Grain weight is a major determinant of crop grain yield and is controlled by naturally occurring quantitative trait loci （QTLs）. We earlier identified a major QTL that controls rice grain width and weight, GW5, whic...Grain weight is a major determinant of crop grain yield and is controlled by naturally occurring quantitative trait loci （QTLs）. We earlier identified a major QTL that controls rice grain width and weight, GW5, which was mapped to a recombination hotspot on rice chromosome 5. To gain a better understanding of how GW5 controls rice grain width, we conducted fine mapping of this locus and uncovered a 1 212-bp deletion associated with the increased grain width in the rice cultivar Asominori, in comparison with the slender grain rice IR24. In addition, genotyping analyses of 46 rice cultivars revealed that this deletion is highly correlated with the grain-width phenotype, suggesting that the GW5 deletion might have been selected during rice domestication. GW5 encodes a novel nuclear protein of 144 amino acids that is localized to the nucleus. Furthermore, we show that GW5 physically interacts with polyubiquitin in a yeast two-hybrid assay. Together, our results suggest that GW5 represents a major QTL underlying rice width and weight, and that it likely acts in the ubiquitin-proteasome pathway to regulate cell division during seed development. This study provides novel insights into the molecular mechanisms controlling rice grain development and suggests that GW5 could serve as a potential tool for high-yield breeding of crops.展开更多
Tiller angle of rice （Oryza sativa L.） is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yiel...Tiller angle of rice （Oryza sativa L.） is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yield. Although enormous efforts have been made over the past decades to study mutants with extremely spreading or compact tillers, the molecular mechanism underlying the control of tiller angle of cereal crops remains unknown. Here we report the cloning of the LAZY1 （LA1） gene that regulates shoot gravitropism by which the rice tiller angle is controlled. We show that LA1, a novel grass-specific gene, is temporally and spatially expressed, and plays a negative role in polar auxin transport （PAT）. Loss-of-function of LA1 enhances PAT greatly and thus alters the endogenous IAA distribution in shoots, leading to the reduced gravitropism, and therefore the tiller-spreading phenotype of rice plants.展开更多
AIM:To compare the effect of endoscopic variceal ligation(EVL)with that of endoscopic injection sclerotherapy(EIS)in the treatment of patients withesophageal variceal bleeding.METHODS:We performed a systematic literat...AIM:To compare the effect of endoscopic variceal ligation(EVL)with that of endoscopic injection sclerotherapy(EIS)in the treatment of patients withesophageal variceal bleeding.METHODS:We performed a systematic literature search of multiple online electronic databases.Metaanalysis was conducted to evaluate risk ratio(RR)and95%confidence interval(CI)of combined studies for the treatment of patients with esophageal variceal bleeding between EVL and EIS.RESULTS:Fourteen studies comprising 1236 patients were included in the meta-analysis.The rebleeding rate in actively bleeding varices patients in the EVL group was significantly lower than that in the EIS group(RR=0.68,95%CI:0.57-0.81).The variceal eradication rate in actively bleeding varices patients in the EVL group was significantly higher than that in the EIS group(RR=1.06,95%CI:1.01-1.12).There was no significant difference about mortality rate between the EVL group and EIS group(RR=0.95,95%CI:0.77-1.17).The rate of complications in actively bleeding varices patients in the EVL group was significantly lower than that in the EIS group(RR=0.28,95%CI:0.13-0.58).CONCLUSION:Our meta-analysis has found that EVL is better than EIS in terms of the lower rates of rebleeding,complications,and the higher rate of variceal eradication.Therefore,EVL is the first choice for esophageal variceal bleeding.展开更多
Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genoty...Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley （Hordeum vulgare L.）. These traits included chlorophyll content, initial fluorescence （Fo）, maximum primary yield of photochemistry of photosystem Ⅱ （Fv /Fo） and maximum quantum yield of photosystem Ⅱ （Fv/Fm）. Four genotypes （Tadmor, Arta, Morocco9-75 and WI2291） variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv/Fo and Fv/Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.展开更多
Since the Earth day,April 22,1970,American Environmental Movement has got great achievements,especially in promoting the people’s environmental consciousness and pushing the acts of federal,states and local governmen...Since the Earth day,April 22,1970,American Environmental Movement has got great achievements,especially in promoting the people’s environmental consciousness and pushing the acts of federal,states and local governments for protecting the environment.However,in the 1990’s,American environmental movement has met some new barriers.Therefore,the American environmentalists,most of them are from the white middle class,have to face the new challenges.When the new age is coming,not only have they been forced to be engaged in the political struggles,beyond their capabilities,to defend the existed and expected national acts,but also to rethink the definitions of Environmentalism,which they have held for a long time.展开更多
文摘Grain weight is a major determinant of crop grain yield and is controlled by naturally occurring quantitative trait loci （QTLs）. We earlier identified a major QTL that controls rice grain width and weight, GW5, which was mapped to a recombination hotspot on rice chromosome 5. To gain a better understanding of how GW5 controls rice grain width, we conducted fine mapping of this locus and uncovered a 1 212-bp deletion associated with the increased grain width in the rice cultivar Asominori, in comparison with the slender grain rice IR24. In addition, genotyping analyses of 46 rice cultivars revealed that this deletion is highly correlated with the grain-width phenotype, suggesting that the GW5 deletion might have been selected during rice domestication. GW5 encodes a novel nuclear protein of 144 amino acids that is localized to the nucleus. Furthermore, we show that GW5 physically interacts with polyubiquitin in a yeast two-hybrid assay. Together, our results suggest that GW5 represents a major QTL underlying rice width and weight, and that it likely acts in the ubiquitin-proteasome pathway to regulate cell division during seed development. This study provides novel insights into the molecular mechanisms controlling rice grain development and suggests that GW5 could serve as a potential tool for high-yield breeding of crops.
基金grants from the Ministry of Science and Technology of China(2005CB 1208)the National Natural Science Foundation of China(30330040 and 30570161).
文摘Tiller angle of rice （Oryza sativa L.） is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yield. Although enormous efforts have been made over the past decades to study mutants with extremely spreading or compact tillers, the molecular mechanism underlying the control of tiller angle of cereal crops remains unknown. Here we report the cloning of the LAZY1 （LA1） gene that regulates shoot gravitropism by which the rice tiller angle is controlled. We show that LA1, a novel grass-specific gene, is temporally and spatially expressed, and plays a negative role in polar auxin transport （PAT）. Loss-of-function of LA1 enhances PAT greatly and thus alters the endogenous IAA distribution in shoots, leading to the reduced gravitropism, and therefore the tiller-spreading phenotype of rice plants.
基金Supported by National Natural Science Foundation of China,No.81300273
文摘AIM:To compare the effect of endoscopic variceal ligation(EVL)with that of endoscopic injection sclerotherapy(EIS)in the treatment of patients withesophageal variceal bleeding.METHODS:We performed a systematic literature search of multiple online electronic databases.Metaanalysis was conducted to evaluate risk ratio(RR)and95%confidence interval(CI)of combined studies for the treatment of patients with esophageal variceal bleeding between EVL and EIS.RESULTS:Fourteen studies comprising 1236 patients were included in the meta-analysis.The rebleeding rate in actively bleeding varices patients in the EVL group was significantly lower than that in the EIS group(RR=0.68,95%CI:0.57-0.81).The variceal eradication rate in actively bleeding varices patients in the EVL group was significantly higher than that in the EIS group(RR=1.06,95%CI:1.01-1.12).There was no significant difference about mortality rate between the EVL group and EIS group(RR=0.95,95%CI:0.77-1.17).The rate of complications in actively bleeding varices patients in the EVL group was significantly lower than that in the EIS group(RR=0.28,95%CI:0.13-0.58).CONCLUSION:Our meta-analysis has found that EVL is better than EIS in terms of the lower rates of rebleeding,complications,and the higher rate of variceal eradication.Therefore,EVL is the first choice for esophageal variceal bleeding.
文摘Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley （Hordeum vulgare L.）. These traits included chlorophyll content, initial fluorescence （Fo）, maximum primary yield of photochemistry of photosystem Ⅱ （Fv /Fo） and maximum quantum yield of photosystem Ⅱ （Fv/Fm）. Four genotypes （Tadmor, Arta, Morocco9-75 and WI2291） variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv/Fo and Fv/Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.
文摘Since the Earth day,April 22,1970,American Environmental Movement has got great achievements,especially in promoting the people’s environmental consciousness and pushing the acts of federal,states and local governments for protecting the environment.However,in the 1990’s,American environmental movement has met some new barriers.Therefore,the American environmentalists,most of them are from the white middle class,have to face the new challenges.When the new age is coming,not only have they been forced to be engaged in the political struggles,beyond their capabilities,to defend the existed and expected national acts,but also to rethink the definitions of Environmentalism,which they have held for a long time.
