Aluminum exposure affects transferrin-dependent and -independent iron uptake by K562 cells

Aluminum (Al) and iron (Fe) share several physicochemical characteristics and they both bind to transferrin (Tf), entering the cell via Tf receptors (TfR). Previously, we found similar values of affinity constant for the binding of TfR to Tf carrying either Al or Fe. The competitive interaction between both metals prevented normal Fe incorporation into K562 cells and triggered the upregulation of Fe transport. In the present work we demonstrated that Al modified Fe uptake without affecting the expression of Tf receptors. Both TfR and TfR2 mRNA levels, evaluated by RT-PCR, and TfR antigenic sites, analyzed by flow cytometry, were found unchanged after Al exposure. In turn, Al did induce upregulation of non-Tf bound Fe (NTBI) uptake. This modulation was not due to intracellular Fe decrease since NTBI transport proved not to be regulated by Fe depletion. Unlike its behavior in the presence of Tf, Al was unable to compete with NTBI uptake, suggesting that both metals do not share the same alternative transport pathway. We propose that Al interference with TfR-mediated Fe incorporation might trigger the upregulation of NTBI uptake, an adaptation aimed at incorporating the essential metal required for cellular metabolism without allowing the simultaneous access of a potentially toxic metal.     

Expression and secretion of human apolipoprotein A-I in the heart

Nuclear envelope-peripheral heterochromatin fractions contain multiple histone kinase activities. In vitro assays and amino-terminal sequencing show that one of these activities co-isolates with heterochromatin protein 1 (HP1) and phosphorylates histone H3 at threonine 3. Antibodies recognizing this post-translational modification reveal that in vivo phosphorylation at threonine 3 commences at early prophase in the vicinity of the nuclear envelope, spreads to pericentromeric chromatin during prometaphase and is fully reversed by late anaphase. This spatio-temporal pattern is distinct from H3 phosphorylation at serine 10, which also occurs during cell division, suggesting segregation of differentially phosphorylated chromatin to different regions of mitotic chromosomes.     

Culture of bovine hepatocytes: a non-perfusion technique for cell isolation

In this work we have studied the isolation and culture of mature bovine hepatocytes on plastic dishes without exogenous matrix. The liver has been disaggregated in a collagenase solution instead of undergoing a perfusion step. After a few days in culture, the plates showed several clusters of different cell types. Although the average yield was 1.60±0.57×10⁸ viable liver cells per gram of tissue, these cultures were formed by non-parenchymal cells and only very few or none by parenchymal cells. In these cultures, actin structures used as a marker for Stellate (Ito) cells have been visualized by immunocytochemical techniques. In order to increase the proportion of parenchymal cells a centrifugation on Percoll, which separates cell sub-populations, has been introduced. Though the yield was lower than in the previous method, these pre-purified cultures were only composed of hepatocytes. It has been shown that these cells exhibited albumin synthesis, which is a specific hepatocytes function. In addition, these cultures were capable of producing metabolites of 7-ethoxycoumarin at a higher rate than non purified cell cultures. Therefore this simplified procedure for the isolation and culture of functional and viable hepatocytes may be applied for in vitro studies in bovine.     

Biological activity of Bifidobacterium longum in response to environmental pH

The influence of environmental pH on biological activity of Bifidobacterium longum CRL 849 grown in MRS-raffinose was evaluated. At pH 6.0, 5.5 and 5.0, raffinose was completely consumed by this microorganism, showing different consumption rates at each pH value (between 3.03 and 0.76 mmol l⁻¹ h⁻¹). At pH 4.5, the growth was lowest. The removal of raffinose was due to the α-galactosidase (α-gal) activity of this bifidobacteria, which was highest at pH 6.0–5.5 (1,280–1,223 mU ml⁻¹). The production of β-glucosidase (β-glu) showed a similar pattern to α-gal activity with major values. The yield of organic acids produced during raffinose consumption was also highest at pH 6.0–5.5. The results of this study will allow the selection of the optimum growth conditions of B. longum CRL 849, with elevated levels of α-gal to be used in the reduction of nondigestible α-oligosaccharide in soy products and β-glu activities involved in isoflavone conversion to bioactive forms when used as starter culture.     

Responsive regions for direct organogenesis in sunflower cotyledons

Regeneration efficiency from three different regions of cotyledonary explants was examined in six sunflower inbred lines. Proximal, middle and distal regions from seedling cotyledons were cultured on regeneration medium supplemented with growth regulators. Plant regeneration by direct organogenesis was observed after four weeks. Significant differences among inbred lines were found for regeneration percentage and average number of shoots per total explants. Also a decreasing regeneration capacity was observed from proximal to distal sections for all inbred lines. Regeneration ability from cotyledonary explants in this species is strongly influenced by the genotype and by the region from which the explant was obtained. The distance to the cotyledonary node plays a preponderant role in the expression of shoot forming capacity. Shoot differentiation via seedling cotyledons depends upon the presence of the proximal region of cotyledon regardless of the genotype.     

Calluses of Cynara cardunculus Var. Cardunculus cardoon (Asteraceae): determination of cynarine and chlorogenic acid by automated high-performance capillary electrophoresis

Summary Cynara cardunculus var. cardunculus L., also known as cardoon, is a perennial weed naturalized in the Pampas region of Argentina. A quantification of cynarine and chlorogenic acid of callus and leaves from cardoon was performed by means of micellar electrokinetic capillary chromatography, showing that the content of cynarine is higher in calluses than in vivo leaves. The scavenging effect of the callus extract, determined by the thiobarbituric acid method, demonstrated its significant antioxidant capacity. The obtained results revealed that in vitro tissue culture is an excellent tool for producing cynarine for therapeutical purposes.     

Identification of IRF8, TMEM39A, and IKZF3-ZPBP2 as susceptibility loci for systemic lupus erythematosus in a large-scale multiracial replication study

Systemic lupus erythematosus (SLE) is a chronic heterogeneous autoimmune disorder characterized by the loss of tolerance to self-antigens and dysregulated interferon responses. The etiology of SLE is complex, involving both heritable and environmental factors. Candidate-gene studies and genome-wide association (GWA) scans have been successful in identifying new loci that contribute to disease susceptibility; however, much of the heritable risk has yet to be identified. In this study, we sought to replicate 1,580 variants showing suggestive association with SLE in a previously published GWA scan of European Americans; we tested a multiethnic population consisting of 7,998 SLE cases and 7,492 controls of European, African American, Asian, Hispanic, Gullah, and Amerindian ancestry to find association with the disease. Several genes relevant to immunological pathways showed association with SLE. Three loci exceeded the genome-wide significance threshold: interferon regulatory factor 8 (IRF8; rs11644034; p_meta-Euro = 2.08 × 10⁻¹⁰), transmembrane protein 39A (TMEM39A; rs1132200; p_meta-all = 8.62 × 10⁻⁹), and 17q21 (rs1453560; p_meta-all = 3.48 × 10⁻¹⁰) between IKAROS family of zinc finger 3 (AIOLOS; IKZF3) and zona pellucida binding protein 2 (ZPBP2). Fine mapping, resequencing, imputation, and haplotype analysis of IRF8 indicated that three independent effects tagged by rs8046526, rs450443, and rs4843869, respectively, were required for risk in individuals of European ancestry. Eleven additional replicated effects (5 × 10⁻⁸ < p_meta-Euro < 9.99 × 10⁻⁵) were observed with CFHR1, CADM2, LOC730109/IL12A, LPP, LOC63920, SLU7, ADAMTSL1, C10orf64, OR8D4, FAM19A2, and STXBP6. The results of this study increase the number of confirmed SLE risk loci and identify others warranting further investigation.     

Mannitol production by heterofermentative <Emphasis Type="BoldItalic">Lactobacillus reuteri</Emphasis> CRL 1101 and <Emphasis Type="BoldItalic">Lactobacillus fermentum</Emphasis> CRL 573 in free and controlled pH batch fermentations

Certain lactic acid bacteria, especially heterofermentative strains, are capable to produce mannitol under adequate culture conditions. In this study, mannitol production by Lactobacillus reuteri CRL 1101 and Lactobacillus fermentum CRL 573 in modified MRS medium containing a mixture of fructose and glucose in a 6.5:1.0 ratio was investigated during batch fermentations with free pH and constant pH 6.0 and 5.0. Mannitol production and yields were higher under constant pH conditions compared with fermentations with free pH, the increase being more pronounced in the case of the L. fermentum strain. Maximum mannitol production and yields from fructose for L. reuteri CRL 1101 (122 mM and 75.7 mol%, respectively) and L. fermentum CRL 573 (312 mM and 93.5 mol%, respectively) were found at pH 5.0. Interestingly, depending on the pH conditions, fructose was used only as an alternative external electron acceptor or as both electron acceptor and energy source in the case of the L. reuteri strain. In contrast, L. fermentum CRL 573 used fructose both as electron acceptor and carbon source simultaneously, independently of the pH value, which strongly affected mannitol production by this strain. Studies on the metabolism of these relevant mannitol-producing lactobacilli provide important knowledge to either produce mannitol to be used as food additive or to produce it in situ during fermented food production.