Tetrodotoxin(TTX)is a potent neurotoxin firstly discovered in the ovary of pufferfish.The genetic basis of voltage-gated sodium channel resistance to TTX has been widely studied,but it remains unclear in the evolution...Tetrodotoxin(TTX)is a potent neurotoxin firstly discovered in the ovary of pufferfish.The genetic basis of voltage-gated sodium channel resistance to TTX has been widely studied,but it remains unclear in the evolution history of voltage-gated sodium channel resistance to TTX in pufferfish with different TTX concentrations.In this study,six scn4aa coding sequences of pufferfish were firstly cloned and sequenced,then used to investigate the adaptive evolution of scn4aa associated with TTX concentration and reconstruct ancestral sequences with seven scn4aa of other fishes.The result of CODEML(codon substitution model)program from the PAML(phylogenetic analysis by maximum likelihood)package shows only in the genus of Takifugu,which contains TTX highly in the liver,under positive selection.The result also indicates that three of four positively selected sites are located in the intracellular regions,which may compensate for normal function.The ancestral sequence reconstruction may suggest that the replacements providing weak toxin resistance might have appeared first in scn4aa,then the genus Takifugu evolved stronger resistance to TTX later.These results contribute to the explanation of the evolutional history of voltage-gated sodium channel resistance to TTX in pufferfish.展开更多
Lysine-specific demethylase 4A(KDM4A)catalyzes demethylation of histone lysine residues,which regulates chromatin state and transcription.In drosophila and mice,KDM4A plays an important role in multiple biological pro...Lysine-specific demethylase 4A(KDM4A)catalyzes demethylation of histone lysine residues,which regulates chromatin state and transcription.In drosophila and mice,KDM4A plays an important role in multiple biological processes including development,aging,metabolism,and immunity,however the functions of KDM4A in fish are still unclear.There are two copies of the kdm4a gene in zebrafish,namely kdm4aa and kdm4ab,kdm4aa was edited using CRISPR/Cas9 technology in the present study,then homozygous kdm4aa mutants(kdm4aa^(-/-))were obtained,and loss of kdm4aa was confirmed by sequencing and increased H3K9me3.Whole-mount in situ hybridization showed that kdm4aa is widely expressed during the embryonic development of zebrafish.Compared with WT zebrafish,kdm4aa^(-/-)zebrafish showed no significant difference in gamete formation and fertilization,but the survival rate of kdm4aa^(-/-)embryos dramatically reduced to 21%at 26 hpf.Further observation showed that about 80%of survived kdm4aa^(-/-)zebrafish experienced disruption in stripe formation,and 10%of survived kdm4aa^(-/-)zebrafish underwent vertebral malformation.Alizarin red S staining demonstrated the abnormal spinal development in kdm4aa^(-/-)zebrafish.These results indicated that kdm4aa is required for normal embryonic development of zebrafish,loss of kdm4aa function leads to decreased survival during the early stages of zebrafish development and morphological variation in adult zebrafish.展开更多
The plastic flow behaviors of AA6061-T4 sheets at different temperatures(21-300°C)and strain rates(0.002-4 s^(-1))were studied.Significant nonlinear effects of temperature and strain rate on flow behaviors were r...The plastic flow behaviors of AA6061-T4 sheets at different temperatures(21-300°C)and strain rates(0.002-4 s^(-1))were studied.Significant nonlinear effects of temperature and strain rate on flow behaviors were revealed,as well as underlying micromechanical factors.Phenomenology and machine learning-based constitutive models were developed.Both models were formulated in the framework of a temperature-dependent linear combination regulated by a transition function to capture the evolution of strain-hardening behavior with increasing temperature.Novel mathematical functions for describing temperature and strain rate sensitivities were formulated for the phenomenological constitutive model.The threshold temperature related to microstructure evolution was considered in the modeling.A data-enrichment strategy based on extrapolating experimental data via classical strain hardening laws was adopted to improve neural network training.An efficient inverse identification strategy,focusing solely on the transition function,was proposed to enhance the prediction accuracy of post-necking deformation by both constitutive models.展开更多
A compound ethyl(5S,6R)-2-(4-methylphenyl)-6-[(1R)-tert-butyldimethylsilyloxyethy]-penem-3-carboxylate was synthesized through displacement,acylation and Wittig cyclization reaction of optically active material(3R,4R)...A compound ethyl(5S,6R)-2-(4-methylphenyl)-6-[(1R)-tert-butyldimethylsilyloxyethy]-penem-3-carboxylate was synthesized through displacement,acylation and Wittig cyclization reaction of optically active material(3R,4R)-3-[(1R)-tert-butyldimethylsilyloxyethyl]-4-acetoxy-2-azetidi-none(4AA)upon thionocarboxlic acid.The intermediates and the target product were characterized by 1HNMR,IR,elementary analysis and MS.展开更多
The optimum volume ratio of Zn(AA) SO4 · H2O crystallizing from mixed solvent of water with acetone has been determined, which are 1∶ 3, 1∶ 9, 1∶ 10, and 1∶ 30 of water∶ acetone, respectively. The crystal gr...The optimum volume ratio of Zn(AA) SO4 · H2O crystallizing from mixed solvent of water with acetone has been determined, which are 1∶ 3, 1∶ 9, 1∶ 10, and 1∶ 30 of water∶ acetone, respectively. The crystal growth processes of the compounds at 298.15K are investigated by microcalorimetry. The experimental results show that the processes are in accord with the Burton Cabrera Frank dislocation theory.展开更多
Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried out.SiC particles were uniformly dispersed into an AA6061-T4 matrix.Also SiC particles promoted the grain refinement of the AA606...Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried out.SiC particles were uniformly dispersed into an AA6061-T4 matrix.Also SiC particles promoted the grain refinement of the AA6061-T4 matrix by FSP.The mean grain size of the stir zone (SZ) with the SiC particles was obviously smaller than that of the stir zone without the SiC particles.The microhardness of the SZ with the SiC particles reached about HV80 due to the grain refinement and the distribution of the SiC particles.展开更多
基金supported by National Natural Science Foundation of China (41176108)Key Innovation Project of Shanghai Education Commission (14zz145).
文摘Tetrodotoxin(TTX)is a potent neurotoxin firstly discovered in the ovary of pufferfish.The genetic basis of voltage-gated sodium channel resistance to TTX has been widely studied,but it remains unclear in the evolution history of voltage-gated sodium channel resistance to TTX in pufferfish with different TTX concentrations.In this study,six scn4aa coding sequences of pufferfish were firstly cloned and sequenced,then used to investigate the adaptive evolution of scn4aa associated with TTX concentration and reconstruct ancestral sequences with seven scn4aa of other fishes.The result of CODEML(codon substitution model)program from the PAML(phylogenetic analysis by maximum likelihood)package shows only in the genus of Takifugu,which contains TTX highly in the liver,under positive selection.The result also indicates that three of four positively selected sites are located in the intracellular regions,which may compensate for normal function.The ancestral sequence reconstruction may suggest that the replacements providing weak toxin resistance might have appeared first in scn4aa,then the genus Takifugu evolved stronger resistance to TTX later.These results contribute to the explanation of the evolutional history of voltage-gated sodium channel resistance to TTX in pufferfish.
基金from Shanghai Agriculture Applied Technology Development Program,China(Grant No.G20190102)National Natural Science Foundation of China(Grant No.81770165 to BH)Shanghai Municipal Education Commission(Project for Gaofeng Discipline of Fishery).
文摘Lysine-specific demethylase 4A(KDM4A)catalyzes demethylation of histone lysine residues,which regulates chromatin state and transcription.In drosophila and mice,KDM4A plays an important role in multiple biological processes including development,aging,metabolism,and immunity,however the functions of KDM4A in fish are still unclear.There are two copies of the kdm4a gene in zebrafish,namely kdm4aa and kdm4ab,kdm4aa was edited using CRISPR/Cas9 technology in the present study,then homozygous kdm4aa mutants(kdm4aa^(-/-))were obtained,and loss of kdm4aa was confirmed by sequencing and increased H3K9me3.Whole-mount in situ hybridization showed that kdm4aa is widely expressed during the embryonic development of zebrafish.Compared with WT zebrafish,kdm4aa^(-/-)zebrafish showed no significant difference in gamete formation and fertilization,but the survival rate of kdm4aa^(-/-)embryos dramatically reduced to 21%at 26 hpf.Further observation showed that about 80%of survived kdm4aa^(-/-)zebrafish experienced disruption in stripe formation,and 10%of survived kdm4aa^(-/-)zebrafish underwent vertebral malformation.Alizarin red S staining demonstrated the abnormal spinal development in kdm4aa^(-/-)zebrafish.These results indicated that kdm4aa is required for normal embryonic development of zebrafish,loss of kdm4aa function leads to decreased survival during the early stages of zebrafish development and morphological variation in adult zebrafish.
文摘The plastic flow behaviors of AA6061-T4 sheets at different temperatures(21-300°C)and strain rates(0.002-4 s^(-1))were studied.Significant nonlinear effects of temperature and strain rate on flow behaviors were revealed,as well as underlying micromechanical factors.Phenomenology and machine learning-based constitutive models were developed.Both models were formulated in the framework of a temperature-dependent linear combination regulated by a transition function to capture the evolution of strain-hardening behavior with increasing temperature.Novel mathematical functions for describing temperature and strain rate sensitivities were formulated for the phenomenological constitutive model.The threshold temperature related to microstructure evolution was considered in the modeling.A data-enrichment strategy based on extrapolating experimental data via classical strain hardening laws was adopted to improve neural network training.An efficient inverse identification strategy,focusing solely on the transition function,was proposed to enhance the prediction accuracy of post-necking deformation by both constitutive models.
文摘A compound ethyl(5S,6R)-2-(4-methylphenyl)-6-[(1R)-tert-butyldimethylsilyloxyethy]-penem-3-carboxylate was synthesized through displacement,acylation and Wittig cyclization reaction of optically active material(3R,4R)-3-[(1R)-tert-butyldimethylsilyloxyethyl]-4-acetoxy-2-azetidi-none(4AA)upon thionocarboxlic acid.The intermediates and the target product were characterized by 1HNMR,IR,elementary analysis and MS.
文摘The optimum volume ratio of Zn(AA) SO4 · H2O crystallizing from mixed solvent of water with acetone has been determined, which are 1∶ 3, 1∶ 9, 1∶ 10, and 1∶ 30 of water∶ acetone, respectively. The crystal growth processes of the compounds at 298.15K are investigated by microcalorimetry. The experimental results show that the processes are in accord with the Burton Cabrera Frank dislocation theory.
基金Project(10038688)supported by the Fundamental R&D Program for Core Technology of Materials Funded by the Ministry of Knowledge Economy,Republic of Korea
文摘Friction stir processing of AA6061-T4 alloy with SiC particles was successfully carried out.SiC particles were uniformly dispersed into an AA6061-T4 matrix.Also SiC particles promoted the grain refinement of the AA6061-T4 matrix by FSP.The mean grain size of the stir zone (SZ) with the SiC particles was obviously smaller than that of the stir zone without the SiC particles.The microhardness of the SZ with the SiC particles reached about HV80 due to the grain refinement and the distribution of the SiC particles.
