Based on comparative studies on four regional floras from northwest, west, south and southeast of Yunnan respectively, the formerly suggested two biogeographical lines, i.e. the “Tanaka Line" and the “Ecogeogra...Based on comparative studies on four regional floras from northwest, west, south and southeast of Yunnan respectively, the formerly suggested two biogeographical lines, i.e. the “Tanaka Line" and the “Ecogeographical Diagonal Line", both going from northwest to southeast of Yunnan, and their significance are discussed. In family and generic levels, similarity coefficients among the four compared floras are more than 93% and 60% separately, which indicate the close floristic affinities among them. The highest similarity coefficient, i.e. 98.7% in family level and 78.6% in generic level separately, is found between the regional flora of northwest Yunnan and the flora of southeast Yunnan although these two regions are the most distant away each other among the compared regional floras. The flora of northwest Yunnan is also the most similar to the flora of southeast Yunnan in floristic composition. These support the idea of “Ecogeographical Diagonal Line". In specific level, the relatively high similarity coefficient is between the regional flora of west Yunnan and the one of south Yunnan. The floristic affinities among these regional floras and some distribution patterns could be explained by the geological history and tectonic theory of Yunnan.展开更多
AIM:To develop an affinity peptide that binds to gastric cancer used for the detection of early gastric cancer.METHODS:A peptide screen was performed by biopanning the PhD-12 phage display library,clearing non-specifi...AIM:To develop an affinity peptide that binds to gastric cancer used for the detection of early gastric cancer.METHODS:A peptide screen was performed by biopanning the PhD-12 phage display library,clearing non-specific binders against tumor-adjacent normal appearing gastric mucosa and obtaining selective binding against freshly harvested gastric cancer tissues.Tumortargeted binding of selected peptides was confirmed by bound phage counts,enzyme-linked immunosorbent assay,competitive inhibition,fluorescence microscopy and semi-quantitative analysis on immunohistochemistry using different types of cancer tissues.RESULTS:Approximately 92.8% of the non-specific phage clones were subtracted from the original phage library after two rounds of biopanning against normal-appearing gastric mucosa.After the third round of positive screening,the peptide sequence AADNAKTKSFPV(AAD) appeared in 25%(12/48) of the analyzed phages.For the control peptide,these values were 6.8 ± 2.3,5.1 ± 1.7,3.5 ± 2.1,4.6 ± 1.9 and 1.1 ± 0.5,respectively.The values for AAD peptide were statistically signif icant(P < 0.01) for gastric cancer as compared with other histological classif ications and control peptide.CONCLUSION:A novel peptide is discovered to have a specific binding activity to gastric cancer,and can be used to distinguish neoplastic from normal gastric mucosa,demonstrating the potential for early cancer detection on endoscopy.展开更多
Chinese semi-winter rapeseed,genetically differing from winter and spring rapeseed,has been considered to possess strong potential as parent in winter and spring rapeseed hybrid breeding programs. However,no detailed ...Chinese semi-winter rapeseed,genetically differing from winter and spring rapeseed,has been considered to possess strong potential as parent in winter and spring rapeseed hybrid breeding programs. However,no detailed researches have been documented whether winter and spring rapeseed lines have potential for Chinese semiwinter rapeseed hybrid breeding. The objectives of this study are to estimate the potential of winter and spring rapeseed for semi-winter rapeseed hybrid breeding,and to investigate the association of general combining ability(GCA) with adaptation of parental lines by combining with the data in our previous studies. Four winter and four spring male sterile lines were crossed with 14 Chinese semi-winter rapeseed lines to develop 112 hybrids,which were evaluated together with their parents for seed yield under three environments in China. The exotic parental lines were not adapted to local environment as demonstrated by late flowering,low seed weight and poor seed yield per se. However,the hybrids,especially derived from winter rapeseed exhibited strong heterosis for seed yield,indicating that winter rapeseed germplasm has a great potential for rapeseed hybrid breeding in China. Our data suggested a strong association of GCA with their adaptation ability of parental lines,since high to middle correlations were found for local parental lines and low correlations for exotic parental lines under spring,winter and semi-winter eco-growth environments. The hybrid breeding program using exotic germplasm in rapeseed was discussed.展开更多
In order to improve the functional affinity of the humanized VH single domain antibody against human lung cancer, the genes coding the homogenous dimers dihu3D3Vn and tetramers tehu3D3VH were constructed by fusing the...In order to improve the functional affinity of the humanized VH single domain antibody against human lung cancer, the genes coding the homogenous dimers dihu3D3Vn and tetramers tehu3D3VH were constructed by fusing the SV5-Cys short peptide and p53 tetramefization structural domain gene to hu3D3VH gene via recombinant PCR technique, respectively. Then, the dihu3D3VH and tehu3D3VH genes were cloned to the prokaryotic expression vector pET-22b( + ) and expressed in E. coli BL21 (DE3). The proteins expressed were purified through Ni^2+ -affinity chromatographic column. Meanwhile, the hu3D3VH, dihu3D3VH and tehu3D3VH proteins were labeled with FTTC, and their reactivity with antigen and specificity were analyzed by immunofluorescence assay. As to their functional affinities, it was analyzed and compared by flow cytometry. The results indicated that these two genes were expressed as monomers and mainly as inclusion bodies. After purification and renaturation, there were about 50% of dimers and 70% of tetramer remaining in the protein solution. In addition, the dihu3D3VH and tehu3D3VH proteins still remained the reactivity with antigen and specificity of hu3D3VH protein, and their functional affinities were increased about 60% or 100% respectively, compared with those of hu3D3VH protein. It is evident that the functional affinity of hu3D3VH protein can be greatly improved by increasing its binding valency.展开更多
Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the re...Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.展开更多
A water-soluble adjuvant named QuickAntibody (QA) was introduced into the procedure of mouse immunization for the development of hapten-specific monoclonal antibodies (mAbs), using four kinds of pesticides as mode...A water-soluble adjuvant named QuickAntibody (QA) was introduced into the procedure of mouse immunization for the development of hapten-specific monoclonal antibodies (mAbs), using four kinds of pesticides as model compounds. Compared with conventional Freund's adjuvants, QA treatments offered relatively low but acceptable antiserum titers after three inoculations, gave little adverse effects to the experimental animals, and were preferable in harvesting splenocytes during the steps of cell fusion. Afterwards, hybridomas from the QA group were prepared and screened by both non-competitive and competitive indirect enzyme-linked immunosorbent assays (ELISAs). The efficiency of gaining immune-positive hybridomas was satisfactory, and the resultant mAbs showed sensitivities (half maximal inhibitory concentration (IC50)) of 0.91, 2.46, 3.72, and 6.22 ng/ml to triazophos, parathion, chlorpyrifos, and fenpropathrin, respectively. Additionally, the performance of QA adjuvant was further confirmed by acquiring a high-affinity mAb against okadaic acid (IC50 of 0.36 ng/ml) after three immunizations. These newly developed mAbs showed similar or even better sensitivities compared with previously reported mAbs specific to the corresponding analytes. This study suggested that the easy-to-use adjuvant could be applicable to the efficient gen- eration of highly sensitive mAbs against small compounds.展开更多
Since aptamer and its in vitro selection process called SELEX were independently described by Ellington and Gold in 1990, extensive research has been undertaken and numerous isolated aptamers for various targets have ...Since aptamer and its in vitro selection process called SELEX were independently described by Ellington and Gold in 1990, extensive research has been undertaken and numerous isolated aptamers for various targets have been applied. Aptamers can bind to a wide range of targets that include small organic molecules, inorganic compounds, haptens and even whole cells with high binding affinity and specificity. Aptamers for a wide range of targets have been selected currently. In addition, aptamers are thermo stable and can also be regenerated easily within a few minutes denaturation, which makes them easy to store or handle. These advantages make aptamers extremely suitable for applications based on molecular recognition as analytical, diagnostic and therapeutic tools. In this review, the recent applications of aptamers for chemistry analysis, medicine and food security, along with the future trend will be discussed.展开更多
RCAN1, also known as DSCR1, is an endogenous regulator of calcineurin, a serine/threonine protein phosphatase that plays a critical role in many physiological processes. In this report, we demonstrate that p38a MAP ki...RCAN1, also known as DSCR1, is an endogenous regulator of calcineurin, a serine/threonine protein phosphatase that plays a critical role in many physiological processes. In this report, we demonstrate that p38a MAP kinase can phosphorylate RCAN1 at multiple sites in vitro and show that phospho-RCAN1 is a good protein substrate for calcineurin. In addition, we found that unphosphorylated RCANI noncompetitively inhibits calcineurin protein phosphatase activity and that the phosphorylation of RCAN1 by p38a MAP kinase decreases the binding affinity of RCAN1 for calcineurin. These findings reveal the molecular mechanism by which p38a MAP kinase regulates the function of RCAN1/calcineurin through phosphorylation.展开更多
In this work, the most detrimental missense mutations of aspartoacylase that cause Canavan's disease were identified computationally and the substrate binding efficiencies of those missense mutations were analyzed...In this work, the most detrimental missense mutations of aspartoacylase that cause Canavan's disease were identified computationally and the substrate binding efficiencies of those missense mutations were analyzed. Out of 30 missense mutations, I-Mutant 2.0, SIFT and PolyPhen programs identified 22 variants that were less stable, deleterious and damaging respectively. Subsequently, modeling of these 22 variants was performed to understand the change in their conformations with respect to the native aspartoacylase by computing their root mean squared deviation (RMSD). Furthermore, the native protein and the 22 mutants were docked with the substrate NAA (N-Acetyl-Aspartic acid) to explain the substrate binding efficiencies of those detrimental missense mutations. Among the 22 mutants, the docking studies identified that 15 mutants caused lower binding affinity for NAA than the native protein. Finally, normal mode analysis determined that the loss of binding affinity of these 15 mutants was caused by altered flexibility in the amino acids that bind to NAA compared with the native protein. Thus, the pre- sent study showed that the majority of the substrate-binding amino acids in those 15 mutants displayed loss of flexibility, which could be the theoretical explanation of decreased binding affinity between the mutant aspartoacylases and NAA.展开更多
Hybrid speciation is increasingly recognized as a mechanism for novel evolutionary trajectories. However, we know very little about the ecology of a contact zone that has arisen in sympatry. This study examines the fo...Hybrid speciation is increasingly recognized as a mechanism for novel evolutionary trajectories. However, we know very little about the ecology of a contact zone that has arisen in sympatry. This study examines the foraging behavior and fitness of two species of Darwin's tree finches (Camarhynchus parvulus, C pauper) and hybrid offspring on Floreana Island. Previous study showed that the percentage of hybrids in the tree finch population increased from 19% in 2005 to 41% in 2010, and their body and beak size increased by -5% (parental phenotype did not change). In 2005-2006, all three tree finch groups (two paren- tal species and hybrid birds) used the same foraging substrate, technique, and height. By 2010-2013, the small tree finch C. par- vulus had changed its foraging technique and the medium tree finch C. pauper had changed its foraging height. Both parental species had higher body condition when foraging at (divergent) mean foraging heights per species but hybrid birds did not. We discuss the implications of conserving forest to facilitate vertical niche expansion and the role of hybridization for genetic persis- tence [Current Zoology 61 (1): 181-190, 2015].展开更多
G-quadruplexes attract more and more attention in recent years.Numerous small molecules which can induce or stabilize the formation of G-quadruplexes have been investigated on the purpose of anticancer drug developmen...G-quadruplexes attract more and more attention in recent years.Numerous small molecules which can induce or stabilize the formation of G-quadruplexes have been investigated on the purpose of anticancer drug development.As a motif existed in physiological condition,flanking sequences are an important part of G-quadruplexes but the study on the impact of flanking sequences on (G-quadruplex)-ligand binding is rarely reported.In this paper,the effects of flanking sequences on binding affinity between a series of unimolecular parallel-stranded G-quadruplex sequences derived from c-myc oncogene promoter (termed as c-myc G-quadruplexes) and their ligands are discussed in detail.The results showed that the flanking sequences on c-myc G-quadruplexes play key roles in (G-quadruplex)-ligand interaction.When a c-myc G-quadruplex is bound to its ligands,the flanking sequences might form a binding cavity above the terminal G-quartet,which could provide a suitable site for ligands to dock in.Moreover,the bases on flanking sequences could interact with ligand through π-π stacking,and finally form a sandwich-stacking mode (terminal G-quartet,ligand and bases on the flanking sequence).This mode could stabilize the (G-quadruplex)-ligand complex effectively and enhance the binding affinity dramatically.However,flanking sequences are also found to exhibit steric hindrance effect which could impede the (G-quadruplex)-ligand binding.展开更多
Methyl-CpG-binding domain (MBD) proteins can specifically recognize and bind methylated CpG sites of DNA, thus repress gene transcription. In this study, we designed and expressed two recombinant proteins, MBD2b and...Methyl-CpG-binding domain (MBD) proteins can specifically recognize and bind methylated CpG sites of DNA, thus repress gene transcription. In this study, we designed and expressed two recombinant proteins, MBD2b and SNAP-MBD2b, in E. coli. An optimized protocol was developed to purify the proteins using Ni-NTA affinity cartridge and cation exchange resin. The engineered proteins purified by this method exhibited more than 93% purity and high binding avidity. We found that both SNAP-MBD2b and MBD2b were prone to aggregate during dialysis. However, this could be prevented by the use of 0.3 mol/L NaCI. The fusion of SNAP-tag with MBD2b significantly enhanced the expression of MBD2b protein in E. coli and reduced the adsorption of MBD2b on solid interfaces involved in protein purification and immobilization. The engineered proteins can be used for the study of interaction with methylated DNA and the assays for DNA methylation.展开更多
Several novel fluorescent probes targeting α_1-adrenergic receptors were well designed and synthesized by conjugating phenylpiperazine pharmacophore with coumarin and fluorescein fluorophores. These compounds showed ...Several novel fluorescent probes targeting α_1-adrenergic receptors were well designed and synthesized by conjugating phenylpiperazine pharmacophore with coumarin and fluorescein fluorophores. These compounds showed suitable fluorescence property, high receptor affinity, and low cytotoxicity. Moreover, the cell imaging results displayed that these probes can be effective tools for the real-time detection of ligand-receptor interactions, as well as the visualization and location of α_1-adrenergic receptors in living cells.展开更多
The paper reports a novel amperometric biosensor for catechol based on immobilization of a highly sensitive horseradish peroxidase by affinity interactions on metal chelate-functionalized agarose/carbon nanotubes comp...The paper reports a novel amperometric biosensor for catechol based on immobilization of a highly sensitive horseradish peroxidase by affinity interactions on metal chelate-functionalized agarose/carbon nanotubes composites. Metal chelate affinity takes advantage of the affinity of Ni2+ ions to bind strongly and reversibly to histidine or cysteine tails found on the surface of the horseradish peroxidase. Thus, enzymes with such residues in their molecules can be easily attached to functionalized aga- rose/carbon nanotubes composites support containing a nickel chelate. Linear sweep voltammograms and amperometry are used to study the proposed electrochemical biosensor. Catechol is determined by direct reduction of biocatalytically liberated quinone species at -0.05 V (vs. SCE). The effect ofpH, applied electrode potential and the concentration of H2O2 on the sensitivity of the biosensor has been investigated. The performance of the proposed biosensor is tested using four different phenolic compounds, showing very high sensitivity, in particular, the linearity of cateehol is observed from 2.0 × 10-8 to 1.05×10-5 M with a detection limit of 5.0×10-9 M.展开更多
文摘Based on comparative studies on four regional floras from northwest, west, south and southeast of Yunnan respectively, the formerly suggested two biogeographical lines, i.e. the “Tanaka Line" and the “Ecogeographical Diagonal Line", both going from northwest to southeast of Yunnan, and their significance are discussed. In family and generic levels, similarity coefficients among the four compared floras are more than 93% and 60% separately, which indicate the close floristic affinities among them. The highest similarity coefficient, i.e. 98.7% in family level and 78.6% in generic level separately, is found between the regional flora of northwest Yunnan and the flora of southeast Yunnan although these two regions are the most distant away each other among the compared regional floras. The flora of northwest Yunnan is also the most similar to the flora of southeast Yunnan in floristic composition. These support the idea of “Ecogeographical Diagonal Line". In specific level, the relatively high similarity coefficient is between the regional flora of west Yunnan and the one of south Yunnan. The floristic affinities among these regional floras and some distribution patterns could be explained by the geological history and tectonic theory of Yunnan.
基金Supported by The National Natural Science Foundation of China,No.81172359
文摘AIM:To develop an affinity peptide that binds to gastric cancer used for the detection of early gastric cancer.METHODS:A peptide screen was performed by biopanning the PhD-12 phage display library,clearing non-specific binders against tumor-adjacent normal appearing gastric mucosa and obtaining selective binding against freshly harvested gastric cancer tissues.Tumortargeted binding of selected peptides was confirmed by bound phage counts,enzyme-linked immunosorbent assay,competitive inhibition,fluorescence microscopy and semi-quantitative analysis on immunohistochemistry using different types of cancer tissues.RESULTS:Approximately 92.8% of the non-specific phage clones were subtracted from the original phage library after two rounds of biopanning against normal-appearing gastric mucosa.After the third round of positive screening,the peptide sequence AADNAKTKSFPV(AAD) appeared in 25%(12/48) of the analyzed phages.For the control peptide,these values were 6.8 ± 2.3,5.1 ± 1.7,3.5 ± 2.1,4.6 ± 1.9 and 1.1 ± 0.5,respectively.The values for AAD peptide were statistically signif icant(P < 0.01) for gastric cancer as compared with other histological classif ications and control peptide.CONCLUSION:A novel peptide is discovered to have a specific binding activity to gastric cancer,and can be used to distinguish neoplastic from normal gastric mucosa,demonstrating the potential for early cancer detection on endoscopy.
基金Forschungs-und Entwicklungsfonds RapsGrants from the Fundamental Research Funds for the Central Universities to Qian wei+1 种基金National Natural Science Foundation of China(No.31171585)Chongqing Science&Technology Commission(No.201180001)
文摘Chinese semi-winter rapeseed,genetically differing from winter and spring rapeseed,has been considered to possess strong potential as parent in winter and spring rapeseed hybrid breeding programs. However,no detailed researches have been documented whether winter and spring rapeseed lines have potential for Chinese semiwinter rapeseed hybrid breeding. The objectives of this study are to estimate the potential of winter and spring rapeseed for semi-winter rapeseed hybrid breeding,and to investigate the association of general combining ability(GCA) with adaptation of parental lines by combining with the data in our previous studies. Four winter and four spring male sterile lines were crossed with 14 Chinese semi-winter rapeseed lines to develop 112 hybrids,which were evaluated together with their parents for seed yield under three environments in China. The exotic parental lines were not adapted to local environment as demonstrated by late flowering,low seed weight and poor seed yield per se. However,the hybrids,especially derived from winter rapeseed exhibited strong heterosis for seed yield,indicating that winter rapeseed germplasm has a great potential for rapeseed hybrid breeding in China. Our data suggested a strong association of GCA with their adaptation ability of parental lines,since high to middle correlations were found for local parental lines and low correlations for exotic parental lines under spring,winter and semi-winter eco-growth environments. The hybrid breeding program using exotic germplasm in rapeseed was discussed.
文摘In order to improve the functional affinity of the humanized VH single domain antibody against human lung cancer, the genes coding the homogenous dimers dihu3D3Vn and tetramers tehu3D3VH were constructed by fusing the SV5-Cys short peptide and p53 tetramefization structural domain gene to hu3D3VH gene via recombinant PCR technique, respectively. Then, the dihu3D3VH and tehu3D3VH genes were cloned to the prokaryotic expression vector pET-22b( + ) and expressed in E. coli BL21 (DE3). The proteins expressed were purified through Ni^2+ -affinity chromatographic column. Meanwhile, the hu3D3VH, dihu3D3VH and tehu3D3VH proteins were labeled with FTTC, and their reactivity with antigen and specificity were analyzed by immunofluorescence assay. As to their functional affinities, it was analyzed and compared by flow cytometry. The results indicated that these two genes were expressed as monomers and mainly as inclusion bodies. After purification and renaturation, there were about 50% of dimers and 70% of tetramer remaining in the protein solution. In addition, the dihu3D3VH and tehu3D3VH proteins still remained the reactivity with antigen and specificity of hu3D3VH protein, and their functional affinities were increased about 60% or 100% respectively, compared with those of hu3D3VH protein. It is evident that the functional affinity of hu3D3VH protein can be greatly improved by increasing its binding valency.
基金The Natural Science Foundation of Jiangsu Province(No.BK20130602)the Applied Basic Research Program of Suzhou(No.SYG201836)the Project of the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest(No.201203094-3)the Scientific Research Fund of Zhejiang Provincial Education Department(No.Y201329970)+1 种基金the National Natural Science Foundation of China(No.31401768)the Experimental Technology Research Project of Zhejiang University(No.SZD201404),China
文摘A water-soluble adjuvant named QuickAntibody (QA) was introduced into the procedure of mouse immunization for the development of hapten-specific monoclonal antibodies (mAbs), using four kinds of pesticides as model compounds. Compared with conventional Freund's adjuvants, QA treatments offered relatively low but acceptable antiserum titers after three inoculations, gave little adverse effects to the experimental animals, and were preferable in harvesting splenocytes during the steps of cell fusion. Afterwards, hybridomas from the QA group were prepared and screened by both non-competitive and competitive indirect enzyme-linked immunosorbent assays (ELISAs). The efficiency of gaining immune-positive hybridomas was satisfactory, and the resultant mAbs showed sensitivities (half maximal inhibitory concentration (IC50)) of 0.91, 2.46, 3.72, and 6.22 ng/ml to triazophos, parathion, chlorpyrifos, and fenpropathrin, respectively. Additionally, the performance of QA adjuvant was further confirmed by acquiring a high-affinity mAb against okadaic acid (IC50 of 0.36 ng/ml) after three immunizations. These newly developed mAbs showed similar or even better sensitivities compared with previously reported mAbs specific to the corresponding analytes. This study suggested that the easy-to-use adjuvant could be applicable to the efficient gen- eration of highly sensitive mAbs against small compounds.
基金supported by the 863 Project(2012AA022703,2015AA020502)the National Natural Science Foundation of China(61271056)
文摘Since aptamer and its in vitro selection process called SELEX were independently described by Ellington and Gold in 1990, extensive research has been undertaken and numerous isolated aptamers for various targets have been applied. Aptamers can bind to a wide range of targets that include small organic molecules, inorganic compounds, haptens and even whole cells with high binding affinity and specificity. Aptamers for a wide range of targets have been selected currently. In addition, aptamers are thermo stable and can also be regenerated easily within a few minutes denaturation, which makes them easy to store or handle. These advantages make aptamers extremely suitable for applications based on molecular recognition as analytical, diagnostic and therapeutic tools. In this review, the recent applications of aptamers for chemistry analysis, medicine and food security, along with the future trend will be discussed.
基金supported in part by Ministry of Science and Technology of China (Grant 2011CB910803)
文摘RCAN1, also known as DSCR1, is an endogenous regulator of calcineurin, a serine/threonine protein phosphatase that plays a critical role in many physiological processes. In this report, we demonstrate that p38a MAP kinase can phosphorylate RCAN1 at multiple sites in vitro and show that phospho-RCAN1 is a good protein substrate for calcineurin. In addition, we found that unphosphorylated RCANI noncompetitively inhibits calcineurin protein phosphatase activity and that the phosphorylation of RCAN1 by p38a MAP kinase decreases the binding affinity of RCAN1 for calcineurin. These findings reveal the molecular mechanism by which p38a MAP kinase regulates the function of RCAN1/calcineurin through phosphorylation.
文摘In this work, the most detrimental missense mutations of aspartoacylase that cause Canavan's disease were identified computationally and the substrate binding efficiencies of those missense mutations were analyzed. Out of 30 missense mutations, I-Mutant 2.0, SIFT and PolyPhen programs identified 22 variants that were less stable, deleterious and damaging respectively. Subsequently, modeling of these 22 variants was performed to understand the change in their conformations with respect to the native aspartoacylase by computing their root mean squared deviation (RMSD). Furthermore, the native protein and the 22 mutants were docked with the substrate NAA (N-Acetyl-Aspartic acid) to explain the substrate binding efficiencies of those detrimental missense mutations. Among the 22 mutants, the docking studies identified that 15 mutants caused lower binding affinity for NAA than the native protein. Finally, normal mode analysis determined that the loss of binding affinity of these 15 mutants was caused by altered flexibility in the amino acids that bind to NAA compared with the native protein. Thus, the pre- sent study showed that the majority of the substrate-binding amino acids in those 15 mutants displayed loss of flexibility, which could be the theoretical explanation of decreased binding affinity between the mutant aspartoacylases and NAA.
文摘Hybrid speciation is increasingly recognized as a mechanism for novel evolutionary trajectories. However, we know very little about the ecology of a contact zone that has arisen in sympatry. This study examines the foraging behavior and fitness of two species of Darwin's tree finches (Camarhynchus parvulus, C pauper) and hybrid offspring on Floreana Island. Previous study showed that the percentage of hybrids in the tree finch population increased from 19% in 2005 to 41% in 2010, and their body and beak size increased by -5% (parental phenotype did not change). In 2005-2006, all three tree finch groups (two paren- tal species and hybrid birds) used the same foraging substrate, technique, and height. By 2010-2013, the small tree finch C. par- vulus had changed its foraging technique and the medium tree finch C. pauper had changed its foraging height. Both parental species had higher body condition when foraging at (divergent) mean foraging heights per species but hybrid birds did not. We discuss the implications of conserving forest to facilitate vertical niche expansion and the role of hybridization for genetic persis- tence [Current Zoology 61 (1): 181-190, 2015].
文摘G-quadruplexes attract more and more attention in recent years.Numerous small molecules which can induce or stabilize the formation of G-quadruplexes have been investigated on the purpose of anticancer drug development.As a motif existed in physiological condition,flanking sequences are an important part of G-quadruplexes but the study on the impact of flanking sequences on (G-quadruplex)-ligand binding is rarely reported.In this paper,the effects of flanking sequences on binding affinity between a series of unimolecular parallel-stranded G-quadruplex sequences derived from c-myc oncogene promoter (termed as c-myc G-quadruplexes) and their ligands are discussed in detail.The results showed that the flanking sequences on c-myc G-quadruplexes play key roles in (G-quadruplex)-ligand interaction.When a c-myc G-quadruplex is bound to its ligands,the flanking sequences might form a binding cavity above the terminal G-quartet,which could provide a suitable site for ligands to dock in.Moreover,the bases on flanking sequences could interact with ligand through π-π stacking,and finally form a sandwich-stacking mode (terminal G-quartet,ligand and bases on the flanking sequence).This mode could stabilize the (G-quadruplex)-ligand complex effectively and enhance the binding affinity dramatically.However,flanking sequences are also found to exhibit steric hindrance effect which could impede the (G-quadruplex)-ligand binding.
基金supported by the National Basic Research Program of China(21077129,20877091,20890112,21125523,20921063)the National Natural Science Foundation of China(2009CB421605,2010CB933502)
文摘Methyl-CpG-binding domain (MBD) proteins can specifically recognize and bind methylated CpG sites of DNA, thus repress gene transcription. In this study, we designed and expressed two recombinant proteins, MBD2b and SNAP-MBD2b, in E. coli. An optimized protocol was developed to purify the proteins using Ni-NTA affinity cartridge and cation exchange resin. The engineered proteins purified by this method exhibited more than 93% purity and high binding avidity. We found that both SNAP-MBD2b and MBD2b were prone to aggregate during dialysis. However, this could be prevented by the use of 0.3 mol/L NaCI. The fusion of SNAP-tag with MBD2b significantly enhanced the expression of MBD2b protein in E. coli and reduced the adsorption of MBD2b on solid interfaces involved in protein purification and immobilization. The engineered proteins can be used for the study of interaction with methylated DNA and the assays for DNA methylation.
基金supported by the Fok Ying Tong Education Foundation (122036)the Program of New Century Excellent Talents in University (NCET-11-0306)+2 种基金the Major Project of Science and Technology of Shandong Province (2015ZDJS04001)the Shandong Natural Science Foundation (JQ201019)the Independent Innovation Foundation of Shandong University (2010JQ005)
文摘Several novel fluorescent probes targeting α_1-adrenergic receptors were well designed and synthesized by conjugating phenylpiperazine pharmacophore with coumarin and fluorescein fluorophores. These compounds showed suitable fluorescence property, high receptor affinity, and low cytotoxicity. Moreover, the cell imaging results displayed that these probes can be effective tools for the real-time detection of ligand-receptor interactions, as well as the visualization and location of α_1-adrenergic receptors in living cells.
基金supported by the National Outstanding Youth Foundations of China (50725825)National Basic Research Program of China (2007CB310501 & 2011CB935704)+2 种基金National Natural Science Foundation of China (50908113)the Natural Science Foundation of Jiangxi Province (2008GZH0008)the Youth Foundation of Jiangxi Provincial Department of Education (GJJ09483)
文摘The paper reports a novel amperometric biosensor for catechol based on immobilization of a highly sensitive horseradish peroxidase by affinity interactions on metal chelate-functionalized agarose/carbon nanotubes composites. Metal chelate affinity takes advantage of the affinity of Ni2+ ions to bind strongly and reversibly to histidine or cysteine tails found on the surface of the horseradish peroxidase. Thus, enzymes with such residues in their molecules can be easily attached to functionalized aga- rose/carbon nanotubes composites support containing a nickel chelate. Linear sweep voltammograms and amperometry are used to study the proposed electrochemical biosensor. Catechol is determined by direct reduction of biocatalytically liberated quinone species at -0.05 V (vs. SCE). The effect ofpH, applied electrode potential and the concentration of H2O2 on the sensitivity of the biosensor has been investigated. The performance of the proposed biosensor is tested using four different phenolic compounds, showing very high sensitivity, in particular, the linearity of cateehol is observed from 2.0 × 10-8 to 1.05×10-5 M with a detection limit of 5.0×10-9 M.