Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)...Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)metabolism.Blue-diode based PAM technology was used to measure the Photosynthetic Oxygen Evolution Rate(POER:1O_(2)≡4e^(-)).Optimum Irradiance(E_(opt)),maximum POER(POER_(max))and quantum efficiency(α_(0))all vary on a diurnal cycle.The shape of the POER vs.E curves is different in seedling,submerged and surface leaves.Both E_(opt)and POER_(max)are very low in seedling leaves(E_(opt)≈104μmol photon m^(-2)s^(-1),PPFD;POER_(max)≈4.95µmol O_(2)g^(-1)Chl a s^(-1)),intermediate in mature submerged leaves(E_(opt)≈419µmol photon m^(-2)s^(-1)PPFD,POER_(max)≈38.1µmol O_(2)g^(-1)Chl a s^(-1))and very high in surface leaves(E_(opt)≈923µmol photon m^(-2)s^(-1)PPFD,POER_(max)≈76.1µmol O_(2)g^(-1)Chl a s^(-1)).Leaf titratable acid(C4 acid pool)is too small(≈20 to 50 mol H+m^(-3))to support substantial SAM metabolism.Gross daily photosynthesis of surface leaves is≈3.71 g C m^(-2)d^(-1)in full sun and as much as 1.4 gC m^(-2)d^(-1)in shaded submerged leaves.There is midday inhibition of photosynthesis.展开更多
Pigments are widely used as indices for estimation of phytoplankton biomass and composition,and many protocols have been developed to analyze pigments in phytoplankton.Different protocols were compared using four solv...Pigments are widely used as indices for estimation of phytoplankton biomass and composition,and many protocols have been developed to analyze pigments in phytoplankton.Different protocols were compared using four solvents(methanol,95%methanol,dimethylformamide,and 90%acetone)and two instruments(fluorometer and high-performance liquid chromatography(HPLC)coupled with diode array detector).Analysis of chlorophyll a(Chl a)with fluorometer could lead to over-or underestimation due to the interference from its derivatives in all probability.Among the four extractants,90%acetone had a high recovery for chlorophylls.In contrast,95%methanol was a poor extractant for chlorophylls due to the degradation of Chl a,especially in diatoms.The 95%methanol,however,had high extraction efficiencies for most diagnostic xanthophylls.Therefore,the selection of pigment analytical protocols should follow the specific purpose of phytoplankton study.In addition to fluorometry,an HPLC method with 90%acetone as extractant shall be a good choice for the analysis of Chl a to estimate phytoplankton biomass,especially for diatom-dominated samples,while an HPLC method with 95%methanol as extractant be more suitable to characterize different taxa in phytoplankton communities.展开更多
The management of cyanobacteria and potential exposure to associated biotoxins requires the allocation of scarce resources across a range of freshwater resources within various jurisdictions. Cost effective and reliab...The management of cyanobacteria and potential exposure to associated biotoxins requires the allocation of scarce resources across a range of freshwater resources within various jurisdictions. Cost effective and reliable methods for sample processing and analysis form the foundation of the protocol yielding reliable data from which to derive important decisions. In this study the utilization of new methods to collect, process and analyze samples enhanced our ability to evaluate cyanobacterial populations. Extraction of phycocyanin using the single freeze thaw method provided more accurate and precise measurements (CV 4.7% and 6.4%), offering a simple and cost-effective means to overcome the influence of morphological variability. In-vacuo concentration of samples prior to ELISA analysis provided a detection limit of 0.001 μg·L?1 MC. Fractionation of samples (?1) = ?0.279 + (1.368 ? Log PC (μg·L?1) while in an Aphanizomemon spp. dominant system Log MC (ng·L?1) = 0.385 + (0.449 ? Log PC (μg·L?1). These methods and sampling protocol could be used in other aquatic systems across a broader regional landscape to estimate the levels of microcystins.展开更多
Global warming has been the subject of concern in today’s world with elevating temperature causing the melting of polar ice and increasing sea level.The aim of this study was to investigate the physiological and phot...Global warming has been the subject of concern in today’s world with elevating temperature causing the melting of polar ice and increasing sea level.The aim of this study was to investigate the physiological and photosynthetic performance of two polar Chlorella,namely Chlorella UMACC 250 and Chlorella UMACC 234 to elevating temperatures as might be experienced under future warming scenarios.The cultures were exposed to three different temperatures of 4℃,8℃and 12℃.The growth and photosynthetic activity were determined every 2 d for a period of 10 d.At the end of the experiment,the cultures were harvested and analysed for biochemical composition.Both Chlorella strains were able to tolerate higher temperatures than their ambient temperature.The final pigments content showed an increasing trend with increased temperatures for both strains.The photosynthetic activities were measured using pulse-amplitude modulation(PAM)fluorometer.The photosynthetic parameters including maximum quantum efficiency(Fv/Fm),maximum relative electron transport rate(r ETRmax),light harvesting efficiency(a)and photoadaptive index(Ek)were derived from the rapid light curves(RLCs).Both Chlorella strains showed a slight decline in growth and photosynthetic activities at the initial part of the experiment.However,they showed the ability to recuperate with Chlorella UMACC 250 recovers better compared to Chlorella UMACC 234.Both Chlorella strains showed similar trend in their carbohydrate content at 12℃,while the protein content of Chlorella UMACC 234 decreased when exposed to increasing temperatures.The results indicated that polar Chlorella are able to survive at increased temperatures throughout the experiment.展开更多
OMEGA is a system for cultivating microalgae using wastewater contained in floating photobioreactors (PBRs) deployed in marine environments and thereby eliminating competition with agriculture for water, fertilizer, a...OMEGA is a system for cultivating microalgae using wastewater contained in floating photobioreactors (PBRs) deployed in marine environments and thereby eliminating competition with agriculture for water, fertilizer, and land. The offshore placement in protected bays near coastal cities co-locates OMEGA with wastewater outfalls and sources of CO2-rich flue gas on shore. To evaluate the feasibility of OMEGA, microalgae were grown on secondary-treated wastewater supplemented with simulated flue gas (8.5% CO2 V/V) in a 110-liter prototype system tested using a seawater tank. The flow-through system consisted of tubular PBRs made of transparent linear low-density polyethylene, a gas exchange and harvesting column (GEHC), two pumps, and an instrumentation and control (I&C) system. The PBRs contained regularly spaced swirl vanes to create helical flow and mixing for the circulating culture. About 5% of the culture volume was continuously diverted through the GEHC to manage dissolved oxygen concentrations, provide supplemental CO2, harvest microalgae from a settling chamber, and add fresh wastewater to replenish nutrients. The I&C system controlled CO2 injection and recorded dissolved oxygen levels, totalized CO2 flow, temperature, circulation rates, photosynthetic active radiation (PAR), and the photosynthetic efficiency as determined by fast repetition rate fluorometry. In two experimental trials, totaling 23 days in April and May 2012, microalgae productivity averaged 14.1 ± 1.3 grams of dry biomass per square meter of PBR surface area per day (n = 16), supplemental CO2 was converted to biomass with >50% efficiency, and >90% of the ammonia-nitrogen was recovered from secondary effluent. If OMEGA can be optimized for energy efficiency and scaled up economically, it has the potential to contribute significantly to biofuels production and wastewater treatment.展开更多
Ion channels,as membrane proteins,are the sensors of the cell.They act as the first line of communication with the world beyond the plasma membrane and transduce changes in the external and internal environments into ...Ion channels,as membrane proteins,are the sensors of the cell.They act as the first line of communication with the world beyond the plasma membrane and transduce changes in the external and internal environments into unique electrical signals to shape the responses of excitable cells.Because of their importance in cellular communication,ion channels have been intensively studied at the structural and functional levels.Here,we summarize the diverse approaches,including molecular and cellular,chemical,optical,biophysical,and computational,used to probe the structural and functional rearrangements that occur during channel activation（or sensitization）,inactivation（or desensitization）,and various forms of modulation.The emerging insights into the structure and function of ion channels by multidisciplinary approaches allow the development of new pharmacotherapies as well as new tools useful in controlling cellular activity.展开更多
A simple sensitive and quick assay for simultaneously determining magnolol （MOL） and honokiol （HOL） has been described based on their natural fluorescence. This method is based on the fact that synchronous fluorom...A simple sensitive and quick assay for simultaneously determining magnolol （MOL） and honokiol （HOL） has been described based on their natural fluorescence. This method is based on the fact that synchronous fluorometry could resolve the overlapping of fluorescence spectra, which was aroused by their similar molecular structures. In this work, the synchronous spectrum, maintaining a constant difference of Aλ =10 nm between the emission and excitation wavelengths, has been selected for the determination of HOL and MOL. Under the optimum conditions, the fluorescence intensity is proportional to the concentration of MOL and HOL in solution over the range 0.075-0.7 μg/mL and 0.05-0.9 μg/mL with the detection limit of 0.029 μg/mL and 0.019 μg/mL, respectively. The method was applied to the simultaneous determination of MOL and HOL in pharmaceutical dosage with satisfactory results.展开更多
The development of genetically modified crops requires new promoters and regulatory regions to achieve high gene ex- pression and/or tissue-specific expression patterns in plants. To obtain promoter sequences of plant...The development of genetically modified crops requires new promoters and regulatory regions to achieve high gene ex- pression and/or tissue-specific expression patterns in plants. To obtain promoter sequences of plants with new properties, we analyzed the expression traits of the cotton （Gossypium hirsutum） translation elongation factor 1A gene family. The results showed that the GhEF1A8 gene is highly expressed in different organs of cotton plants, and showed much higher transcript levels in stems and leaves. Its promoter （GhEFIA1.7） and the 5＂ untranslated region （5＂ UTR）, comprising a regulatory region named PGhEFIA8, were isolated from cotton and studied in stably transformed tobacco plants. The regulatory region sequences were fused to the 13-glucuronidase （GUS） reporter gene to characterize its expression pattern in tobacco. Histochemical and fiuorometric GUS activity assays demonstrated that PGhEF1A8 could direct GUS gene expression in all tissues and organs in transgenic tobacco, including leaves, stems, flowers, and roots. The level of GUS activity in the leaves and stems was significantly higher than in cauliflower mosaic virus （CaMV） 35S promoter：：GUS plants, but as same as CaMV 35S promoter：：GUS plants in flower and root tissues. GUS expression levels decreased 2-10-fold when the 5＂ UTR was absent from PGhEF1A8. Deletion analysis of the PGhEFIA8 sequence showed that the region -647 to -323 might possess negative elements that repress transgene expression in tobacco plants. The results suggested that the GhEFIA8 regulation region may represent a practical choice to direct high-level constitutive expression of transgenes and could be a valuable new tool in plant genetic engineering.展开更多
A simple setup using a 365 nm LED coupled to a USB spectrometer through an optical fibre, in a front-face fluorescence configuration, was used to investigate the ability of fluorescence spectroscopy technique to discr...A simple setup using a 365 nm LED coupled to a USB spectrometer through an optical fibre, in a front-face fluorescence configuration, was used to investigate the ability of fluorescence spectroscopy technique to discriminate between varieties of olive oil. To achieve this task, Virgin Olive Oils (VOO) from two major Tunisian olive cultivars known as Chetoui and Chemlali were used. Spectral analysis showed a clear separation between these two VOO varieties. A one-way ANOVA attests that this discrimination is significant. The Principal Components Analyses (PCA) showed that the normalized fluorescence intensities are the good parameters for this discrimination. This observation strengthens the potential of our spectral parameters to perform reliable analysis.展开更多
Over the last decades, the usage of PAM （pulse amplitude modulated） fluorometers for assessment of chlorophyll-a fluorescence variations became widely applied on marine macroalgae physiology and ecophysiology resear...Over the last decades, the usage of PAM （pulse amplitude modulated） fluorometers for assessment of chlorophyll-a fluorescence variations became widely applied on marine macroalgae physiology and ecophysiology researches. Due to the increased use of these methods, a large number of studies, mainly relating to macroalgae ecology and physiology were worldwide reported. In this context, it was also created a mismatch of concepts about fluorescence of the chlorophyll-a and its application. Under this background, this study compile and summarize the state of the art knowledge regarding to the chlorophyll fluorescence, contextualizing the use of the PAM method with the main factors regulating photosynthesis （light, temperature, salinity nitrogen and phosphorus） in marine macroalgae. Moreover, this study also references the most used terms and shows some examples found in literature about the applicability of fluorescence parameters. The herein findings and the discussed examples, helps to emphasize the importance of fluorescence usage, that highlights the understanding of photosynthetic responses in macroalgal physiology and ecology.展开更多
Transient receptor potential vanilloid 1(TRPV1)channel plays an important role in a wide range of physiological and pathological processes,and a comprehensive understanding of TRPV1 gating will create opportunities fo...Transient receptor potential vanilloid 1(TRPV1)channel plays an important role in a wide range of physiological and pathological processes,and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention.Recent incredible advances in cryo-electron microscopy(cryo-EM)have yielded high-resolution structures of all TRPV subtypes(TRPV1-6)and all of them share highly conserved six transmembrane(TM)domains(S1-S6).As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist(capsaicin or resiniferatoxin),TM helices S1 to S4 form a bundle that remains quiescent during channel activation,highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels.Here,however,we argue that the structural dynamics rather than quiescence of S1-S4 domains is necessary for capsaicin-mediated activation of TRPV1.Using fluorescent unnatural amino acid(flUAA)incorporation and voltage-clamp fluorometry(VCF)analysis,we directly observed allostery of the S1-S4 bundle upon capsaicin binding.Covalent occupation of VCF-identified sites,single-channel recording,cell apoptosis analysis,and exploration of the role of PSFL828,a novel non-vanilloid agonist we identified,have collectively confirmed the essential role of this coordinated S1-S4 motility in capsaicin-mediated activation of TRPV1.This study concludes that,in contrast to cryo-EM structural studies,vanilloid agonists are also required for S1-S4 movement during TRPV1 activation.Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.展开更多
Synchronous fluorometry can cause a band-narrowing effect to improving the fluorometric selectivity (Fig. 1). However, since the △λ value selected is usually small (generally about 0—5 nm) in synchronous scanning, ...Synchronous fluorometry can cause a band-narrowing effect to improving the fluorometric selectivity (Fig. 1). However, since the △λ value selected is usually small (generally about 0—5 nm) in synchronous scanning, the interference of solvents scattering light (mainly Rayleigh scattering light) is so serious that the sensitivity and the detection limit are harmed greatly.展开更多
It is very important to quantitate the cytotoxicity of natural killer cell （NK cell） in the fields of cell immune assessment and life science studies. The currently used methods are based on labelling target with ra...It is very important to quantitate the cytotoxicity of natural killer cell （NK cell） in the fields of cell immune assessment and life science studies. The currently used methods are based on labelling target with radioactivity materials such as <sup>51</sup>CrO<sub>4</sub><sup>2-</sup>, [<sup>3</sup>H] thymidine展开更多
Probing the onset of micellization,or determining the critical micelle concentration(CMC),is of crucial importance while remains to be challenged by growing demand for extraordinary sensitivity and accuracy.Although f...Probing the onset of micellization,or determining the critical micelle concentration(CMC),is of crucial importance while remains to be challenged by growing demand for extraordinary sensitivity and accuracy.Although fluorometry has attracted wide attention owing to its superiority in simplicity and sensitivity over other methods,the presence and fluctuation of background fluorescence of conventional fluorescent probes undermine the accuracy of CMC determination.Herein,a series of novel fluorescent probes without background fluorescence at a concentration below CMC owing to absolute aggregation-caused quenching(aACQ)are utilized for sensitive and accurate measurement of CMC.The aACQ probes aggregate spontaneously and instantly in an aqueous environment owing to molecular π-π stacking with fluorescence quenching absolutely.Therefore,the absence of background fluorescence at a concentration below CMC clears relevant interference associated with conventional fluorophores.In this study,the new method is applied for versatile surfactants with CMCs ranging from nanomolar to millimolar concentrations,especially copolymers with ultralow CMC.The higher sensitivity and accuracy are highlighted by comparison with conventional probes.展开更多
文摘Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)metabolism.Blue-diode based PAM technology was used to measure the Photosynthetic Oxygen Evolution Rate(POER:1O_(2)≡4e^(-)).Optimum Irradiance(E_(opt)),maximum POER(POER_(max))and quantum efficiency(α_(0))all vary on a diurnal cycle.The shape of the POER vs.E curves is different in seedling,submerged and surface leaves.Both E_(opt)and POER_(max)are very low in seedling leaves(E_(opt)≈104μmol photon m^(-2)s^(-1),PPFD;POER_(max)≈4.95µmol O_(2)g^(-1)Chl a s^(-1)),intermediate in mature submerged leaves(E_(opt)≈419µmol photon m^(-2)s^(-1)PPFD,POER_(max)≈38.1µmol O_(2)g^(-1)Chl a s^(-1))and very high in surface leaves(E_(opt)≈923µmol photon m^(-2)s^(-1)PPFD,POER_(max)≈76.1µmol O_(2)g^(-1)Chl a s^(-1)).Leaf titratable acid(C4 acid pool)is too small(≈20 to 50 mol H+m^(-3))to support substantial SAM metabolism.Gross daily photosynthesis of surface leaves is≈3.71 g C m^(-2)d^(-1)in full sun and as much as 1.4 gC m^(-2)d^(-1)in shaded submerged leaves.There is midday inhibition of photosynthesis.
基金Supported by the Joint Project of Guangxi Provincial and China National Natural Science Foundations(Nos.U 20 A 20104,42306152)the Taishan Scholars Program to Prof.Rencheng YU。
文摘Pigments are widely used as indices for estimation of phytoplankton biomass and composition,and many protocols have been developed to analyze pigments in phytoplankton.Different protocols were compared using four solvents(methanol,95%methanol,dimethylformamide,and 90%acetone)and two instruments(fluorometer and high-performance liquid chromatography(HPLC)coupled with diode array detector).Analysis of chlorophyll a(Chl a)with fluorometer could lead to over-or underestimation due to the interference from its derivatives in all probability.Among the four extractants,90%acetone had a high recovery for chlorophylls.In contrast,95%methanol was a poor extractant for chlorophylls due to the degradation of Chl a,especially in diatoms.The 95%methanol,however,had high extraction efficiencies for most diagnostic xanthophylls.Therefore,the selection of pigment analytical protocols should follow the specific purpose of phytoplankton study.In addition to fluorometry,an HPLC method with 90%acetone as extractant shall be a good choice for the analysis of Chl a to estimate phytoplankton biomass,especially for diatom-dominated samples,while an HPLC method with 95%methanol as extractant be more suitable to characterize different taxa in phytoplankton communities.
文摘The management of cyanobacteria and potential exposure to associated biotoxins requires the allocation of scarce resources across a range of freshwater resources within various jurisdictions. Cost effective and reliable methods for sample processing and analysis form the foundation of the protocol yielding reliable data from which to derive important decisions. In this study the utilization of new methods to collect, process and analyze samples enhanced our ability to evaluate cyanobacterial populations. Extraction of phycocyanin using the single freeze thaw method provided more accurate and precise measurements (CV 4.7% and 6.4%), offering a simple and cost-effective means to overcome the influence of morphological variability. In-vacuo concentration of samples prior to ELISA analysis provided a detection limit of 0.001 μg·L?1 MC. Fractionation of samples (?1) = ?0.279 + (1.368 ? Log PC (μg·L?1) while in an Aphanizomemon spp. dominant system Log MC (ng·L?1) = 0.385 + (0.449 ? Log PC (μg·L?1). These methods and sampling protocol could be used in other aquatic systems across a broader regional landscape to estimate the levels of microcystins.
基金funded by a research grant from the Ministry of Higher Education Malaysia under the Fundamental Research Grant Scheme(Grant no.FRGS/1/2017/STG05/TAYLOR/02/2)。
文摘Global warming has been the subject of concern in today’s world with elevating temperature causing the melting of polar ice and increasing sea level.The aim of this study was to investigate the physiological and photosynthetic performance of two polar Chlorella,namely Chlorella UMACC 250 and Chlorella UMACC 234 to elevating temperatures as might be experienced under future warming scenarios.The cultures were exposed to three different temperatures of 4℃,8℃and 12℃.The growth and photosynthetic activity were determined every 2 d for a period of 10 d.At the end of the experiment,the cultures were harvested and analysed for biochemical composition.Both Chlorella strains were able to tolerate higher temperatures than their ambient temperature.The final pigments content showed an increasing trend with increased temperatures for both strains.The photosynthetic activities were measured using pulse-amplitude modulation(PAM)fluorometer.The photosynthetic parameters including maximum quantum efficiency(Fv/Fm),maximum relative electron transport rate(r ETRmax),light harvesting efficiency(a)and photoadaptive index(Ek)were derived from the rapid light curves(RLCs).Both Chlorella strains showed a slight decline in growth and photosynthetic activities at the initial part of the experiment.However,they showed the ability to recuperate with Chlorella UMACC 250 recovers better compared to Chlorella UMACC 234.Both Chlorella strains showed similar trend in their carbohydrate content at 12℃,while the protein content of Chlorella UMACC 234 decreased when exposed to increasing temperatures.The results indicated that polar Chlorella are able to survive at increased temperatures throughout the experiment.
文摘OMEGA is a system for cultivating microalgae using wastewater contained in floating photobioreactors (PBRs) deployed in marine environments and thereby eliminating competition with agriculture for water, fertilizer, and land. The offshore placement in protected bays near coastal cities co-locates OMEGA with wastewater outfalls and sources of CO2-rich flue gas on shore. To evaluate the feasibility of OMEGA, microalgae were grown on secondary-treated wastewater supplemented with simulated flue gas (8.5% CO2 V/V) in a 110-liter prototype system tested using a seawater tank. The flow-through system consisted of tubular PBRs made of transparent linear low-density polyethylene, a gas exchange and harvesting column (GEHC), two pumps, and an instrumentation and control (I&C) system. The PBRs contained regularly spaced swirl vanes to create helical flow and mixing for the circulating culture. About 5% of the culture volume was continuously diverted through the GEHC to manage dissolved oxygen concentrations, provide supplemental CO2, harvest microalgae from a settling chamber, and add fresh wastewater to replenish nutrients. The I&C system controlled CO2 injection and recorded dissolved oxygen levels, totalized CO2 flow, temperature, circulation rates, photosynthetic active radiation (PAR), and the photosynthetic efficiency as determined by fast repetition rate fluorometry. In two experimental trials, totaling 23 days in April and May 2012, microalgae productivity averaged 14.1 ± 1.3 grams of dry biomass per square meter of PBR surface area per day (n = 16), supplemental CO2 was converted to biomass with >50% efficiency, and >90% of the ammonia-nitrogen was recovered from secondary effluent. If OMEGA can be optimized for energy efficiency and scaled up economically, it has the potential to contribute significantly to biofuels production and wastewater treatment.
基金supported by grants from the National Natural Science Foundation of China(91132303,30830035)the National Basic Research Development Program of China (2011CBA00408)the China Postdoctoral Science Foundation(2012M511105)
文摘Ion channels,as membrane proteins,are the sensors of the cell.They act as the first line of communication with the world beyond the plasma membrane and transduce changes in the external and internal environments into unique electrical signals to shape the responses of excitable cells.Because of their importance in cellular communication,ion channels have been intensively studied at the structural and functional levels.Here,we summarize the diverse approaches,including molecular and cellular,chemical,optical,biophysical,and computational,used to probe the structural and functional rearrangements that occur during channel activation（or sensitization）,inactivation（or desensitization）,and various forms of modulation.The emerging insights into the structure and function of ion channels by multidisciplinary approaches allow the development of new pharmacotherapies as well as new tools useful in controlling cellular activity.
基金supported by the Natural Science Foundation of Shanxi(No.20041030).
文摘A simple sensitive and quick assay for simultaneously determining magnolol （MOL） and honokiol （HOL） has been described based on their natural fluorescence. This method is based on the fact that synchronous fluorometry could resolve the overlapping of fluorescence spectra, which was aroused by their similar molecular structures. In this work, the synchronous spectrum, maintaining a constant difference of Aλ =10 nm between the emission and excitation wavelengths, has been selected for the determination of HOL and MOL. Under the optimum conditions, the fluorescence intensity is proportional to the concentration of MOL and HOL in solution over the range 0.075-0.7 μg/mL and 0.05-0.9 μg/mL with the detection limit of 0.029 μg/mL and 0.019 μg/mL, respectively. The method was applied to the simultaneous determination of MOL and HOL in pharmaceutical dosage with satisfactory results.
基金supported by the New Genetically Modified Organisms Varieties Cultivation Project, China (2014ZX08005-004)
文摘The development of genetically modified crops requires new promoters and regulatory regions to achieve high gene ex- pression and/or tissue-specific expression patterns in plants. To obtain promoter sequences of plants with new properties, we analyzed the expression traits of the cotton （Gossypium hirsutum） translation elongation factor 1A gene family. The results showed that the GhEF1A8 gene is highly expressed in different organs of cotton plants, and showed much higher transcript levels in stems and leaves. Its promoter （GhEFIA1.7） and the 5＂ untranslated region （5＂ UTR）, comprising a regulatory region named PGhEFIA8, were isolated from cotton and studied in stably transformed tobacco plants. The regulatory region sequences were fused to the 13-glucuronidase （GUS） reporter gene to characterize its expression pattern in tobacco. Histochemical and fiuorometric GUS activity assays demonstrated that PGhEF1A8 could direct GUS gene expression in all tissues and organs in transgenic tobacco, including leaves, stems, flowers, and roots. The level of GUS activity in the leaves and stems was significantly higher than in cauliflower mosaic virus （CaMV） 35S promoter：：GUS plants, but as same as CaMV 35S promoter：：GUS plants in flower and root tissues. GUS expression levels decreased 2-10-fold when the 5＂ UTR was absent from PGhEF1A8. Deletion analysis of the PGhEFIA8 sequence showed that the region -647 to -323 might possess negative elements that repress transgene expression in tobacco plants. The results suggested that the GhEFIA8 regulation region may represent a practical choice to direct high-level constitutive expression of transgenes and could be a valuable new tool in plant genetic engineering.
文摘A simple setup using a 365 nm LED coupled to a USB spectrometer through an optical fibre, in a front-face fluorescence configuration, was used to investigate the ability of fluorescence spectroscopy technique to discriminate between varieties of olive oil. To achieve this task, Virgin Olive Oils (VOO) from two major Tunisian olive cultivars known as Chetoui and Chemlali were used. Spectral analysis showed a clear separation between these two VOO varieties. A one-way ANOVA attests that this discrimination is significant. The Principal Components Analyses (PCA) showed that the normalized fluorescence intensities are the good parameters for this discrimination. This observation strengthens the potential of our spectral parameters to perform reliable analysis.
文摘Over the last decades, the usage of PAM （pulse amplitude modulated） fluorometers for assessment of chlorophyll-a fluorescence variations became widely applied on marine macroalgae physiology and ecophysiology researches. Due to the increased use of these methods, a large number of studies, mainly relating to macroalgae ecology and physiology were worldwide reported. In this context, it was also created a mismatch of concepts about fluorescence of the chlorophyll-a and its application. Under this background, this study compile and summarize the state of the art knowledge regarding to the chlorophyll fluorescence, contextualizing the use of the PAM method with the main factors regulating photosynthesis （light, temperature, salinity nitrogen and phosphorus） in marine macroalgae. Moreover, this study also references the most used terms and shows some examples found in literature about the applicability of fluorescence parameters. The herein findings and the discussed examples, helps to emphasize the importance of fluorescence usage, that highlights the understanding of photosynthetic responses in macroalgal physiology and ecology.
基金supported by the Natural Science Foundation of Jiangsu Province(BK20202002)the National Natural Science Foundation of China(81603409,31900808,81902480,21977021,31570832,31971146,and 31971042)+4 种基金Innovation and Entrepreneurship Talent Program of Jiangsu ProvinceState Key Laboratory of Utilization of Woody Oil Resource(2019XK2002)the Natural Science Foundation of Hunan Province(2018JJ1012)Hunan“Huxiang”High-level Talent Program(2021)“Xing Yao”Leading Scholars of China Pharmaceutical University(2021)。
文摘Transient receptor potential vanilloid 1(TRPV1)channel plays an important role in a wide range of physiological and pathological processes,and a comprehensive understanding of TRPV1 gating will create opportunities for therapeutic intervention.Recent incredible advances in cryo-electron microscopy(cryo-EM)have yielded high-resolution structures of all TRPV subtypes(TRPV1-6)and all of them share highly conserved six transmembrane(TM)domains(S1-S6).As revealed by the open structures of TRPV1 in the presence of a bound vanilloid agonist(capsaicin or resiniferatoxin),TM helices S1 to S4 form a bundle that remains quiescent during channel activation,highlighting differences in the gating mechanism of TRPV1 and voltage-gated ion channels.Here,however,we argue that the structural dynamics rather than quiescence of S1-S4 domains is necessary for capsaicin-mediated activation of TRPV1.Using fluorescent unnatural amino acid(flUAA)incorporation and voltage-clamp fluorometry(VCF)analysis,we directly observed allostery of the S1-S4 bundle upon capsaicin binding.Covalent occupation of VCF-identified sites,single-channel recording,cell apoptosis analysis,and exploration of the role of PSFL828,a novel non-vanilloid agonist we identified,have collectively confirmed the essential role of this coordinated S1-S4 motility in capsaicin-mediated activation of TRPV1.This study concludes that,in contrast to cryo-EM structural studies,vanilloid agonists are also required for S1-S4 movement during TRPV1 activation.Redefining the gating process of vanilloid agonists and the discovery of new non-vanilloid agonists will allow the evaluation of new strategies aimed at the development of TRPV1 modulators.
文摘Synchronous fluorometry can cause a band-narrowing effect to improving the fluorometric selectivity (Fig. 1). However, since the △λ value selected is usually small (generally about 0—5 nm) in synchronous scanning, the interference of solvents scattering light (mainly Rayleigh scattering light) is so serious that the sensitivity and the detection limit are harmed greatly.
基金Project supported by the National Natural Science Foundation of China
文摘It is very important to quantitate the cytotoxicity of natural killer cell （NK cell） in the fields of cell immune assessment and life science studies. The currently used methods are based on labelling target with radioactivity materials such as <sup>51</sup>CrO<sub>4</sub><sup>2-</sup>, [<sup>3</sup>H] thymidine
基金National Natural Science Foundation of China,Grant/Award Numbers:81872815,82030107,81690263Science and Technology Commission of Shanghai Municipality,Grant/Award Number:19XD1400300。
文摘Probing the onset of micellization,or determining the critical micelle concentration(CMC),is of crucial importance while remains to be challenged by growing demand for extraordinary sensitivity and accuracy.Although fluorometry has attracted wide attention owing to its superiority in simplicity and sensitivity over other methods,the presence and fluctuation of background fluorescence of conventional fluorescent probes undermine the accuracy of CMC determination.Herein,a series of novel fluorescent probes without background fluorescence at a concentration below CMC owing to absolute aggregation-caused quenching(aACQ)are utilized for sensitive and accurate measurement of CMC.The aACQ probes aggregate spontaneously and instantly in an aqueous environment owing to molecular π-π stacking with fluorescence quenching absolutely.Therefore,the absence of background fluorescence at a concentration below CMC clears relevant interference associated with conventional fluorophores.In this study,the new method is applied for versatile surfactants with CMCs ranging from nanomolar to millimolar concentrations,especially copolymers with ultralow CMC.The higher sensitivity and accuracy are highlighted by comparison with conventional probes.
