Phylogeny and metabolic scaling in mammals

The scaling of metabolic rates to body size is widely considered to be of great biological and ecological importance, and much attention has been devoted to determining its theoretical and empirical value. Most debate centers on whether the underlying power law describing metabolic rates is 2/3 (as predicted by scaling of surface area/volume relationships) or 3/4 ("Kleiber's law"). Although recent evidence suggests that empirically derived exponents vary among clades with radically different metabolic strategies, such as ectotherms and endotherms, models, such as the metabolic theory of ecology, depend on the assumption that there is at least a predominant, if not universal, metabolic scaling exponent. Most analyses claimed to support the predictions of general models, however, failed to control for phylogeny. We used phylogenetic generalized least-squares models to estimate allometric slopes for both basal metabolic rate (BMR) and field metabolic rate (FMR) in mammals. Metabolic rate scaling conformed to no single theoretical prediction, but varied significantly among phylogenetic lineages. In some lineages we found a 3/4 exponent, in others a 2/3 exponent, and in yet others exponents differed significantly from both theoretical values. Analysis of the phylogenetic signal in the data indicated that the assumptions of neither species-level analysis nor independent contrasts were met. Analyses that assumed no phylogenetic signal in the data (species-level analysis) or a strong phylogenetic signal (independent contrasts), therefore, returned estimates of allometric slopes that were erroneous in 30% and 50% of cases, respectively. Hence, quantitative estimation of the phylogenetic signal is essential for determining scaling exponents. The lack of evidence for a predominant scaling exponent in these analyses suggests that general models of metabolic scaling, and macro-ecological theories that depend on them, have little explanatory power.

Visual enhancement of touch in spatial body representation

Perception of our own bodies is based on integration of visual and tactile inputs, notably by neurons in the brain’s parietal lobes. Here we report a behavioural consequence of this integration process. Simply viewing the arm can speed up reactions to an invisible tactile stimulus on the arm. We observed this visual enhancement effect only when a tactile task required spatial computation within a topographic map of the body surface and the judgements made were close to the limits of performance. This effect of viewing the body surface was absent or reversed in tasks that either did not require a spatial computation or in which judgements were well above performance limits. We consider possible mechanisms by which vision may influence tactile processing.

Placentation and maternal investment in mammals

The mammalian placenta exhibits striking interspecific morphological variation, yet the implications of such diversity for reproductive strategies and fetal development remain obscure. More invasive hemochorial placentas, in which fetal tissues directly contact the maternal blood supply, are believed to facilitate nutrient transfer, resulting in higher fetal growth rates, and to be a state of relative fetal advantage in the evolution of maternal-offspring conflict. The extent of interdigitation between maternal and fetal tissues has received less attention than invasiveness but is also potentially important because it influences the surface area for exchange. We show that although increased placental invasiveness and interdigitation are both associated with shorter gestations, interdigitation is the key variable. Gestation times associated with highly interdigitated labyrinthine placentas are 44% of those associated with less interdigitated villous and trabecular placentas. There is, however, no relationship between placental traits and neonatal body and brain size. Hence, species with more interdigitated placentas produce neonates of similar body and brain size but in less than half the time. We suggest that the effects of placental interdigitation on growth rates and the way that these are traded off against gestation length may be promising avenues for understanding the evolutionary dynamics of parentoffspring conflict. Keywords: placenta, parent-offspring conflict, life history, brain evolution, reproductive strategies, gestation.

Multi-site evaluation of an urban land-surface model: intra-urban heterogeneity, seasonality and parameter complexity requirements

An extensive off-line evaluation of the Noah/Single Layer Urban Canopy Model (Noah/SLUCM) urban land-surface model is presented using data from 15 sites to assess (1) the ability of the scheme to reproduce the surface energy balance observed in a range of urban environments, including seasonal changes, and (2) the impact of increasing complexity of input parameter information. Model performance is found to be most dependent on representation of vegetated surface area cover; refinement of other parameter values leads to smaller improvements. Model biases in net all-wave radiation and trade-offs between turbulent heat fluxes are highlighted using an optimization algorithm. Here we use the Urban Zones to characterize Energy partitioning (UZE) as the basis to assign default SLUCM parameter values. A methodology (FRAISE) to assign sites (or areas) to one of these categories based on surface characteristics is evaluated. Using three urban sites from the Basel Urban Boundary Layer Experiment (BUBBLE) dataset, an independent evaluation of the model performance with the parameter values representative of each class is performed. The scheme copes well with both seasonal changes in the surface characteristics and intra-urban heterogeneities in energy flux partitioning, with RMSE performance comparable to similar state-of-the-art models for all fluxes, sites and seasons. The potential of the methodology for high-resolution atmospheric modelling application using the Weather Research and Forecasting (WRF) model is highlighted. This analysis supports the recommendations that (1) three classes are appropriate to characterize the urban environment, and (2) that the parameter values identified should be adopted as default values in WRF.

Alternative body sites for heat stress measurement in milking cows under tropical conditions and their relationship to the thermal discomfort of the animals

This study was conducted to determine the relationship among temperatures measured at different anatomical sites of the animal body and their daily pattern as indicative of the thermal stress in lactating dairy cows under tropical conditions. Environmental dry bulb (DBT) and black globe (BGT) temperatures and relative humidity (RH) were recorded. Rectal temperature (RT), respiratory frequency (RF), body surface (BST), internal base of tail (TT), vulva (VT) and auricular temperatures (AT) were collected, from 37 Black and White Holstein cows at 0700, 1300 and 1800 hours. RT showed a moderately and positive correlations with all body temperatures, ranging from 0.59 with TT to 0.64 with BST. Correlations among AT, VT and TT with RF were very similar (from 0.63 to 0.64) and were greater than those observed for RF with RT (0.55) or with BST (0.54). RF and RT were positively correlated to TT (0.63 and 0.59, respectively), AT (r = 0.63 for both) and VT (r = 0.64 and 0.63, respectively). Positive and very high correlations were observed among AT, VT and TT (from 0.94 to 0.97) indicating good association of temperatures measured in these anatomical sites. Correlations of BST with AT and VT were positive and very similar (0.71 and 0.72, respectively) and lower with TT (0.66). The AT, TT, VT and BST presented similar patterns and follow the variations of DBT through the day. Temperatures measured at different anatomical sites of the animal body have the potential to be used as indicative of the thermal stress in lactating dairy cows.

A comparative study of cleaning activity of two reef fishes at Fernando de Noronha Archipelago, tropical West Atlantic

Cleaner fishes are usually classified as obligate or facultative cleaners according to their diet and the extent to which their nutritional requirements in the different ontogenetic stages are gained from cleaning. While obligate cleaners clean throughout their lives and ingest mainly food taken from the clients` body surface, facultative cleaners clean only as juveniles and have a broader diet. In addition, some facultative cleaners may experience a relatively higher predation risk, and thus rarely interact with piscivorous fishes. Despite these acknowledged differences, there are very few studies that compare cleaning activity of obligate and facultative cleaners within the same area. Cleaning activity of the obligate cleaner goby Elacatinus cf. randalli and the facultative cleaner wrasse Thalassoma noronhanum were comparatively examined at Fernando de Noronha Archipelago, tropical West Atlantic. The client assemblage attended by the two cleaners differed, as the goby attended a slightly greater diversity of species (22), mostly piscivores and zoobenthivores, and the wrasse attended fewer species (19), mostly planktivores. Chromis multilineata was the most common client species of both cleaners, although body size (which is expected to be positively correlated to clients` ectoparasite load) of C. multilineata individuals attended by the goby was larger than that of the individuals attended by the wrasse. Despite such differences, T. noronhanum showed a surprisingly species-rich client assemblage when compared with other cleaners of the genus Thalassoma. In addition, the frequency and time spent on cleaning interactions, as well as the number of client species attended per 10-min period, was similar for both cleaner species, which indicate that they have important yet complimentary ecological roles in the reef community at Fernando de Noronha Archipelago.

Linshuichonetes gen. nov., a new rugosochonetid (Brachiopoda) genus from the Liangshan Formation (Early Permian) in Sichuan, China, and its ecology

A new genus and species, Linshuichonetes elfinis, belonging to the Rugosochonetidae, is described from the Early Permian (Late Artinskian or early Kungurian) Liangshan Formation of the Yangtze block. The new genus is defined externally by the presence of fine, but delayed, capillation and a weak or absent median sulcus and fold and by the presence of a distinct posteromedian sinus on the ventral umbo; and internally by a lack of median, lateral and accessory septa in the dorsal interior; absence of vascular trunks in the ventral interior and the presence of distinct radiating rows of papillae in the interior of both valves, particularly an unusual clustered arrangement of papillae on the posteromedian portion of the dorsal interior. The local environment during the deposition of the Liangshan Formation appears to have been a restricted tidal flat or lagoon which experienced frequent sealevel fluctuations associated with the onset of the Yanghsingian transgression. The new species, L. elfinis, appears to have several morphological adaptations enabling successful exploitation of this environment. It was typically a very small and thin-valved species with a high surface area to volume ratio, an advantage in an oxygen restricted environment. The small size and numerous body spinules would have aided individuals to remain suspended at the top of the fine, soft substrate. It also dominated the brachiopod assemblage in the Liangshan Formation, comprising up to 94%of specimens within a bed. These factors indicate that the new species appears to be an opportunistic species.

Influence of particle concentration on initial collection efficiency and surface coverage in porous media filtration

Four sizes (0.095, 0.53, 1.0 and 2.01 μm) of polystyrene latex particles were used to prepare monodispersed suspensions at three different ionic strengths (10−3, 10−2.5 and 10−2M KCl). Filtration experiments were conducted using those suspensions in a filter column with glass beads as porous medium. The filter bed depth and the filtration velocity were kept at 5 cm and 1 m/h, respectively. When suspensions with equal mass concentrations (0.2 mg/L) or equal surface area concentrations (0.12 cm2/mL) were filtered through the system, the largest particles exhibited higher initial single collector efficiency, η. The difference between the η of largest particles and the smaller particles was prominent for suspensions with equal surface area concentrations at higher ionic strengths. The collision efficiency, α of those particles exhibits higher values at higher ionic strengths. Both at equal mass concentration and equal surface area concentration, α is only slightly dependent on particle sizes when compared to its dependence on ionic strength. Further, it was found that the specific surface coverage was similar for 0.095 μm, 0.53 μm and 1.0 μm particles during the transient stage of filtration at any ionic strength when the surface area concentrations of those suspension were equal.

Surface coverage of filter medium in deep bed filtration : mathematical modelling and experiments

This paper highlights the importance of surface coverage in modeling the removal of particles in deep bed filtration. A model that considers the saturation of sites on which particle deposition occurs is used. Experimental results obtained with monodispersed suspensions of 0.46 and 0.816 μm latex particles at different influent concentrations and ionic strengths were used to calculate the fraction of filter grain surface (β1) on which actual particle deposition occurs. This will be useful in evaluating the filter performance in terms of the utilization of available surface area of the filter medium. Further, the level of dendrite formation of particles on filter grains during filtration is expressed in terms of β1 and the specific surface coverage, θT (the fraction of a filter grain surface that is covered by particles at time T, assuming that the filter grain is covered by a monolayer of particles). This can be used to compare the contribution of deposited particles in the removal efficiency of deep bed filtration for suspensions with different physical and chemical characteristics.

Superhydrophobic nanofibre membranes : effects of particulate coating on hydrophobicity and surface properties

Superhydrophobic electrospun polyacrylonitrile nanofibre membranes have been prepared by surface coating of silica nanoparticles and fluorinated alkyl silane. The coated membranes were characterised by scanning electron microscopy, water contact angle, thermogravimetry analysis, Brunauer–Emmett–Teller, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. It was shown that the loading of nanoparticle on the nanofibre membrane was controlled by the particle concentration in the coating solution, which played a critical role in the formation of superhydrophobic surface. Increased particle loading led to higher surface roughness and WCA. The nanoparticle coating had little influence on the porosity of the nanofibre membranes. However, overloading of the particles would affect the specific surface area of the nanofibre membrane.

Cell biological responses of osteoblasts on anodized nanotubular surface of a titanium-zirconium alloy

Anodization of titanium and its alloys, under controlled conditions, generates a nanotubular architecture on the material surface. The biological consequences of such changes are poorly understood, and therefore, we have analyzed the cellular and molecular responses of osteoblasts that were plated on nanotubular anodized surface of a titanium-zirconium (TiZr) alloy. Upon comparing these results with those obtained on acid etched and polished surfaces of the same alloy, we observed a significant increase in adhesion and proliferation of cells on anodized surfaces as compared to acid etched or polished surface. The expression of genes related to cell adhesion was high only on anodized TiZr, but that of genes related to osteoblast differentiation and osteocalcin protein and extracellular matrix secretion were higher on both anodized and acid etched surfaces. Examination of surface morphology, topography, roughness, surface area and wettability using scanning electron microscopy, atomic force microscopy, and contact angle goniometry, showed that higher surface area, hydrophilicity, and nanoscale roughness of nanotubular TiZr surfaces, which were generated specifically by the anodization process, could strongly enhance the adhesion and proliferation of osteoblasts. We propose that biological properties of known bioactive titanium alloys can be further enhanced by generating nanotubular surfaces using anodization.

Relationship between processing, surface energy and bulk properties of ultrafine silk particles

Silk particles of different sizes and shapes were produced by milling and interactions with a series of polar and non-polar gaseous probes were investigated using an inverse gas chromatography technique. The surface energy of all silk materials is mostly determined by long range dispersive interactions such as van der Waals forces. The surface energy increases and surface energy heterogeneity widens after milling. All samples have amphoteric surfaces and the concentration of acidic groups increases after milling while the surfaces remain predominantly basic. We also examined powder compression and flow behaviours using a rheometer. Increase in surface energy, surface area, and static charges in sub-micron air jet milled particles contributed to their aggregation and therefore improved flowability. However they collapse under large pressures and form highly cohesive powder. Alkaline hydrolysis resulted in more crystalline fibres which on milling produced particles with higher density, lower surface energy and improved flowability. The compressibility, bulk density and cohesion of the powders depend on the surface energy as well as on particle size, surface area, aggregation state and the testing conditions, notably the consolidated and unconsolidated states. The study has helped in understanding how surface energy and flowability of particles can be changed via different fabrication approaches.

Nerve guidance conduits from aligned nanofibers: improvement of nerve regeneration through longitudinal nanogrooves on a fiber surface

A novel fibrous conduit consisting of well-aligned nanofibers with longitudinal nanogrooves on the fiber surface was prepared by electrospinning and was subjected to an in vivo nerve regeneration study on rats using a sciatic nerve injury model. For comparison, a fibrous conduit having a similar fiber alignment structure without surface groove and an autograft were also conducted in the same test. The electrophysiological, walking track, gastrocnemius muscle, triple-immunofluorescence, and immunohistological analyses indicated that grooved fibers effectively improved sciatic nerve regeneration. This is mainly attributed to the highly ordered secondary structure formed by surface grooves and an increase in the specific surface area. Fibrous conduits made of longitudinally aligned nanofibers with longitudinal nanogrooves on the fiber surface may offer a new nerve guidance conduit for peripheral nerve repair and regeneration.

Investigation about the copper adsorption on the chloropropylsilica gel surface modified with a nanostructured dendrimer DAB-Am-16: an analytical application for determination of copper in different samples

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Pancreas Transplantation Prevents Morphologic and Ultrastructural Changes in Pulmonary Parenchyma of Alloxan-Induced Diabetic Rats

Purpose. The aim of this study was to evaluate whether pancreas transplantation (PT) is a suitable method for controlling histopathologic changes in lungs of alloxan-induced diabetic rats.Methods. Sixty inbred male Lewis rats were randomly assigned to 3 experimental groups: NC, 20 nondiabetic control rats; DC, 20 untreated diabetic control rats; and PT, 20 diabetic rats that received syngeneic PT from normal donor Lewis rats. Each group was further divided into 2 subgroups of 10 rats each, which were killed after 4 and 12 weeks of follow-up. Clinical and laboratory parameters, fresh and fixed lung weights, and fixed lung volumes were recorded for all rats. Total number of alveoli, alveolar perimeter, alveolar surface area, and alveolar epithelial (AE) and endothelial capillary (EC) basal laminae thickening were randomly measured in 5 rats from each subgroup by using an image analyzer. For light microscopy, 250 alveoli were analyzed in each subgroup. For electron microscopy, 50 electron micrographs were examined for each subgroup.Results. The DC rats showed elevated blood glucose and glycosylated hemoglobin levels, with insulin blood levels significantly lower than the NC rats (P < .001). Fresh and fixed lung weights and fixed volumes were significantly reduced in these rats, although their proportions to body weight were increased at 12 weeks (P < .01). The total number of alveoli in diabetic rats was higher than in control rats, whereas alveolar perimeter and surface area were significantly diminished (P < .01). AE and EC basal laminae were significantly thicker in DC than in NC (P < .01). Successful PT corrected all clinical and metabolic changes in diabetic rats, with sustained normoglycemia throughout the study. Morphologic and morphometric changes observed in diabetic lungs were completely prevented in PT rats from 4 weeks after transplant.Conclusion. We conclude that PT can control morphologic and ultrastructural changes in pulmonary parenchyma, suggesting a promising perspective for preventing other chronic diabetic lesions.