Volatile and molecular analysis of Juniperus brevifolia (Seub.) Antoine,an Azorean endemic species

Chemical and molecular analyses were performed for the characterization of Juniperus brevifolia (Seub.) Antoine (Cupressaceae), an Azorean endemic species. Forty-two individual twig samples were collected at seven Azorean islands (S. Miguel, Terceira, S. Jorge, Pico, Faial, Flores and Corvo). Volatile compounds were isolated by distillation–extraction and analyzed by GC and GC-MS. The volatile oils consisted mainly of monoterpene hydrocarbons (84–96%), limonene (33–87%), α-pinene (1–48%) and β-myrcene (1–5%) being the main components, and cluster analysis showed a high correlation among all samples (S_corr = 0.84). DNA fingerprinting was performed using thirty-seven RAPD and eleven ISSR primers, generating 881 polymorphic bands. Cluster analysis showed a moderate correlation among accessions (S_Dice = 0.43), which grouped according to their geographical origin. Chemical and molecular data did not show superimposable clustering profiles. Although the molecular approaches tested were useful in assessing genetic diversity, no straight correlation could be drawn between chemical and molecular data sets.     

Identification of a new hexadentate iron chelator capable of restricting the intramacrophagic growth of Mycobacterium avium

Iron accumulation has been suggested to contribute to an increase of the susceptibility to mycobacterial infections. In this study we tested the effect of an array of iron chelating ligands of the 3-hydroxy-4-pyridinone family, in the intramacrophagic growth of Mycobacterium avium. We found that bidentate chelators, namely N-alkyl-3-hydroxy-4-pyridinones and N-aryl-3-hydroxy-4-pyridinones, did not affect the growth of M. avium inside mouse macrophages. In the case of the hexadentate chelators, those synthesized using an alkylamine (CP262) or a benzene ring (CP252) to link the three bidentate units, did not have an inhibitory effect on intramacrophagic growth of M. avium while those synthesized from a tripodal structure to anchor the bidentate units were capable of inhibiting the intramacrophagic growth of M. avium. The molecule we designated CP777 had the strongest inhibitory activity. The growth-reducing activity of CP777 was abrogated when this molecule was saturated with iron. These results confirm that iron deprivation, by the use of iron chelating compounds, restricts M. avium growth and that new iron chelators offer an approach to controlling mycobacterial infections.     

An NMR structural study of nickel-substituted rubredoxin

The Ni(II) and Zn(II) derivatives of Desulfovibrio vulgaris rubredoxin (DvRd) have been studied by NMR spectroscopy to probe the structure at the metal centre. The βCH₂ proton pairs from the cysteines that bind the Ni(II) atom have been identified using 1D nuclear Overhauser enhancement (NOE) difference spectra and sequence specifically assigned via NOE correlations to neighbouring protons and by comparison with the published X-ray crystal structure of a Ni(II) derivative of Clostridium pasteurianum rubredoxin. The solution structures of DvRd(Zn) and DvRd(Ni) have been determined and the paramagnetic form refined using pseudocontact shifts. The determination of the magnetic susceptibility anisotropy tensor allowed the contact and pseudocontact contributions to the observed chemical shifts to be obtained. Analysis of the pseudocontact and contact chemical shifts of the cysteine Hβ protons and backbone protons close to the metal centre allowed conclusions to be drawn as to the geometry and hydrogen-bonding pattern at the metal binding site. The importance of NH–S hydrogen bonds at the metal centre for the delocalization of electron spin density is confirmed for rubredoxins and can be extrapolated to metal centres in Cu proteins: amicyanin, plastocyanin, stellacyanin, azurin and pseudoazurin.     

Surface adsorption of protein corona controls the cell internalization mechanism of DC-Chol-DOPE/DNA lipoplexes in serum

Serum has often been reported as a barrier to efficient lipid-mediated transfection. Here we found that the transfection efficiency of DC-Chol-DOPE/DNA lipoplexes increases in serum. To provide insight into the mechanism of lipoplex-serum interaction, several state-of-the-art methodologies have been applied. The nanostructure of DC-Chol-DOPE/DNA lipoplexes was found to be serum-resistant as revealed by high resolution synchrotron small angle X-ray scattering, while dynamic light scattering measurements showed a marked size increase of complexes. The structural stability of DC-Chol-DOPE/DNA lipoplexes was confirmed by electrophoresis on agarose gel demonstrating that plasmid DNA remained well protected by lipids. Proteomics experiments showed that serum proteins competed for the cationic surface of lipid membranes leading to the formation of a rich a ‘protein corona’. Combining structural results with proteomics findings, we suggest that such a protein corona can promote large aggregation of intact lipoplexes. According to a recently proposed size-dependent mechanism of lipoplex entry within cells, protein corona-induced formation of large aggregates most likely results in a switch from a clathrin-dependent to caveolae-mediated entry pathway into the cells which is likely to be responsible for the observed transfection efficiency boost. As a consequence, we suggest that surface adsorption of protein corona can have a high biological impact on serum-resistant cationic formulations for in vitro and in vivo lipid-mediated gene delivery applications.     

Colonization,mouse-style

Several recent papers, including one in BMC Evolutionary Biology, examine the colonization history of house mice. As well as background for the analysis of mouse adaptation, such studies offer a perspective on the history of movements of the humans that accidentally transported the mice.     

Social dynamics and individual plasticity of infant care behavior in cooperatively breeding cotton‐top tamarins

Individual variation in infant caretaking behavior is prevalent among marmoset and tamarin monkeys. Although most group members participate in infant care, the timing and amount provided differs greatly. In this study, we quantified general trends in infant carrying behavior by using a longitudinal database that included 11 years of instantaneous scan observations following 80 births of cotton‐top tamarins. Using detailed focal observations on a subset of the same families (10 births) we identified influences that affected expression of infant care at the group and individual levels. Fathers were the primary carriers and paternal carry time gradually decreased with increasing infant age. Paternal carry time also decreased significantly with an increasing number of older sibling helpers. Most fathers began to carry on the first day postpartum. However, we report circumstances in which fathers delayed carrying until almost a month postpartum. Fathers retrieved infants the most, although adult brothers' rates of retrievals peaked and surpassed fathers' rates during week 4 postpartum. Fathers delayed rejection of infants until week 4, whereas mothers rejected infants immediately and throughout the eight weeks. Nonetheless, infants climbed onto their mothers more than onto any other family member. Mothers showed a high initial investment in carrying during the first two weeks, decreasing quickly thereafter. Maternal contributions to infant carrying remained low and relatively consistent regardless of group size. However, mothers dramatically increased their infant carrying behavior in families in which fathers were absent. Older siblings cared for infants more than did younger siblings, and brothers retrieved and carried infants more than did sisters. Individual expression of infant care changed to accommodate infant needs and changed according to varying social dynamics and circumstances across litters. Am. J. Primatol. 72:296–306, 2010. © 2009 Wiley‐Liss, Inc.     

Diaspora and the Anthropology of Latino Education: Challenges, Affinities, and Intersections

In this article, I highlight the challenges, tensions, and affinities between Latino educational anthropology and diaspora studies. Some of the urgent questions include attention to new Latino destinations, transnationalism, and Latino diversity. It concludes by suggesting future pathways through Latina feminist thought.     

Synthetic consolidants attacked by melanin-producing fungi: case study of the biodeterioration of Milan (Italy) cathedral marble treated with acrylics

Monuments and artistic stone surfaces are often consolidated and protected with synthetic polymers, in particular, acrylics. Although it is generally thought that acrylic polymers are resistant to biodeterioration, we report for the first time the systematic occurrence of dematiaceous meristematic fungi on many marble samples of the cathedral in Milan (Italy) previously treated with this material. Fourier transform infrared spectroscopy applied to the Milan cathedral stone samples revealed characteristic features of biodeteriorated synthetic resins that differentiated them from the aged but nonbiodeteriorated samples. Samples showing biological colonization were analyzed for the presence of fungi. Cultivation and morphological characterization and methods independent from cultivation, such as denaturing gradient gel electrophoresis coupled with partial 18S rRNA gene sequencing and immunofluorescence staining with melanin-binding antibodies, showed that melanin-producing species are heavily present on stone surfaces protected with acrylic resins. This observation raises the question of the effectiveness of acrylics in protecting stone artworks.     

Up or down in space? Uniting the bottom‐up versus top‐down paradigm and spatial ecology

Why is the World green – what keeps herbivores, and herbivorous insects in particular, from consuming all of their food? When this question was first posed, the relative importance of top‐down and bottom‐up effects was hotly disputed. While modern ecologists may agree that impacts from several different directions will affect local insect densities, the bottom‐up vs top‐down jargon seems to be stuck in a unidimensional world. Here, we argue that the strength of almost every bottom‐up and top‐down force is likely to vary in space, and that in itself, spatial structure invokes new processes which defy classification in the traditional bottom‐up top‐down scheme. To understand the relative importance of different forces keeping herbivore numbers in check, we feel that we need a fresh synthesis between the novel paradigm of spatial ecology and the classical paradigms of top‐down and bottom‐up studies. This synthesis requires a consideration of forces beyond the standard framework of top‐down vs bottom‐up effects, and should be based on comparing the relative strength of such forces at several sites in a spatially explicit framework. Overall, we should switch our focus from whether the relative strength of top‐down and bottom‐up factors vary in space to why there is variation, how much variation there is, and at what spatial scale(s) it occurs.