Citrus Huanglongbing （HLB,yellow shoot disease） was first observed in the coastal Chaoshan Plain of Guangdong Province,China,in the late 19th century based on descriptions of yellow shoot symptoms. “Candidatus Libe...Citrus Huanglongbing （HLB,yellow shoot disease） was first observed in the coastal Chaoshan Plain of Guangdong Province,China,in the late 19th century based on descriptions of yellow shoot symptoms. “Candidatus Liberibacter asiaticus”has been considered as a putative pathogen associated with HLB since 1994.Information about the curent prevalence of this bacterium is important for HLB control in Guangdong and also provides useful reference for HLB study elsewhere.In 2007,we collected HLB symptomatic citrus samples from 16 cultivars in 12 prefecture cities,mostly in the north and west regions of Guangdong,where major citrus fruits are currently produced.Among the 359 samples collected,241 （67.1%） were positive for “Ca.L.asiaticus”,distributed in 15 out of the 16 cultivars from all 12 cities,indicating the widespread prevalence of “Ca.L.asiaticus” in Guangdong Province.The detection rates varied from 16.7 to 100% depending on location and cultivar.Lower detection rates were found in newer citrus cultivation cities among the previously less popular but now promoted cultivars.In reviewing the citrus management and pest control practice,we believe that infected nursery stocks play a key role in the current spread of “Ca.L.asiaticus”.展开更多
Candidatus Liberibacter asiaticus （CaLas）, an uncultured Gram-negative alphaproteobacterium, is the causal agent of Huanglongbing （HLB） in citrus. CaLas resides in phloem sieve tubes and has been shown to be unequ...Candidatus Liberibacter asiaticus （CaLas）, an uncultured Gram-negative alphaproteobacterium, is the causal agent of Huanglongbing （HLB） in citrus. CaLas resides in phloem sieve tubes and has been shown to be unequally distributed in different tissues. Although HLB is a disease of citrus plants, it has been demonstrated that periwinkle can serve as an experimental host of CaLas, which can be transmitted from citrus to periwinkle via the parasitic plant dodder （Cuscuta spp.）. To investigate the distribution of CaLas in various periwinkle tissues, the bacteria were transmitted from an infected periwinkle plant to healthy periwinkles by top-grafting. The movement of the inoculum and associated titer changes were observed over time in various tissues. CaLas could be detected in the leaves, main stems, and roots of infected periwinkle by conventional PCR, and in all three tissues a clear time-dependent change in CaLas titer was observed, with titer increasing soon after inoculation and then decreasing as disease symptoms became severe. The highest titer was found at 25, 35 and 35 days after inoculation in leaves, main stems and roots, respectively. The titer in leaves was much higher than in the main stems and roots at the same time point, and the spatial distribution of CaLas in the leaves, main stems and roots of infected periwinkle was uneven, similar to what has been shown in citrus. The results provide guidance for selecting the proper periwinkle tissues and sampling times for early detection of CaLas.展开更多
目的探讨基于保护动机理论的延续性护理干预对脑出血患者术后的影响。方法选取广东省丰顺县人民医院2018年4月至2020年5月收治的84例脑出血患者,按随机数字表法分入对照组和观察组,各42例。对照组患者给予常规护理,观察组患者给予基于...目的探讨基于保护动机理论的延续性护理干预对脑出血患者术后的影响。方法选取广东省丰顺县人民医院2018年4月至2020年5月收治的84例脑出血患者,按随机数字表法分入对照组和观察组,各42例。对照组患者给予常规护理,观察组患者给予基于保护动机理论的延续性护理干预。两组患者均随访3个月。统计并比较两组再出血率、简易精神状态评价表(MMSE)评分、依从性、自我管理能力、凝血酶原时间(PT)和活化部分凝血活酶时间(APTT)指标。结果观察组的再出血率为7.14%,显著低于对照组的23.81%(P<0.05)。护理后,观察组的M M SE评分、依从性评分、自我管理能力评分、PT和APTT水平均显著高于对照组(P值均<0.05)。结论基于保护动机理论的延续性护理干预不仅能有效提高脑出血患者的认知能力和自我管理水平,改善凝血功能和依从性,而且能显著降低再出血率。展开更多
Two miniature inverted-repeat transposable elements（MITEs）, MCLas-A and MCLas-B, were recently identified from ‘Candidatus Liberibacter asiaticus＇ known to be associated with citrus Huanglongbing（HLB, yellow shoo...Two miniature inverted-repeat transposable elements（MITEs）, MCLas-A and MCLas-B, were recently identified from ‘Candidatus Liberibacter asiaticus＇ known to be associated with citrus Huanglongbing（HLB, yellow shoot disease）. MCLas-A was suggested as an active MITE because of its mobility. The immediate upstream gene of the two MITEs was predicted to be a putative transposase. The goal of this study is to analyze the sequence variation in the upstream putative transposase of MITEs and explore the possible correlation between sequence variation of transposase gene and MITE activity. PCR and sequence analysis showed that 12 sequence types were found in six major amplicon types from 43 representative ‘Ca. L. asiaticus＇ isolates from China, the United States and Brazil. Out of the 12 sequence types, three（T4, T5-2, T6） were reported for the first time. Recombination events were found in the two unique sequence types（T5-2 and T6） which were detected in all Brazilian isolates. Notably, no sequence variation or recombination events were detected in the upstream putative transposase gene of MCLas-A, suggesting the conservation of the transposase gene might be closely related with the MITE activity. Phylogenetic analysis demonstrated two well supported clades including five subclades were identified, clearly reflecting the geographical origins of isolates, especially that of Ruili isolates, S？o Paulo isolates and a few Florida isolates.展开更多
基金supported by the Chinese Modern Agricultural Technology Systems(CARS-27)the Special Fundfor Agro-Scientific Research in the Public Interest,China(2010003067)the project of Asian Citrus Psyllid and Huanglongbing Field Research and Outreach by North Carolina State University and United State Department of Agriculture(2010-0195-02)
文摘Citrus Huanglongbing （HLB,yellow shoot disease） was first observed in the coastal Chaoshan Plain of Guangdong Province,China,in the late 19th century based on descriptions of yellow shoot symptoms. “Candidatus Liberibacter asiaticus”has been considered as a putative pathogen associated with HLB since 1994.Information about the curent prevalence of this bacterium is important for HLB control in Guangdong and also provides useful reference for HLB study elsewhere.In 2007,we collected HLB symptomatic citrus samples from 16 cultivars in 12 prefecture cities,mostly in the north and west regions of Guangdong,where major citrus fruits are currently produced.Among the 359 samples collected,241 （67.1%） were positive for “Ca.L.asiaticus”,distributed in 15 out of the 16 cultivars from all 12 cities,indicating the widespread prevalence of “Ca.L.asiaticus” in Guangdong Province.The detection rates varied from 16.7 to 100% depending on location and cultivar.Lower detection rates were found in newer citrus cultivation cities among the previously less popular but now promoted cultivars.In reviewing the citrus management and pest control practice,we believe that infected nursery stocks play a key role in the current spread of “Ca.L.asiaticus”.
基金supported by the earmarked fund for China Agriculture Research System (CARS-27)the Special Fund for Agro-Scientific Research in the Public Interest, China (2010003067)
文摘Candidatus Liberibacter asiaticus （CaLas）, an uncultured Gram-negative alphaproteobacterium, is the causal agent of Huanglongbing （HLB） in citrus. CaLas resides in phloem sieve tubes and has been shown to be unequally distributed in different tissues. Although HLB is a disease of citrus plants, it has been demonstrated that periwinkle can serve as an experimental host of CaLas, which can be transmitted from citrus to periwinkle via the parasitic plant dodder （Cuscuta spp.）. To investigate the distribution of CaLas in various periwinkle tissues, the bacteria were transmitted from an infected periwinkle plant to healthy periwinkles by top-grafting. The movement of the inoculum and associated titer changes were observed over time in various tissues. CaLas could be detected in the leaves, main stems, and roots of infected periwinkle by conventional PCR, and in all three tissues a clear time-dependent change in CaLas titer was observed, with titer increasing soon after inoculation and then decreasing as disease symptoms became severe. The highest titer was found at 25, 35 and 35 days after inoculation in leaves, main stems and roots, respectively. The titer in leaves was much higher than in the main stems and roots at the same time point, and the spatial distribution of CaLas in the leaves, main stems and roots of infected periwinkle was uneven, similar to what has been shown in citrus. The results provide guidance for selecting the proper periwinkle tissues and sampling times for early detection of CaLas.
文摘目的探讨基于保护动机理论的延续性护理干预对脑出血患者术后的影响。方法选取广东省丰顺县人民医院2018年4月至2020年5月收治的84例脑出血患者,按随机数字表法分入对照组和观察组,各42例。对照组患者给予常规护理,观察组患者给予基于保护动机理论的延续性护理干预。两组患者均随访3个月。统计并比较两组再出血率、简易精神状态评价表(MMSE)评分、依从性、自我管理能力、凝血酶原时间(PT)和活化部分凝血活酶时间(APTT)指标。结果观察组的再出血率为7.14%,显著低于对照组的23.81%(P<0.05)。护理后,观察组的M M SE评分、依从性评分、自我管理能力评分、PT和APTT水平均显著高于对照组(P值均<0.05)。结论基于保护动机理论的延续性护理干预不仅能有效提高脑出血患者的认知能力和自我管理水平,改善凝血功能和依从性,而且能显著降低再出血率。
基金provided by the Special Fund for Agro-Scientific Research in the Public Interest, China (201003067-02)the Natural Science Foundation Project of CQ CSTC (cstc2012jj A80025)the Fundamental Research Funds for the Central Universities, China (XDJK2014A001, XDJK2014D004)
文摘Two miniature inverted-repeat transposable elements（MITEs）, MCLas-A and MCLas-B, were recently identified from ‘Candidatus Liberibacter asiaticus＇ known to be associated with citrus Huanglongbing（HLB, yellow shoot disease）. MCLas-A was suggested as an active MITE because of its mobility. The immediate upstream gene of the two MITEs was predicted to be a putative transposase. The goal of this study is to analyze the sequence variation in the upstream putative transposase of MITEs and explore the possible correlation between sequence variation of transposase gene and MITE activity. PCR and sequence analysis showed that 12 sequence types were found in six major amplicon types from 43 representative ‘Ca. L. asiaticus＇ isolates from China, the United States and Brazil. Out of the 12 sequence types, three（T4, T5-2, T6） were reported for the first time. Recombination events were found in the two unique sequence types（T5-2 and T6） which were detected in all Brazilian isolates. Notably, no sequence variation or recombination events were detected in the upstream putative transposase gene of MCLas-A, suggesting the conservation of the transposase gene might be closely related with the MITE activity. Phylogenetic analysis demonstrated two well supported clades including five subclades were identified, clearly reflecting the geographical origins of isolates, especially that of Ruili isolates, S？o Paulo isolates and a few Florida isolates.
