A unicellular cyanobacterium Synechococcus sp. strain PCC 7002 was transformedwith plasmid pQL1, on which β-lactamase gene (bla) and β-galactosidase gene (lacZ) were encoded.The transformant cells released β-lactam...A unicellular cyanobacterium Synechococcus sp. strain PCC 7002 was transformedwith plasmid pQL1, on which β-lactamase gene (bla) and β-galactosidase gene (lacZ) were encoded.The transformant cells released β-lactamase into medium by an abrupt drop of osmotic pressure. This re-sult indicates that this cyanobacterium recognizes and processes the signal sequence of β-lactamase, andaccumulates the enzyme in periplasm. Repeated release of β-lactamase was possible by repeated osmoticshocks without impairing cell viability. On the other hand, most of the β-galactosidase remained in cyto-plasm under the osmotic shock.展开更多
The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), ...The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), butmarkably inhibited by abrupt hyperosmotic shock (2.0mol/L → 3.5 mol/L NaCl) and hypoosmotic shock (2.0mol/L → 1.0 mol/L NaCl; 2.0 mol/L→0.67 mol/L NaCl).With the adaptation of algal cells to osmotic shock by accumulating or degrading intracellular glycerol, the plasmalemma redox activities were also restored. The O2 uptake stimulated by NADH could be promoted by FA and SHAM. Hypoosmotic shock increases the basal respiration rate of alga cells, but weakened the stimulating effects of NADH, FA and SHAM on O2 uptake. On the other hand, hyperosmotic shock reduced the basal respiration rate, but relatively enhanced the above effects of NADH, FA and SHAM. H+ extrusion of alga cells was inhibited by NADH and stimulated by Fe(CN)63- Vanadate and DES could inhibit H+ efflux, but had little effect in the presence of NADH and Fe(CN)63-. Both hyperand hypoosmotic shock stimulated H+ extrusion. This effect could be totally inhibited by vanadate and DES, but almost unaffected by 8-hydroxyquinoline. It was suggested that H+-ATPase probably played a more important role in H+ extrusion and osmoregulation under the conditions of osmotic shock.展开更多
In cryopreservation,the addition of cryoprotectant can change the intra-and extra-cellular osmotic pressure,affect the cell morphology,and induce blebs on the plasma membrane.In this study,the blebs of cells microenca...In cryopreservation,the addition of cryoprotectant can change the intra-and extra-cellular osmotic pressure,affect the cell morphology,and induce blebs on the plasma membrane.In this study,the blebs of cells microencapsulated in the alginate microsphere induced by osmotic shock were studied,and the effects of microencapsulation on bleb size and cell viability were determined.Firstly,a coaxial co-flow focusing device was applied to generate cell-laden microcapsules using alginate hydrogel in this paper.Then,cellular blebs induced by DMSO with various concentrations under microencapsulation were compared with that when non-encapsulated,and the dynamic process of cellular bleb was investigated.Finally,the qualitative relationship between bleb size and cell viability in the presence of DMSO was built,and thus the effects of microencapsulation on bleb size and viability were evaluated.The results show that the bleb size is smaller and the cell viability is higher,and cell microencapsulation can significantly inhibit the excessively large blebs generated on the cell membrane and reduce the osmotic damage to cells when loading cryoprotectant and then to improve cell viability during cryopreservation.This work can provide insights for optimizing cryoprotectant-loading protocols,offer a new avenue to study cell blebbing,and advance future research on cryopreservation of rare cells and biomaterials.展开更多
Both the mechanosensitive actin cytoskeleton and caveolae contribute to active processes such as cell migration,morphogenesis,and vesicular trafficking.Although distinct actin components are well studied,how they cont...Both the mechanosensitive actin cytoskeleton and caveolae contribute to active processes such as cell migration,morphogenesis,and vesicular trafficking.Although distinct actin components are well studied,how they contribute to cytoplasmic caveolae,especially in the context of mechano-stress,has remained elusive.Here,we identify two actin-associated mobility stereotypes of caveolin-1(CAV-1)-marked intracellular vesicles,which are characterized as‘dwelling’and‘go and dwelling’.In order to exploit the reason for their distinct dynamics,elongated actin-associated formin functions are perturbed.We find drastically decreased density,increased clustering,and compromised motility of cytoplasmic CAV-1 vesicles resulting from lacking actin nucleator formins by both chemical treatment and RNA silencing of formin genes.Furthermore,hypo-osmosis-stimulated diminishing of CAV-1 is dramatically intensified upon blocking formins.The clustering of CAV-1 vesicles when cells are cultured on soft substrate is also aggravated under formin inhibition condition.Together,we reveal that actin-associated formins are essential for maintaining the dynamic organization of cytoplasmic CAV-1 and importantly its sensitivity upon mechanical challenge.We conclude that tension-controlled actin formins act as a safety valve dampening excessive tension on CAV-1 and safeguarding CAV-1 against mechanical damage.展开更多
文摘A unicellular cyanobacterium Synechococcus sp. strain PCC 7002 was transformedwith plasmid pQL1, on which β-lactamase gene (bla) and β-galactosidase gene (lacZ) were encoded.The transformant cells released β-lactamase into medium by an abrupt drop of osmotic pressure. This re-sult indicates that this cyanobacterium recognizes and processes the signal sequence of β-lactamase, andaccumulates the enzyme in periplasm. Repeated release of β-lactamase was possible by repeated osmoticshocks without impairing cell viability. On the other hand, most of the β-galactosidase remained in cyto-plasm under the osmotic shock.
文摘The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), butmarkably inhibited by abrupt hyperosmotic shock (2.0mol/L → 3.5 mol/L NaCl) and hypoosmotic shock (2.0mol/L → 1.0 mol/L NaCl; 2.0 mol/L→0.67 mol/L NaCl).With the adaptation of algal cells to osmotic shock by accumulating or degrading intracellular glycerol, the plasmalemma redox activities were also restored. The O2 uptake stimulated by NADH could be promoted by FA and SHAM. Hypoosmotic shock increases the basal respiration rate of alga cells, but weakened the stimulating effects of NADH, FA and SHAM on O2 uptake. On the other hand, hyperosmotic shock reduced the basal respiration rate, but relatively enhanced the above effects of NADH, FA and SHAM. H+ extrusion of alga cells was inhibited by NADH and stimulated by Fe(CN)63- Vanadate and DES could inhibit H+ efflux, but had little effect in the presence of NADH and Fe(CN)63-. Both hyperand hypoosmotic shock stimulated H+ extrusion. This effect could be totally inhibited by vanadate and DES, but almost unaffected by 8-hydroxyquinoline. It was suggested that H+-ATPase probably played a more important role in H+ extrusion and osmoregulation under the conditions of osmotic shock.
基金partially supported by the National Natural Science Foundation of China (81571768)
文摘In cryopreservation,the addition of cryoprotectant can change the intra-and extra-cellular osmotic pressure,affect the cell morphology,and induce blebs on the plasma membrane.In this study,the blebs of cells microencapsulated in the alginate microsphere induced by osmotic shock were studied,and the effects of microencapsulation on bleb size and cell viability were determined.Firstly,a coaxial co-flow focusing device was applied to generate cell-laden microcapsules using alginate hydrogel in this paper.Then,cellular blebs induced by DMSO with various concentrations under microencapsulation were compared with that when non-encapsulated,and the dynamic process of cellular bleb was investigated.Finally,the qualitative relationship between bleb size and cell viability in the presence of DMSO was built,and thus the effects of microencapsulation on bleb size and viability were evaluated.The results show that the bleb size is smaller and the cell viability is higher,and cell microencapsulation can significantly inhibit the excessively large blebs generated on the cell membrane and reduce the osmotic damage to cells when loading cryoprotectant and then to improve cell viability during cryopreservation.This work can provide insights for optimizing cryoprotectant-loading protocols,offer a new avenue to study cell blebbing,and advance future research on cryopreservation of rare cells and biomaterials.
基金This study was supported by grants from the National Natural Science Foundation of China(92054104 and 31970660)CAS–VPST Silk Road Science Fund 2021(GJHZ2021138)+2 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX02)Natural Science Foundation of Shanghai(19ZR1463000)‘100 Talents Program’from the Chinese Academy of Sciences.
文摘Both the mechanosensitive actin cytoskeleton and caveolae contribute to active processes such as cell migration,morphogenesis,and vesicular trafficking.Although distinct actin components are well studied,how they contribute to cytoplasmic caveolae,especially in the context of mechano-stress,has remained elusive.Here,we identify two actin-associated mobility stereotypes of caveolin-1(CAV-1)-marked intracellular vesicles,which are characterized as‘dwelling’and‘go and dwelling’.In order to exploit the reason for their distinct dynamics,elongated actin-associated formin functions are perturbed.We find drastically decreased density,increased clustering,and compromised motility of cytoplasmic CAV-1 vesicles resulting from lacking actin nucleator formins by both chemical treatment and RNA silencing of formin genes.Furthermore,hypo-osmosis-stimulated diminishing of CAV-1 is dramatically intensified upon blocking formins.The clustering of CAV-1 vesicles when cells are cultured on soft substrate is also aggravated under formin inhibition condition.Together,we reveal that actin-associated formins are essential for maintaining the dynamic organization of cytoplasmic CAV-1 and importantly its sensitivity upon mechanical challenge.We conclude that tension-controlled actin formins act as a safety valve dampening excessive tension on CAV-1 and safeguarding CAV-1 against mechanical damage.
