It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen...It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen starvation is seldom understood. One Δ6 FAD gene( MiD6 fad) from an arachidonic acidrich microalga M yrmecia incisa Reisigl(Chlorophyta) was first heterologously expressed in S accharomyces cerevisiae for the identification of function. The fatty acid profile of transgenic yeast detected by gas chromatography-mass spectrometry illustrated that the enzyme MiD6 FAD could convert linoleic and ?-linolenic acids to γ-linolenic and stearidonic acids, respectively, demonstrating that M iD6 fad encoded a Δ6 FAD. A 1 965-bp fragment of the cloned 2 347-bp 5′-upstream region of M iD6 fad was next subcloned and fused upstream with green fluorescent protein(GFP) gene to replace the GAL1 promoter of the vector pYES2. The generated construct was transformed into S. cerevisiae for function determination. Confocal microscopic images of the transformed line illustrated that this inserted fragment could drive GFP expression, which was further verified by fluorescence intensity quantification and Western blot analysis using antiGFP antibody. The conversion efficiency(approximately 2%-3%) of MiD6 FAD was much lower than the reported ? 3 FAD and Δ6 elongase in this microalga, suggesting that MiD6 FAD catalysed the possible ratelimiting step for ArA biosynthesis. The presence of several putative c is-acting regulatory elements in this identified promoter sheds new light on the regulation mechanism research of Δ6 FAD transcription for the ArA production in M. incisa in changing environmental factors.展开更多
Fatty acid(FA)desaturases,as the key enzymes in lipid metabolism,are responsible for biosynthesis of the unsaturated fatty FAs,which play important roles in maintaining cell membrane integrity and multiple stress resp...Fatty acid(FA)desaturases,as the key enzymes in lipid metabolism,are responsible for biosynthesis of the unsaturated fatty FAs,which play important roles in maintaining cell membrane integrity and multiple stress responses.Although attention has been drawn to some plant FA desaturase genes,their global landscape in oil crops is still lacking.Here,we performed systematic characterization and phylogenomic synteny network analyses of the FA desaturase gene family in polyploid oil crop B.napus and other 54 species covering major streptophyte lineages.A total of 1653 FA desaturase genes were identified from these plant genomes.Based on the broad-scale family phylogeny and functional domains,we proposed a unified eight-group classification system for angiosperm FA desaturases,and found that the origin of genes responsible for FA desaturation evolved early and some genes were absent in different species.Phylogenomic analyses revealed deeply conserved syntenic relationships within each of the eight FA desaturase groups.B.napus contains up to 93 FA desaturase genes from the eight groups.Recurrent duplication events in Brassicaceae contributed to the expansion of FA desaturase genes in B.napus,leading to further functional diversification.These FA desaturase genes exhibited spatio-temporal specific expression patterns in different tissues of B.napus,and a set of FA desaturase genes seem to be orchestrated by key transcriptional factors during seed development,such as zf-HD,B3,GATA3,PEI1,NFYA7,YAB1 and YAB2.Altogether,our data have inferred the evolutionary trajectory of this important gene family across distinct plant lineages,providing theoretical basis for future manipulation of FA desaturase genes to improve the seed oil quality of B.napus.展开更多
This study investigated the effect of dietary lipid on the growth, fatty acid composition and Δ5 fatty acyl desaturase genes(Fads) expression of juvenile abalone(Haliotis discus hannai Ino) hepatopancreas. Six purifi...This study investigated the effect of dietary lipid on the growth, fatty acid composition and Δ5 fatty acyl desaturase genes(Fads) expression of juvenile abalone(Haliotis discus hannai Ino) hepatopancreas. Six purified diets were formulated to contain tripalmitin(TP), olive oil(OO, 72.87% 18:1n-9), grape seed oil(GO, 68.67% 18:2n-6), linseed oil(LO, 70.48% 18:3n-3), ARA oil(AO, 41.81% ARA) or EPA oil(EO, 44.09% EPA and 23.67% DAH). No significant difference in survival rate was observed among abalone fed with different diets. Weight gain rate(WGR) and daily growth rate of shell length(DGRSL) were significantly increased in abalone fed with diets containing OO, AO and EO, but decreased in abalone fed with LO diet(P < 0.05) in comparison with those fed with TP. High level of dietary 18:2n-6 resulted in higher content of n-6 polyunsaturated fatty acids(PUFAs) in abalone fed with GO than those fed with TP, OO, LO and EO(P < 0.05). n-3 PUFAs in abalone fed with LO was significantly higher than those in abalone fed with TP, OO, GO and AO(P < 0.05). The highest contents of 20:1n-9 and 22:1n-9 were observed in abalone fed with OO. The expression of Δ5 Fads in hepatopancreas of abalone was enhanced by high concentration of 18:3n-3 and suppressed by dietary LC-PUFAs; however it was not affected by dietary high concentration of 18:1n-9 or 18:2n-6. These results provided valuable information for understanding the synthesis of LC-PUFAs and nutritional regulation of Δ5 Fads expression in abalone.展开更多
Using degenerate primers and RT-PCR, RACE techniques, a 1491 bp cDNA segment of stearoyl-acyl carrier protein desaturase （SAD） is cloned from developing seeds of Jatropha curcas L. The segment contains a 1191 bp of ...Using degenerate primers and RT-PCR, RACE techniques, a 1491 bp cDNA segment of stearoyl-acyl carrier protein desaturase （SAD） is cloned from developing seeds of Jatropha curcas L. The segment contains a 1191 bp of complete open reading frame （ORF）. Analysis in the BLAST on NCBI shows that Jatropha curcas SAD （JSAD） gene encodes a protein precursor composed of a signal peptide of 33 amino acids and a mature peptide of 363 amino acids. The homological analysis shows that JSAD has high level of homology both in nucleotide sequence and in amino acid sequence to other plants SADs. The nucleotide and peptide identity of JSAD to Ricinus communis SAD （RSAD） is up to 89% and 96.2% respectively. Molecular modeling of JSAD indicates that its three-dimensional structure strongly resembled the crystal structure of RSAD.展开更多
脂肪酸是影响家鸡肉品质的重要风味物质,Δ6-脂肪酸脱氢酶基因(FADS2)是不饱和脂肪酸生物合成过程中的关键酶。研究以武定鸡和大围山微型鸡为研究对象,检测肌肉组织中脂肪酸含量及FADS2基因表达量,比较不同鸡种脂肪酸含量及FADS2基因表...脂肪酸是影响家鸡肉品质的重要风味物质,Δ6-脂肪酸脱氢酶基因(FADS2)是不饱和脂肪酸生物合成过程中的关键酶。研究以武定鸡和大围山微型鸡为研究对象,检测肌肉组织中脂肪酸含量及FADS2基因表达量,比较不同鸡种脂肪酸含量及FADS2基因表达差异。结果显示,整体上,武定鸡腿肌中饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、不饱和脂肪酸(USFA)、多不饱和脂肪酸(PUFA)、必需脂肪酸(EFA)及总脂肪酸含量和FADS2 m RNA表达量均显著高于大围山微型鸡,且在部位和周龄上存在显著差异。研究表明,武定鸡风味比大围山微型鸡优良,FADS2基因是影响家鸡肉品质的重要候选基因。展开更多
Fatty acid desaturase-2 (FAD2) introduces a double bond in position 12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter...Fatty acid desaturase-2 (FAD2) introduces a double bond in position 12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter/fad2 cDNA/SV40 polyA, was constructedto produce transgenic mice. Among 63 healthy offspring, 10 founders (15.9%) integrated the cotton fad2 transgene into their genomes, as demonstrated by PCR and Southern blotting analysis. All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography. One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05) in transgenic muscles compared to their nontransgenic littermates. Moreover, it exhibited an 87% and a 9% increase (P<0.05) in arachidonic acid (20:4 n-6) in muscles and liver, compared to their nontransgenic littermates. The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.展开更多
基金Supported by the National Natural Science Foundation of China(No.31172389)the Special Project of Marine Renewable Energy from the State Oceanic Administration(No.SHME2011SW02)the Shanghai Universities Peak Discipline Project of Aquaculture
文摘It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen starvation is seldom understood. One Δ6 FAD gene( MiD6 fad) from an arachidonic acidrich microalga M yrmecia incisa Reisigl(Chlorophyta) was first heterologously expressed in S accharomyces cerevisiae for the identification of function. The fatty acid profile of transgenic yeast detected by gas chromatography-mass spectrometry illustrated that the enzyme MiD6 FAD could convert linoleic and ?-linolenic acids to γ-linolenic and stearidonic acids, respectively, demonstrating that M iD6 fad encoded a Δ6 FAD. A 1 965-bp fragment of the cloned 2 347-bp 5′-upstream region of M iD6 fad was next subcloned and fused upstream with green fluorescent protein(GFP) gene to replace the GAL1 promoter of the vector pYES2. The generated construct was transformed into S. cerevisiae for function determination. Confocal microscopic images of the transformed line illustrated that this inserted fragment could drive GFP expression, which was further verified by fluorescence intensity quantification and Western blot analysis using antiGFP antibody. The conversion efficiency(approximately 2%-3%) of MiD6 FAD was much lower than the reported ? 3 FAD and Δ6 elongase in this microalga, suggesting that MiD6 FAD catalysed the possible ratelimiting step for ArA biosynthesis. The presence of several putative c is-acting regulatory elements in this identified promoter sheds new light on the regulation mechanism research of Δ6 FAD transcription for the ArA production in M. incisa in changing environmental factors.
基金funded by the Agricultural Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences(CAAS-ASTIP-OCRI),the National Natural Science Foundation of China(grant number 31801399)the Research Foundation of Education Bureau of Hunan Province,China(grant number 21A0135)。
文摘Fatty acid(FA)desaturases,as the key enzymes in lipid metabolism,are responsible for biosynthesis of the unsaturated fatty FAs,which play important roles in maintaining cell membrane integrity and multiple stress responses.Although attention has been drawn to some plant FA desaturase genes,their global landscape in oil crops is still lacking.Here,we performed systematic characterization and phylogenomic synteny network analyses of the FA desaturase gene family in polyploid oil crop B.napus and other 54 species covering major streptophyte lineages.A total of 1653 FA desaturase genes were identified from these plant genomes.Based on the broad-scale family phylogeny and functional domains,we proposed a unified eight-group classification system for angiosperm FA desaturases,and found that the origin of genes responsible for FA desaturation evolved early and some genes were absent in different species.Phylogenomic analyses revealed deeply conserved syntenic relationships within each of the eight FA desaturase groups.B.napus contains up to 93 FA desaturase genes from the eight groups.Recurrent duplication events in Brassicaceae contributed to the expansion of FA desaturase genes in B.napus,leading to further functional diversification.These FA desaturase genes exhibited spatio-temporal specific expression patterns in different tissues of B.napus,and a set of FA desaturase genes seem to be orchestrated by key transcriptional factors during seed development,such as zf-HD,B3,GATA3,PEI1,NFYA7,YAB1 and YAB2.Altogether,our data have inferred the evolutionary trajectory of this important gene family across distinct plant lineages,providing theoretical basis for future manipulation of FA desaturase genes to improve the seed oil quality of B.napus.
基金supported by the National Natural Science Foundation of China (No. 30871930)
文摘This study investigated the effect of dietary lipid on the growth, fatty acid composition and Δ5 fatty acyl desaturase genes(Fads) expression of juvenile abalone(Haliotis discus hannai Ino) hepatopancreas. Six purified diets were formulated to contain tripalmitin(TP), olive oil(OO, 72.87% 18:1n-9), grape seed oil(GO, 68.67% 18:2n-6), linseed oil(LO, 70.48% 18:3n-3), ARA oil(AO, 41.81% ARA) or EPA oil(EO, 44.09% EPA and 23.67% DAH). No significant difference in survival rate was observed among abalone fed with different diets. Weight gain rate(WGR) and daily growth rate of shell length(DGRSL) were significantly increased in abalone fed with diets containing OO, AO and EO, but decreased in abalone fed with LO diet(P < 0.05) in comparison with those fed with TP. High level of dietary 18:2n-6 resulted in higher content of n-6 polyunsaturated fatty acids(PUFAs) in abalone fed with GO than those fed with TP, OO, LO and EO(P < 0.05). n-3 PUFAs in abalone fed with LO was significantly higher than those in abalone fed with TP, OO, GO and AO(P < 0.05). The highest contents of 20:1n-9 and 22:1n-9 were observed in abalone fed with OO. The expression of Δ5 Fads in hepatopancreas of abalone was enhanced by high concentration of 18:3n-3 and suppressed by dietary LC-PUFAs; however it was not affected by dietary high concentration of 18:1n-9 or 18:2n-6. These results provided valuable information for understanding the synthesis of LC-PUFAs and nutritional regulation of Δ5 Fads expression in abalone.
基金Project supported by"Tenth Five Years"Key Program of the State Science and Technology Commission in China(Grant Nos.2002BA901A15,2004BA411B01)
文摘Using degenerate primers and RT-PCR, RACE techniques, a 1491 bp cDNA segment of stearoyl-acyl carrier protein desaturase （SAD） is cloned from developing seeds of Jatropha curcas L. The segment contains a 1191 bp of complete open reading frame （ORF）. Analysis in the BLAST on NCBI shows that Jatropha curcas SAD （JSAD） gene encodes a protein precursor composed of a signal peptide of 33 amino acids and a mature peptide of 363 amino acids. The homological analysis shows that JSAD has high level of homology both in nucleotide sequence and in amino acid sequence to other plants SADs. The nucleotide and peptide identity of JSAD to Ricinus communis SAD （RSAD） is up to 89% and 96.2% respectively. Molecular modeling of JSAD indicates that its three-dimensional structure strongly resembled the crystal structure of RSAD.
文摘脂肪酸是影响家鸡肉品质的重要风味物质,Δ6-脂肪酸脱氢酶基因(FADS2)是不饱和脂肪酸生物合成过程中的关键酶。研究以武定鸡和大围山微型鸡为研究对象,检测肌肉组织中脂肪酸含量及FADS2基因表达量,比较不同鸡种脂肪酸含量及FADS2基因表达差异。结果显示,整体上,武定鸡腿肌中饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、不饱和脂肪酸(USFA)、多不饱和脂肪酸(PUFA)、必需脂肪酸(EFA)及总脂肪酸含量和FADS2 m RNA表达量均显著高于大围山微型鸡,且在部位和周龄上存在显著差异。研究表明,武定鸡风味比大围山微型鸡优良,FADS2基因是影响家鸡肉品质的重要候选基因。
基金Supported by the National Basic Research and Development Program of China (Grant No 2004CB117500)the National Natural Science Foundation of China (Grant No 30571332)the National Major Special Project on New Varieties Cultivation for Transgenic Organisms (Grant No 2008ZX08008-003)
文摘Fatty acid desaturase-2 (FAD2) introduces a double bond in position 12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter/fad2 cDNA/SV40 polyA, was constructedto produce transgenic mice. Among 63 healthy offspring, 10 founders (15.9%) integrated the cotton fad2 transgene into their genomes, as demonstrated by PCR and Southern blotting analysis. All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography. One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05) in transgenic muscles compared to their nontransgenic littermates. Moreover, it exhibited an 87% and a 9% increase (P<0.05) in arachidonic acid (20:4 n-6) in muscles and liver, compared to their nontransgenic littermates. The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.
