The heterotrimeric guanine nucleotide-binding protein （G-protein） has been demonstrated to mediate various signaling pathways in plants. However, its role in phytochrome A （phyA） signaling remains elusive. In this...The heterotrimeric guanine nucleotide-binding protein （G-protein） has been demonstrated to mediate various signaling pathways in plants. However, its role in phytochrome A （phyA） signaling remains elusive. In this study, we discover a new phyA-mediated phenotype designated far-red irradiation （FR） preconditioned cell death, which occurs only in the hypocotyls of FR-grown seedlings following exposure to white light （WL）. The cell death is mitigated in the Gα mutant gpal but aggravated in the Gβ mutant agbl in comparison with the wild type （WT）, indicative of antagonistic roles of GPA1 and AGBI in the phyA-mediated cell-death pathway. Further investigation indicates that FR-induced accumulation of nonphotoconvertible protochlorophyllide （Pchlide^633）, which generates reactive oxygen species （ROS） on exposure to WL, is required for FR-preconditioned cell death. Moreover, ROS is mainly detected in chloroplasts using the fluorescent probe. Interestingly, the application of H2O2 to dark-grown seedlings results in a phenotype similar to FR-preconditioned cell death. This reveals that ROS is a critical mediator for the ceil death. In addition, we observe that agb1 is more sensitive to H2O2 than WT seedlings, indicating that the G-protein may also modify the sensitivity of the seedlings to ROS stress. Taking these results together, we infer that the G-protein may be involved in the phyA signaling pathway to regulate FR-preconditioned cell death ofArabidopsis hypocotyls. A possible mechanism underlying the involvement of the G-protein in phyA signaling is discussed in this study.展开更多
The effects of powders from dry flower buds of Eugenia aromatica Baill., seeds of Piper guineense Schum and Thonn and fruits of Capsicum frutescens L. on adult behaviour, mortality and reproductive fitness of the cowp...The effects of powders from dry flower buds of Eugenia aromatica Baill., seeds of Piper guineense Schum and Thonn and fruits of Capsicum frutescens L. on adult behaviour, mortality and reproductive fitness of the cowpea seed beetle, Callosobruchus maculatus (Fab.) were investigated under ambient laboratory conditions. All experiments were carried out in glass Petri plates. All powders elicited aversion in adult beetles. The contact toxicity symptoms included restlessness, loss of coordination, knock down and eventual death of adult beetles. These behaviours were more pronounced with E. aromatica in which adult beetles died within 16 hours. P. guineense and C. frutescens powders did not cause 100% mortality of adult beetles, even after 24 hours. Each of the three powders significantly (P<0.05) reduced the mating competition of adult males after sub-lethal exposure for one, two, and three hours, respectively. E. aromatica powder caused more reduction in male mating competition for females than any of the other two powders after each period of exposure. Receptiveness of treated females to courting males was also decreased by exposure to any of the three powders. Similarly, E. aromatica powder caused greater decreases in female receptiveness to males than any of the other two powders after each period of exposure. Exposure of either adult male or female C. maculatus to the powders for sub-lethal times of three, six and nine hours significantly reduced the fecundity of the beetles. E. aromatica powder caused the most reduction of eggs laid and also significantly reduced fertility of the eggs.展开更多
Aim. Comparison of the trascranial Doppler (TCD) characteristics of cerebral circulation in persistent vegetative status (PVS), locked in syndrome and brain death patients. Methods. Using ...Aim. Comparison of the trascranial Doppler (TCD) characteristics of cerebral circulation in persistent vegetative status (PVS), locked in syndrome and brain death patients. Methods. Using TCD ultrasound to detect the flow velocity and waveform patterns of middle cerebral artery (MCA) and basilar artery (BA) in patients with PVS, locked in syndrome and brain death. Results. The mean velocities of middle cerebral artery (Vmca) and basilar artery (Vba) were 30.0cm/s and 24.3cm/s in PVS patients respectively, which decreased 45.0% and 14.4% in comparing with normal value. For patients with locked in syndrome, Vmca and Vba were 49.7cm/s and 9.8cm/s, which decreased 5.0% and 61.7% than the normal value respectively. These results showed that the decrease of anterior circulation was predominant in PVS, and the decrease of posterior circulation was predominant in locked in syndrome. A unique diastolic reverse flow, short peak systolic wave or undetectable flow signal in middle cerebral artery were predominant in brain death patients, which was completely different from that of either PVS or locked in syndrome. Conclusion. TCD was a valuable tool in distinguishing PVS, locked in syndrome and brain death patients according to the differences in velocities and patterns of anterior and posterior cerebral arteries.展开更多
The importance of phytoplankton cell death is being increasingly recognized, however, there are still no published reports on this in Xiamen Bay. In this study, the proportion of dead phytoplankton cells associated wi...The importance of phytoplankton cell death is being increasingly recognized, however, there are still no published reports on this in Xiamen Bay. In this study, the proportion of dead phytoplankton cells associated with environmental factors was assessed at a station in Xiamen Bay from December 2012 to December 2013, using a cell digestion assay, which is an effective method to analyze dead/ living ceils in complex natural phytoplankton communities. The percentages of dead cells （% DC） in the total phytoplankton in summer （16%＋6%） were lower than those in winter （27%q-16%）. Six groups of phytoplankton （G1-G6） were categorized by flow cytometry. These phytoplankton communities with diverse seasonal variations in % DC had different responses to environmental constraints. The main factors affecting mortality were temperature and salinity, while nutrient concentration showed little influence on phytoplankton death. Additio^aally, our results provide evidence that chlorophyll a concentrations had an inverse relationship with total phytoplankton % DC and viable cell abundance was more meaningful than total cells to explain variations in environmental parameters （such as Chl a）. Moreover, the lowest mean % DC in total phytoplankton was 16%q-6% at our sample site, which is in a subtropical area with high water temperatures, full solar radiation, and rich nutrients. This indicates that phytoplankton cell death is a process that cannot be ignored. In summary, phytoplankton cell death is important in understanding the dynamics of phytoplankton communities and the fimctioning of subtropical ecosystems.展开更多
计划火烧作为管理植被生态系统的有效手段之一,越来越受到国内外植被管理者及研究者的关注。系统总结国内外计划火烧研究进展对我国林火生态学研究及植被恢复管理具有重要意义。文中利用国际科学论文Web of Science(WOS)数据库和CNKI数...计划火烧作为管理植被生态系统的有效手段之一,越来越受到国内外植被管理者及研究者的关注。系统总结国内外计划火烧研究进展对我国林火生态学研究及植被恢复管理具有重要意义。文中利用国际科学论文Web of Science(WOS)数据库和CNKI数据库中近10年的计划火烧研究文献,分析了计划火烧和野火的关系,计划火烧对植物物种丰富度、植物死亡率及植被恢复的影响,计划火烧对土壤性质、微生物及种子库的影响;对于未来研究,提出可利用计划火烧中的频率、强度、规格和时间参数,针对不同区域、不同经营目标的植被类型研发计划火烧模式,长期定位研究计划火烧对植被-土壤系统结构与功能的影响。展开更多
文摘The heterotrimeric guanine nucleotide-binding protein （G-protein） has been demonstrated to mediate various signaling pathways in plants. However, its role in phytochrome A （phyA） signaling remains elusive. In this study, we discover a new phyA-mediated phenotype designated far-red irradiation （FR） preconditioned cell death, which occurs only in the hypocotyls of FR-grown seedlings following exposure to white light （WL）. The cell death is mitigated in the Gα mutant gpal but aggravated in the Gβ mutant agbl in comparison with the wild type （WT）, indicative of antagonistic roles of GPA1 and AGBI in the phyA-mediated cell-death pathway. Further investigation indicates that FR-induced accumulation of nonphotoconvertible protochlorophyllide （Pchlide^633）, which generates reactive oxygen species （ROS） on exposure to WL, is required for FR-preconditioned cell death. Moreover, ROS is mainly detected in chloroplasts using the fluorescent probe. Interestingly, the application of H2O2 to dark-grown seedlings results in a phenotype similar to FR-preconditioned cell death. This reveals that ROS is a critical mediator for the ceil death. In addition, we observe that agb1 is more sensitive to H2O2 than WT seedlings, indicating that the G-protein may also modify the sensitivity of the seedlings to ROS stress. Taking these results together, we infer that the G-protein may be involved in the phyA signaling pathway to regulate FR-preconditioned cell death ofArabidopsis hypocotyls. A possible mechanism underlying the involvement of the G-protein in phyA signaling is discussed in this study.
文摘The effects of powders from dry flower buds of Eugenia aromatica Baill., seeds of Piper guineense Schum and Thonn and fruits of Capsicum frutescens L. on adult behaviour, mortality and reproductive fitness of the cowpea seed beetle, Callosobruchus maculatus (Fab.) were investigated under ambient laboratory conditions. All experiments were carried out in glass Petri plates. All powders elicited aversion in adult beetles. The contact toxicity symptoms included restlessness, loss of coordination, knock down and eventual death of adult beetles. These behaviours were more pronounced with E. aromatica in which adult beetles died within 16 hours. P. guineense and C. frutescens powders did not cause 100% mortality of adult beetles, even after 24 hours. Each of the three powders significantly (P<0.05) reduced the mating competition of adult males after sub-lethal exposure for one, two, and three hours, respectively. E. aromatica powder caused more reduction in male mating competition for females than any of the other two powders after each period of exposure. Receptiveness of treated females to courting males was also decreased by exposure to any of the three powders. Similarly, E. aromatica powder caused greater decreases in female receptiveness to males than any of the other two powders after each period of exposure. Exposure of either adult male or female C. maculatus to the powders for sub-lethal times of three, six and nine hours significantly reduced the fecundity of the beetles. E. aromatica powder caused the most reduction of eggs laid and also significantly reduced fertility of the eggs.
文摘Aim. Comparison of the trascranial Doppler (TCD) characteristics of cerebral circulation in persistent vegetative status (PVS), locked in syndrome and brain death patients. Methods. Using TCD ultrasound to detect the flow velocity and waveform patterns of middle cerebral artery (MCA) and basilar artery (BA) in patients with PVS, locked in syndrome and brain death. Results. The mean velocities of middle cerebral artery (Vmca) and basilar artery (Vba) were 30.0cm/s and 24.3cm/s in PVS patients respectively, which decreased 45.0% and 14.4% in comparing with normal value. For patients with locked in syndrome, Vmca and Vba were 49.7cm/s and 9.8cm/s, which decreased 5.0% and 61.7% than the normal value respectively. These results showed that the decrease of anterior circulation was predominant in PVS, and the decrease of posterior circulation was predominant in locked in syndrome. A unique diastolic reverse flow, short peak systolic wave or undetectable flow signal in middle cerebral artery were predominant in brain death patients, which was completely different from that of either PVS or locked in syndrome. Conclusion. TCD was a valuable tool in distinguishing PVS, locked in syndrome and brain death patients according to the differences in velocities and patterns of anterior and posterior cerebral arteries.
基金Supported by the National Natural Science Foundation of China(Nos.41330961,41406143)the Chinese Academy of Sciences Special Pilot Program(No.XDA10020103)+1 种基金the SOA Ocean Research Project,China(No.201105021-03)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130121110031)
文摘The importance of phytoplankton cell death is being increasingly recognized, however, there are still no published reports on this in Xiamen Bay. In this study, the proportion of dead phytoplankton cells associated with environmental factors was assessed at a station in Xiamen Bay from December 2012 to December 2013, using a cell digestion assay, which is an effective method to analyze dead/ living ceils in complex natural phytoplankton communities. The percentages of dead cells （% DC） in the total phytoplankton in summer （16%＋6%） were lower than those in winter （27%q-16%）. Six groups of phytoplankton （G1-G6） were categorized by flow cytometry. These phytoplankton communities with diverse seasonal variations in % DC had different responses to environmental constraints. The main factors affecting mortality were temperature and salinity, while nutrient concentration showed little influence on phytoplankton death. Additio^aally, our results provide evidence that chlorophyll a concentrations had an inverse relationship with total phytoplankton % DC and viable cell abundance was more meaningful than total cells to explain variations in environmental parameters （such as Chl a）. Moreover, the lowest mean % DC in total phytoplankton was 16%q-6% at our sample site, which is in a subtropical area with high water temperatures, full solar radiation, and rich nutrients. This indicates that phytoplankton cell death is a process that cannot be ignored. In summary, phytoplankton cell death is important in understanding the dynamics of phytoplankton communities and the fimctioning of subtropical ecosystems.
文摘计划火烧作为管理植被生态系统的有效手段之一,越来越受到国内外植被管理者及研究者的关注。系统总结国内外计划火烧研究进展对我国林火生态学研究及植被恢复管理具有重要意义。文中利用国际科学论文Web of Science(WOS)数据库和CNKI数据库中近10年的计划火烧研究文献,分析了计划火烧和野火的关系,计划火烧对植物物种丰富度、植物死亡率及植被恢复的影响,计划火烧对土壤性质、微生物及种子库的影响;对于未来研究,提出可利用计划火烧中的频率、强度、规格和时间参数,针对不同区域、不同经营目标的植被类型研发计划火烧模式,长期定位研究计划火烧对植被-土壤系统结构与功能的影响。
