The roles of marginal lagoons in the maintenance of genetic diversity in the Brazilian migratory fishes Prochilodus argenteus and P. costatus

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

Rock outcrop orchids reveal the genetic connectivity and diversity of inselbergs of northeastern Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Inferring population connectivity across the range of distribution of the stiletto shrimp Artemesia longinaris Spence Bate, 1888 (Decapoda, Penaeidae) from DNA barcoding: implications for fishery management

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

An evolutionary approach to improve connectivity prediction in mobile wireless sensor networks

Connectivity is the basic factor for the proper operation of any wireless network. In a mobile wireless sensor network it is a challenge for applications and protocols to deal with connectivity problems, as links might get up and down frequently. In these scenarios, having knowledge of the node remaining connectivity time could both improve the performance of the protocols (e.g. handoff mechanisms) and save possible scarce nodes resources (CPU, bandwidth, and energy) by preventing unfruitful transmissions. The current paper provides a solution called Genetic Machine Learning Algorithm (GMLA) to forecast the remainder connectivity time in mobile environments. It consists in combining Classifier Systems with a Markov chain model of the RF link quality. The main advantage of using an evolutionary approach is that the Markov model parameters can be discovered on-the-fly, making it possible to cope with unknown environments and mobility patterns. Simulation results show that the proposal is a very suitable solution, as it overcomes the performance obtained by similar approaches.

Effects of lithium on the proliferation and migration of neuroblasts in the rostral migratory stream in adult mice

The discovery of neurogenesis in adult brains opened the possibility of cellular therapy strategies for the treatment of neurodegenerative diseases, such as Alzheimer’s disease. Neurogenesis in the adult brain occurs in two areas: subgranular zone of the hippocampus and subventricular zone (SVZ) of the lateral ventricles. Neurons that originate from the SVZ migrate to the olfactory bulb (OB) through the rostral migratory stream (RMS). In Alzheimer’s disease, there is a progressive neuronal dysfunction and degeneration, resulting in brain atrophy and cognitive impairments including olfactory dysfunction. Several studies have demonstrated that pharmacological treatment with lithium exerts positive effects on adult neurogenesis, and one pathway seems to be the modulation of factors that regulate the migration of neuroblasts. The objective of this study was to investigate whether treatment with lithium promotes the increase of migratory neuroblasts using as parameter the RMS. Adult male C57BL/6 mice were divided into control and lithium-treated groups. The animals were treated for 6 weeks and, at four different time points, i.e., 10 days, 7 days, 3 days and 1 day before the end of treatments, they received an injection of BrdU (cell proliferation marker). The animals were sacrificed by perfusion fixation and the brains were immunohistochemically labeled for BrdU for analysis of migrating neuroblasts in the RMS. The results showed that the number of BrdU+ cells in the RMS was not significantly different between the two groups, suggesting that lithium, alone, is not capable of increasing the number of neuroblasts migrating from the SVZ to the OB

Coexistence between Nearctic-Neotropical migratory shorebirds and humans on urban beaches of the Southern Hemisphere: a current conservation challenge in developing countries

The arrival of migratory shorebirds on beaches in urban communities in developing countries is a current challenge for the protection of these migrant birds. Nearctic-Neotropical migrants rely on roosting and feeding sites during their stopover on wintering sites in the Southern Hemisphere to acquire sufficient energy to complete their migratory cycles. On the other hand, cities in the Southern Hemisphere are growing rapidly, which results in increasing competition for space between humans and birds, such as for use in beach habitats. In the present study, I analyze the probability for occurrence for Nearctic-Neotropical migratory birds relative to the number of people in southeastern Brazil, the most populated region of South America. The frequency of occurrence of migrants, their distance of tolerance to people and the number of people were recorded in sample areas (circle plots with 20 m radius) on a 9 km stretch of urban beaches from November to February from 2009 to 2013. The probability of occurrence of Nearctic birds decreased as the number of people increased. When the number of people exceeded 20, the probability of occurrence of birds was almost zero. Furthermore, more than 95 % of birds moved off when people were within 16 m of reach. These results are discussed in the context of conservation actions since no management plan has been developed for migrant shorebirds that use urban beaches as stopover or wintering sites in developing countries.

High connectivity of the crocodile shark between the atlantic and southwest indian oceans: highlights for conservation

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

Historical Observations of Humpback And Blue Whales in the North Atlantic Ocean: Clues to Migratory Routes and Possibly Additional Feeding Grounds

The seasonal distributions of humpback and blue whales (Megaptera novaeangliae and Balaenoptera musculus, respectively) in the North Atlantic Ocean are not fully understood. Although humpbacks have been studied intensively in nearshore or coastal feeding and breeding areas, their migratory movements between these areas have been largely inferred. Blue whales have only been studied intensively along the north shore of the Gulf of St. Lawrence, and their seasonal occurrence and movements elsewhere in the North Atlantic are poorly known. We investigated the historical seasonal distributions of these two species using sighting and catch data extracted from American 18th and 19th century whaling logbooks. These data suggest that humpback whales migrated seasonally from low-latitude calving/ breeding grounds over a protracted period, and that some of them traveled far offshore rather than following coastal routes. Also, at least some humpbacks apparently fed early in the summer west of the Mid-Atlantic Ridge, well south of their known present-day feeding grounds. In assessing the present status of the North Atlantic humpback population, it will be important to determine whether such offshore feeding does in fact occur. Blue whales were present across the southern half of the North Atlantic during the autumn and winter months, and farther north in spring and summer, but we had too few data points to support inferences about these whales’ migratory timing and routes.

Interactive quadrangulation with reeb atlases and connectivity textures

Creating high-quality quad meshes from triangulated surfaces is a highly nontrivial task that necessitates consideration of various application specific metrics of quality. In our work, we follow the premise that automatic reconstruction techniques may not generate outputs meeting all the subjective quality expectations of the user. Instead, we put the user at the center of the process by providing a flexible, interactive approach to quadrangulation design. By combining scalar field topology and combinatorial connectivity techniques, we present a new framework, following a coarse to fine design philosophy, which allows for explicit control of the subjective quality criteria on the output quad mesh, at interactive rates. Our quadrangulation framework uses the new notion of Reeb atlas editing, to define with a small amount of interactions a coarse quadrangulation of the model, capturing the main features of the shape, with user prescribed extraordinary vertices and alignment. Fine grain tuning is easily achieved with the notion of connectivity texturing, which allows for additional extraordinary vertices specification and explicit feature alignment, to capture the high-frequency geometries. Experiments demonstrate the interactivity and flexibility of our approach, as well as its ability to generate quad meshes of arbitrary resolution with high-quality statistics, while meeting the user's own subjective requirements.

The influence of connectivity on the firing rate in a neuronal network with electrical and chemical synapses

We study the firing rate properties of a cellular automaton model for a neuronal network with chemical synapses. We propose a simple mechanism in which the nonlocal connections are included, through electrical and chemical synapses. In the latter case, we introduce a time delay which produces self-sustained activity. Nonlocal connections, or shortcuts, are randomly introduced according to a specified connection probability. There is a range of connection probabilities for which neuron firing occurs, as well as a critical probability for which the firing ceases in the absence of time delay. The critical probability for nonlocal shortcuts depends on the network size according to a power-law. We also compute the firing rate amplification factor by varying both the connection probability and the time delay for different network sizes. (C) 2011 Elsevier B.V. All rights reserved.

E series prostaglandins alter the proliferative, apoptotic and migratory properties of T98G human glioma cells in vitro

Background: In many types of cancer, prostaglandin E-2 (PGE(2)) is associated with tumour related processes including proliferation, migration, angiogenesis and apoptosis. However in gliomas the role of this prostanoid is poorly understood. Here, we report on the proliferative, migratory, and apoptotic effects of PGE(1), PGE(2) and Ibuprofen (IBP) observed in the T98G human glioma cell line in vitro. Methods: T98G human glioma cells were treated with IBP, PGE(1) or PGE(2) at varying concentrations for 24-72 hours. Cell proliferation, mitotic index and apoptotic index were determined for each treatment. Caspase-9 and caspase-3 activity was measured using fluorescent probes in live cells (FITC-LEHD-FMK and FITC-DEVD-FMK respectively). The migratory capacity of the cells was quantified using a scratch migration assay and a transwell migration assay. Results: A significant decrease was seen in cell number (54%) in the presence of 50 mu M IBP. Mitotic index and bromodeoxyuridine (BrdU) incorporation were also decreased 57% and 65%, respectively, by IBP. The apoptotic index was increased (167%) and the in situ activity of caspase-9 and caspase-3 was evident in IBP treated cells. The inhibition of COX activity by IBP also caused a significant inhibition of cell migration in the monolayer scratch assay (74%) and the transwell migration assay (36%). In contrast, the presence of exogenous PGE(1) or PGE(2) caused significant increases in cell number (37% PGE(1) and 45% PGE(2)). When mitotic index was measured no change was found for either PG treatment. However, the BrdU incorporation rate was significantly increased by PGE(1) (62%) and to a greater extent by PGE(2) (100%). The apoptotic index was unchanged by exogenous PGs. The addition of exogenous PGs caused an increase in cell migration in the monolayer scratch assay (43% PGE(1) and 44% PGE(2)) and the transwell migration assay (28% PGE(1) and 68% PGE(2)). Conclusions: The present study demonstrated that treatments which alter PGE(1) and PGE(2) metabolism influence the proliferative and apoptotic indices of T98G glioma cells. The migratory capacity of the cells was also significantly affected by the change in prostaglandin metabolism. Modifying PG metabolism remains an interesting target for future studies in gliomas.

Relationship between connectivity and academic productivity

A relevant factor in the growth of academic productivity in the second half of 20th century is the implementation of the internet, particularly in developing countries. One of the first networks in Brazil is the Academic Network at Sao Paulo (ANSP), a regional network implemented in the state of Sao Paulo, which contains the largest concentration of researchers in the country. This study presents a unique metric for analyzing the impact of ANSP in academic productivity in the state of Sao Paulo. We correlate academic production and available bandwidth using Fisher ideal price index with suitable variables to evaluate the impact of the internet on research centers and universities. We find that the members of ANSP show a steady growth in academic productivity compared with other institutions outside of the ANSP network. These results suggest that policies which increase available bandwidth can positively affect academic productivity.

Associations of Forest Cover, Fragment Area, and Connectivity with Neotropical Understory Bird Species Richness and Abundance

Theoretical and empirical studies demonstrate that the total amount of forest and the size and connectivity of fragments have nonlinear effects on species survival. We tested how habitat amount and configuration affect understory bird species richness and abundance. We used mist nets (almost 34,000 net hours) to sample birds in 53 Atlantic Forest fragments in southeastern Brazil. Fragments were distributed among 3 10,800-ha landscapes. The remaining forest in these landscapes was below (10% forest cover), similar to (30%), and above (50%) the theoretical fragmentation threshold (approximately 30%) below which the effects of fragmentation should be intensified. Species-richness estimates were significantly higher (F = 3715, p = 0.00) where 50% of the forest remained, which suggests a species occurrence threshold of 30-50% forest, which is higher than usually occurs (<30%). Relations between forest cover and species richness differed depending on species sensitivity to forest conversion and fragmentation. For less sensitive species, species richness decreased as forest cover increased, whereas for highly sensitive species the opposite occurred. For sensitive species, species richness and the amount of forest cover were positively related, particularly when forest cover was 30-50%. Fragment size and connectivity were related to species richness and abundance in all landscapes, not just below the 30% threshold. Where 10% of the forest remained, fragment size was more related to species richness and abundance than connectivity. However, the relation between connectivity and species richness and abundance was stronger where 30% of the landscape was forested. Where 50% of the landscape was forested, fragment size and connectivity were both related to species richness and abundance. Our results demonstrated a rapid loss of species at relatively high levels of forest cover (30-50%). Highly sensitive species were 3-4 times more common above the 30-50% threshold than below it; however, our results do not support a unique fragmentation threshold.

Predicting the connectivity of primate cortical networks from topological and spatial node properties

Abstract Background The organization of the connectivity between mammalian cortical areas has become a major subject of study, because of its important role in scaffolding the macroscopic aspects of animal behavior and intelligence. In this study we present a computational reconstruction approach to the problem of network organization, by considering the topological and spatial features of each area in the primate cerebral cortex as subsidy for the reconstruction of the global cortical network connectivity. Starting with all areas being disconnected, pairs of areas with similar sets of features are linked together, in an attempt to recover the original network structure. Results Inferring primate cortical connectivity from the properties of the nodes, remarkably good reconstructions of the global network organization could be obtained, with the topological features allowing slightly superior accuracy to the spatial ones. Analogous reconstruction attempts for the C. elegans neuronal network resulted in substantially poorer recovery, indicating that cortical area interconnections are relatively stronger related to the considered topological and spatial properties than neuronal projections in the nematode. Conclusion The close relationship between area-based features and global connectivity may hint on developmental rules and constraints for cortical networks. Particularly, differences between the predictions from topological and spatial properties, together with the poorer recovery resulting from spatial properties, indicate that the organization of cortical networks is not entirely determined by spatial constraints.