My essay on Heart of Darkness explores Conrad’s dramatization of the voice and heart dynamic in the novella as a penetration of the deep-lying rationale of colonial operation and more generally the human condition at...My essay on Heart of Darkness explores Conrad’s dramatization of the voice and heart dynamic in the novella as a penetration of the deep-lying rationale of colonial operation and more generally the human condition at the turn of the 20th century.Three different forms of assumed centrality in the novella-capital,Eurocentrism,and the African interior as detrimental void symbolized by the heart of darkness form concentric circles that interconnect and work in concert as the core colonial ideology and produce a sense of incongruity and absurdity.The voice of this colonial ideological apparatus disguised as the universal subject of humanity and rationality finds its best expression in the eloquence of Kurtz,the specimen of culture seduced by its very opposite-the wilderness-right in the heart of darkness.“The horror”,as his final verdict of life as a European with real intent of living on his own terms at the turn of the 20th century,sums up the predicament of a civilization with too much culture and self-absorption for its own good.展开更多
With the discouraging, and horrifying descriptions, Conrad and Golding unanimously present the universal subject matter that at his heart, man is an evil, vicious, and"fallen"being. Furthermore, human being ...With the discouraging, and horrifying descriptions, Conrad and Golding unanimously present the universal subject matter that at his heart, man is an evil, vicious, and"fallen"being. Furthermore, human being is just susceptible to his own sinister nature. Both Heart of Darkness and Lord of the Flies imply that every man has an evil heart of darkness which is more often than not drowned out by the glow of civilization.展开更多
Spring water but not double-distilled water was exposed, in darkness, to a temporally patterned weak magnetic field that has been shown to affect planarian behavior and slow the rate of cancer cell proliferation. Expo...Spring water but not double-distilled water was exposed, in darkness, to a temporally patterned weak magnetic field that has been shown to affect planarian behavior and slow the rate of cancer cell proliferation. Exposure to the magnetic field caused a reliable shift in the peak (longer) wave-length of ~10 nm for fluorescence emissions and a ~20% increase (~100 counts) in fluorescence intensity. Spectral analyses verified a shift of 5 and 10 nm, equivalent to ~1.5 × 10-20 J “periodicity” across the measured wavelengths, which could reflect a change in the an intrinsic energy as predicted by Del Giudice and Preparata and could correspond to two lengths of O-H bonds. Wrapping the water sample containers during exposure with copper foil, aluminum foil, or plastic altered these fluorescent profiles. The most conspicuous effect was the elimination of a ~280 nm peak in the UV-VIS emission spectra only for samples wrapped with copper foil but not aluminum or plastic. These results suggest that weak magnetic fields produce alterations in the water-ionic complexes sufficient to be reliably measured by spectrophotometry. Because the effect was most pronounced when the spring water was exposed in darkness and was not disturbed the role of thixotropic phenomena and Del Giudice entrapment of magnetic fields within coherent domains of Pollack virtual exclusion zones (EZ) may have set the conditions for subsequent release of the energy as photons.展开更多
Heart of Darkness, a chilling tale of horror set in the Congo during the period of rapid colonial expansion in the 19th century written by the renowned British novelist Joseph Conrad, is a world famous novella. Since ...Heart of Darkness, a chilling tale of horror set in the Congo during the period of rapid colonial expansion in the 19th century written by the renowned British novelist Joseph Conrad, is a world famous novella. Since its publication, it remains an indisputably classic text and arguably Conrad's finest work. And it has been regarded as a significant text in British literature because of its modernistic features, innovative narration and artistic style. Heart of Darkness deals with the highly disturbing effects of economic, social and political exploitation of European and African societies. It has inspired filmmakers and such authors as F. Scott Fitzgerald, Gabriel Garica Marquez, D. H. Lawrence and Virginia,Woolf. This article is aimed to analyse it from the perspective of primitiveness and civilization. Through the analysis, readers can sense Conrad's attitude towards the two aspects.展开更多
Plants must maintain a balance between their carbon(C)supply and utilization during the day–night cycle for continuous growth since C starvation often causes irreversible damage to crop production.It is not well know...Plants must maintain a balance between their carbon(C)supply and utilization during the day–night cycle for continuous growth since C starvation often causes irreversible damage to crop production.It is not well known how C fixation and allocation in the leaves of crops such as maize adapt to sudden environmental changes.Here,to quantify primary C fixation and partitioning in photosynthetic maize leaves under extended darkness and to relate these factors to plant growth,maize seedlings were subjected to extended darkness(ED)for three successive days at the 6 th leaf fully expanded stage(V6).ED reduced plant growth and leaf chlorophyll levels but not the rate of net CO_2 exchange.As a result of the reduction in photoassimilates,the accumulation of starch and total soluble carbohydrates(TSC)in mature leaves also decreased under ED.However,the percentage of the daily C fixation reserved in mature leaves increased.These transient C pools were largely composed of TSC and were mainly used for consumption by increased nocturnal respiration rather than for transport.As the days went on,both the amount of C accumulated and the percentage of the daily fixed C that was reserved in leaves decreased,which could be largely accounted for by the attenuated starch synthesis in all treatments.The activities of ADPglucose pyrophosphorylase and soluble starch synthase decreased significantly over time.Therefore,this study concluded that both starch and TSC are involved in the coordination of the C supply and plant growth under a sudden C shortage but that they may be involved in different ways.While the ratio of reserved C to daily fixed C increased to maintain blade function under acute C starvation,both the amount and the proportion of C reserved in mature leaves decreased as plant growth continued in order to meet the growth demands of the plant.展开更多
This paper presents the results of darkness adaptationtest for drivers. It is shown that there is a significant difference ( p <0.05)in their darkness adaptation ability between the drivers in accident group and ...This paper presents the results of darkness adaptationtest for drivers. It is shown that there is a significant difference ( p <0.05)in their darkness adaptation ability between the drivers in accident group and non-accident group. It is further revealed that the accident rate of the drivers with darkness adaptation time ≤10 s is 2.6%, while that with darkness adaptation time >10 s is 7.3%, implying that the high accident rate of the drivers in accident group might be caused by their longer darkness adaptation time.展开更多
Heart of Darkness is one of the masterpieces of Joseph Conrad （1857-1924）, which shows the author＇s great humanity and his unreserved horror at the crimes committed by the colonists and imperialists all over the wo...Heart of Darkness is one of the masterpieces of Joseph Conrad （1857-1924）, which shows the author＇s great humanity and his unreserved horror at the crimes committed by the colonists and imperialists all over the world. This thesis tries to analyze its three themes： the Colonists＇ material essence, the dark side of human nature, and the disillusionment of civilization. Kurtz, the main character in the novel, is characterized by his greed for material gain and power. The dark side of human nature is reflected in Kurtz＇s cruel behavior towards the natives, his sense of superiority to the marginalized, and his dominance in discourse over the colonial people. Along with the colonists＇ crazy behaviors, there is disillusion with the modem civilization.展开更多
Joseph Conrad in Heart of Darkness calls for the suppressed species on humanitarian grounds.In this sense,this paper aims to dredge how the suppressed species utter their voices of rebellion and form a special soundsc...Joseph Conrad in Heart of Darkness calls for the suppressed species on humanitarian grounds.In this sense,this paper aims to dredge how the suppressed species utter their voices of rebellion and form a special soundscape.The African natives make use of unique ways of drumming and shouting,to tell how they are enslaved and how they resist the domination of the British pilgrims.In the meanwhile,the black female also uses voices to rebel against her marginal condition compared to males,including white and her native males.By putting the story’s sound narrative in the framework of ecofeminism,this paper intends to not only disclose the rebellious spirit of those suppressed species,but also raise people’s awareness of caring for the living creatures in the marginal status,including women,the blacks,animals,and the ecological environment as a whole.展开更多
Joseph Conrad is one of the most influential writers at the turn of 20th century. Heart of Darkness is one of his representative novels which were partly based on Conrad＇ s four-month journey to Belgian Congo in 1890...Joseph Conrad is one of the most influential writers at the turn of 20th century. Heart of Darkness is one of his representative novels which were partly based on Conrad＇ s four-month journey to Belgian Congo in 1890. The plot of Heart of Darkness is simple, but the meaning of the plot is not easy to grasp. The masterpiece bears very strong symbolic colors in the description of the setting and characters, which is worth further research.展开更多
The article is a book review of Joseph Conrad's novella:Heart of Darkness. In this novella, the author criticizes colonial-ism by telling the story of Marlow and Kurtz. This article analyzes Heart of Darkness from...The article is a book review of Joseph Conrad's novella:Heart of Darkness. In this novella, the author criticizes colonial-ism by telling the story of Marlow and Kurtz. This article analyzes Heart of Darkness from the following aspects:background, charac-terization, symbolization and influence.展开更多
As one of the most important and greatest novels of Joseph Conrad, Heart of Darkness, has attracted extensive attention from literature fields in the world and has always been under critics since its publication. This...As one of the most important and greatest novels of Joseph Conrad, Heart of Darkness, has attracted extensive attention from literature fields in the world and has always been under critics since its publication. This paper,from the perspective of Edward Said's postcolonial theory—Orientalism,aims to analyze this classical work from the following three aspects: distorted description of the nature settings in Africa, distorted description of the image of the Africans as well as the white's blame on Africa for their degeneration.展开更多
Human nature is one of the most thoroughly studied topics in human history.Even today the argument continues in all different social contexts,and by studying Conrad's two stories:Heart of Darkness and The Secret S...Human nature is one of the most thoroughly studied topics in human history.Even today the argument continues in all different social contexts,and by studying Conrad's two stories:Heart of Darkness and The Secret Sharer,the author tries to analyze the two sides of the nature,both good and evil,which are inherent in us humans.In the essay the author explores the two heroes in the stories and tries to prove that only when we realize and admit our capability for the evil,can we make the good and kind side of nature to flourish.展开更多
We extract key information on dark energy from current observations of BAO,OHD and H_(0),and find hints of dynamical behavior of dark energy.In particular,a dynamical dark energy model whose equation of state crosses-...We extract key information on dark energy from current observations of BAO,OHD and H_(0),and find hints of dynamical behavior of dark energy.In particular,a dynamical dark energy model whose equation of state crosses-1 is favored by observations.We also find that the Universe has started accelerating at a lower redshift than expected.展开更多
In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la...In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la is dimmer than expected.This dimming effect is considered observational evidence for the existence of dark energy in the universe.It should be noted that this conclusion is based on an assumption that the mass density of the cosmic plasma is very small.Therefore,the dimming effect caused by the Compton scattering of free electrons in cosmic plasma can be neglected.X-ray observations suggest that the mass density of the cosmic plasma may be very large.In theory,the observed dimming effect of high redshift supernovae Ia may be caused by the Compton scattering of free electrons in the cosmic plasma.In this paper it will be shown that this idea is reasonable.Therefore,there is no need to introduce the confusing concept of dark energy into cosmology.展开更多
PHYTOCHROME-INTERACTING FACTORS(PIFs)are a group of basic helix-loop-helix transcription factors that can physically interact with photoreceptors,including phytochromes and cryptochromes.It was previously demonstrated...PHYTOCHROME-INTERACTING FACTORS(PIFs)are a group of basic helix-loop-helix transcription factors that can physically interact with photoreceptors,including phytochromes and cryptochromes.It was previously demonstrated that PIFs accumulated in darkness and repressed seedling photomorphogenesis,and that PIFs linked different photosensory and hormonal pathways to control plant growth and development.In this study,we show that PIFs positively regulate the ABA signaling pathway during the seedling stage specifically in darkness.We found that PIFs positively regulate ABI5 transcript and protein levels in darkness in response to exogenous ABA treatment by binding directly to the G-box motifs in the ABI5 promoter.Consistently,PIFs and the G-box motifs in the ABI5 promoter determine ABI5 expression in darkness,and overexpression of ABI5 could rescue the ABA-insensitive phenotypes of pifq mutants in the dark.Moreover,we discovered that PIFs can physically interact with the ABA receptors PYL8 and PYL9,and that this interaction is not regulated by ABA.Further analyses showed that PYL8 and PYL9 promote PIF4 protein accumulation in the dark and enhance PIF4 binding to the ABI5 promoter,but negatively regulate PIF4-mediated ABI5 activation.Taken together,our data demonstrate that PIFs interact with ABA receptors to orchestrate ABA signaling in darkness by controlling ABI5 expression,providing new insights into the pivotal roles of PIFs as signal integrators in regulating plant growth and development.展开更多
The role and signaling of sphingosine-l-phosphate （SIP） during darkness-induced stomatal closure were examined in Vicia faba. Darkness substantially raised S 1P and hydrogen peroxide （H202） levels and closed stoma...The role and signaling of sphingosine-l-phosphate （SIP） during darkness-induced stomatal closure were examined in Vicia faba. Darkness substantially raised S 1P and hydrogen peroxide （H202） levels and closed stomata. These darkness effects were significantly suppressed by DL-threo-dihydrosphingosine （DL-threo-DHS） and N,N-dimethylsphingosine （DMS）, two inhibi- tors of long-chain base kinases. Exogenous SIP led to stomatal closure and H202 production, and the effects of SIP were largely prevented by the H202 modulators ascorbic acid, catalase, and diphenyleneiodonium. These results indicated that SIP mediated darkness-induced stomatal closure by triggering H202 production. In addition, DL-threo-DHS and DMS significantly suppressed both darkness-induced cytosolic alkalization in guard cells and stomatal closure. Exogenous SIP caused cytosolic alkalization and stomatal closure, which could be largely abolished by butyric acid. These results demonstrated that SIP syn-thesis was necessary for cytosolic alkalization during stomatal closure caused by darkness. Furthermore, together with the data described above, inhibition of darkness-induced H202 production by butyric acid revealed that S 1P synthesis-induced cytosolic alkalization was a prerequisite for H202 production during stomatal closure caused by darkness, a conclusion supported by the facts that the pH increase caused by exogenous SIP had a shorter lag and peaked faster than H202 levels and that butyric acid prevented exogenous SIP-induced H202 production. Altogether, our data suggested that darkness induced SIP synthesis, causing cytosolic alkalization and subsequent H202 production, finally leading to stomatal closure.展开更多
文摘My essay on Heart of Darkness explores Conrad’s dramatization of the voice and heart dynamic in the novella as a penetration of the deep-lying rationale of colonial operation and more generally the human condition at the turn of the 20th century.Three different forms of assumed centrality in the novella-capital,Eurocentrism,and the African interior as detrimental void symbolized by the heart of darkness form concentric circles that interconnect and work in concert as the core colonial ideology and produce a sense of incongruity and absurdity.The voice of this colonial ideological apparatus disguised as the universal subject of humanity and rationality finds its best expression in the eloquence of Kurtz,the specimen of culture seduced by its very opposite-the wilderness-right in the heart of darkness.“The horror”,as his final verdict of life as a European with real intent of living on his own terms at the turn of the 20th century,sums up the predicament of a civilization with too much culture and self-absorption for its own good.
文摘With the discouraging, and horrifying descriptions, Conrad and Golding unanimously present the universal subject matter that at his heart, man is an evil, vicious, and"fallen"being. Furthermore, human being is just susceptible to his own sinister nature. Both Heart of Darkness and Lord of the Flies imply that every man has an evil heart of darkness which is more often than not drowned out by the glow of civilization.
文摘Spring water but not double-distilled water was exposed, in darkness, to a temporally patterned weak magnetic field that has been shown to affect planarian behavior and slow the rate of cancer cell proliferation. Exposure to the magnetic field caused a reliable shift in the peak (longer) wave-length of ~10 nm for fluorescence emissions and a ~20% increase (~100 counts) in fluorescence intensity. Spectral analyses verified a shift of 5 and 10 nm, equivalent to ~1.5 × 10-20 J “periodicity” across the measured wavelengths, which could reflect a change in the an intrinsic energy as predicted by Del Giudice and Preparata and could correspond to two lengths of O-H bonds. Wrapping the water sample containers during exposure with copper foil, aluminum foil, or plastic altered these fluorescent profiles. The most conspicuous effect was the elimination of a ~280 nm peak in the UV-VIS emission spectra only for samples wrapped with copper foil but not aluminum or plastic. These results suggest that weak magnetic fields produce alterations in the water-ionic complexes sufficient to be reliably measured by spectrophotometry. Because the effect was most pronounced when the spring water was exposed in darkness and was not disturbed the role of thixotropic phenomena and Del Giudice entrapment of magnetic fields within coherent domains of Pollack virtual exclusion zones (EZ) may have set the conditions for subsequent release of the energy as photons.
文摘Heart of Darkness, a chilling tale of horror set in the Congo during the period of rapid colonial expansion in the 19th century written by the renowned British novelist Joseph Conrad, is a world famous novella. Since its publication, it remains an indisputably classic text and arguably Conrad's finest work. And it has been regarded as a significant text in British literature because of its modernistic features, innovative narration and artistic style. Heart of Darkness deals with the highly disturbing effects of economic, social and political exploitation of European and African societies. It has inspired filmmakers and such authors as F. Scott Fitzgerald, Gabriel Garica Marquez, D. H. Lawrence and Virginia,Woolf. This article is aimed to analyse it from the perspective of primitiveness and civilization. Through the analysis, readers can sense Conrad's attitude towards the two aspects.
基金supported by the National Key Research and Development Program of China(2016YFD0300301)the earmarked fund for China Agriculture Research System of MOF and MARA(CARS-02-13)the Education Department of Jiangxi Province,China(190233)。
文摘Plants must maintain a balance between their carbon(C)supply and utilization during the day–night cycle for continuous growth since C starvation often causes irreversible damage to crop production.It is not well known how C fixation and allocation in the leaves of crops such as maize adapt to sudden environmental changes.Here,to quantify primary C fixation and partitioning in photosynthetic maize leaves under extended darkness and to relate these factors to plant growth,maize seedlings were subjected to extended darkness(ED)for three successive days at the 6 th leaf fully expanded stage(V6).ED reduced plant growth and leaf chlorophyll levels but not the rate of net CO_2 exchange.As a result of the reduction in photoassimilates,the accumulation of starch and total soluble carbohydrates(TSC)in mature leaves also decreased under ED.However,the percentage of the daily C fixation reserved in mature leaves increased.These transient C pools were largely composed of TSC and were mainly used for consumption by increased nocturnal respiration rather than for transport.As the days went on,both the amount of C accumulated and the percentage of the daily fixed C that was reserved in leaves decreased,which could be largely accounted for by the attenuated starch synthesis in all treatments.The activities of ADPglucose pyrophosphorylase and soluble starch synthase decreased significantly over time.Therefore,this study concluded that both starch and TSC are involved in the coordination of the C supply and plant growth under a sudden C shortage but that they may be involved in different ways.While the ratio of reserved C to daily fixed C increased to maintain blade function under acute C starvation,both the amount and the proportion of C reserved in mature leaves decreased as plant growth continued in order to meet the growth demands of the plant.
文摘This paper presents the results of darkness adaptationtest for drivers. It is shown that there is a significant difference ( p <0.05)in their darkness adaptation ability between the drivers in accident group and non-accident group. It is further revealed that the accident rate of the drivers with darkness adaptation time ≤10 s is 2.6%, while that with darkness adaptation time >10 s is 7.3%, implying that the high accident rate of the drivers in accident group might be caused by their longer darkness adaptation time.
文摘Heart of Darkness is one of the masterpieces of Joseph Conrad （1857-1924）, which shows the author＇s great humanity and his unreserved horror at the crimes committed by the colonists and imperialists all over the world. This thesis tries to analyze its three themes： the Colonists＇ material essence, the dark side of human nature, and the disillusionment of civilization. Kurtz, the main character in the novel, is characterized by his greed for material gain and power. The dark side of human nature is reflected in Kurtz＇s cruel behavior towards the natives, his sense of superiority to the marginalized, and his dominance in discourse over the colonial people. Along with the colonists＇ crazy behaviors, there is disillusion with the modem civilization.
文摘Joseph Conrad in Heart of Darkness calls for the suppressed species on humanitarian grounds.In this sense,this paper aims to dredge how the suppressed species utter their voices of rebellion and form a special soundscape.The African natives make use of unique ways of drumming and shouting,to tell how they are enslaved and how they resist the domination of the British pilgrims.In the meanwhile,the black female also uses voices to rebel against her marginal condition compared to males,including white and her native males.By putting the story’s sound narrative in the framework of ecofeminism,this paper intends to not only disclose the rebellious spirit of those suppressed species,but also raise people’s awareness of caring for the living creatures in the marginal status,including women,the blacks,animals,and the ecological environment as a whole.
文摘Joseph Conrad is one of the most influential writers at the turn of 20th century. Heart of Darkness is one of his representative novels which were partly based on Conrad＇ s four-month journey to Belgian Congo in 1890. The plot of Heart of Darkness is simple, but the meaning of the plot is not easy to grasp. The masterpiece bears very strong symbolic colors in the description of the setting and characters, which is worth further research.
文摘The article is a book review of Joseph Conrad's novella:Heart of Darkness. In this novella, the author criticizes colonial-ism by telling the story of Marlow and Kurtz. This article analyzes Heart of Darkness from the following aspects:background, charac-terization, symbolization and influence.
文摘As one of the most important and greatest novels of Joseph Conrad, Heart of Darkness, has attracted extensive attention from literature fields in the world and has always been under critics since its publication. This paper,from the perspective of Edward Said's postcolonial theory—Orientalism,aims to analyze this classical work from the following three aspects: distorted description of the nature settings in Africa, distorted description of the image of the Africans as well as the white's blame on Africa for their degeneration.
文摘Human nature is one of the most thoroughly studied topics in human history.Even today the argument continues in all different social contexts,and by studying Conrad's two stories:Heart of Darkness and The Secret Sharer,the author tries to analyze the two sides of the nature,both good and evil,which are inherent in us humans.In the essay the author explores the two heroes in the stories and tries to prove that only when we realize and admit our capability for the evil,can we make the good and kind side of nature to flourish.
基金supported by the National Key R&D Program of China(2023YFA1607800 and 2023YFA1607803)National Natural Science Foundation of China (NSFC,Grant Nos.11925303 and 11890691)+3 种基金supported by the National Natural Science Foundation of China (NSFC,Grant No.12203062)by a CAS Project for Young Scientists in Basic Research (No.YSBR-092)supported by science research grants from the China Manned Space Project with No.CMS-CSST-2021-B01supported by the New Cornerstone Science Foundation through the XPLORER prize。
文摘We extract key information on dark energy from current observations of BAO,OHD and H_(0),and find hints of dynamical behavior of dark energy.In particular,a dynamical dark energy model whose equation of state crosses-1 is favored by observations.We also find that the Universe has started accelerating at a lower redshift than expected.
文摘In observational cosmology,a supernova la is used as a standard candle in order to extend the Hubble diagram to a higher redshift range.Astrophysicists found that the observed brightness of high redshift supernovae la is dimmer than expected.This dimming effect is considered observational evidence for the existence of dark energy in the universe.It should be noted that this conclusion is based on an assumption that the mass density of the cosmic plasma is very small.Therefore,the dimming effect caused by the Compton scattering of free electrons in cosmic plasma can be neglected.X-ray observations suggest that the mass density of the cosmic plasma may be very large.In theory,the observed dimming effect of high redshift supernovae Ia may be caused by the Compton scattering of free electrons in the cosmic plasma.In this paper it will be shown that this idea is reasonable.Therefore,there is no need to introduce the confusing concept of dark energy into cosmology.
基金supported by grants from the National Natural Science Foundation of China(31970262 and 31770321)the Ministry of Agriculture of China for Transgenic Research(2019ZX08010003-002-005)Beijing Outstanding University Discipline Program,and the Recruitm ent Program of Global Youth Experts of China.
文摘PHYTOCHROME-INTERACTING FACTORS(PIFs)are a group of basic helix-loop-helix transcription factors that can physically interact with photoreceptors,including phytochromes and cryptochromes.It was previously demonstrated that PIFs accumulated in darkness and repressed seedling photomorphogenesis,and that PIFs linked different photosensory and hormonal pathways to control plant growth and development.In this study,we show that PIFs positively regulate the ABA signaling pathway during the seedling stage specifically in darkness.We found that PIFs positively regulate ABI5 transcript and protein levels in darkness in response to exogenous ABA treatment by binding directly to the G-box motifs in the ABI5 promoter.Consistently,PIFs and the G-box motifs in the ABI5 promoter determine ABI5 expression in darkness,and overexpression of ABI5 could rescue the ABA-insensitive phenotypes of pifq mutants in the dark.Moreover,we discovered that PIFs can physically interact with the ABA receptors PYL8 and PYL9,and that this interaction is not regulated by ABA.Further analyses showed that PYL8 and PYL9 promote PIF4 protein accumulation in the dark and enhance PIF4 binding to the ABI5 promoter,but negatively regulate PIF4-mediated ABI5 activation.Taken together,our data demonstrate that PIFs interact with ABA receptors to orchestrate ABA signaling in darkness by controlling ABI5 expression,providing new insights into the pivotal roles of PIFs as signal integrators in regulating plant growth and development.
基金supported by the Graduate Education Innovation Program Projects of Ministry of Education, China (Grant No. F-0922)
文摘The role and signaling of sphingosine-l-phosphate （SIP） during darkness-induced stomatal closure were examined in Vicia faba. Darkness substantially raised S 1P and hydrogen peroxide （H202） levels and closed stomata. These darkness effects were significantly suppressed by DL-threo-dihydrosphingosine （DL-threo-DHS） and N,N-dimethylsphingosine （DMS）, two inhibi- tors of long-chain base kinases. Exogenous SIP led to stomatal closure and H202 production, and the effects of SIP were largely prevented by the H202 modulators ascorbic acid, catalase, and diphenyleneiodonium. These results indicated that SIP mediated darkness-induced stomatal closure by triggering H202 production. In addition, DL-threo-DHS and DMS significantly suppressed both darkness-induced cytosolic alkalization in guard cells and stomatal closure. Exogenous SIP caused cytosolic alkalization and stomatal closure, which could be largely abolished by butyric acid. These results demonstrated that SIP syn-thesis was necessary for cytosolic alkalization during stomatal closure caused by darkness. Furthermore, together with the data described above, inhibition of darkness-induced H202 production by butyric acid revealed that S 1P synthesis-induced cytosolic alkalization was a prerequisite for H202 production during stomatal closure caused by darkness, a conclusion supported by the facts that the pH increase caused by exogenous SIP had a shorter lag and peaked faster than H202 levels and that butyric acid prevented exogenous SIP-induced H202 production. Altogether, our data suggested that darkness induced SIP synthesis, causing cytosolic alkalization and subsequent H202 production, finally leading to stomatal closure.
