Maize plants adapt to low phosphorus （P） stress by increasing root growth. It is of importance to know the extent to which genetic improvement of root growth can enhance P acquisiton. In the present study, the contr...Maize plants adapt to low phosphorus （P） stress by increasing root growth. It is of importance to know the extent to which genetic improvement of root growth can enhance P acquisiton. In the present study, the contribution of root growth improvement to efficient P acquisition was evaluated in two soils using T149 and T222, a pair of near isogenic maize testcrosses which were derived from a backcross BC 4 F 3 population. T149 and T222 showed no difference in shoot biomass and leaf area under normal growth conditions, but differed greatly in root growth. T149 had longer lateral roots and a larger root surface area compared to T222. In calcareous soil, when P was insufficient, i.e., when P was either supplied as KH 2 PO 4 at a concentration of 50 mg P kg-1 soil, or in the form of Phy-P, Ca3-P or Ca10-P, a 43% increase in root length in T149 compared to T222 resulted in an increase in P uptake by 53%, and shoot biomass by 48%. In acid soil, however, when P supply was insufficient, i.e., when P was supplied as KH 2 PO 4 at a concentration of 100 mg P kg-1 soil, or in the form of Phy-P, Fe-P or Al-P, a 32% increase in root length in T149 compared to T222 resulted in an increase in P uptake by only 12%, and shoot biomass by 7%. No significant differences in the exudation of organic acids and APase activity were found between the two genotypes. It is concluded that genetic improvement of root growth can efficiently increase P acquisition in calcareous soils. In acid soils, however, improvements in the physiological traits of roots, in addition to their size, seem to be required for efficient P acquisition.展开更多
Objective The results of studies on association between -148C/T polymorphism in promoter region of β3-fibrinogen gene and susceptibility to cerebral infarction in Chinese population are controversial. In this study, ...Objective The results of studies on association between -148C/T polymorphism in promoter region of β3-fibrinogen gene and susceptibility to cerebral infarction in Chinese population are controversial. In this study, we summarize the results of published works in this field by a meta-analysis. Data sources Genetic association studies evaluating the β-fibdnogen gene -148C/T polymorphisms and cerebral infarction involving Chinese population published before December 2005 were collected from PubMed, EMBASE and CNKI. Study selection Case control studies involving unrelated, Han subjects aged from 18 to 80 years, and the internationally recognized diagnostic standard of cerebral infarction and genotype frequencies in control group consistent with Hardy-Weinberg equilibrium were used. Publication bias was tested by funnel plot and the odds ratios of all studies were combined dependent on the result of heterogeneity test among the individual studies. The software Review Manager （Version 4.2） was used for meta-analysis. Results Eleven studies including 1223 patients and 1433 controls met the selection criteria. There was no heterogeneity among the odds ratios （ORs） of individual studies （Х^2=17.82, P=0.06）. The combined OFt of susceptibility to cerebral infarction in -148T allele carriers compared to the wild homozygote was 1.32 （95%CI 1.12 to 1.55, P=-0.0008）. In the patients with cerebral infarction, the average plasma fibrinogen level of allele T carrier was 0.42 g/L （95% CI 0.29 to 0.54, P〈0.001）, higher than that of -148C/C homozygous ones. Conclusions β3-fibrinogen gene -148C/T polymorphism might contribute to susceptibility to cerebral infarction in Han Chinese. To reach a definitive conclusion, further gene to gene and gene to environment interactions studies on β3-fibrinogen polymorphisms and cerebral infarction with large sample size are required.展开更多
Tripterygium hypoglaucum(Levl.)Hutch,a traditional Chinese medicinal herb with a long history of use,is widely distributed in China.One of its main active components,celastrol,has great potential to be developed into ...Tripterygium hypoglaucum(Levl.)Hutch,a traditional Chinese medicinal herb with a long history of use,is widely distributed in China.One of its main active components,celastrol,has great potential to be developed into anti-cancer and anti-obesity drugs.Although it exhibits strong pharmacological activities,there is a lack of sustainable sources of celastrol and its derivatives,making it crucial to develop novel sources of these drugs through synthetic biology.The key step in the biosynthesis of celastrol is considered to be the cyclization of 2,3-oxidosqualene into friedelin under the catalysis of 2,3-oxidosqualene cyclases.Friedelin was speculated to be oxidized into celastrol by cytochrome P450 oxidases(CYP450s).Here,we reported a cytochrome P450 ThCYP712K1 from Tripterygium hypoglaucum(Levl.)Hutch that catalyzed the oxidation of friedelin into polpuonic acid when heterologously expressed in yeast.Through substrate supplementation and in vitro enzyme analysis,ThCYP712K1 was further proven to catalyze the oxidation of friedelin at the C-29 position to produce polpunonic acid,which is considered a vital step in the biosynthesis of celastrol,and will lay a foundation for further analysis of its biosynthetic pathway.展开更多
基金supported by the National Natural Science Foundation of China(31121062and31071852)EU Seventh Framework Programme of European Union(NUE-CROPS,222645)the Special Fund for the Agricultural Profession of China(201103003)
文摘Maize plants adapt to low phosphorus （P） stress by increasing root growth. It is of importance to know the extent to which genetic improvement of root growth can enhance P acquisiton. In the present study, the contribution of root growth improvement to efficient P acquisition was evaluated in two soils using T149 and T222, a pair of near isogenic maize testcrosses which were derived from a backcross BC 4 F 3 population. T149 and T222 showed no difference in shoot biomass and leaf area under normal growth conditions, but differed greatly in root growth. T149 had longer lateral roots and a larger root surface area compared to T222. In calcareous soil, when P was insufficient, i.e., when P was either supplied as KH 2 PO 4 at a concentration of 50 mg P kg-1 soil, or in the form of Phy-P, Ca3-P or Ca10-P, a 43% increase in root length in T149 compared to T222 resulted in an increase in P uptake by 53%, and shoot biomass by 48%. In acid soil, however, when P supply was insufficient, i.e., when P was supplied as KH 2 PO 4 at a concentration of 100 mg P kg-1 soil, or in the form of Phy-P, Fe-P or Al-P, a 32% increase in root length in T149 compared to T222 resulted in an increase in P uptake by only 12%, and shoot biomass by 7%. No significant differences in the exudation of organic acids and APase activity were found between the two genotypes. It is concluded that genetic improvement of root growth can efficiently increase P acquisition in calcareous soils. In acid soils, however, improvements in the physiological traits of roots, in addition to their size, seem to be required for efficient P acquisition.
基金the Guangdong Science Technology Project Foundation (No. 2005B3370321)the Zhuhai Municipal Science Technology Foundation (No. PB20051015).
文摘Objective The results of studies on association between -148C/T polymorphism in promoter region of β3-fibrinogen gene and susceptibility to cerebral infarction in Chinese population are controversial. In this study, we summarize the results of published works in this field by a meta-analysis. Data sources Genetic association studies evaluating the β-fibdnogen gene -148C/T polymorphisms and cerebral infarction involving Chinese population published before December 2005 were collected from PubMed, EMBASE and CNKI. Study selection Case control studies involving unrelated, Han subjects aged from 18 to 80 years, and the internationally recognized diagnostic standard of cerebral infarction and genotype frequencies in control group consistent with Hardy-Weinberg equilibrium were used. Publication bias was tested by funnel plot and the odds ratios of all studies were combined dependent on the result of heterogeneity test among the individual studies. The software Review Manager （Version 4.2） was used for meta-analysis. Results Eleven studies including 1223 patients and 1433 controls met the selection criteria. There was no heterogeneity among the odds ratios （ORs） of individual studies （Х^2=17.82, P=0.06）. The combined OFt of susceptibility to cerebral infarction in -148T allele carriers compared to the wild homozygote was 1.32 （95%CI 1.12 to 1.55, P=-0.0008）. In the patients with cerebral infarction, the average plasma fibrinogen level of allele T carrier was 0.42 g/L （95% CI 0.29 to 0.54, P〈0.001）, higher than that of -148C/C homozygous ones. Conclusions β3-fibrinogen gene -148C/T polymorphism might contribute to susceptibility to cerebral infarction in Han Chinese. To reach a definitive conclusion, further gene to gene and gene to environment interactions studies on β3-fibrinogen polymorphisms and cerebral infarction with large sample size are required.
基金supported by the National Key R&D Program of China(No.2020YFA0908000)the National Natural Science Foundation of China(Nos.81773830 and 81973418)the Key Project at Central Government Level:the ability establishment of sustainable use for valuable Chinese medicine resources(No.2060302-1806-03),and the National Program for Special Support of Eminent Professionals.
文摘Tripterygium hypoglaucum(Levl.)Hutch,a traditional Chinese medicinal herb with a long history of use,is widely distributed in China.One of its main active components,celastrol,has great potential to be developed into anti-cancer and anti-obesity drugs.Although it exhibits strong pharmacological activities,there is a lack of sustainable sources of celastrol and its derivatives,making it crucial to develop novel sources of these drugs through synthetic biology.The key step in the biosynthesis of celastrol is considered to be the cyclization of 2,3-oxidosqualene into friedelin under the catalysis of 2,3-oxidosqualene cyclases.Friedelin was speculated to be oxidized into celastrol by cytochrome P450 oxidases(CYP450s).Here,we reported a cytochrome P450 ThCYP712K1 from Tripterygium hypoglaucum(Levl.)Hutch that catalyzed the oxidation of friedelin into polpuonic acid when heterologously expressed in yeast.Through substrate supplementation and in vitro enzyme analysis,ThCYP712K1 was further proven to catalyze the oxidation of friedelin at the C-29 position to produce polpunonic acid,which is considered a vital step in the biosynthesis of celastrol,and will lay a foundation for further analysis of its biosynthetic pathway.
