The karst process acts as carbon sequestration for atmospheric CO_2.The amount of karst carbon sequestration (KCS) depends on the discharge of karst catchment and inorganic carbon concentration of the water body.Based...The karst process acts as carbon sequestration for atmospheric CO_2.The amount of karst carbon sequestration (KCS) depends on the discharge of karst catchment and inorganic carbon concentration of the water body.Based on the data from the monitoring station on Banzhai subterranean stream located in Maolan National Nature Reserve of Guizhou province,the process and influence factors of KCS have been analyzed.It shows that the amount of KCS is about 353 t C per year in the catchment of Banzhai subterranean stream,and there is good linear relationship between the strength of KCS and discharge of the stream at various time scales.Therefore,how to monitor the discharge accurately is the key to the estimation of KCS.And stations with real-time monitoring function are very important for KCS calculation because of strong seasonal variability of the karst water cycle.展开更多
为建立可同时检测猪流行性腹泻病毒(PEDV)和猪丁型冠状病毒(PDCoV)的双重Taq Man qRT-PCR方法,本研究根据Gen Bank中的PEDV M基因及PDCo V N基因设计了两对特异性引物和探针,构建重组质粒作为标准品,绘制标准曲线,建立其检测方法,结果显...为建立可同时检测猪流行性腹泻病毒(PEDV)和猪丁型冠状病毒(PDCoV)的双重Taq Man qRT-PCR方法,本研究根据Gen Bank中的PEDV M基因及PDCo V N基因设计了两对特异性引物和探针,构建重组质粒作为标准品,绘制标准曲线,建立其检测方法,结果显示,根据两种病毒质粒标准品构建的标准曲线的相关系数(R2)均为1,线性关系良好。该方法特异性强,与猪圆环病毒2型(PCV2)、猪圆环病毒3型(PCV3)、伪狂犬病毒(PRV)、猪繁殖与呼吸综合征病毒(PRRSV)、传染性胃肠炎病毒(TGEV)、猪博卡病毒(PBo V)及猪瘟病毒(CSFV)均无交叉反应;敏感性试验结果显示,建立的单一与双重荧光定量PCR对PEDV及PDCo V的质粒标准品检测下限均分别为4.7×10^(1)拷贝/μL和3.17×10^(1)拷贝/μL,敏感性高;对该检测方法的重复性进行验证,结果显示,该方法组内和组间的变异系数均小于3%,重复性好。利用建立的该双重Taq Man q RT-PCR检测方法分别对118份猪粪便样品进行检测,结果显示,PEDV阳性检出率为56.8%(67/118),PDCo V阳性检出率为33.1%(39/118),二者共感染率为16.1%(19/118)。本研究首次以PEDV M基因及PDCo V N基因为靶基因,建立了同时检测PEDV和PDCo V的双重Taq Man q RT-PCR,该方法具有快速、灵敏、准确、重复性高等优点,可用于这两种病毒的同时检测和快速排查。展开更多
[ Objective] To study the therapeutic effects of traditional Chinese medicine prescriptions on infectious bronchitis （IB） and find a novel avenue for prevention and treatment of viral diseases in poultry. [Method] A...[ Objective] To study the therapeutic effects of traditional Chinese medicine prescriptions on infectious bronchitis （IB） and find a novel avenue for prevention and treatment of viral diseases in poultry. [Method] A total of 160 cockerels at the age of 15 d were divided into four groups randomly, including traditional Chinese medicine group, moroxydine control group, challenge control group and healthy control group. Except the healthy control group, other groups were challenged with infectious bronchitis virus （IBV） on Day 15. After 48 h post challenge, the traditional Chinese medicine groupand moroxydine control group were respectively administrated with Chinese herbal medicine prescription and moroxydine, continuously for 5 d. The immune organ indexes and macrephage phagocytic indexes were detected on Day 18, 24 and 30, respectively. [ Result] The immune organ indexes and macrophage phagocytic indexes were not significantly different between traditional Chinese medicine group and moroxydine control group on Day 18. But all the indexes of the traditional Chinese medicine groups were increased significantly （ P 〈 0.05） on Day 24 and 30, and showed extremely significant difference （ P 〈 0.01 ） with those of challenge control group on Day 30. [ Conclusion] The traditional Chinese herbal medicine can enhance macrophage phagocytic indexes and immune organs indexes of chickens infected by IBV.展开更多
This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion...This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6 T, T105 A and L239 M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid(99%). Lastly, the number of chromosomal copies of the balanced crtW*-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid(99%) with a specific titer of 0.88 g·L^(-1) without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products.展开更多
基金funded by the project (No.41072192)from National Natural Science Foundation of Chinathe project(No.1212011087122)from China Geological Survey
文摘The karst process acts as carbon sequestration for atmospheric CO_2.The amount of karst carbon sequestration (KCS) depends on the discharge of karst catchment and inorganic carbon concentration of the water body.Based on the data from the monitoring station on Banzhai subterranean stream located in Maolan National Nature Reserve of Guizhou province,the process and influence factors of KCS have been analyzed.It shows that the amount of KCS is about 353 t C per year in the catchment of Banzhai subterranean stream,and there is good linear relationship between the strength of KCS and discharge of the stream at various time scales.Therefore,how to monitor the discharge accurately is the key to the estimation of KCS.And stations with real-time monitoring function are very important for KCS calculation because of strong seasonal variability of the karst water cycle.
文摘为建立可同时检测猪流行性腹泻病毒(PEDV)和猪丁型冠状病毒(PDCoV)的双重Taq Man qRT-PCR方法,本研究根据Gen Bank中的PEDV M基因及PDCo V N基因设计了两对特异性引物和探针,构建重组质粒作为标准品,绘制标准曲线,建立其检测方法,结果显示,根据两种病毒质粒标准品构建的标准曲线的相关系数(R2)均为1,线性关系良好。该方法特异性强,与猪圆环病毒2型(PCV2)、猪圆环病毒3型(PCV3)、伪狂犬病毒(PRV)、猪繁殖与呼吸综合征病毒(PRRSV)、传染性胃肠炎病毒(TGEV)、猪博卡病毒(PBo V)及猪瘟病毒(CSFV)均无交叉反应;敏感性试验结果显示,建立的单一与双重荧光定量PCR对PEDV及PDCo V的质粒标准品检测下限均分别为4.7×10^(1)拷贝/μL和3.17×10^(1)拷贝/μL,敏感性高;对该检测方法的重复性进行验证,结果显示,该方法组内和组间的变异系数均小于3%,重复性好。利用建立的该双重Taq Man q RT-PCR检测方法分别对118份猪粪便样品进行检测,结果显示,PEDV阳性检出率为56.8%(67/118),PDCo V阳性检出率为33.1%(39/118),二者共感染率为16.1%(19/118)。本研究首次以PEDV M基因及PDCo V N基因为靶基因,建立了同时检测PEDV和PDCo V的双重Taq Man q RT-PCR,该方法具有快速、灵敏、准确、重复性高等优点,可用于这两种病毒的同时检测和快速排查。
基金supported by Research Fund of Hebei Agricultural University
文摘[ Objective] To study the therapeutic effects of traditional Chinese medicine prescriptions on infectious bronchitis （IB） and find a novel avenue for prevention and treatment of viral diseases in poultry. [Method] A total of 160 cockerels at the age of 15 d were divided into four groups randomly, including traditional Chinese medicine group, moroxydine control group, challenge control group and healthy control group. Except the healthy control group, other groups were challenged with infectious bronchitis virus （IBV） on Day 15. After 48 h post challenge, the traditional Chinese medicine groupand moroxydine control group were respectively administrated with Chinese herbal medicine prescription and moroxydine, continuously for 5 d. The immune organ indexes and macrephage phagocytic indexes were detected on Day 18, 24 and 30, respectively. [ Result] The immune organ indexes and macrophage phagocytic indexes were not significantly different between traditional Chinese medicine group and moroxydine control group on Day 18. But all the indexes of the traditional Chinese medicine groups were increased significantly （ P 〈 0.05） on Day 24 and 30, and showed extremely significant difference （ P 〈 0.01 ） with those of challenge control group on Day 30. [ Conclusion] The traditional Chinese herbal medicine can enhance macrophage phagocytic indexes and immune organs indexes of chickens infected by IBV.
基金supported by the National Key R&D Program of China (No. 2019YFA0905700)the National Natural Science Foundation of China (No. 31870058)。
文摘This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6 T, T105 A and L239 M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid(99%). Lastly, the number of chromosomal copies of the balanced crtW*-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid(99%) with a specific titer of 0.88 g·L^(-1) without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products.
