Fontes florais usadas por abelhas (Hymenoptera, Apoidea) em área de cerrado no Município de Cassilândia, Mato Grosso do Sul, Brasil.

Conduziu-se este trabalho, com o objetivo de inventariar as plantas visitadas por abelhas em uma área de cerrado no município de Cassilândia/MS (19°06 48"S; 51°44 03"W), classificando-as para a elaboração de umcatálogo de pasto apícola. Os dados foram obtidos quinzenalmente, de março/2003 a fevereiro/2004, em uma trilha com 3000 metros de extensão. A flora apícola foi representada por 49 espécies pertencentes a 41 gêneros e 26 famílias. A família Malpighiaceae apresentou maior número de espécies visitadas (12,2%) e a família Sapindaceae o maior número de abelhas coletadas (18%). Com relação ao nicho trófico ocupado pelas abelhas, apenas Apis mellifera e Trigona spinipes apresentaram atividade de forrageamento em um grande número de plantas, sendo 36,7% do total de espécies identificadas visitados pelas duas espécies. Os diferentes períodos de florescimento das espécies vegetais existentes no cerrado garantem oferta de recurso alimentar durante todo o ano

Caracterização físico-química de amostras de méis produzidas por Apis mellifera L. em fragmento de cerrado no município de Itirapina, São Paulo.

A fisionomia vegetal mais representativa do país, depois da floresta amazônica, é o cerrado, que ocupa atualmente dois milhões de km2 do território brasileiro. Este trabalho teve como objetivo determinar as características físicoquímicas de amostras de mel produzidas por Apis mellifera em um fragmento de cerrado, localizado em Itirapina, SP (22º14?S e 47º49?W). As amostras foram coletadas mensalmente, em cinco colméias, entre fevereiro e outubro de 2005 e as características avaliadas foram: açúcares redutores, redutores totais, sacarose, umidade, hidroximetilfurfural (HMF), cor, condutividade elétrica, pH, acidez, índice de formol, teor de cinzas, proteínas e viscosidade, além da análise polínica. Os resultados obtidos indicam que os limites estabelecidos pela legislação brasileira para parâmetros físico-químicos analisados são atendidos pela maioria das amostras de mel. Com relação à análise polínica, foi verificada a presença de Eucalyptus sp. como pólen dominante nos meses de fevereiro a julho e o de Citrus sp. no mês de outubro, em virtude da maior atratividade destes dois cultivos sobre as abelhas

Critical involvement of calcium-dependent cytosolic phospholipase A2\u3b1 in aortic valve interstitial cell calcification

The involvement of calcium-dependent cytosolic phospholipase A2\u3b1 (cPLA2\u3b1) in aortic valve calcification is not exhaustively elucidated. Here, cPLA2\u3b1 expression in aortic valve interstitial cell (AVIC) pro-calcific cultures simulating either metastatic or dystrophic calcification was estimated by qPCR, Western blotting, and counting of cPLA2\u3b1-immunoreactive cells, with parallel ultrastructural examination of AVIC calcific degeneration. These evaluations also involved pro-calcific AVIC cultures treated with cPLA2\u3b1 inhibitor dexamethasone. cPLA2\u3b1 over-expression resulted for both types of pro-calcific AVIC cultures. Compared to controls, enzyme content was found to increase by up to 300% and 186% in metastatic and dystrophic calcification-like cultures, respectively. Increases in mRNA amounts were also observed, although they were not as striking as those in enzyme content. Moreover, cPLA2\u3b1 increases were time-dependent and strictly associated with mineralization progression. Conversely, drastically lower levels of enzyme content resulted for the pro-calcific AVIC cultures supplemented with dexamethasone. In particular, cPLA2\u3b1 amounts were found to decrease by almost 88% and 48% in metastatic and dystrophic calcification-like cultures, respectively, with mRNA amounts showing a similar trend. Interestingly, these drastic decreases in cPLA2\u3b1 amounts were paralleled by drastic decreases in mineralization degrees, as revealed ultrastructurally. In conclusion, cPLA2\u3b1 may be regarded as a crucial co-factor contributing to AVIC mineralization in vitro, thus being an attractive potential target for designing novel therapeutic strategies aimed to counteract onset or progression of calcific aortic valve diseases

Characterization of nanometer-sized, mechanically exfoliated graphene on the H-passivated Si(100) surface using scanning tunnelling microscopy

We have developed a method for depositing graphene monolayers and bilayers with minimum lateral dimensions of 2-10 nm by the mechanical exfoliation of graphite onto the Si(100)-2x1:H surface. Room temperature, ultra-high vacuum (UHV) tunnelling spectroscopy measurements of nanometer-sized single-layer graphene reveal a size dependent energy gap ranging from 0.1-1 eV. Furthermore, the number of graphene layers can be directly determined from scanning tunnelling microscopy (STM) topographic contours. This atomistic study provides an experimental basis for probing the electronic structure of nanometer-sized graphene which can assist the development of graphene-based nanoelectronics.Comment: Accepted for publication in Nanotechnolog

Reconstructing Bioinvasion Dynamics Through Micropaleontologic Analysis Highlights the Role of Temperature Change as a Driver of Alien Foraminifera Invasion

Invasive alien species threaten biodiversity and ecosystem structure and functioning, but incomplete assessments of their origins and temporal trends impair our ability to understand the relative importance of different factors driving invasion success. Continuous time-series are needed to assess invasion dynamics, but such data are usually difficult to obtain, especially in the case of small-sized taxa that may remain undetected for several decades. In this study, we show how micropaleontologic analysis of sedimentary cores coupled with radiometric dating can be used to date the first arrival and to reconstruct temporal trends of foraminiferal species, focusing on the alien Amphistegina lobifera and its cryptogenic congener A. lessonii in the Maltese Islands. Our results show that the two species had reached the Central Mediterranean Sea several decades earlier than reported in the literature, with considerable implications for all previous hypotheses of their spreading patterns and rates. By relating the population dynamics of the two foraminifera with trends in sea surface temperature, we document a strong relationship between sea warming and population outbreaks of both species. We conclude that the micropaleontologic approach is a reliable procedure for reconstructing the bioinvasion dynamics of taxa having mineralized remains, and can be added to the toolkit for studying invasions

Novel Cu(I)-5-nitropyridine-2-thiol Cluster with NIR Emission: Structural and Photophysical Characterization

A novel Cu(I) cluster compound has been synthesized by reacting CuI with the 2,2′-dithiobis(5-nitropyridine) ligand under solvothermal conditions. During the reaction, the original ligand breaks into the 5-nitropyridine-2-thiolate moiety, which acts as the coordinating ligand with both N- and S-sites, leading to a distorted octahedral Cu6S6 cluster. The structure has been determined by single-crystal X-ray diffraction and FT-IR analysis, and the photophysical properties have been determined in the solid state by means of steady-state and time-resolved optical techniques. The cluster presents a near-infrared emission showing an unusual temperature dependence: when passing from 77 to 298 K, a blue-shift of the emission band is observed, associated with a decrease in its intensity. Time-dependent-density functional theory calculations suggest that the observed behavior can be ascribed to a complex interplay of excited states, basically in the triplet manifold

Cyclic RGD peptidomimetics containing bifunctional diketopiperazine scaffolds as new potent integrin ligands

The synthesis of eight bifunctional diketopiperazine (DKP) scaffolds is described; these were formally derived from 2,3-diaminopropionic acid and aspartic acid (DKP-1-DKP-7) or glutamic acid (DKP-8) and feature an amine and a carboxylic acid functional group. The scaffolds differ in the configuration at the two stereocenters and the substitution at the diketopiperazinic nitrogen atoms. The bifunctional diketopiperazines were introduced into eight cyclic peptidomimetics containing the Arg-Gly-Asp (RGD) sequence. The resulting RGD peptidomimetics were screened for their ability to inhibit biotinylated vitronectin binding to the purified integrins \u3b1 v\u3b2 3 and \u3b1 v\u3b2 5, which are involved in tumor angiogenesis. Nanomolar IC 50 values were obtained for the RGD peptidomimetics derived from trans DKP scaffolds (DKP-2-DKP-8). Conformational studies of the cyclic RGD peptidomimetics by 1H NMR spectroscopy experiments (VT-NMR and NOESY spectroscopy) in aqueous solution and Monte Carlo/Stochastic Dynamics (MC/SD) simulations revealed that the highest affinity ligands display well-defined preferred conformations featuring intramolecular hydrogen-bonded turn motifs and an extended arrangement of the RGD sequence [C\u3b2(Arg)-C\u3b2(Asp) average distance 658.8 \uc5]. Docking studies were performed, starting from the representative conformations obtained from the MC/SD simulations and taking as a reference model the crystal structure of the extracellular segment of integrin \u3b1 v\u3b2 3 complexed with the cyclic pentapeptide, Cilengitide. The highest affinity ligands produced top-ranked poses conserving all the important interactions of the X-ray complex. Copyright \ua9 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Multivariate analysis based on the physicochemical characteristics of samples of honey produced by Apis mellifera L. (Hymenoptera: Apidae) from the northern coast of Bahia state, Brazil

This research was carried out to determine how honey samples are grouped based on physicochemical characteristics. A total of 36 honey samples, collected from January of 1999 to June of 2000, on the northern coast of Bahia State, were evaluated. with regard to humidity, color, protein, pH, acidity, formol index, electrical conductivity, ash, diastase number, hydroxymethylfurfural (HMF), total sugar, reducing sugars, sucrose, and types of pollen. The results indicate that HMF, reducing sugar and total sugars are the characteristics that most influenced the grouping. Two plant genera, Eucalyptus and Mimosa, were observed as predominant bee plants in the region

Mmf1p, a novel yeast mitochondrial protein conserved throughout evolution and involved in maintenance of the mitochondrial genome

A novel protein family (p14.5, or YERO57c/YJGFc) highly conserved throughout evolution has recently been identified. The biological role of these proteins is not yet well characterized. Two members of the p14.5 family are present in the yeast Saccharomyces cerevisiae. In this study, we have characterized some of the biological functions of the two yeast proteins. Mmf1p is a mitochondrial matrix factor, and homologous Mmf1p factor (Hmf1p) copurifies with the soluble cytoplasmic fraction. Δmmf1 cells lose mitochondrial DNA (mtDNA) and have a decreased growth rate, while Δhmf1 cells do not display any visible phenotype. Furthermore, we demonstrate by genetic analysis that Mmf1p does not play a direct role in replication and segregation of the mtDNA. rho(+) Δmmf1 haploid cells can be obtained when tetrads are directly dissected on medium containing a nonfermentable carbon source. Our data also indicate that Mmf1p and Hmf1p have similar biological functions in different subcellular compartments. Hmf1p, when fused with the Mmf1p leader peptide, is transported into mitochondria and is able to functionally replace Mmf1p. Moreover, we show that homologous mammalian proteins are functionally related to Mmf1p. Human p14.5 localizes in yeast mitochondria and rescues the Δmmf1-associated phenotypes. In addition, fractionation of rat liver mitochondria showed that rat p14.5, like Mmf1p, is a soluble protein of the matrix. Our study identifies a biological function for Mmf1p and furthermore indicates that this function is conserved between members of the p14.5 family