Homozygous human embryonic stem cells （hESCs） are thought to be better cell sources for hESC banking because their human leukocyte antigen （HLA） haplotype would strongly increase the degree of matching for certain...Homozygous human embryonic stem cells （hESCs） are thought to be better cell sources for hESC banking because their human leukocyte antigen （HLA） haplotype would strongly increase the degree of matching for certain populations with relatively smaller cohorts of cell lines. Homozygous hESCs can be generated from parthenogenetic embryos, but only heterozygous hESCs have been established using the current strategy to artificially activate the oocyte without second polar body extrusion. Here we report the first successful derivation of a human homozygous ESC line （chHES- 32） from a one-pronuclear oocyte following routine in vitro fertilization treatment, chHES-32 cells express common markers and genes with normal hESCs. They have been propagated in an undifferentiated state for more than a year （〉P50） and have maintained a stable karyotype of 46, XX. When differentiated in vivo and in vitro, chHES-32 cells can form derivatives from all three embryonic germ layers. The almost undetectable expression of five paternally expressed imprinted genes and their HLA genotype identical to the oocyte donor indicated their parthenogenetic origin. Using genome-wide single-nucleotide polymorphism analysis and DNA fingerprinting, the homozygosity of chHES-32 cells was further confirmed. The results indicated that ‘ unwanted＇ one-pronuclear oocytes might be a potential source for human homozygous and parthenogenetic ESCs, and suggested an alternative strategyfor obtaining homozygous hESC lines from parthenogenetic haploid oocytes.展开更多
The native protein structures in buffer solution are maintained by the electrostatic force as well as the hydrophobic force, salt ions play an important role in maintaining the protein native structures, and their eff...The native protein structures in buffer solution are maintained by the electrostatic force as well as the hydrophobic force, salt ions play an important role in maintaining the protein native structures, and their effect on the protein stability has attracted tremendous interests. Infrared spectroscopy has been generally used in molecular structure analysis due to its fingerprint resolution for different species including macromolecules as proteins. However spectral intensities have received much less attention than the vibrational frequencies. Here we report that the spectral intensities of protein amide I band, the finger prints for the protein secondary structures, are very sensitive to the local electric field known as Onsager reaction field caused by salt ions. IR absorbance thermal titrations have been conducted for a series of samples including simple water soluble amino acids, water soluble monomeric protein cytochrome c and dimeric protein DsbC and its single-site mutant G49R. We found that at lower temperature range （10-20℃）, there exists a thermal activated salting-in process, where the IR intensity increases with a rise in the temperature, corresponding to the ions binding of the hydrophobic surface of protein. This process is absent for the amino acids. When further raising the temperature, the IR intensity decreases, this is interpreted as the thermal activated breaking of the ion-protein surface binding. Applying Van＇t Hoff plot to the thermal titration curves, the thermodynamic parameters such as AH and AS for salting-in and ion unbinding processes can be derived for various protein secondary structural components, revealing quantitatively the extent of hydrophobic interaction as well as the strength of the ion-protein binding.展开更多
The possibilities of changes of ORP （oxidation-reduction water potential） with the help of chemical and physical-chemical methods were explored. Distillation and membrane technology were used as physical-chemical me...The possibilities of changes of ORP （oxidation-reduction water potential） with the help of chemical and physical-chemical methods were explored. Distillation and membrane technology were used as physical-chemical methods. In the case of application of chemical methods well-soluble substances were added into water. It was ascertained that the application of membrane technology makes it possible to obtain antioxidant water with negative ORR. Different energy change in a time unit can be applied in a whole number of technological processes and reveals new possibilities for many branches of industry.展开更多
In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. The ability to dope graphene with electron-donor nitrogen heteroatoms is highly important for modulating electrical proper...In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. The ability to dope graphene with electron-donor nitrogen heteroatoms is highly important for modulating electrical properties of graphene. Here we demonstrate a transfer-free method to directly grow large area quasi free-standing N-doped graphene bilayers on an insulating substrate （Si3N4）. Electron-bombardment heating under nitrogen flux results in simultaneous growth of N-doped graphene and a Si3N4 layer on the SiC surface. The decoupling of N-doped graphene from the substrate and the presence of Si3N4 are identified by X-ray photoemission spectroscopy and low-energy electron diffraction. The substitution of nitrogen atoms in the graphene planes was confirmed using high resolution X-ray photoemission spectroscopy which reveals several atomic configurations for the nitrogen atoms： Graphitic-like, pyridine-like, and pyrrolic- like. Furthermore, we demonstrated for the first time that N-doped graphene could be used to efficiently probe oxygen molecules via nitrogen atom defects.展开更多
文摘Homozygous human embryonic stem cells （hESCs） are thought to be better cell sources for hESC banking because their human leukocyte antigen （HLA） haplotype would strongly increase the degree of matching for certain populations with relatively smaller cohorts of cell lines. Homozygous hESCs can be generated from parthenogenetic embryos, but only heterozygous hESCs have been established using the current strategy to artificially activate the oocyte without second polar body extrusion. Here we report the first successful derivation of a human homozygous ESC line （chHES- 32） from a one-pronuclear oocyte following routine in vitro fertilization treatment, chHES-32 cells express common markers and genes with normal hESCs. They have been propagated in an undifferentiated state for more than a year （〉P50） and have maintained a stable karyotype of 46, XX. When differentiated in vivo and in vitro, chHES-32 cells can form derivatives from all three embryonic germ layers. The almost undetectable expression of five paternally expressed imprinted genes and their HLA genotype identical to the oocyte donor indicated their parthenogenetic origin. Using genome-wide single-nucleotide polymorphism analysis and DNA fingerprinting, the homozygosity of chHES-32 cells was further confirmed. The results indicated that ‘ unwanted＇ one-pronuclear oocytes might be a potential source for human homozygous and parthenogenetic ESCs, and suggested an alternative strategyfor obtaining homozygous hESC lines from parthenogenetic haploid oocytes.
基金This work was supported by the National Natural Science Foundation of China （No.20373088）, the Program for Innovation Group （No.60321002）, the Innovative Project of Chinese Academy of Sciences （No.KJCX2-SW-w29）, and the National Key Project for Basic Research No.2006CB910302）. We thank Prof. Chih-chen Wang and Dr. Hui-min Ke in the Institute of Biophysics, Chinese Academy of Science, for the preparation of samples DsbC and G49R. We also thank Prof. Xiang-gang Qiu in the Institute of physics, Chinese Academy of Sciences, for help in FTIR measurement.
文摘The native protein structures in buffer solution are maintained by the electrostatic force as well as the hydrophobic force, salt ions play an important role in maintaining the protein native structures, and their effect on the protein stability has attracted tremendous interests. Infrared spectroscopy has been generally used in molecular structure analysis due to its fingerprint resolution for different species including macromolecules as proteins. However spectral intensities have received much less attention than the vibrational frequencies. Here we report that the spectral intensities of protein amide I band, the finger prints for the protein secondary structures, are very sensitive to the local electric field known as Onsager reaction field caused by salt ions. IR absorbance thermal titrations have been conducted for a series of samples including simple water soluble amino acids, water soluble monomeric protein cytochrome c and dimeric protein DsbC and its single-site mutant G49R. We found that at lower temperature range （10-20℃）, there exists a thermal activated salting-in process, where the IR intensity increases with a rise in the temperature, corresponding to the ions binding of the hydrophobic surface of protein. This process is absent for the amino acids. When further raising the temperature, the IR intensity decreases, this is interpreted as the thermal activated breaking of the ion-protein surface binding. Applying Van＇t Hoff plot to the thermal titration curves, the thermodynamic parameters such as AH and AS for salting-in and ion unbinding processes can be derived for various protein secondary structural components, revealing quantitatively the extent of hydrophobic interaction as well as the strength of the ion-protein binding.
文摘The possibilities of changes of ORP （oxidation-reduction water potential） with the help of chemical and physical-chemical methods were explored. Distillation and membrane technology were used as physical-chemical methods. In the case of application of chemical methods well-soluble substances were added into water. It was ascertained that the application of membrane technology makes it possible to obtain antioxidant water with negative ORR. Different energy change in a time unit can be applied in a whole number of technological processes and reveals new possibilities for many branches of industry.
文摘In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. The ability to dope graphene with electron-donor nitrogen heteroatoms is highly important for modulating electrical properties of graphene. Here we demonstrate a transfer-free method to directly grow large area quasi free-standing N-doped graphene bilayers on an insulating substrate （Si3N4）. Electron-bombardment heating under nitrogen flux results in simultaneous growth of N-doped graphene and a Si3N4 layer on the SiC surface. The decoupling of N-doped graphene from the substrate and the presence of Si3N4 are identified by X-ray photoemission spectroscopy and low-energy electron diffraction. The substitution of nitrogen atoms in the graphene planes was confirmed using high resolution X-ray photoemission spectroscopy which reveals several atomic configurations for the nitrogen atoms： Graphitic-like, pyridine-like, and pyrrolic- like. Furthermore, we demonstrated for the first time that N-doped graphene could be used to efficiently probe oxygen molecules via nitrogen atom defects.
