Fatty acids bound to vitamin D-binding protein (DBP) from human and bovine sera

Human and bovine vitamin D-binding protein (DBP) have been isolated from serum by a method that does not involve denaturing steps. This method includes Cibacron Blue-Sepharose chromatography, gel filtration, DEAE-Sephadex chromatography and albumin immunoadsorption. Analysis of fatty acids bound to the isolated human and bovine DBP showed molar ratios of fatty acid to protein of 0.4 and 1.3 respectively meanwhile human and bovine albumin have bound 1.8 and 1.5 moles per mol respectively. Most of fatty acids bound to human and bovine DBP are monounsaturated and saturated, mainly oleic and palmitic acids, which together account for 50% of the total of fatty acids in both species. By contrast, polyunsaturated fatty acids represented a minor component, less than 5%.     

Two high affinity estrogen binding proteins of different specificity in the immature rat uterus cytosol

The presence of two high affinity estrogen binding proteins in the uterine cytosol of the immature rat has been observed.Besides the 8 S cytosol estrogen $\text{receptor}$, there is a 4–5 S fraction binding estradiol and estrone with a large capacity. In fact, the two binding systems have a different affinity for estradiol and estrone, the receptor binding more the former and the 4–5 S fraction more the latter. Exposure of the cytosol to specific anti-α₁-Fetoprotein antibodies suppresses a large part of the 4–5 S binder, if not the totality. Moreover the estrogen binding 4–5 S fraction decreases with increasing age until puberty, while the $\text{receptor}$ increases. These results suggest therefore that the estradiol-estrone binding 4–5 S peak of the uterine cytosol is mainly made up of Estradiol Binding Plasma Protein-α₁-Fetoprotein (EBP-AFP). Also they confirm that “cytosol” should be taken as an operational fraction which may include extracellular components.During the course of these experiments, it has been observed that the increase of the estradiol $\text{receptor}$ is more rapid than the other uterine cytosol proteins until the 8th day, and that there is a second period of growth when it follows the development of the uterus and of the animal, as if it had reached a constant number of binding sites per cell.     

Expression of mRNAs for alpha-fetoprotein (AFP) and albumin and incorporation of AFP and docosahexaenoic acid in baboon fetuses.

alpha-Fetoprotein and albumin, two members of a multigene family, reversibly bind fatty acids with high affinity. The origin of alpha-fetoprotein (AFP) and albumin present in fetal tissues other than the liver and yolk sac is a subject of controversy. In this work, we have searched for the presence of the albumin and AFP mRNA molecules in different fetal organs of the baboon (Papio cinocephalus), using a highly sensitive gel-blot hybridization assay with human albumin and AFP cDNA probes. Large amounts of albumin and AFP mRNA molecules were found in the fetal liver; significant quantities were also present in the gastrointestinal tract and in the kidney. No detectable levels were found in the other tissues examined (brain, skin, spleen, pancreas, muscle, heart, thymus, placenta, and amnion). After injection of radiolabeled AFP into pregnant baboons, all fetal tissues took up the protein. White adipose tissue, kidney, intestine, lung, liver, and cerebral cortex showed a great uptake of exogenous AFP. [14C]Docosahexaenoic acid (22:6, n-3), injected at the same time, was actively transferred from the maternal compartment across the placenta and incorporated into cellular lipids by all fetal tissues and particularly by liver (around 70% of total incorporation). The levels of [14C]docosahexaenoic acid per gram of tissue increased in the order: maternal blood less than placenta less than fetal liver, indicating a selective accumulation of this fatty acid by the fetus. These results indicate that intracellular AFP in non-hepatic tissues of the developing baboon is, for the most part, of plasma origin.     

Fatty acid metabolism in human lymphocytes. I. Time-course changes in fatty acid composition and membrane fluidity during blastic transformation of peripheral blood lymphocytes

The time-course changes in fatty acid composition of human T-lymphocytes during blastic transformation were analysed, as well as the variations in membrane fluidity determined by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), using a fluorescence-activated cell sorter. The more important changes observed, in activated relative to quiescent cells, started after 24 h and consisted in an increase in the proportion of oleic (18:1(n - 9)), docosapentaenoic (22:5(n - 3)) and docosahexaenoic (22:6(n - 3)) acids and a decrease in that of linoleic (18:2(n - 6)) and arachidonic (20:4(n - 6)) acids. This represented a relative increase of 26% for 18:1, 56% for 22:5 and 84% for 22:6 in peripheral blood mononuclear cells (PBMC) and 35%, 182% and 94%, respectively, in purified T-lymphocytes, both activated for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and 19%, respectively, for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and phosphatidylethanolamine) rather than neutral lipids. The 18:1/18:0 ratio increased greatly in major cell phospholipids. The proportion of 20:4, 22:5 and 22:6 in phosphatidylinositol was not significantly altered after 72 h of activation. The molar ratio cholesterol/phospholipids was reduced in 72-h-activated lymphocytes (0.29) compared to quiescent cells (0.5). On the other hand, the stimulation of human T-lymphocytes caused a significant decrease in the order parameter (S) of DPH, according to the observed changes in lipid composition. After 72 h in culture, the S value for quiescent and stimulated T-lymphocytes was 0.530 and 0.326, respectively. In conclusion, the blastic transformation of human T-lymphocytes is associated with changes in lipid composition which modify the physical properties of their membranes. These modifications could modulate, in turn, the activity of membrane proteins implicated in the process of blastic transformation.     

Structural changes of vegetation and its association with microclimate in a successional gradient of low thorn forest in northeastern Mexico

Understanding how microclimate and vegetation are associated during secondary succession is of primary importance for plant conservation in the face of the increasing land cover modification. However, these patterns are still unstudied for many plant communities. This study aimed to evaluate the structure (species richness, Shannon's diversity index, Simpson´s dominance index, abundance of each species, average height of species, species cover (%), species composition, and indicator values) of a low thorn forest fragment and to analyze its relation with microclimate along a successional gradient. Four stages of succession were delimited by the analysis of Landsat images, in the state of Tamaulipas, northeast Mexico. Statistical models incorporated species richness, diversity indices, abundance, height, and cover, as variables for searching differences between stages, or to evaluate microclimate associations. A total of 70 species, 54 genera, and 27 families were determined. Height of tree layer was the most important variable for discrimination of the successional stages. Conserved areas differed floristically from other stages, associated mainly with the lowest values of wind speed originated by tree layer characteristics. A significant association between species and microclimate was found, being wind speed and relative humidity the most important variables. Some species, due to their high importance values and their patterns of association with microclimate, may be considered as key taxa for low thorn forest, which is a threatened semitropical community in northeast Mexico. Conserved and late successional areas account for climatic regulation of this plant community, and the importance of these forest patches may be considered when establishing biodiversity protection areas.

     

A virulence attenuated amoebapore-less mutant of Entamoeba histolytica and its interaction with host cells

Entamoeba histolytica, the protozoan parasite which causes amoebiasis, is an exclusively human pathogen so developing a vaccine could effectively impact the spread of the disease. Recently we developed a genetically modified avirulent strain, termed G3, from the virulent E. histolytica strain HM-1:IMSS. The new strain lacks the important virulence factor, the amoebapore-A. The objective of our current study was to investigate the avirulence of the attenuated strain as well as to examine the antigenic and immunogenic responses of these trophozoites as potential candidates for a live vaccine. Functional assays were conducted to characterise the virulent behaviour of the G3 strain. This behaviour was compared to the virulent strain HM-1:IMSS and the non-virulent strain Rahman. Western blots were conducted to confirm the lack of amoebapore-A in the E. histolytica G3 strain and to demonstrate that it had no influence on the presence of other virulence factors. Results of these two sets of tests proved the G3 strain to be phenotypically similar to the avirulent Rahman strain while antigenically identical to the virulent HM-1:IMSS, apart from the lack of the amoebapore-A protein. Intraperitoneal immunisation of hamsters with G3 trophozoites compared to sham immunised hamsters resulted in IgG anti-HM-1:IMSS antibodies. The level of humoral response was variable and further testing has to take place before introducing this new strain as a vaccine.     

Chickens fed with biomass of the red microalga Porphyridium sp. have reduced blood cholesterol level and modified fatty acid composition in egg yolk

The biomass of the red alga Porphyridium sp.constitutes a unique combination of soluble sulfatedpolysaccharide that accounts for about 70% of thealgal dry weight, and various polyunsaturatedfatty acids (PUFA) such as arachidonic andeicosapentaenoic acid (AA, 20:4 6 and EPA,20:5 3). In view of earlier results in ourlaboratory showing a reduction in serum cholesteroland triglyceride levels in rodents fed with red algalbiomass, we set out to examine the influence of algalbiomass as a feed additive on the metabolism ofchickens, with an emphasis on blood and eggcholesterol levels. For that purpose, lyophilizedalgal biomass was fed to 12–13, 30-week-old, WhiteLeghorn chickens for 10 days at a proportion of 5% or10% of the standard chicken diet. Twelve chickensfed with unsupplemented diet served as the control. No differences in body weight, egg number, and eggweight were found between the algal-fed chickens (atboth concentrations) and the control. However,chickens fed with algal biomass consumed 10% lessfood for both groups, and their serum cholesterollevels were significantly lower (by 11% and 28% forthe groups fed with 5% and 10% supplement,respectively) as compared with the respective valuesof the control group. Egg yolk of chickens fed withalgae tended to have reduced cholesterol levels (by10%) and increased linoleic acid and arachidonic acidlevels (by 29% and 24%, respectively). In addition,the color of the egg yolk was darker as a result ofthe higher carotenoid levels (2.4 fold higher) forchickens that fed with 5% supplement. Theseresults encourage the development of an improvedchicken feed having dietary fibers and polyunsaturatedfatty acids.