Background：Fatty acid（FA） composition is the most important parameter affecting the flavor and nutritional value of the meat.The final and the only committed step in the biosynthesis of triglycerides is catalyzed b...Background：Fatty acid（FA） composition is the most important parameter affecting the flavor and nutritional value of the meat.The final and the only committed step in the biosynthesis of triglycerides is catalyzed by diacylglycerol acyltransferase 2（DGAT2）.The role of DGAT2 in lipid accumulation has been demonstrated in adipocytes,However,little is known about the effect of DGAT2 on the FA composition of these cells.Methods：To investigate the role of DGAT2 in regulating lipid accumulation,FA composition and the expression of adipogenic genes,we cloned the open reading frame of the porcine DGAT2 gene and established 3T3-L1 cells that overexpressed DGAT2.Cells were then cultured in differentiation medium（DM） without FA,with a mixture of FAs（FA-DM）,or containing a ^（13）C stable isotope-labeled FA mixture（IFA-DM）.The FA composition of adipocytes was analyzed by gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry.Quantitative PCR and western blotting were employed to detect expression of adipogenic genes in 3T3-L1 adipocytes cultured with FA-DM for 12 d.Results：The triacylglyceride（TAG） content was significantly higher in 3T3-L1 adipocytes overexpressing DGAT2 than in control cells.When cultured in DM or FA-DM for 12 d,cells overexpressing DGAT2 showed a higher proportion of unsaturated FAs（C16：1 and C18：1）.However,when cells overexpressing DGAT2 were cultured with FA-DM for30 min,the FA composition was almost identical to that of controls.Further,the proportion of stable isotope-labeled FAs were similar in 3T3-L1 adipocytes overexpressing DGAT2 and control cells cultured in IFA-DM for 12 d.These results collectively indicate that the higher proportion of mono-unsaturated FAs,C16：1 and C18：1,may originate from de novo FA synthesis but not from the uptake of specific FAs from the medium.This hypothesis is further supported by evidence that both mRNA and protein expression of genes involved in FA synthesis（ACACA,FASN,SCD1,and A-FABP）were significantly higher in cells overexpressing DGAT2 than in control cells.Conclusions：In conclusion,our study revealed that TAG accumulation,the proportion of MUFAs,and the expression of adipogenic genes were higher in 3T3-L1 cells overexpressing DGAT2 than in control cells.展开更多
This study evaluated the influence of husbandry（organic feed and management but not free-ranging vs. conventional） and sex（barrows vs. gilts） on pork meat quality. A total of 60 Longissimus thoracis pork muscle sa...This study evaluated the influence of husbandry（organic feed and management but not free-ranging vs. conventional） and sex（barrows vs. gilts） on pork meat quality. A total of 60 Longissimus thoracis pork muscle samples from different 3-way crossbred genotypes were chosen from 3 conventional and 2 organic pig farms. Technological meat quality was measured at 24 h post-mortem and muscle fatty acid content and composition was analysed by gas chromatography. The loin from organic pigs at 24 h of retail display had lower pH, but it had no detrimental effects on drip loss. All the International Commission on Illumination colour attributes except meat lightness differed between husbandry systems. Moisture and crude protein content were lower whereas intramuscular fat content was greater in organic than in conventional pork. Total saturated fatty acid（SFA）, monounsaturated fatty acid（MUFA）, polyunsaturated fatty acid（PUFA） and PUFA n-6 contents did not differ between husbandry systems, but total PUFA n-3（mainly C18：3 n-3） were greater in organic than in conventional pork. Sex did not affect ultimate p H or meat colour attributes but barrows showed lower moisture and greater intramuscular fat than gilts. Total SFA and MUFA content were similar but all the PUFA（both n-6 and n-3） were lower in barrows than in gilts. These results suggest that some bioactive compounds from dietary origin, i.e., linolenic acid（C18：3 n-3） content from dietary vegetable oils（soybean or olive olein）, might be used to highlight the nutritive value of（not free-ranging） organic pork meat. In addition, gilts were leaner than barrows and showed a more favourable PUFA/SFA ratio.展开更多
基金supported by grants from the National Basic Research Program of China-the 973 Program(2012CB1247012013CB127306)+2 种基金the Talent Project of guangdong collegesthe Natural Science Foundation of Guangdong Province of China(S2012020011048)the Research Fund for the Doctoral Program of Higher Education
文摘Background：Fatty acid（FA） composition is the most important parameter affecting the flavor and nutritional value of the meat.The final and the only committed step in the biosynthesis of triglycerides is catalyzed by diacylglycerol acyltransferase 2（DGAT2）.The role of DGAT2 in lipid accumulation has been demonstrated in adipocytes,However,little is known about the effect of DGAT2 on the FA composition of these cells.Methods：To investigate the role of DGAT2 in regulating lipid accumulation,FA composition and the expression of adipogenic genes,we cloned the open reading frame of the porcine DGAT2 gene and established 3T3-L1 cells that overexpressed DGAT2.Cells were then cultured in differentiation medium（DM） without FA,with a mixture of FAs（FA-DM）,or containing a ^（13）C stable isotope-labeled FA mixture（IFA-DM）.The FA composition of adipocytes was analyzed by gas chromatography-mass spectrometry and gas chromatography-isotope ratio mass spectrometry.Quantitative PCR and western blotting were employed to detect expression of adipogenic genes in 3T3-L1 adipocytes cultured with FA-DM for 12 d.Results：The triacylglyceride（TAG） content was significantly higher in 3T3-L1 adipocytes overexpressing DGAT2 than in control cells.When cultured in DM or FA-DM for 12 d,cells overexpressing DGAT2 showed a higher proportion of unsaturated FAs（C16：1 and C18：1）.However,when cells overexpressing DGAT2 were cultured with FA-DM for30 min,the FA composition was almost identical to that of controls.Further,the proportion of stable isotope-labeled FAs were similar in 3T3-L1 adipocytes overexpressing DGAT2 and control cells cultured in IFA-DM for 12 d.These results collectively indicate that the higher proportion of mono-unsaturated FAs,C16：1 and C18：1,may originate from de novo FA synthesis but not from the uptake of specific FAs from the medium.This hypothesis is further supported by evidence that both mRNA and protein expression of genes involved in FA synthesis（ACACA,FASN,SCD1,and A-FABP）were significantly higher in cells overexpressing DGAT2 than in control cells.Conclusions：In conclusion,our study revealed that TAG accumulation,the proportion of MUFAs,and the expression of adipogenic genes were higher in 3T3-L1 cells overexpressing DGAT2 than in control cells.
基金funded by Catalonian grants to encourage applied research concerning organic food production (Generalitat de Catalunya, AGEC2011-006)
文摘This study evaluated the influence of husbandry（organic feed and management but not free-ranging vs. conventional） and sex（barrows vs. gilts） on pork meat quality. A total of 60 Longissimus thoracis pork muscle samples from different 3-way crossbred genotypes were chosen from 3 conventional and 2 organic pig farms. Technological meat quality was measured at 24 h post-mortem and muscle fatty acid content and composition was analysed by gas chromatography. The loin from organic pigs at 24 h of retail display had lower pH, but it had no detrimental effects on drip loss. All the International Commission on Illumination colour attributes except meat lightness differed between husbandry systems. Moisture and crude protein content were lower whereas intramuscular fat content was greater in organic than in conventional pork. Total saturated fatty acid（SFA）, monounsaturated fatty acid（MUFA）, polyunsaturated fatty acid（PUFA） and PUFA n-6 contents did not differ between husbandry systems, but total PUFA n-3（mainly C18：3 n-3） were greater in organic than in conventional pork. Sex did not affect ultimate p H or meat colour attributes but barrows showed lower moisture and greater intramuscular fat than gilts. Total SFA and MUFA content were similar but all the PUFA（both n-6 and n-3） were lower in barrows than in gilts. These results suggest that some bioactive compounds from dietary origin, i.e., linolenic acid（C18：3 n-3） content from dietary vegetable oils（soybean or olive olein）, might be used to highlight the nutritive value of（not free-ranging） organic pork meat. In addition, gilts were leaner than barrows and showed a more favourable PUFA/SFA ratio.
