Cell migration is an important biological process regulated by mechanical stimulation,which leads to intracellular calcium response.Cell migration are dependent on the distribution and dynamic changes of intracellular...Cell migration is an important biological process regulated by mechanical stimulation,which leads to intracellular calcium response.Cell migration are dependent on the distribution and dynamic changes of intracellular calcium concentration.However,the temporal relation among mechanical stimulation,cell migration,and intracellular calcium distribution remains unclear.In this study,unidirectional flow and oscillatory flow were applied on osteoclast precursor RAW264.7 cells.The parameters of cell migration under fluid flow and intracellular calcium distribution along the migration or flow direction were calculated.Experimental results suggest the cells to adjust the[Ca^(2+)]i distribution in the migration direction is independent of flow application or the reverse of flow direction,but the[Ca^(2+)]i distribution in the flow direction is determined by the[Ca^(2+)]i distribution-adjusting ability of cells and flow stimulation.Blocking calcium signaling pathways,namely,mechanosensitive cationselective channels,phospholipase C,and endoplasmic reticulum,and removing extracellular calcium inhibited cell migration along the flow direction and the gradient distribution of intracellular calcium.This study provided insights into the mechanism of flow-induced cell migration and quantitative data for the recruitment of osteoclast precursors targeting the location of bone resorption.展开更多
This work focuses on gene regulatory networks driven by intrinsic noise with two-time scales. It uses a stochastic averaging approach for these systems to reduce complexity. Comparing with the traditional quasi-steady...This work focuses on gene regulatory networks driven by intrinsic noise with two-time scales. It uses a stochastic averaging approach for these systems to reduce complexity. Comparing with the traditional quasi-steady- state hypothesis （QSSH）, our approach uses stochastic averaging principle to treat the intrinsic noise coming from both the fast-changing variables and the slow-changing variables, which yields a more precise description of the underlying systems. To provide further insight, this paper also investigates a prototypical two-component activator-repressor genetic circuit model as an example. If all the protein productions were linear, these two methods would yield the same reduction result. However, if one of the protein productions is nonlinear, the stochastic averaging principle leads to a different reduction result from that of the traditional QSSH.展开更多
The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis, Dunaliella salina, Dunaliella bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower...The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis, Dunaliella salina, Dunaliella bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower concentrations of selenite were generally nontoxic and frequently stimulated algal growth, while higher concentrations of selenite inhibited algal growth. Selenite was more toxic to D. salina and D. bardawill than to S. platensis and P. tricornutum . All algae cultured in selenite were able to incorporate Se to different degrees, which depended on algal species. The distributions of selenite among intracellular macromolecular compounds were different among algal species: most of the selenite was associated with proteins in S. platensis, D. salina and D. bardawill , while most of the selenite was associated with lipids in P. tricornutum , which reflected the physiological differences among the algae. These observations suggest that algae are able to accumulate selenite and bind it with intracellular macromolecular compounds when exposed to high concentration of selenite. This may represent a form of storage or detoxification of selenite by the algae.展开更多
基金supported by the National Natural Science Foundation of China[12072034(BH),11572043(BH)].
文摘Cell migration is an important biological process regulated by mechanical stimulation,which leads to intracellular calcium response.Cell migration are dependent on the distribution and dynamic changes of intracellular calcium concentration.However,the temporal relation among mechanical stimulation,cell migration,and intracellular calcium distribution remains unclear.In this study,unidirectional flow and oscillatory flow were applied on osteoclast precursor RAW264.7 cells.The parameters of cell migration under fluid flow and intracellular calcium distribution along the migration or flow direction were calculated.Experimental results suggest the cells to adjust the[Ca^(2+)]i distribution in the migration direction is independent of flow application or the reverse of flow direction,but the[Ca^(2+)]i distribution in the flow direction is determined by the[Ca^(2+)]i distribution-adjusting ability of cells and flow stimulation.Blocking calcium signaling pathways,namely,mechanosensitive cationselective channels,phospholipase C,and endoplasmic reticulum,and removing extracellular calcium inhibited cell migration along the flow direction and the gradient distribution of intracellular calcium.This study provided insights into the mechanism of flow-induced cell migration and quantitative data for the recruitment of osteoclast precursors targeting the location of bone resorption.
文摘This work focuses on gene regulatory networks driven by intrinsic noise with two-time scales. It uses a stochastic averaging approach for these systems to reduce complexity. Comparing with the traditional quasi-steady- state hypothesis （QSSH）, our approach uses stochastic averaging principle to treat the intrinsic noise coming from both the fast-changing variables and the slow-changing variables, which yields a more precise description of the underlying systems. To provide further insight, this paper also investigates a prototypical two-component activator-repressor genetic circuit model as an example. If all the protein productions were linear, these two methods would yield the same reduction result. However, if one of the protein productions is nonlinear, the stochastic averaging principle leads to a different reduction result from that of the traditional QSSH.
文摘The toxicity and bioaccumulation of selenite in four microalgae, Spirulina platensis, Dunaliella salina, Dunaliella bardawill and Phaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower concentrations of selenite were generally nontoxic and frequently stimulated algal growth, while higher concentrations of selenite inhibited algal growth. Selenite was more toxic to D. salina and D. bardawill than to S. platensis and P. tricornutum . All algae cultured in selenite were able to incorporate Se to different degrees, which depended on algal species. The distributions of selenite among intracellular macromolecular compounds were different among algal species: most of the selenite was associated with proteins in S. platensis, D. salina and D. bardawill , while most of the selenite was associated with lipids in P. tricornutum , which reflected the physiological differences among the algae. These observations suggest that algae are able to accumulate selenite and bind it with intracellular macromolecular compounds when exposed to high concentration of selenite. This may represent a form of storage or detoxification of selenite by the algae.
基金supported by the National Natural Science Foundation of China (51120135001)Department of Education of Zhejiang Province(Z201018687)the National Basic Research Program of China(2011CB606203)
