probes with target peptides and proteins have been developed and applied in the field of biological chemistry.Approaches for site-specific modification of native amino ...Numerous strategies for linking desired chemical probes with target peptides and proteins have been developed and applied in the field of biological chemistry.Approaches for site-specific modification of native amino acid residues in test tubes and biological contexts represent novel biological tools for understanding the role of peptides and proteins.Selective N-terminal modification strategies have been broadly studied especially in the last 10 years,as N-terminal positions are typically solvent exposed and provide chemically distinct sites for many peptide and protein targets,making N terminus distinct from other functional groups.A growing number of chemical and enzymatic techniques have been developed to modify N-terminal amino acids,and those techniques have the potential in the fields of medicine,basic research and applied materials science.This review focuses on appraising modification methodologies with the potential for biological applications from the past 10 years.展开更多
Group II chaperonins,which assemble as double-ring complexes,assist in the refolding of nascent peptides or denatured proteins in an ATP-dependent manner.The mo-lecular mechanism of group II chaperonin assembly and th...Group II chaperonins,which assemble as double-ring complexes,assist in the refolding of nascent peptides or denatured proteins in an ATP-dependent manner.The mo-lecular mechanism of group II chaperonin assembly and thermal stability is yet to be elucidated.Here,we selected the group II chaperonins(cpn-αand cpn-β),also called thermosomes,from Acidianus tengchongensis and in-vestigated their assembly and thermal stability.We found that the binding of ATP or its analogs contributed to the successful assembly of thermosomes and enhanced their thermal stabilities.Cpn-βis more thermally stable than cpn-α,while the thermal stability of the hetero thermo-some cpn-αβis intermediate.Cryo-electron microscopy reconstructions of cpn-αand cpn-βrevealed the interwo-ven densities of their non-conserved fl exible N/C-termini around the equatorial planes.The deletion or swapping of their termini and pH-dependent thermal stability assays revealed the key role of the termini electrostatic interac-tions in the assembly and thermal stability of the ther-mosomes.展开更多
文摘The terminus of the Middle America Trench has been traditionally represented as an arc, concave towards the continent. Tres Marías Islands are located at the terminus of the Middle America Trench in western Mexico, and their location is not only intriguing but also a key to the re-construction of the position of Baja California peninsula before separation from the North America plate. Previous re-constructions suggested various places around the location of Tres Marías Islands for the position of the tip of the peninsula, and several converge to a position that invades the area occupied by the islands, offering no explanation for the overlap. Before peninsular separation from North America, the Guadalupe trench followed a smooth curve;recreating the position of this paleo-trench yields a baseline for fixing the position of the peninsula, as well as the original position of the Tres Marías Islands fragment. A new tectonic view of the structure of the Middle America Trench terminus is proposed, replacing the traditional arc representation with a series of en echelon blocks, the northernmost terminates at the Tres Marías Escarpment. The long sides of the blocks correspond to previously identified geological faults in the Bahía de Banderas region, while their offshore continuation is supported by topographic observations. As a test of this model I show the corresponding re-construction of the position of Baja California prior to separation from the North America plate and the positional evolution of the peninsula and the Tres Marías fragment from Chron 4n.2 (7.90 Ma) to Chron 3n.4 (5.12 Ma).
基金supported by the National Natural Science Foundation of China,Nos.91849115 and U1904207(to YX),81974211 and 82171247(to CS)and Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences,No.2020-PT310-01(to YX).
文摘The E3 ubiquitin ligase,carboxyl terminus of heat shock protein 70(Hsp70)interacting protein(CHIP),also functions as a co-chaperone and plays a crucial role in the protein quality control system.In this study,we aimed to investigate the neuroprotective effect of overexpressed CHIP on Alzheimer’s disease.We used an adeno-associated virus vector that can cross the blood-brain barrier to mediate CHIP overexpression in APP/PS1 mouse brain.CHIP overexpression significantly ameliorated the performance of APP/PS1 mice in the Morris water maze and nest building tests,reduced amyloid-βplaques,and decreased the expression of both amyloid-βand phosphorylated tau.CHIP also alleviated the concentration of microglia and astrocytes around plaques.In APP/PS1 mice of a younger age,CHIP overexpression promoted an increase in ADAM10 expression and inhibitedβ-site APP cleaving enzyme 1,insulin degrading enzyme,and neprilysin expression.Levels of HSP70 and HSP40,which have functional relevance to CHIP,were also increased.Single nuclei transcriptome sequencing in the hippocampus of CHIP overexpressed mice showed that the lysosomal pathway and oligodendrocyte-related biological processes were up-regulated,which may also reflect a potential mechanism for the neuroprotective effect of CHIP.Our research shows that CHIP effectively reduces the behavior and pathological manifestations of APP/PS1 mice.Indeed,overexpression of CHIP could be a beneficial approach for the treatment of Alzheimer’s disease.
文摘Glacier response patterns at the catchment scale are highly heterogeneous and defined by a complex interplay of various dynamics and surface factors.Previous studies have explained heterogeneous responses in qualitative ways but quantitative assessment is lacking yet where an intrazone homogeneous climate assumption can be valid.Hence,in the current study,the reason for heterogeneous mass balance has been explained in quantitative methods using a multiple linear regression model in the Sikkim Himalayan region.At first,the topographical parameters are selected from previously published studies,then the most significant topographical and geomorphological parameters are selected with backward stepwise subset selection methods.Finally,the contributions of selected parameters are calculated by least square methods.The results show that,the magnitude of mass balance lies between-0.003±0.24 to-1.029±0.24 m.w.e.a^(-1) between 2000 and 2020 in the Sikkim Himalaya region.Also,the study shows that,out of the terminus type of the glacier,glacier area,debris cover,ice-mixed debris,slope,aspect,mean elevation,and snout elevation of the glaciers,only the terminus type and mean elevation of the glacier are significantly altering the glacier mass balance in the Sikkim Himalayan region.Mathematically,the mass loss is approximately 0.40 m.w.e.a^(-1) higher in the lake-terminating glaciers compared to the land-terminating glaciers in the same elevation zone.On the other hand,a thousand meters mean elevation drop is associated with 0.179 m.w.e.a-1of mass loss despite the terminus type of the glaciers.In the current study,the model using the terminus type of the glaciers and the mean elevation of the glaciers explains 76% of fluctuation of mass balance in the Sikkim Himalayan region.
基金jointly funded by the Third Xinjiang Scientific Expedition Program (2021xjkk0801)the Youth Innovation Promotion Association of Chinese Academy of Sciences (Y2021110)the State Key Laboratory of Cryospheric Science (SKLCS-ZZ-2022)
文摘Topography plays an important role in determining the glacier changes.However,topography has often been oversimplified in the studies of the glacier changes.No systematic studies have been conducted to evaluate the relationship between the glacier changes and topographic features.The present study provided a detailed insight into the changes in the two branches(east branch and west branch)of Urumqi Glacier No.1 in the Chinese Tianshan Mountains since 1993 and systematically discussed the effect of topography on the glacier parameters.This study analyzed comprehensive recently observed data(from 1992/1993 to 2018/2019),including mass balance,ice thickness,surface elevation,ice velocity,terminus,and area,and then determined the differences in the changes of the two branches and explored the effect of topography on the glacier changes.We also applied a topographic solar radiation model to analyze the influence of topography on the incoming shortwave radiation(SW_(in))across the entire glacier,focusing on the difference in the SW_(in) between the two branches.The glacier mass balance of the east branch was more negative than that of the west branch from 1992/1993 to 2018/2019,and this was mainly attributed to the lower average altitude of the east branch.Compared with the west branch,the decrease rate of the ice velocity was lower in the east branch owing to its relatively increased slope.The narrow shape of the west branch and its southeast aspect in the earlier period resulted in a larger glacier terminus retreat of the west branch.The spatial variability of the SW_(in) across the glacier surface became much larger as altitude increased.The SW_(in) received by the east branch was slightly larger than that received by the west branch,and the northern aspect could receive more SW_(in),leading to glacier melting.In the future,the difference of the glacier changes between the two branches will continue to exist due to their topographic differences.This work is fundamental to understanding how topographic features affect the glacier changes,and provides information for building different types of relationship between the glacier area and ice volume to promote further studies on the basin-scale glacier classification.
基金supported by Shandong Provincial Natural Science Foundation,China(No.ZR2020QC081,H.Jiang)Youth Innovation Team Talent Introduction Program of Shandong Province(No.20190164,R.Zhang and H.Jiang)。
文摘Numerous strategies for linking desired chemical probes with target peptides and proteins have been developed and applied in the field of biological chemistry.Approaches for site-specific modification of native amino acid residues in test tubes and biological contexts represent novel biological tools for understanding the role of peptides and proteins.Selective N-terminal modification strategies have been broadly studied especially in the last 10 years,as N-terminal positions are typically solvent exposed and provide chemically distinct sites for many peptide and protein targets,making N terminus distinct from other functional groups.A growing number of chemical and enzymatic techniques have been developed to modify N-terminal amino acids,and those techniques have the potential in the fields of medicine,basic research and applied materials science.This review focuses on appraising modification methodologies with the potential for biological applications from the past 10 years.
文摘Group II chaperonins,which assemble as double-ring complexes,assist in the refolding of nascent peptides or denatured proteins in an ATP-dependent manner.The mo-lecular mechanism of group II chaperonin assembly and thermal stability is yet to be elucidated.Here,we selected the group II chaperonins(cpn-αand cpn-β),also called thermosomes,from Acidianus tengchongensis and in-vestigated their assembly and thermal stability.We found that the binding of ATP or its analogs contributed to the successful assembly of thermosomes and enhanced their thermal stabilities.Cpn-βis more thermally stable than cpn-α,while the thermal stability of the hetero thermo-some cpn-αβis intermediate.Cryo-electron microscopy reconstructions of cpn-αand cpn-βrevealed the interwo-ven densities of their non-conserved fl exible N/C-termini around the equatorial planes.The deletion or swapping of their termini and pH-dependent thermal stability assays revealed the key role of the termini electrostatic interac-tions in the assembly and thermal stability of the ther-mosomes.
