Effect of egg cholesterol and dietary fats on plasma lipids, lipoproteins, and apoproteins of normal women consuming natural diets

Nine normal women, 22 to 37 years old, consumed controlled quantities of natural foods to test their responses to dietary cholesterol and saturated fat. All diets contained, as percentage of calories, 14% protein, 31% fat, and 55% carbohydrate. The main sources of polyunsaturated and saturated fats were corn oil and lard, respectively, and egg yolk was used for cholesterol supplementation. All subjects participated in four diet protocols of 15 days duration, and each diet period was separated by 3 weeks without diet control. The first diet (corn) was based on corn oil, had a polyunsaturated to saturated fat ratio (P/S) of 2.14, and contained 130 mg of cholesterol. The second diet (corn+) was identical to the first but contained a total of 875 mg of cholesterol. The third diet (lard) was based on lard, had a P/S ratio of 0.64, and contained 130 mg of cholesterol. The fourth diet (lard+) was identical to the third, but contained 875 mg of cholesterol per day. Changes of the plasma lipid, lipoprotein and apoprotein parameters relative to the corn diet were as follows: the corn+ diet significantly increased total plasma cholesterol, HDL-cholesterol, LDL-cholesterol, and apoB levels; the lard diet significantly increased total cholesterol, HDL-cholesterol, and apoB; and the lard+ diet significantly increased the total cholesterol, HDL-cholesterol, LDL-cholesterol, and apoA-I and apoB levels. There were no significant variations in VLDL-cholesterol, triglyceride, or apoE levels with these diets. The diets affected both the number of lipoprotein particles as well as the composition of LDL and HDL. Compared to the corn diet, cholesterol and saturated fat each increased the number of LDL particles by 17% and 9%, respectively, and the cholesterol per particle by 9%. The combination of saturated fat and cholesterol increased particle number by 18% and particle size by 24%. Switching from lard+ to lard, corn+, or corn diets reduced LDL-cholesterol of the group by 18%, 11%, and 28%, respectively, while a large inter-individual variability was noted. In summary, dietary fat and cholesterol affect lipid and lipoprotein levels as well as the particle number and chemical composition of both LDL and HDL. There is, however, considerable inter-individual heterogeneity in response to diet.     

Mutagenesis of the glycosylation site of human ApoCIII. O-linked glycosylation is not required for ApoCIII secretion and lipid binding

We have used site-directed in vitro mutagenesis to alter the codon ACT of human apoCIII gene, specifying Thr-74, to GCT (Ala-74). The normal and mutant apoCIII genes were then placed under the control of the mouse metallothionein 1 promoter in a bovine papilloma virus vector and were used for cell transfection and selection of stable cell lines. Blotting analysis of RNA isolated from several independent cell clones showed that both the normal and mutant genes produced apoCIII mRNA in amounts larger than that found in human fetal liver. Pulse-chase analysis of cell clones expressing the normal and mutant apoCIII genes showed that only the normal apoCIII is modified intracellularly to produce a disialated form (apoCIIIs2). Cell clones expressing the normal apoCIII gene secrete exclusively the disialated form, whereas those expressing the mutant gene secrete the unmodified form. The amount of mutant apoCIII protein produced by C127 cell clones expressing the mutant gene was reduced as compared to that produced by the control cells. Density gradient ultracentrifugation analysis of the secreted apoCIII showed that the flotation properties of the secreted normal and mutant proteins were similar. These findings suggest that the intracellular glycosylation of apoCIII is not required for its intracellular transport and secretion. Furthermore, lack of glycosylation has no effect on the relative affinities of apoCIII for plasma very low density lipoproteins and high density lipoproteins.     

Synthesis, intracellular processing, and signal peptide of human apolipoprotein E

Northern blotting analysis has shown apo-E mRNA synthesis by human liver, HepG2 cells, and primary cultures of human monocyte macrophages but not by the macrophage-like cell line U937 and normal or transformed human fibroblasts. Cell-free translation has shown that the primary translation product of apo-E consists of one major and one minor isoprotein of apparent Mr = 28,500 and isoelectric points 6.20 and 6.02, respectively. These isoproteins differ by +1 and 0 charges from apo-E3 and have been designated preapo-E. Co-translational treatment of mRNA with dog pancreatic membranes converts both preapo-E isoproteins to a form which is undistinguishable by two-dimensional gel electrophoresis from plasma apo-E3. The isolation and nucleotide sequence analysis of a full length apo-E cDNA clone has shown that preapo-E contains an 18-amino acid NH2-terminal signal peptide compared to plasma apo-E. The signal peptide sequence is: MetLysValLeuTrpAlaAlaLeuLeuValThrPheLeuAlaGlyCysGlnAla. Comparison of co-translationally modified apo-E with intracellular, secreted, and plasma forms indicates that after the intracellular cleavage of the signal peptide, the protein is glycosylated with carbohydrate chains containing sialic acid, secreted as sialoapo-E (apo-Es), and subsequently desialated in plasma. These findings demonstrate that apo-E is synthesized as preprotein and undergoes intracellular proteolysis and glycosylation and extracellular desialation to attain the major asialoapo-E isoprotein form observed in plasma.     

Expression of the major tyrosyl phosphoprotein of 54 KDa in the integument of the medflyCeratitis capitata

Expression of a 54 kDa tyrosyl phosphorylated protein in epidermal cells during the third instar larval stage was followed. It was demonstrated that the 54 kDa protein moiety and its phosphorylated counterpart follow the same developmental profile. The system seems to be regulated only at the onset of the second moult, by an initial signal which regulates both the synthesis and phosphorylation of a 54 kDa protein. The continuous presence this protein in epidermal cells during the third instar stage, as well as during apolysis and histolysis, suggests that it might participate in cell activities taking place during this developmental period. However, the 54 kDa protein could no be involved in specific epidermal cell activities such as histolysis, melanization and sclerotization, since these activities occur only at specific times during the third instar stage.     

BLOEM: A spatially explicit model of bioenergy and carbon capture and storage,applied to Brazil

Bioenergy could play a major role in decarbonizing energy systems in the context of the Paris Agreement. Large-scale bioenergy deployment could be related to sustainability issues and requires major infrastructure investments. It, therefore, needs to be studied carefully. The Bioenergy and Land Optimization Spatially Explicit Model (BLOEM) presented here allows for assessing different bioenergy pathways while encompassing various dimensions that influence their optimal deployment. In this study, BLOEM was applied to the Brazilian context by coupling it with the Brazilian Land Use and Energy Systems (BLUES) model. This allowed investigating the most cost-effective ways of attending future bioenergy supply projections and studying the role of recovered degraded pasture lands in improving land availability in a sustainable and competitive manner. The results show optimizing for limiting deforestation and minimizing logistics costs results in different outcomes. It also indicates that recovering degraded pasture lands is attractive from both logistics and climate perspectives. The systemic approach of BLOEM provides spatial results, highlighting the trade-offs between crop allocation, land use and the logistics dynamics between production, conversion, and demand, providing valuable insights for regional and national climate policy design. This makes it a useful tool for mapping sustainable bioenergy value chain pathways.     

Protein exporter function and in vitro ATPase activity are correlated in ABC-domain mutants of HlyB

The Escherichia coli toxin exporter HlyB comprises an integral membrane domain fused to a cytoplasmic domain of the ATP-binding casette (ABC) super-family, and it directs translocation of the 110kDa haemolysin protein out of the bacterial cell without using an N-terminal secretion signal peptide. We have exploited the ability to purify the soluble HlyB ABC domain as a fusion with glutathione S-transferase to obtain a direct correlation of the in vivo export of protein by HlyB with the degree of ATP binding and hydrolysis measured in vitro. Mutations in residues that are invariant or highly conserved in the ATP-binding fold and glycine-rich linker peptide of prokaryotic and eukaryotic ABC transporters caused a complete less of both HlyB exporter function and ATPase activity in proteins still able to bind ATP effectively and undergo ATP-induced conformational change. Mutation of less-conserved residues caused reduced export and ATP hydrolysis, but not ATP binding, whereas substitutions of poorly conserved residues did not impair activity either in vivo or in vitro. The data show that protein export by HlyB has an absolute requirement for the hydrolysis of ATP bound by its cytoplasmic domain and indicate that comparable mutations that disable other prokaryotic and eukaryotic ABC transporters also cause a specific loss of enzymatic activity.     

Immunocytochemical and electrophoretic studies on the localization of the major haemolymph proteins (ceratitins) inCeratitis capitata during development

Summary The developmental profile of the major haemolymph proteins (ceratitins) inCeratitis capitata was studied. Ceratitin concentration in the haemolymph decreases dramatically during the last days of pupal life, while the amounts of ceratitins in whole organism extracts remain unchanged. By electrophoretic, immunological and immunofluorescence techniques it was revealed that ceratitins are reabsorbed by the fat body and a fraction of them is deposited in the cuticle. The possible role of ceratitins is discussed.