Preparation and characterisation of silicone-based coatings filled with carbon nanotubes and natural sepiolite and their application as marine fouling-release coatings

This article reports on the preparation and partial characterisation of silicone-based coatings filled with low levels of either synthetic multiwall carbon nanotubes (MWCNTs) or natural sepiolite (NS). The antifouling and fouling-release properties of these coatings were explored through laboratory assays involving representative soft-fouling (Ulva) and hard-fouling (Balanus) organisms. The bulk mechanical properties of the coatings appeared unchanged by the addition of low amounts of filler, in contrast to the surface properties, which were modified on exposure to water. The release of Ulva sporelings (young plants) was improved by the addition of low amounts of both NS and MWCNTs. The most profound effect recorded was the significant reduction of adhesion strength of adult barnacles growing on a silicone elastomer containing a small amount (0.05%) of MWCNTs. All the data indicate that independent of the bulk properties, the surface properties affect settlement, and more particularly, the fouling-release behaviour, of the filled materials.     

Parental investment and its sensitivity to corticosterone is linked to melanin-based coloration in barn owls

Behavioral and physiological responses to unpredictable changes in environmental conditions are, in part, mediated by glucocorticoids (corticosterone in birds). In polymorphic species, individuals of the same sex and age display different heritable melanin-based color morphs, associated with physiological and reproductive parameters and possibly alternative strategies to cope with variation in environmental conditions. We examined whether the role of corticosterone in resolving the trade-off between self-maintenance and reproductive activities covaries with the size of melanin-based spots displayed on the ventral body side of male barn owls. Administration of corticosterone to simulate physiological stress in males revealed pronounced changes in their food-provisioning rates to nestlings compared to control males. Corticosterone-treated males with small eumelanic spots reduced nestling provisioning rates as compared to controls, and also to a greater degree than did corticosterone-treated males with large spots. Large-spotted males generally exhibited lower parental provisioning and appear insensitive to exogenous corticosterone suggesting that the size of the black spots on the breast feathers predicts the ability to cope with stressful situations. The reduced provisioning rate of corticosterone-treated males caused a temporary reduction in nestling growth rates but, did not affect fledgling success. This suggests that moderately elevated corticosterone levels are not inhibitory to current reproduction but rather trigger behavioral responses to maximize lifetime reproductive success.     

Effectiveness of the fatty acid and sterol composition of seeds for the chemotaxonomy of Coffea subgenus Coffea

The chemotaxonomic relationships between Coffea (subgenus Coffea) species have been poorly studied to date and the compounds tested so far - chlorogenic acids, diterpenoids and purine alkaloids - did not enable the establishment of phylogenetic relationships analogous to those revealed by chloroplast and nuclear DNA studies. In the present study, the relationships between African Coffea species were assessed on the basis of their seed lipid composition. Fatty acids and sterols were determined in 59 genotypes belonging to 17 distinct Coffea species/origins. Principal Component Analysis of fatty acid and sterol data enabled easy identification of the few species for which one or several compounds could serve as a quantitative signature. Hierarchical Clustering classified the Coffea species in seven groups with both fatty acids and sterols. However, while groupings based on seed fatty acid composition showed remarkable ecological and geographical coherence, no phylogeographic explanation was found for the clusters retrieved from sterol data. When compared with previous phylogenetic studies, the groups deduced from seed fatty acid composition were remarkably congruent with the clades inferred from nuclear and plastid DNA sequences.     

Locomotor Activity Rhythm in Free-ranging Common Marmosets (Callithrix jacchus)

Locomotor activity rhythm in the common marmoset has been well described and characterized in captivity, but there is no information about rhythmic aspects of this behavior in free-ranging conditions. To investigate if the locomotor activity rhythm in free-ranging common marmosets is similar to that found in captive common marmosets, we observed reproductive animals from two groups that inhabited at the Experimental Forestry Station, in northeastern Brazil (6°5'S, 35°12'W). From December 1992 to October 1993 we recorded the frequency of locomotor activity by focal animal sampling. The records of locomotor activity were submitted to spectral analysis and to the Cosinor test. Common marmosets showed an average duration of the active phase of 11:37 h ± 13.8 min. Similar to recorded in captive common marmosets, circadian rhythmicity was found with peaks in the morning, and in the afternoon, characterizing a bimodal pattern with peaks separated by 8 hours. The presence of a rhythmic pattern in the locomotor activity in free-ranging and captive common marmosets suggests that this pattern is not determined by the environmental conditions in captivity, but it has a endogenous component that play an important role for adaptation of this species to different conditions.     

Spatial autocorrelation and red herrings in geographical ecology

Aim Spatial autocorrelation in ecological data can inflate Type I errors in statistical analyses. There has also been a recent claim that spatial autocorrelation generates ‘red herrings’, such that virtually all past analyses are flawed. We consider the origins of this phenomenon, the implications of spatial autocorrelation for macro‐scale patterns of species diversity and set out a clarification of the statistical problems generated by its presence. Location To illustrate the issues involved, we analyse the species richness of the birds of western/central Europe, north Africa and the Middle East. Methods Spatial correlograms for richness and five environmental variables were generated using Moran's I coefficients. Multiple regression, using both ordinary least‐squares (OLS) and generalized least squares (GLS) assuming a spatial structure in the residuals, were used to identify the strongest predictors of richness. Autocorrelation analyses of the residuals obtained after stepwise OLS regression were undertaken, and the ranks of variables in the full OLS and GLS models were compared. Results Bird richness is characterized by a quadratic north–south gradient. Spatial correlograms usually had positive autocorrelation up to c. 1600 km. Including the environmental variables successively in the OLS model reduced spatial autocorrelation in the residuals to non‐detectable levels, indicating that the variables explained all spatial structure in the data. In principle, if residuals are not autocorrelated then OLS is a special case of GLS. However, our comparison between OLS and GLS models including all environmental variables revealed that GLS de‐emphasized predictors with strong autocorrelation and long‐distance clinal structures, giving more importance to variables acting at smaller geographical scales. Conclusion Although spatial autocorrelation should always be investigated, it does not necessarily generate bias. Rather, it can be a useful tool to investigate mechanisms operating on richness at different spatial scales. Claims that analyses that do not take into account spatial autocorrelation are flawed are without foundation.     

Assembly,plasticity and selective vulnerability to disease of mouse neuromuscular junctions

Although physiological differences among neuromuscular junctions (NMJs) have long been known, NMJs have usually been considered as one type of synapse, restricting their potential value as model systems to investigate mechanisms controlling synapse assembly and plasticity. Here we discuss recent evidence that skeletal muscles in the mouse can be subdivided into two previously unrecognized subtypes, designated FaSyn and DeSyn muscles. These muscles differ in the pattern of neuromuscular synaptogenesis during embryonic development. Differences between classes are intrinsic to the muscles, and manifest in the absence of innervation or agrin. The distinct rates of synaptogenesis in the periphery may influence processes of circuit maturation through retrograde signals. While NMJs on FaSyn and DeSyn muscles exhibit a comparable anatomical organization in postnatal mice, treatments that challenge synaptic stability result in nerve sprouting, NMJ remodeling, and ectopic synaptogenesis selectively on DeSyn muscles. This anatomical plasticity of NMJs diminishes greatly between 2 and 6 months postnatally. NMJs lacking this plasticity are lost selectively and very early on in mouse models of motoneuron disease, suggesting that disease-associated motoneuron dysfunction may fail to initiate maintenance processes at “non-plastic” NMJs. Transgenic mice overexpressing growth-promoting proteins in motoneurons exhibit greatly enhanced stimulus-induced sprouting restricted to DeSyn muscles, supporting the notion that anatomical plasticity at the NMJ is primarily controlled by processes in the postsynaptic muscle. The discovery that entire muscles in the mouse differ substantially in the anatomical plasticity of their synapses establishes NMJs as a uniquely advantageous experimental system to investigate mechanisms controlling synaptic rearrangements at defined synapses in vivo.     

Precipitation of porcine insulin with carbon dioxide

Recent works have pointed to the use of volatile electrolytes such as carbon dioxide (CO₂) dissolved in aqueous solutions as a promising alternative to the precipitating agents conventionally used for protein recovery in the food and pharmaceutical industries. In this work we investigated experimental and theoretical aspects of the precipitation of porcine insulin, a biomolecule of pharmaceutical interest, using CO₂ as an acid‐precipitating agent. The solubility of porcine insulin in NaHCO₃ solutions in pressurized CO₂ was determined as a function of temperature and pressure, with a minimum being observed close to the protein isoelectric point. A thermodynamic model was developed and successfully utilized to correlate the experimental data. Insulin was considered a polyelectrolyte in the model and its self‐association reactions were also taken into account. The biological activity of insulin was maintained after precipitation with CO₂, although some activity can be lost if foam is formed in the depressurization step. Biotechnol. Bioeng. 2009;103: 909–919. © 2009 Wiley Periodicals, Inc.     

The apical/basal-polarity determinant Scribble cooperates with the PCP core factor Stbm/Vang and functions as one of its effectors

Most tissues display several features of cellular polarization. Besides the ubiquitous epithelial polarization in the Apical–Basal (A/B) axis, many epithelia (and associated organs) display a Planar Cell Polarization (PCP). Recently, a crosstalk between the PCP and A/B polarity determinants has been suggested, i.e. the activity or stability of the PCP factor Frizzled is regulated by the A/B determinants aPKC and Bazooka in the Drosophila eye. We have systematically investigated genetic and physical interactions between the Drosophila A/B factors and the core PCP component Strabismus (Stbm)/Van Gogh (Vang). The A/B determinant Scribble was found to interact both genetically and physically with Stbm/Vang. We demonstrate that Scribble binds Stbm/Vang through its PDZ domain 3 and that it cooperates with Stbm/Vang in PCP establishment. Our data indicate that Scribble, in addition to its role in A/B polarity, has a distinct requirement in PCP establishment in the Drosophila eye and wing. We define a scribble allele that is largely PCP specific. Our data show that Scribble is part of the Stbm/Vang PCP complex and further suggest that it might act as an effector of Stbm/Vang during PCP establishment.     

Mesenchymal stromal cells revert multiple myeloma cells to less differentiated phenotype by the combined activities of adhesive interactions and interleukin-6

Multiple myeloma is characterized by the malignant growth of immunoglobulin producing plasma cells, predominantly in the bone marrow. The effects of primary human mesenchymal stromal cells on the differentiation phenotype of multiple myeloma cells were studied by co-culture experiments. The incubation of multiple myeloma cells with bone marrow-derived mesenchymal stromal cells resulted in significant reduction of the expression of the predominant plasma cell differentiation markers CD38 and CD138, and cell surface immunoglobulin light chain. While the down-regulation of CD138 by stromal cells was completely dependent on their adhesive interactions with the multiple myeloma cells, interleukin-6 induced specific down-regulation of CD38. Mesenchymal stromal cells or their conditioned media inhibited the growth of multiple myeloma cell line, thereby reducing the overall amounts of secreted light chains. Analysis of primary multiple myeloma bone marrow samples reveled that the expression of CD38 on multiple myeloma cells was not affected by adhesive interactions. The ex vivo propagation of primary multiple myeloma cells resulted in significant increase in their differentiation markers. Overall, the data indicate that the bone marrow-derived mesenchymal stromal cells revert multiple myeloma cells to less differentiated phenotype by the combined activities of adhesive interactions and interleukin-6.