Three mono-cyclopentadienyl metal complexes, [C_6H_4O_2]CpTiCl (Ⅰ),[C_(12)H_8O_2]CpTiCl (Ⅱ), and [C_(20)H_(12)O_2] CpTiCl (Ⅲ), were prepared via the reactions ofcyclopentadienyl titanium trichloride with catechol, ...Three mono-cyclopentadienyl metal complexes, [C_6H_4O_2]CpTiCl (Ⅰ),[C_(12)H_8O_2]CpTiCl (Ⅱ), and [C_(20)H_(12)O_2] CpTiCl (Ⅲ), were prepared via the reactions ofcyclopentadienyl titanium trichloride with catechol, 2,2i-bisphenol, and 2,2'-bisnaphthol,respectively. In the presence of a moderate amount of methylaluminoxane (MAO), the complexesexhibited catalytic activities for ethylene polymerization. Complex Ⅰ showed the highest activityat Al/Ti molar ratio of 500 at the temperature of 30℃. With increasing of polymerizationtemperature, catalytic activities and molecular weight of the obtained polyethylene tended todecrease, and molecular weight distribution of polyethylene became narrower. With the molecularsimulation method, the charges on titanium atoms of complexes Ⅰ, Ⅱ, and Ⅲ, and the bond anglesformed by Ti and bisphenoxy ligands were calculated. It was concluded that the smaller the netcharge on Ti and the smaller the angle of O1―Ti―O2, the higher the activity of the complex.展开更多
Oral lichen planus （OLP） is a chronic inflammatory disorder and premalignantlesion, of which the mechanisms are still obscure. In the present study, the expression levels of miR-96/182/183 cluster, miR-203, miR-375,...Oral lichen planus （OLP） is a chronic inflammatory disorder and premalignantlesion, of which the mechanisms are still obscure. In the present study, the expression levels of miR-96/182/183 cluster, miR-203, miR-375, and miR-769-5p in both tissues and exfoliative cells of OLP patients as well as healthy volunteers were detected, differentially expressed miRNAs were identified and their correlation with OLP was evaluated by a biplot method. Experimental results show that miR-203 is significantly up-regulated in patient lesion tissues in comparison to volunteer mucosa tissues. Moreover, the contra- dictory insignificant expression changes of miR-203 as well as miR-96/182/183 cluster in comparisons of exfoliative cell samples suggest that different cell compositions in OLP lesion have distinct miRNA regulation, which accords with the histological heterogeneity of OLP. Finally, biplot analyses indicate the expression of miR-203 and miR-96/182/183 cluster are positively correlated in patient lesions. These results provide miR-203 as a molecular indicator of heterogeneity of OLP, and also a potential diagnostic biomarker or therapeutic target that deserves further studies.展开更多
The ubiquitin （Ub）-conjugating enzyme, Ubc13, has been known to be involved in error-free DNA damage tolerance （or post-replication repair） via catalyzing Lys63-linked polyubiquitin chains formation together with ...The ubiquitin （Ub）-conjugating enzyme, Ubc13, has been known to be involved in error-free DNA damage tolerance （or post-replication repair） via catalyzing Lys63-linked polyubiquitin chains formation together with a Ubc variant. However, its functions remain largely unknown in plant species, especial y in monocotyledons. In this study, we cloned a Ub-conjugating enzyme, OsUbc13, that shares the conserved domain of Ubc with AtUBC13B in Oryza sativa L., which encodes a protein of 153 amino acids; the deduced sequence shares high similarities with other homologs. Real-time quantitative polymerase chain reaction （PCR） indicated that OsUbc13 transcripts could be de-tected in al tissues examined, and the expression level was higher in palea, pistil, stamen, and leaf, and lower in root, stem, and lemma;the expression of OsUbc13 was induced by low temperature, methylmethane sulfate （MMS）, and H2O2, but repressed by mannitol, abscisic acid （ABA）, and NaCl. OsUbc13 was probably localized in the plasma and nuclear membranes. About 20 proteins, which are responsible for the positive yeast two-hybrid interaction of OsUbc13, were identified. These include the confirmed OsVDAC （correlated with apoptosis）, OsMADS1 （important for development of floral organs）, OsB22EL8 （related to reactive oxygen species （ROS） scavenging and DNA protection）, and OsCROC-1 （required for formation of Lys63 polyubiquitylation and error-free DNA damage tolerance）. The molecular characterization provides a foundation for the functional study of OsUbc13.展开更多
基金The work is supported by Special Funds for State Major Basic Research Projects of China(No.G1999064801)
文摘Three mono-cyclopentadienyl metal complexes, [C_6H_4O_2]CpTiCl (Ⅰ),[C_(12)H_8O_2]CpTiCl (Ⅱ), and [C_(20)H_(12)O_2] CpTiCl (Ⅲ), were prepared via the reactions ofcyclopentadienyl titanium trichloride with catechol, 2,2i-bisphenol, and 2,2'-bisnaphthol,respectively. In the presence of a moderate amount of methylaluminoxane (MAO), the complexesexhibited catalytic activities for ethylene polymerization. Complex Ⅰ showed the highest activityat Al/Ti molar ratio of 500 at the temperature of 30℃. With increasing of polymerizationtemperature, catalytic activities and molecular weight of the obtained polyethylene tended todecrease, and molecular weight distribution of polyethylene became narrower. With the molecularsimulation method, the charges on titanium atoms of complexes Ⅰ, Ⅱ, and Ⅲ, and the bond anglesformed by Ti and bisphenoxy ligands were calculated. It was concluded that the smaller the netcharge on Ti and the smaller the angle of O1―Ti―O2, the higher the activity of the complex.
基金National Natural Science Foundation of China(Grant No.91029711)
文摘Oral lichen planus （OLP） is a chronic inflammatory disorder and premalignantlesion, of which the mechanisms are still obscure. In the present study, the expression levels of miR-96/182/183 cluster, miR-203, miR-375, and miR-769-5p in both tissues and exfoliative cells of OLP patients as well as healthy volunteers were detected, differentially expressed miRNAs were identified and their correlation with OLP was evaluated by a biplot method. Experimental results show that miR-203 is significantly up-regulated in patient lesion tissues in comparison to volunteer mucosa tissues. Moreover, the contra- dictory insignificant expression changes of miR-203 as well as miR-96/182/183 cluster in comparisons of exfoliative cell samples suggest that different cell compositions in OLP lesion have distinct miRNA regulation, which accords with the histological heterogeneity of OLP. Finally, biplot analyses indicate the expression of miR-203 and miR-96/182/183 cluster are positively correlated in patient lesions. These results provide miR-203 as a molecular indicator of heterogeneity of OLP, and also a potential diagnostic biomarker or therapeutic target that deserves further studies.
基金Project supported by the National High-Tech R&D Program(863)of China(No.2006AA10Z159)the National Natural Science Foundation of China(No.30871502)
文摘The ubiquitin （Ub）-conjugating enzyme, Ubc13, has been known to be involved in error-free DNA damage tolerance （or post-replication repair） via catalyzing Lys63-linked polyubiquitin chains formation together with a Ubc variant. However, its functions remain largely unknown in plant species, especial y in monocotyledons. In this study, we cloned a Ub-conjugating enzyme, OsUbc13, that shares the conserved domain of Ubc with AtUBC13B in Oryza sativa L., which encodes a protein of 153 amino acids; the deduced sequence shares high similarities with other homologs. Real-time quantitative polymerase chain reaction （PCR） indicated that OsUbc13 transcripts could be de-tected in al tissues examined, and the expression level was higher in palea, pistil, stamen, and leaf, and lower in root, stem, and lemma;the expression of OsUbc13 was induced by low temperature, methylmethane sulfate （MMS）, and H2O2, but repressed by mannitol, abscisic acid （ABA）, and NaCl. OsUbc13 was probably localized in the plasma and nuclear membranes. About 20 proteins, which are responsible for the positive yeast two-hybrid interaction of OsUbc13, were identified. These include the confirmed OsVDAC （correlated with apoptosis）, OsMADS1 （important for development of floral organs）, OsB22EL8 （related to reactive oxygen species （ROS） scavenging and DNA protection）, and OsCROC-1 （required for formation of Lys63 polyubiquitylation and error-free DNA damage tolerance）. The molecular characterization provides a foundation for the functional study of OsUbc13.
