The structures of human telomeric DNA have received much attention due to its significant biological importance.Most studies have focused on G-quadruplex structure formed by short telomeric DNA sequence,but little is ...The structures of human telomeric DNA have received much attention due to its significant biological importance.Most studies have focused on G-quadruplex structure formed by short telomeric DNA sequence,but little is known about the structures of long singlestranded telomeric DNAs.Here,we investigated the structure of DNA with a long sequence of d[AGGG(TTAGGG)6](G6-DNA)and the effect of a single repeat sequence d(TTAGGG)(G01-DNA)on the structure of G6-DNA using sedimentation velocity technique,polyacrylamide gel electrophoresis,circular dichroism spectroscopy,and UV melting experiments.The results suggest that the G6-DNA can form dimers in aqueous solutions and G01-DNA can form additional G-quadruplex structures by binding to G6-DNA.However,G01-DNA has no effect on the structure of DNA with a sequence of d[AGGG(TTAGGG)3](G3-DNA).Our study provides new insights into the structure polymorphism of long human single-stranded telomeric DNA.展开更多
AIM:To investigate the mechanism of liver regeneration induced by fusing the omentum to a small traumatic injury created in the liver. We studied three groups of rats. In one group the rats were omentectomized; in ano...AIM:To investigate the mechanism of liver regeneration induced by fusing the omentum to a small traumatic injury created in the liver. We studied three groups of rats. In one group the rats were omentectomized; in another group the omentum was left in situ and was not activated,and in the third group the omentum was activated by polydextran particles. METHODS:We pre-activated the omentum by injecting polydextran particles and then made a small wedge wound in the rat liver to allow the omentum to fuse to the wound. We monitored the regeneration of the liver by determining the ratio of liver weight/body weight,by histological evaluation (including immune staining for cytokeratin-19,an oval cell marker),and by testing for developmental gene activation using reverse transcription polymerase chain reaction (RT-PCR). RESULTS:There was no liver regeneration in the omentectomized rats,nor was there significant regeneration when the omentum was not activated,even though in this instance the omentum had fusedwith the liver. In contrast,the liver in the rats with the activated omentum expanded to a size 50% greater than the original,and there was histologically an interlying tissue between the wounded liver and the activated omentum in which bile ducts,containing cytokeratin-19 positive oval cells,extended from the wound edge. In this interlying tissue,oval cells were abundant and appeared to proliferate to form new liver tissue. In rats pre-treated with drugs that inhibited hepatocyte growth,liver proliferation was ongoing,indicating that regeneration of the liver was the result of oval cell expansion. CONCLUSION:Activated omentum facilitates liver regeneration following injury by a mechanism that depends largely on oval cell proliferation.展开更多
Scaling theory of charged cylindrical polyelectrolyte brushes is developed. The dependence of brush thickness on the grafting density, charge fraction, and chain length is analyzed. A full phase diagram is established...Scaling theory of charged cylindrical polyelectrolyte brushes is developed. The dependence of brush thickness on the grafting density, charge fraction, and chain length is analyzed. A full phase diagram is established. Characteristics and boundaries between different regimes of cylindrical polyelectrolyte brushes are summarized. Special attentions are paid to electrostatic interaction induced stiffening and counterion condensation effects. If the Bjerrum length of the solution is larger than the Kuhn length of the polyelectrolyte chains, counterion condensation occurs in the strongly charged polyeleetrolyte brushes. On the contrary, the electrostatic interaction stretches the strongly charged grafted polyelectrolyte chains to their contour length.展开更多
基金supported by the National Natural Scientific Foundation of China (No.21674107)the Fundamental Research Funds for the Central Universities (No.WK2340000066)
文摘The structures of human telomeric DNA have received much attention due to its significant biological importance.Most studies have focused on G-quadruplex structure formed by short telomeric DNA sequence,but little is known about the structures of long singlestranded telomeric DNAs.Here,we investigated the structure of DNA with a long sequence of d[AGGG(TTAGGG)6](G6-DNA)and the effect of a single repeat sequence d(TTAGGG)(G01-DNA)on the structure of G6-DNA using sedimentation velocity technique,polyacrylamide gel electrophoresis,circular dichroism spectroscopy,and UV melting experiments.The results suggest that the G6-DNA can form dimers in aqueous solutions and G01-DNA can form additional G-quadruplex structures by binding to G6-DNA.However,G01-DNA has no effect on the structure of DNA with a sequence of d[AGGG(TTAGGG)3](G3-DNA).Our study provides new insights into the structure polymorphism of long human single-stranded telomeric DNA.
基金Supported by An Unrestricted Grant from the Hektoen Institute of Medicine, Chicago, IL USA
文摘AIM:To investigate the mechanism of liver regeneration induced by fusing the omentum to a small traumatic injury created in the liver. We studied three groups of rats. In one group the rats were omentectomized; in another group the omentum was left in situ and was not activated,and in the third group the omentum was activated by polydextran particles. METHODS:We pre-activated the omentum by injecting polydextran particles and then made a small wedge wound in the rat liver to allow the omentum to fuse to the wound. We monitored the regeneration of the liver by determining the ratio of liver weight/body weight,by histological evaluation (including immune staining for cytokeratin-19,an oval cell marker),and by testing for developmental gene activation using reverse transcription polymerase chain reaction (RT-PCR). RESULTS:There was no liver regeneration in the omentectomized rats,nor was there significant regeneration when the omentum was not activated,even though in this instance the omentum had fusedwith the liver. In contrast,the liver in the rats with the activated omentum expanded to a size 50% greater than the original,and there was histologically an interlying tissue between the wounded liver and the activated omentum in which bile ducts,containing cytokeratin-19 positive oval cells,extended from the wound edge. In this interlying tissue,oval cells were abundant and appeared to proliferate to form new liver tissue. In rats pre-treated with drugs that inhibited hepatocyte growth,liver proliferation was ongoing,indicating that regeneration of the liver was the result of oval cell expansion. CONCLUSION:Activated omentum facilitates liver regeneration following injury by a mechanism that depends largely on oval cell proliferation.
基金Supported by National Natural Science Foundation of China under Grant Nos. 20973176,20990234,20874111973 Program of the Ministry of Science and Technology (MOST) 2011CB808502
文摘Scaling theory of charged cylindrical polyelectrolyte brushes is developed. The dependence of brush thickness on the grafting density, charge fraction, and chain length is analyzed. A full phase diagram is established. Characteristics and boundaries between different regimes of cylindrical polyelectrolyte brushes are summarized. Special attentions are paid to electrostatic interaction induced stiffening and counterion condensation effects. If the Bjerrum length of the solution is larger than the Kuhn length of the polyelectrolyte chains, counterion condensation occurs in the strongly charged polyeleetrolyte brushes. On the contrary, the electrostatic interaction stretches the strongly charged grafted polyelectrolyte chains to their contour length.
