No description available.

Intramuscular fat occurring in the muscle of cattle is supposed to be prerequisite for high-quality beef. Marbling has effect on juiciness, tenderness and flavor of the meat. Selection of cattle at higher marbling score brings increased meat tenderness. It is influenced by many factors, among which we classify genetic background, age of animal, nutrition, sex and pedigree of animal. The aim is to perform association analysis beetween dinucleotide polymorphism in the gene DGAT1 (diacylglycerol acyltransferase 1) and the marbling score. Part of thesis is elaboration of literature, present state of the problem, genes affecting metabolism of intramuscular fat in cattle, the role of the enzyme DGAT1 in the biosynthesis of triacylglycerols and its physiological function (energy metabolism, glucose metabolism, relation to fat accumulation and obesity). In this study a singificant difference of allelic contribution to intermuscular fat content in tested samples was found. Nevertheless, effect of Q allele was reverse than observed in similar studies.

Triacylglycerols are the predominant storage form of energy in eukaryotes. As obesity has become a worldwide problem and excessive accumulation of triacylglycerols in adipose tissue causes obesity, enzymes catalyzing the synthesis of triacylglycerols are of great interest. Acyl CoA:diacylglycerol acyltransferase (DGAT), including the isoforms DGAT1 and DGAT2, catalyze the final and committed step in triacylglycerol synthesis. Proteins that physically interact with DGAT1 may provide information regarding the metabolic role of DGAT1. We chose HEK-293T cell line to express DGAT1 and used mass spectrometry to identify proteins that co-immunoprecipitated with DGAT1. We confirmed that DGAT2 and ACAT1 did interact with DGAT1. The interaction of DGAT1 with DGAT2 appeared to interrupt the synthesis of triacylglycerol since the co-expression of DGAT1 and DGAT2 was expected to increase triacylglycerol synthesis. This implied that DGAT1 and DGAT2 might serve different functional roles. On the other hand, DGAT1 overexpression may increase the synthesis of cholesterol esters that was the product of ACAT1. Additionally, ACAT1 overexpression did increase triacylglycerol synthesis and ACAT1 disruption by siRNA did decrease triacylglycerol synthesis. Our findings indicated that DGAT1 and ACAT1 might be involved in the same lipid-synthesizing protein complex.

The avocado mesocarp contains up to 60-70% oil by dry weight where triacylglycerol (TAG) is the major constituent. There is significant human nutritional demand for vegetable oil, but its use in production of renewable biomaterials and fuels has intensified the need to further increase oil production. In plants, the final and committed step in TAG biosynthesis is catalyzed by diacylglycerol acyltransferases (DGAT) and/or a phospholipid: diacylglycerol acyltransferases (PDAT). Both DGAT and PDAT contribute to TAG biosynthesis in an independent or overlapping manner, depending on the species. However, preferred pathway for TAG biosynthesis is not well studied in nonseed tissues such as mesocarp. Based on the transcriptome data of Persea americana it is hypothesized that both DGAT and PDAT are likely to catalyze the conversion of diacylglycerol to TAG. In this study, putative DGAT1 was identified and comprehensive in silico analyses were conducted to determine the respective start codons, full-length coding sequences, transmembrane domains, predicted protein structures and phylogenetic relationships with other known DGAT1s. These data reveal that the putative DGAT1 of a basal angiosperm species retain features that are conserved not only among angiosperms but also other eukaryotes. For further functional analysis, the avocado DGAT1 was expressed in H1246, a TAG-deficient yeast strain and lipotoxicity rescue assays, TLC analysis, Nile Red staining were conducted. The complementation of this yeast strain confirmed enzyme activity and supported the possible role of avocado DGAT1 in TAG biosynthesis. Finally, substrate specificity of DGAT was determined by incubating microsomes with different radiolabeled substances and found that avocado DGAT1 has a preference toward oleic acid (18:1) compared to palmitic acid (16:0) while it is converting diacylglycerol (DAG) to triacylglycerol. In summary, we characterized functional DGAT1 in a basal angiosperm species, which may be metabolically engineered into crop species to produce TAG enriched in oleic acid.

No description available.

No description available.

No description available.

No description available.

The neutral lipid triacylglycerol (TAG) is the main storage lipid in plants. When stored in seeds, TAG provides the carbon and energy source during germination. There is significant human nutritional demand for vegetable oil, but its use in production of renewable biomaterials and fuels has intensified the need to increase oil production. In plants, the final and committed step in TAG biosynthesis is catalyzed by diacylglycerol acyltransferases (DGAT) and/or a phospholipid: diacylglycerol acyltransferases (PDAT). Both DGAT and PDAT contribute to seed TAG biosynthesis in an independent or overlapping manner, depending on the species. However, in nonseed tissues such as mesocarp of avocado, the regulation of TAG biosynthesis is not well-studied. Based on the transcriptome data of Persea americana it is hypothesized that both DGAT and PDAT are likely to catalyze the conversion of diacylglycerol to TAG. In this study, putative DGAT1 and DGAT2 were identified and comprehensive in silico analyses were conducted to determine the respective start codons, full-length coding sequences, transmembrane domains, predicted protein structures and phylogenetic relationships with other known DGATs. These data reveal that the putative DGATs of a basal angiosperm species retain features that are conserved not only among angiosperms but also other eukaryotes. For further biochemical characterization, the avocado DGATs were expressed in a TAGdeficient yeast strain and lipotoxicity rescue assays were conducted. The complementation of this yeast strain confirmed enzyme activity and supported the possible role of both avocado DGATs in TAG biosynthesis. Future studies will be focused on determining the substrate specificity of DGAT and its role, relative to PDATs in TAG biosynthesis in avocado mesocarp.

The avocado mesocarp contains up to 60-70% oil by dry weight where triacylglycerol (TAG) is the major constituent. This neutral lipid, TAG is utilized by plants for the carbon and energy source when stores in seed tissue. There is significant human nutritional demand for vegetable oil, but its use in production of renewable biomaterials and fuels has intensified the need to increase oil production. In plants, the final and committed step in TAG biosynthesis is catalyzed by diacylglycerol acyltransferases (DGAT) and/or a phospholipid: diacylglycerol acyltransferases (PDAT). Both DGAT and PDAT contribute to seed TAG biosynthesis in an independent or overlapping manner, depending on the species. However, the regulation of TAG biosynthesis is not well-studied in nonseed tissues such as mesocarp of avocado. Based on the transcriptome data of Persea americana it is hypothesized that both DGAT and PDAT are likely to catalyze the conversion of diacylglycerol to TAG. In this study, putative DGAT1 and DGAT2 were identified and comprehensive in silico analyses were conducted to determine the respective start codons, full-length coding sequences, transmembrane domains, predicted protein structures and phylogenetic relationships with other known DGATs. These data reveal that the putative DGATs of a basal angiosperm species retain features that are conserved not only among angiosperms but also other eukaryotes. For further functional analysis, the avocado DGATs were expressed in H1246, a TAG-deficient yeast strain and lipotoxicity rescue assays were conducted. The complementation of this yeast strain confirmed enzyme activity and supported the possible role of both avocado DGATs in TAG biosynthesis. Future studies will be focused on determining the substrate specificity of DGAT and its role, relative to PDATs in TAG biosynthesis in avocado mesocarp.