In order to solve the serious leaching problem of supported heteropoly acid catalysts in polar reaction media, 12-molybdophosphoric acid encapsulated in the supercage of Cs^＋-exchanged Y zeolite was prepared by the ...In order to solve the serious leaching problem of supported heteropoly acid catalysts in polar reaction media, 12-molybdophosphoric acid encapsulated in the supercage of Cs^＋-exchanged Y zeolite was prepared by the ＂ship in the bottle＂ synthesis. The influence of ion-exchange conditions and the synthesis parameters on the encaosulation of PMo12 were investigated. The obtained solid sample was characterized by X-ray diffraction （XRD）, 31p magic angle spin nuclear magnetic resonance （MAS NMR） and Fourier Transform Infrared Spectroscopy （FT-IR）, and its catalytic activity in the esterification of acetic acid and n-butanol was tested. The ion-exchange time, concentration of aqueous Cs^＋ solution, pH value, and amount of Mo added in the synthesis mixture were revealed to influence the encapsulation very remarkably. Under the optimal conditions, 12-molybdophosphoric acid could be successfully encapsulated in the supercage of CsY zeolite, and the samples showed considerable catalytic activity and excellent reusability in the esterification reaction.展开更多
A full-length sequence coding for △^12 fatty acid desaturase gene from peanut（Arachis hypogaea L.）was cloned into the expression vector, pRSETB, to generate recombinant plasmid pRSET/HO-A, which was subsequently tr...A full-length sequence coding for △^12 fatty acid desaturase gene from peanut（Arachis hypogaea L.）was cloned into the expression vector, pRSETB, to generate recombinant plasmid pRSET/HO-A, which was subsequently transformed into expression Escherichia. coli BL21（DE3）pLysS. The △^12 fatty acid desaturase was highly expressed in E. coli BL21（DE3）pLysS in the presence of isopropyl-D-thiogalactopyranoside （IPTG）. The fusion protein was purified and used to form a reaction system in vitro by adding oleic acid as substrate and incubating it at 20℃ for 6 h. Total fatty acids was extracted and methlesterified and then analyzed with gas chromatography. A novel peak corresponding to linoleic acid methyl ester standards was detected with the same retention time. GC-MS （gas chromatogram and gas chromatogram-mass spectrometry） analysis showed that the novel peak was linoleic acid methyl ester. These results exhibited △^12 fatty acid desaturase activity, which could convert oleic acid to linoleic acid specifically.展开更多
△^12 fatty acid desaturase gene has been targeted as a logical candidate controlling the high oleate trait in peanut seeds. By RT-PCR method, the full-length cDNAs of △^12 fatty acid desaturase gene were isolated fr...△^12 fatty acid desaturase gene has been targeted as a logical candidate controlling the high oleate trait in peanut seeds. By RT-PCR method, the full-length cDNAs of △^12 fatty acid desaturase gene were isolated from peanut （Arachis hypogaea L.） genotypes with normal and high ratio of oleic to linoleic acid, which were designated AhFAD2B and AhFAD2B＇, respectively. Sequence alignment of their coding regions revealed that an extra A was inserted at the position ＋442 bp of AhFAD2B＇ sequence of high oleic acid genotypes, which resulted in the shift of open reading frame and a truncated protein AhFAD2B＇, with the loss of one histidine box involved in metal ion complex required for the reduction of oxygen. Analysis of transcript level showed that the expression of △^12 fatty acid desaturase gene in high oleic acid genotype was slightly lower than that in normal genotype. The enzyme activity experiment of yeast （Saccharomyces cerevisiae） cell transformed with AhFAD2B or AhFAD2B＇ proved that only AhFAD2B gene product showed significant △^12 fatty acid desaturase activity, but AhFAD2B＇ gene product did not. These results suggested that the change of AhFAD2B＇ gene sequence resulted in lower activity or deactivation of △^12 fatty acid desaturase in high oleic acid genotype.展开更多
A reversed phase high performance liquid chromatography （HPLC） method was established for the simultaneous determination of 12, 13-dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture. A Grace Apollo Cl8 col...A reversed phase high performance liquid chromatography （HPLC） method was established for the simultaneous determination of 12, 13-dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture. A Grace Apollo Cl8 column （250 mm × 4.6 mm, 5 μm） was used as the stationary phase and the mobile phase was composed of acetonitrile and aqueous phosphoric acid （0.2%, v/v）. Gradient elution was carried out at the flow rate of 1.0 mL/min and the column temperature was 30 ℃. An ultraviolet （UV） detector was used with a selected wavelength of 240 nm. Calibration curves were linear within the concentration range of 4.6-45.75 μg/mL for 12, 13-dihydroxyeuparin （r〉0.9999） and 106.9-1068.9μg/mL for glycyrrhizic acid （r〉0.9999）, respectively. Recoveries were 102.18% for 12, 13-dihydroxyeuparin and 101.17% for glycyrrhizic acid. The method developed could be applied to the simultaneous determination of 12, 13- dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture.展开更多
Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse differential reactor. From the performance of the catalysts with differ...Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse differential reactor. From the performance of the catalysts with different compositions and configurations, it is proposed that acetic acid is predominantly produced via an intermediate of acetaldehyde. This can be easily confirmed by comparing the product distributions in the integral and the differential reactors. The active sites for acetic acid formation are considered to exist mainly at the boundaries between the H4SiW12O40 and the Pd particles. The Pd-based catalysts reduced by H2/N2 have higher activities than those reduced by hydrazine, as explained by the degree of Pd dispersion obtained from the characteristics of hydrogen chemical adsorption. It was found that the Pd-Se-SiW12/SiO2 catalyst with selenium tetrachloride as a precursor was more active than that with potassium selenite, and that the acetic acid yield can be greatly increased by adding a suitable amount of dichloroethane (C2H4C12/C2H4 mole ratio=0.03) to the reactants.展开更多
The cDNA of the delta-12 fatty acid desaturase gene, IgFAD2, was cloned from the marine microalgae Isochrysis galbana, a species capable of producing docosahexaenoic acid. Sequence analysis indicated that the open rea...The cDNA of the delta-12 fatty acid desaturase gene, IgFAD2, was cloned from the marine microalgae Isochrysis galbana, a species capable of producing docosahexaenoic acid. Sequence analysis indicated that the open reading frame measured a length of 1 158 bp and encoded 386 amino acids with a predicted molecular weight of 42.8 kDa and an isoelectric point of 9.2. Computational analysis of the protein sequence of IgFAD2 showed typical features of membrane-bound desaturase such as three conserved histidine boxes along with four membranespanning regions that were universally present among plant desaturases. Quantitative real-time PCR results showed that the abundance of IgFAD2 transcript was significantly upregulated under different environmental stresses including low temperature(15℃), high salinity(salinity of 62 and 93), and nitrogen starvation(220 μmol/L). Heterologous expression indicated that yeast cells transformed with a plasmid construct containing IgFAD2 could convert endogenous oleic acid(18:1^(?9), OA) into linoleic acid(18:2^(?9, 12), LA). These findings confirm that I. galbana IgFAD2 plays important roles in the biosynthetic pathways of unsaturated fatty acids.展开更多
The freshwater microalga Haematococcus pluvialis accumulates large amounts of fatty acids in response to adverse conditions.However,the key fatty acid desaturase genes in H.pluvialis remain unknown.In this study,we cl...The freshwater microalga Haematococcus pluvialis accumulates large amounts of fatty acids in response to adverse conditions.However,the key fatty acid desaturase genes in H.pluvialis remain unknown.In this study,we cloned and functionally characterized aΔ12 fatty acid desaturase gene,and designated it as HpFAD2.The open reading frame of HpFAD2 consisted of 1137 base pairs and encoded 378 amino acids.The deduced polypeptide showed 70%identity to other endoplasmic reticulumΔ12 fatty acid desaturases,whereas it had only 44%identity to plastidΔ12 fatty acid desaturases.The PSORT algorithm and phylogenetic analysis further confirmed its affiliation to the endoplasmic reticulumΔ12 fatty acid desaturases.Heterologous expression was performed in Saccharomyces cerevisiae cells transformed with the recombinant plasmid pYES2-HpFAD2.Two additional fatty acids(C16:2 and C18:2)were detected in the yeast transformants.The results indicatedΔ12 desaturation activity and substrate preference for C18:1 over C16:1.The transcriptional levels of H.pluvialis HpFAD2 at different growth stages were measured by quantitative polymerase chain reaction(PCR),indicating that the HpFAD2 transcriptional levels were significantly higher in red cells than those in green cells.Our study brings more insight into the fatty acid biosynthetic pathway of H.pluvialis.展开更多
A novel environmental friendly catalyst, H4SiW12O40/PAn was prepared and identified by FT-IR, XRD and TG/DTA. The optimal synthetic protocol was a PAn to H4SiW12O40 mass ratio of 1 ： 1, a 20 mL of methanol and a reac...A novel environmental friendly catalyst, H4SiW12O40/PAn was prepared and identified by FT-IR, XRD and TG/DTA. The optimal synthetic protocol was a PAn to H4SiW12O40 mass ratio of 1 ： 1, a 20 mL of methanol and a reaction time of 2 h at reflux. It was used in catalytic synthesis of ten important ketals and acetals with a high catalytic activity. With an aldehyde/ketone to glycol molar ratio of 1 ： 1.5 and a 1 wt% catalyst loading, the yields of ketals and acetals could reach 60.0%- 93.8 % after 1 h.展开更多
AIM： To clone △^12 -fatty acid desaturase gene of Mortierella isabellina and to functionally characterize this gene in vitro and in vivo.METHODS： Reverse transcriptional polymerase chain reaction （RT-PCR） was use...AIM： To clone △^12 -fatty acid desaturase gene of Mortierella isabellina and to functionally characterize this gene in vitro and in vivo.METHODS： Reverse transcriptional polymerase chain reaction （RT-PCR） was used to clone the open reading frame of △^12-fatty acid desaturase gene （D12D） of Mortierella isabellina. Plasmids pEMICL12 and pYMICL12 were constructed with it. pEMICL12 was transformed into Escherichia coli（E.coli） strain BL21 using CaCl2 method for expression after induction with IPTG. pTMICL12 was transformed into Saccharomyces cerevisiae strain IN- VSc1 using lithium acetate method for expression under the induction of galactose. Northern blotting method was used to investigate the effect of temperature on the transcriptional level of this gene in S.cerevisiae strain IN- VSc1.RESULTS： Recombinant plasmids pEMICL12 and pTMICL12 were successfully constructed and transformed into E. coli and S.cerevisiae separately with appropriate method. After induction with IPTG and galactose, it was found that expression of △^12-fatty acid desaturase genes in E.coli and S. cerevisiae under appropriate conditions led to the production of active △^12-fatty acid desaturase, which could convert 17.876% and 17.604% of oleic acid respectively to linoleic acid by GC-MS detection in vitro and in vivo.CONCLUSION： Cloning and expression of M.isabellina D12D gene in E.coli and S.cerevisiae is successfully completed.展开更多
2β,3α--Dihydroxyurs-12-en-28-oic acid （6） is a naturally occurring diastereoisomer of corosolic acid with glycogen phosphorylase inhibitory activity. A new strategy for the semi-synthesis of 6 was developed. Using...2β,3α--Dihydroxyurs-12-en-28-oic acid （6） is a naturally occurring diastereoisomer of corosolic acid with glycogen phosphorylase inhibitory activity. A new strategy for the semi-synthesis of 6 was developed. Using the commercially available ursolic acid （1） as the starting materials, 6 was synthesized through five facile reactions with a high stereoselectivity and an overall yield of 47,3%, The structure of 6 was confirmed by optical rotation, ESI-MS, 1H NMR and 13C NMR data,展开更多
Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a ...Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).展开更多
The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid （decanoic acid and decanedioic acid）. The xerogels, powders and ceramics were characterized by ...The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid （decanoic acid and decanedioic acid）. The xerogels, powders and ceramics were characterized by the methods of TG-DTG, FT-IR, XRD, SEM and TEM. The dielectric properties of the ceramics were also measured. The results indicated that the powders calcined at 850 ℃ for 2 h are both nanometer scale particles. After sintering, the ceramics mainly consist of the CaCu3Ti4O12 phase. Compared with the powders prepared using monoacid, the particle size of the powders prepared using diacid obviously increases, and the grain size, the relative density and the whole permittivity of the ceramics increase as well. Specially, the ceramic prepared using decanedioic acid has higher relative density （97.3%）, dielectric constant （316 808） and lower dielectric loss （0.242 5） at 30 ℃ （10 kIaz）展开更多
Aluminum has been associated with neurodegenerative diseases.ALA(α-linolenic acid),an essential dietary component for human health,possesses prominent biological activities.Herein,we aim to explore the neuroprotectiv...Aluminum has been associated with neurodegenerative diseases.ALA(α-linolenic acid),an essential dietary component for human health,possesses prominent biological activities.Herein,we aim to explore the neuroprotective effects of ALA on aluminum toxicity and reveal the underlying mechanism.Results show that aluminum chloride(denoted as Al)enabled cell viability decline and apoptosis with oxidative stress and mitochondrial damage in differentiated rat pheochromocytoma cells(PC12)for 24 h incubation.Compared with Al(10 mmol/L)treatment alone,ALA(50μmol/L)pretreatment for 24 h significantly enhanced cell viability by 28.40%,and hindered cell apoptosis by 12.35%,together with recovering redox state balance and alleviating mitochondrial damage.It was measured that ALA treatment upregulated Bcl-2 expression and down-regulated Bax level,accompanied with an expression decline of caspase-3 and caspase-9.Meanwhile,ALA pretreatment was proved to increase protein kinase A(PKA)expression and to promote phosphorylation of cAMP response element-binding protein(p-CREB),resulting in elevation on the level of brain-derived neurotrophic factor(BDNF).The above results showed that ALA attenuated Al toxicity in PC12 cells by mediating the PKA-CREBBDNF signaling pathway.展开更多
Context: Metformin is frequently prescribed for the treatment of type 2 diabetes mellitus. It is recommended as a first line agent by the American Diabetes Association. Vitamin B12 deficiency has been suggested as a s...Context: Metformin is frequently prescribed for the treatment of type 2 diabetes mellitus. It is recommended as a first line agent by the American Diabetes Association. Vitamin B12 deficiency has been suggested as a side effect of metformin therapy;however, previous studies have not assessed the utility of methylmalonic acid levels as an indicator of vitamin B12 status. Objective: To investigate the prevalence of vitamin B12 deficiency in patients on metformin therapy for diabetes by utilizing both vitamin B12 and methylmalonic acid levels. Design, Setting, and Patients: Eighty-eight patients with diabetes, who were either on or off metformin therapy for at least thirty days, were enrolled in a case-controlled study. Blood work and questionnaires were used for analysis. Main Outcome Measures Study: Aims were to detect a clinically significant difference in the prevalence of vitamin B12 deficiency between metformin users and non-users, where such deficiency is defined by both low vitamin B12 and elevated methylmalonic acid levels. Results: Two Sample Equal Variance T-Tests were used to compare averages of measured values and the Chisquare test was used to determine the significance of calculated vitamin B12 deficiency rates between the two groups of patients. Two separate methods for defining vitamin B12 deficiency were utilized. There was no difference in the prevalence of vitamin B12 deficiency in metformin users compared with non-users by either method. Average homocysteine levels were higher in those not on metformin therapy. Conclusion: Vitamin B12 deficiency as defined by an elevated methylmalonic acid level was no greater in patients with diabetes on metformin therapy versus those patients not on metformin treatment.展开更多
A novel adenine(Ade) salt of 12-phosphotungstic acid was synthesized and characterized by elemental analyses,IR, 1H NMR,CV and single crystal X-ray diffraction. The compound crystallized in a triclinic system with...A novel adenine(Ade) salt of 12-phosphotungstic acid was synthesized and characterized by elemental analyses,IR, 1H NMR,CV and single crystal X-ray diffraction. The compound crystallized in a triclinic system with a space group P 1 and a =1.3108(3) nm, b =1.3515(3) nm,c =1.3870(3) nm, V =2.0217(7) nm 3,Z =1,R _1=0.0391,wR _2=0.0959. The structure unit of the complex was constructed from [HPW_ 12 ·O_ 40 ] -,(C_5H_6N_5) + and C_3H_7NO,which further extends to form a novel three-dimensional host-vip network via hydrogen-bonding interactions. The anti-tumor activity of the compound was examined in two human tumor cell lines in vitro .展开更多
Heteropoly acid H3PW12040 （PW） has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4（3H）-one derivatives. The present methodology offers several advantages, such as high yields, shor...Heteropoly acid H3PW12040 （PW） has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4（3H）-one derivatives. The present methodology offers several advantages, such as high yields, short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.展开更多
基金Supported by the National Natural Science Foundation of China （20476046） and the ＂Qinglan＂ Project of Jiangsu Province for Young Researchers.
文摘In order to solve the serious leaching problem of supported heteropoly acid catalysts in polar reaction media, 12-molybdophosphoric acid encapsulated in the supercage of Cs^＋-exchanged Y zeolite was prepared by the ＂ship in the bottle＂ synthesis. The influence of ion-exchange conditions and the synthesis parameters on the encaosulation of PMo12 were investigated. The obtained solid sample was characterized by X-ray diffraction （XRD）, 31p magic angle spin nuclear magnetic resonance （MAS NMR） and Fourier Transform Infrared Spectroscopy （FT-IR）, and its catalytic activity in the esterification of acetic acid and n-butanol was tested. The ion-exchange time, concentration of aqueous Cs^＋ solution, pH value, and amount of Mo added in the synthesis mixture were revealed to influence the encapsulation very remarkably. Under the optimal conditions, 12-molybdophosphoric acid could be successfully encapsulated in the supercage of CsY zeolite, and the samples showed considerable catalytic activity and excellent reusability in the esterification reaction.
基金This work was supported by Chinese National Programs for High Technology Research and Development (No. 2002AA207004).
文摘A full-length sequence coding for △^12 fatty acid desaturase gene from peanut（Arachis hypogaea L.）was cloned into the expression vector, pRSETB, to generate recombinant plasmid pRSET/HO-A, which was subsequently transformed into expression Escherichia. coli BL21（DE3）pLysS. The △^12 fatty acid desaturase was highly expressed in E. coli BL21（DE3）pLysS in the presence of isopropyl-D-thiogalactopyranoside （IPTG）. The fusion protein was purified and used to form a reaction system in vitro by adding oleic acid as substrate and incubating it at 20℃ for 6 h. Total fatty acids was extracted and methlesterified and then analyzed with gas chromatography. A novel peak corresponding to linoleic acid methyl ester standards was detected with the same retention time. GC-MS （gas chromatogram and gas chromatogram-mass spectrometry） analysis showed that the novel peak was linoleic acid methyl ester. These results exhibited △^12 fatty acid desaturase activity, which could convert oleic acid to linoleic acid specifically.
文摘△^12 fatty acid desaturase gene has been targeted as a logical candidate controlling the high oleate trait in peanut seeds. By RT-PCR method, the full-length cDNAs of △^12 fatty acid desaturase gene were isolated from peanut （Arachis hypogaea L.） genotypes with normal and high ratio of oleic to linoleic acid, which were designated AhFAD2B and AhFAD2B＇, respectively. Sequence alignment of their coding regions revealed that an extra A was inserted at the position ＋442 bp of AhFAD2B＇ sequence of high oleic acid genotypes, which resulted in the shift of open reading frame and a truncated protein AhFAD2B＇, with the loss of one histidine box involved in metal ion complex required for the reduction of oxygen. Analysis of transcript level showed that the expression of △^12 fatty acid desaturase gene in high oleic acid genotype was slightly lower than that in normal genotype. The enzyme activity experiment of yeast （Saccharomyces cerevisiae） cell transformed with AhFAD2B or AhFAD2B＇ proved that only AhFAD2B gene product showed significant △^12 fatty acid desaturase activity, but AhFAD2B＇ gene product did not. These results suggested that the change of AhFAD2B＇ gene sequence resulted in lower activity or deactivation of △^12 fatty acid desaturase in high oleic acid genotype.
基金supported by Guangdong Natural Product Reference Material Research & Development Central Lab,the First Affiliate Hospital of Sun Yat-sen University and the Industry-University-Research Cooperation Program from Science and Technology Department of Guangdong Province (No:2010B090400533)
文摘A reversed phase high performance liquid chromatography （HPLC） method was established for the simultaneous determination of 12, 13-dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture. A Grace Apollo Cl8 column （250 mm × 4.6 mm, 5 μm） was used as the stationary phase and the mobile phase was composed of acetonitrile and aqueous phosphoric acid （0.2%, v/v）. Gradient elution was carried out at the flow rate of 1.0 mL/min and the column temperature was 30 ℃. An ultraviolet （UV） detector was used with a selected wavelength of 240 nm. Calibration curves were linear within the concentration range of 4.6-45.75 μg/mL for 12, 13-dihydroxyeuparin （r〉0.9999） and 106.9-1068.9μg/mL for glycyrrhizic acid （r〉0.9999）, respectively. Recoveries were 102.18% for 12, 13-dihydroxyeuparin and 101.17% for glycyrrhizic acid. The method developed could be applied to the simultaneous determination of 12, 13- dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture.
文摘Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse differential reactor. From the performance of the catalysts with different compositions and configurations, it is proposed that acetic acid is predominantly produced via an intermediate of acetaldehyde. This can be easily confirmed by comparing the product distributions in the integral and the differential reactors. The active sites for acetic acid formation are considered to exist mainly at the boundaries between the H4SiW12O40 and the Pd particles. The Pd-based catalysts reduced by H2/N2 have higher activities than those reduced by hydrazine, as explained by the degree of Pd dispersion obtained from the characteristics of hydrogen chemical adsorption. It was found that the Pd-Se-SiW12/SiO2 catalyst with selenium tetrachloride as a precursor was more active than that with potassium selenite, and that the acetic acid yield can be greatly increased by adding a suitable amount of dichloroethane (C2H4C12/C2H4 mole ratio=0.03) to the reactants.
基金The Basic Scientific Fund for National Public Research Institutes of China under contract No.2017Q09the Aoshan Science and Technology Innovation Project of Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2016ASKJ02+3 种基金the National Natural Science Foundation of China-Shandong Joint Funded Project under contract No.U1606404the National Natural Science Foundation of China under contract Nos 41776176 and 41806201the 973 Project from Chinese Ministry of Science and Technology under contract No.2015CB755904the Shandong Provincial Natural Science Foundation under contract No.ZR2015PD003
文摘The cDNA of the delta-12 fatty acid desaturase gene, IgFAD2, was cloned from the marine microalgae Isochrysis galbana, a species capable of producing docosahexaenoic acid. Sequence analysis indicated that the open reading frame measured a length of 1 158 bp and encoded 386 amino acids with a predicted molecular weight of 42.8 kDa and an isoelectric point of 9.2. Computational analysis of the protein sequence of IgFAD2 showed typical features of membrane-bound desaturase such as three conserved histidine boxes along with four membranespanning regions that were universally present among plant desaturases. Quantitative real-time PCR results showed that the abundance of IgFAD2 transcript was significantly upregulated under different environmental stresses including low temperature(15℃), high salinity(salinity of 62 and 93), and nitrogen starvation(220 μmol/L). Heterologous expression indicated that yeast cells transformed with a plasmid construct containing IgFAD2 could convert endogenous oleic acid(18:1^(?9), OA) into linoleic acid(18:2^(?9, 12), LA). These findings confirm that I. galbana IgFAD2 plays important roles in the biosynthetic pathways of unsaturated fatty acids.
基金This study was supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ16D060001)the National Natural Science Foundation of China(No.41606163)+3 种基金the Natural Science Foundation of the Ningbo Government(No.2017A610288)the Ningbo Science and Technology Research Projects,China(No.2019B10006)the Zhejiang Major Science Project,China(No.2019C02057)the Earmarked Fund for Modern Agro-Industry Technology Research System,China(No.CARS-49)and partly sponsored by K.C.Wong Magna Fund at Ningbo University.
文摘The freshwater microalga Haematococcus pluvialis accumulates large amounts of fatty acids in response to adverse conditions.However,the key fatty acid desaturase genes in H.pluvialis remain unknown.In this study,we cloned and functionally characterized aΔ12 fatty acid desaturase gene,and designated it as HpFAD2.The open reading frame of HpFAD2 consisted of 1137 base pairs and encoded 378 amino acids.The deduced polypeptide showed 70%identity to other endoplasmic reticulumΔ12 fatty acid desaturases,whereas it had only 44%identity to plastidΔ12 fatty acid desaturases.The PSORT algorithm and phylogenetic analysis further confirmed its affiliation to the endoplasmic reticulumΔ12 fatty acid desaturases.Heterologous expression was performed in Saccharomyces cerevisiae cells transformed with the recombinant plasmid pYES2-HpFAD2.Two additional fatty acids(C16:2 and C18:2)were detected in the yeast transformants.The results indicatedΔ12 desaturation activity and substrate preference for C18:1 over C16:1.The transcriptional levels of H.pluvialis HpFAD2 at different growth stages were measured by quantitative polymerase chain reaction(PCR),indicating that the HpFAD2 transcriptional levels were significantly higher in red cells than those in green cells.Our study brings more insight into the fatty acid biosynthetic pathway of H.pluvialis.
基金Funded by the Natural Science Foundation of Hubei Province (No.2005ABA053)Hubei Key Laboratory of Pollutant Analysis & Reuse Technologythe National Natural Science Foundation of China (No. 20471044)
文摘A novel environmental friendly catalyst, H4SiW12O40/PAn was prepared and identified by FT-IR, XRD and TG/DTA. The optimal synthetic protocol was a PAn to H4SiW12O40 mass ratio of 1 ： 1, a 20 mL of methanol and a reaction time of 2 h at reflux. It was used in catalytic synthesis of ten important ketals and acetals with a high catalytic activity. With an aldehyde/ketone to glycol molar ratio of 1 ： 1.5 and a 1 wt% catalyst loading, the yields of ketals and acetals could reach 60.0%- 93.8 % after 1 h.
基金Supported by the National Natural Science Foundation of China, No. 30200167 Tianjin Natural Science Foundation, No. 013802511
文摘AIM： To clone △^12 -fatty acid desaturase gene of Mortierella isabellina and to functionally characterize this gene in vitro and in vivo.METHODS： Reverse transcriptional polymerase chain reaction （RT-PCR） was used to clone the open reading frame of △^12-fatty acid desaturase gene （D12D） of Mortierella isabellina. Plasmids pEMICL12 and pYMICL12 were constructed with it. pEMICL12 was transformed into Escherichia coli（E.coli） strain BL21 using CaCl2 method for expression after induction with IPTG. pTMICL12 was transformed into Saccharomyces cerevisiae strain IN- VSc1 using lithium acetate method for expression under the induction of galactose. Northern blotting method was used to investigate the effect of temperature on the transcriptional level of this gene in S.cerevisiae strain IN- VSc1.RESULTS： Recombinant plasmids pEMICL12 and pTMICL12 were successfully constructed and transformed into E. coli and S.cerevisiae separately with appropriate method. After induction with IPTG and galactose, it was found that expression of △^12-fatty acid desaturase genes in E.coli and S. cerevisiae under appropriate conditions led to the production of active △^12-fatty acid desaturase, which could convert 17.876% and 17.604% of oleic acid respectively to linoleic acid by GC-MS detection in vitro and in vivo.CONCLUSION： Cloning and expression of M.isabellina D12D gene in E.coli and S.cerevisiae is successfully completed.
基金Financial support from the Fundamental Research Funds for the Central Universities(No.DUT12JB08)
文摘2β,3α--Dihydroxyurs-12-en-28-oic acid （6） is a naturally occurring diastereoisomer of corosolic acid with glycogen phosphorylase inhibitory activity. A new strategy for the semi-synthesis of 6 was developed. Using the commercially available ursolic acid （1） as the starting materials, 6 was synthesized through five facile reactions with a high stereoselectivity and an overall yield of 47,3%, The structure of 6 was confirmed by optical rotation, ESI-MS, 1H NMR and 13C NMR data,
基金Supported by the National Natural Science Foundation of China(21476065)the China National Tobacco Corporation
文摘Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).
基金Projects(CC20120031,CC20110048)supported by Changzhou Science and Technology Innovation Project,China
文摘The CaCu3Ti4O12 xerogels, powders and ceramics were prepared through the sol-gel method using two kinds of organic acid （decanoic acid and decanedioic acid）. The xerogels, powders and ceramics were characterized by the methods of TG-DTG, FT-IR, XRD, SEM and TEM. The dielectric properties of the ceramics were also measured. The results indicated that the powders calcined at 850 ℃ for 2 h are both nanometer scale particles. After sintering, the ceramics mainly consist of the CaCu3Ti4O12 phase. Compared with the powders prepared using monoacid, the particle size of the powders prepared using diacid obviously increases, and the grain size, the relative density and the whole permittivity of the ceramics increase as well. Specially, the ceramic prepared using decanedioic acid has higher relative density （97.3%）, dielectric constant （316 808） and lower dielectric loss （0.242 5） at 30 ℃ （10 kIaz）
基金supported by the National Natural Science Foundation of China (31972041, 32101955)the China Agriculture Research System of MOF and MARA (CARS-12)+1 种基金the Agricultural Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences (CAASASTIP-2016-OCRI)the Key Scientific Research Projects of Hubei Province (2020BCA086)
文摘Aluminum has been associated with neurodegenerative diseases.ALA(α-linolenic acid),an essential dietary component for human health,possesses prominent biological activities.Herein,we aim to explore the neuroprotective effects of ALA on aluminum toxicity and reveal the underlying mechanism.Results show that aluminum chloride(denoted as Al)enabled cell viability decline and apoptosis with oxidative stress and mitochondrial damage in differentiated rat pheochromocytoma cells(PC12)for 24 h incubation.Compared with Al(10 mmol/L)treatment alone,ALA(50μmol/L)pretreatment for 24 h significantly enhanced cell viability by 28.40%,and hindered cell apoptosis by 12.35%,together with recovering redox state balance and alleviating mitochondrial damage.It was measured that ALA treatment upregulated Bcl-2 expression and down-regulated Bax level,accompanied with an expression decline of caspase-3 and caspase-9.Meanwhile,ALA pretreatment was proved to increase protein kinase A(PKA)expression and to promote phosphorylation of cAMP response element-binding protein(p-CREB),resulting in elevation on the level of brain-derived neurotrophic factor(BDNF).The above results showed that ALA attenuated Al toxicity in PC12 cells by mediating the PKA-CREBBDNF signaling pathway.
文摘Context: Metformin is frequently prescribed for the treatment of type 2 diabetes mellitus. It is recommended as a first line agent by the American Diabetes Association. Vitamin B12 deficiency has been suggested as a side effect of metformin therapy;however, previous studies have not assessed the utility of methylmalonic acid levels as an indicator of vitamin B12 status. Objective: To investigate the prevalence of vitamin B12 deficiency in patients on metformin therapy for diabetes by utilizing both vitamin B12 and methylmalonic acid levels. Design, Setting, and Patients: Eighty-eight patients with diabetes, who were either on or off metformin therapy for at least thirty days, were enrolled in a case-controlled study. Blood work and questionnaires were used for analysis. Main Outcome Measures Study: Aims were to detect a clinically significant difference in the prevalence of vitamin B12 deficiency between metformin users and non-users, where such deficiency is defined by both low vitamin B12 and elevated methylmalonic acid levels. Results: Two Sample Equal Variance T-Tests were used to compare averages of measured values and the Chisquare test was used to determine the significance of calculated vitamin B12 deficiency rates between the two groups of patients. Two separate methods for defining vitamin B12 deficiency were utilized. There was no difference in the prevalence of vitamin B12 deficiency in metformin users compared with non-users by either method. Average homocysteine levels were higher in those not on metformin therapy. Conclusion: Vitamin B12 deficiency as defined by an elevated methylmalonic acid level was no greater in patients with diabetes on metformin therapy versus those patients not on metformin treatment.
文摘A novel adenine(Ade) salt of 12-phosphotungstic acid was synthesized and characterized by elemental analyses,IR, 1H NMR,CV and single crystal X-ray diffraction. The compound crystallized in a triclinic system with a space group P 1 and a =1.3108(3) nm, b =1.3515(3) nm,c =1.3870(3) nm, V =2.0217(7) nm 3,Z =1,R _1=0.0391,wR _2=0.0959. The structure unit of the complex was constructed from [HPW_ 12 ·O_ 40 ] -,(C_5H_6N_5) + and C_3H_7NO,which further extends to form a novel three-dimensional host-vip network via hydrogen-bonding interactions. The anti-tumor activity of the compound was examined in two human tumor cell lines in vitro .
文摘Heteropoly acid H3PW12040 （PW） has been used as an effective catalyst for the synthesis of thieno[2,3-d]pyrimidin-4（3H）-one derivatives. The present methodology offers several advantages, such as high yields, short reaction times, mild reaction condition and a recyclable catalyst with a very easy work up.
