Variations of nectar spur length allow pollinators to utilize resources in novel ways,leading to the different selective pressures on spurs and allowing taxa to diversify.However,the mechanisms underlying spur length ...Variations of nectar spur length allow pollinators to utilize resources in novel ways,leading to the different selective pressures on spurs and allowing taxa to diversify.However,the mechanisms underlying spur length variation remain unclear.Interspecific comparisons of spur length suggest that both cell division and anisotropic expansion could explain the changes of spur length,and that hormone-related genes contribute to the process of spur formation.In contrast,little is known about intraspecific spur length variation.In Aquilegia rockii,spur length varies strikingly,ranging from 1 mm to 18 mm.To examine the potential mechanisms underlying spur length variation in A.rockii,we observed cell morphology and analyzed RNA-seq of short-and long-spurred flowers.Scanning electron microscopy revealed that at two positions on spurs there were no differences in either cell density or cell anisotropy between short-and long-spurred flowers,suggesting that in A.rockii changes in cell number may explain variations in spur length.In addition,we screened transcriptomes of short-and long-spurred flowers for differentially expressed genes;this screen identified several genes linked to cell division(e.g.,F-box,CDKB2-2,and LST8),a finding which is consistent with our analysis of the cellular morphology of spurs.However,we did not find any highly expressed genes involved in the hormone pathway in long-spurred flowers.In contrast to previous hypotheses that anisotropic cell expansion leads to interspecific spur variation in Aquilegia,our results suggest that cell number changes and related genes are mainly responsible for spur length variations of A.rockii.Furthermore,the underlying mechanisms of similar floral traits in morphology may be quite different,enriching our understanding of the mechanisms of flower diversity in angiosperms.展开更多
Some people kill others as well as themselves in the hope of achieving fame. Even more, some people seek spectacular displays of carnage. This danger is the focus of my essay. I argue that the pursuit of fame is able ...Some people kill others as well as themselves in the hope of achieving fame. Even more, some people seek spectacular displays of carnage. This danger is the focus of my essay. I argue that the pursuit of fame is able to generate mass killings because of a hope for personal immortality underlying the pursuit. Primarily through the work of Miguel de Unamuno and Ernest Becker, I argue that the hope for immortality is a powerful yet amoral impulse that is able to generate a lethal pursuit of fame. I argue that linking fame to one＇s social immortalization exacerbates the conflict already present in the pursuit of fame as well as enables the fame seeker to reduce all others to a means. Following my theoretical analysis, I turn to the iconic shootings at Columbine High School. The shootings offer a practical exemplification of how the pursuit of social immortalization can generate mass carnage. I argue that understanding the tragedy of Columbine as predicated upon a hope for social immortalization offers a template for destruction that ought to be considered when examining other, and all too frequent, instances of mass violence.展开更多
Stem bark of Dalbergia lanceolaria was subjected to methanolic extraction and extensive phytochemical separation. The process yielded four known compounds namely Jateorin (1), Columbin (2), β-sitosterol (3), and Lupe...Stem bark of Dalbergia lanceolaria was subjected to methanolic extraction and extensive phytochemical separation. The process yielded four known compounds namely Jateorin (1), Columbin (2), β-sitosterol (3), and Lupeol (4). The compounds were identified using nuclear magnetic resonance spectral data namely 1H NMR, 13C NMR, 1H-1H COSY, HMBC, and DEPT-135 and verified by comparing the data with previous literature. All four compounds are being reported for the first time from the species D. lanceolaria. Furthermore, two furanoditerpenes namely Jateorin and Columbin are reported for the first time from the genus Dalbergia. This may lead to potential identification of a new chemotaxonomic marker for this genus.展开更多
基金financially supported by National Natural Science Foundation of China (31760104, 41461014, 31460040, and 31870183)
文摘Variations of nectar spur length allow pollinators to utilize resources in novel ways,leading to the different selective pressures on spurs and allowing taxa to diversify.However,the mechanisms underlying spur length variation remain unclear.Interspecific comparisons of spur length suggest that both cell division and anisotropic expansion could explain the changes of spur length,and that hormone-related genes contribute to the process of spur formation.In contrast,little is known about intraspecific spur length variation.In Aquilegia rockii,spur length varies strikingly,ranging from 1 mm to 18 mm.To examine the potential mechanisms underlying spur length variation in A.rockii,we observed cell morphology and analyzed RNA-seq of short-and long-spurred flowers.Scanning electron microscopy revealed that at two positions on spurs there were no differences in either cell density or cell anisotropy between short-and long-spurred flowers,suggesting that in A.rockii changes in cell number may explain variations in spur length.In addition,we screened transcriptomes of short-and long-spurred flowers for differentially expressed genes;this screen identified several genes linked to cell division(e.g.,F-box,CDKB2-2,and LST8),a finding which is consistent with our analysis of the cellular morphology of spurs.However,we did not find any highly expressed genes involved in the hormone pathway in long-spurred flowers.In contrast to previous hypotheses that anisotropic cell expansion leads to interspecific spur variation in Aquilegia,our results suggest that cell number changes and related genes are mainly responsible for spur length variations of A.rockii.Furthermore,the underlying mechanisms of similar floral traits in morphology may be quite different,enriching our understanding of the mechanisms of flower diversity in angiosperms.
文摘Some people kill others as well as themselves in the hope of achieving fame. Even more, some people seek spectacular displays of carnage. This danger is the focus of my essay. I argue that the pursuit of fame is able to generate mass killings because of a hope for personal immortality underlying the pursuit. Primarily through the work of Miguel de Unamuno and Ernest Becker, I argue that the hope for immortality is a powerful yet amoral impulse that is able to generate a lethal pursuit of fame. I argue that linking fame to one＇s social immortalization exacerbates the conflict already present in the pursuit of fame as well as enables the fame seeker to reduce all others to a means. Following my theoretical analysis, I turn to the iconic shootings at Columbine High School. The shootings offer a practical exemplification of how the pursuit of social immortalization can generate mass carnage. I argue that understanding the tragedy of Columbine as predicated upon a hope for social immortalization offers a template for destruction that ought to be considered when examining other, and all too frequent, instances of mass violence.
文摘Stem bark of Dalbergia lanceolaria was subjected to methanolic extraction and extensive phytochemical separation. The process yielded four known compounds namely Jateorin (1), Columbin (2), β-sitosterol (3), and Lupeol (4). The compounds were identified using nuclear magnetic resonance spectral data namely 1H NMR, 13C NMR, 1H-1H COSY, HMBC, and DEPT-135 and verified by comparing the data with previous literature. All four compounds are being reported for the first time from the species D. lanceolaria. Furthermore, two furanoditerpenes namely Jateorin and Columbin are reported for the first time from the genus Dalbergia. This may lead to potential identification of a new chemotaxonomic marker for this genus.
