Tracing the Distribution of European Lactase Persistence Genotypes Along the Americas.

In adulthood, the ability to digest lactose, the main sugar present in milk of mammals, is a phenotype (lactase persistence) observed in historically herder populations, mainly Northern Europeans, Eastern Africans, and Middle Eastern nomads. As the -13910∗T allele in the MCM6 gene is the most well-characterized allele responsible for the lactase persistence phenotype, the -13910C > T (rs4988235) polymorphism is commonly evaluated in lactase persistence studies. Lactase non-persistent adults may develop symptoms of lactose intolerance when consuming dairy products. In the Americas, there is no evidence of the consumption of these products until the arrival of Europeans. However, several American countries' dietary guidelines recommend consuming dairy for adequate human nutrition and health promotion. Considering the extensive use of dairy and the complex ancestry of Pan-American admixed populations, we studied the distribution of -13910C > T lactase persistence genotypes and its flanking haplotypes of European origin in 7,428 individuals from several Pan-American admixed populations. We found that the -13910∗T allele frequency in Pan-American admixed populations is directly correlated with allele frequency of the European sources. Moreover, we did not observe any overrepresentation of European haplotypes in the -13910C > T flanking region, suggesting no selective pressure after admixture in the Americas. Finally, considering the dominant effect of the -13910∗T allele, our results indicate that Pan-American admixed populations are likely to have higher frequency of lactose intolerance, suggesting that general dietary guidelines deserve further evaluation across the continent.

Towards the production of natural rubber-calcium phosphate hybrid for applications as bioactive coatings.

This paper assesses the morphological, structural and bio-physicochemical stability of natural rubber (NR) Hevea brasiliensis coatings incorporated with microparticles of calcium phosphate-based (CaP) bioactive ceramics. Optical and electronic spectroscopic imaging techniques were employed to successfully evaluate the NR encapsulation capability and the stability of the coating in a biologically relevant media for bio-related application, i.e., simulated body fluid (SBF). The chemical structure of the natural polymer, the microchemical environment at the NR-CaP interface and the morphology of the CaP clusters were fully characterized. Further, the response of the hybrid coating to SBF was evaluated by incubating the samples for 30 days. The hybrid coating formed on Si surface (inert substrate) exhibited both stability and biodegradability in different levels (time dependence), thus opening horizons for applications as coatings for both biomaterials and drug delivery systems.

A novel vasorelaxant lectin purified from seeds of Clathrotropis nitida: partial characterization and immobilization in chitosan beads.

A novel lectin from seeds of Clathrotropis nitida (CNA) was purified and characterized. CNA is a glycoprotein containing approximately 3.3% carbohydrates in its structure. CNA promoted intense agglutination of rabbit erythrocytes, which was inhibited by galactosides and porcine stomach mucin (PSM). The lectin maintained its hemagglutinating activity after incubation in a wide range of temperatures (30-60 °C) and pH (6.0-7.0), and its binding activity was dependent on divalent cations (Ca(+2) and Mg(+2)). SDS-PAGE showed an electrophoretic profile consisting of a single band of 28 kDa, as confirmed by electrospray ionization mass spectrometry, which indicated an average molecular mass of 27,406 ± 2 Da and the possible presence of isoforms and glycoforms. In addition, CNA exhibited no toxicity to Artemia sp. nauplii and elicited reversible and dose-dependent vasorelaxation in precontracted aortic rings. CNA was successfully immobilized on chitosan beads and was able to capture PSM in solution. This study demonstrated that CNA is a lectin that has potential as a biotechnological tool in glycomics and glycoproteomics applications.

Purification and primary structure of a novel mannose-specific lectin from Centrolobium microchaete Mart seeds.

This study aimed to purify and characterize a novel mannose-binding lectin from the seeds of Centrolobium microchaete. Centrolobium microchaete lectin (CML) was purified by affinity chromatography in mannose-Sepharose-4B column. CML agglutinated rabbit erythrocytes and was inhibited by D-mannose, α-methyl-D-mannoside, D-glucose, N-Acetyl-D-glucosamine and sucrose. The lectin was stable at pH 7.0 and 8.0 and temperatures up to 60°C. The monomeric form of CML showed approximately 28kDa, and its native form is probably a homodimer, as determined by gel filtration chromatography. The primary structure of CML was determined by tandem mass spectrometry that showed CML as a protein with two distinct forms (isolectins CML-1 and CML-2) with 246 and 247 residues, respectively. CML-2 possesses one residue of Asn more than CML-1 in C-terminal. The primary structure of CML agrees with the molecular weights found by electrospray ionization mass spectrometry: 27,224 and 27,338Da for CML-1 and CML-2, respectively. CML is a metal-dependent glycoprotein. Moreover, the glycan composition of CML and its structure were predicted.