The City Passing by the River. The San Francisco River Canalization and Construction of Avenida Jiménez de Quesada in Bogota at the Beginning of the 20th Century

The document refers to the San Francisco river canalization and subsequent construction of the Avenida Jiménez de Quesada. Understanding that the project was ascribed to the modernizing policy of the time, the investigation identifies the different stages in the canalization process, and shows its relations with the spatial structure of the city and the local conditions that developed on the river surroundings. The financing of the project through the “property increase duty” permits an illustration of the progress of canalization and construction of the Jiménez Avenue process, providing a less technical and more social meaning to the sequence in which the project executed. Consequently, the document approaches the shaping dynamics of Bogotá´s spatial structure at the beginning of the XX century.

Molecular basis of canalization in an ascidian species complex adapted to different thermal conditions

Canalization is a result of intrinsic developmental buffering that ensures phenotypic robustness under genetic variation and environmental perturbation. As a consequence, animal phenotypes are remarkably consistent within a species under a wide range of conditions, a property that seems contradictory to evolutionary change. Study of laboratory model species has uncovered several possible canalization mechanisms, however, we still do not understand how the level of buffering is controlled in natural populations. We exploit wild populations of the marine chordate Ciona intestinalis to show that levels of buffering are maternally inherited. Comparative transcriptomics show expression levels of genes encoding canonical chaperones such as Hsp70 and Hsp90 do not correlate with buffering. However the expression of genes encoding endoplasmic reticulum (ER) chaperones does correlate. We also show that ER chaperone genes are widely conserved amongst animals. Contrary to previous beliefs that expression level of Heat Shock Proteins (HSPs) can be used as a measurement of buffering levels, we propose that ER associated chaperones comprise a cellular basis for canalization. ER chaperones have been neglected by the fields of development, evolution and ecology, but their study will enhance understanding of both our evolutionary past and the impact of global environmental change.

Molecular basis of canalization in an ascidian species complex adapted to different thermal conditions

Canalization is a result of intrinsic developmental buffering that ensures phenotypic robustness under genetic variation and environmental perturbation. As a consequence, animal phenotypes are remarkably consistent within a species under a wide range of conditions, a property that seems contradictory to evolutionary change. Study of laboratory model species has uncovered several possible canalization mechanisms, however, we still do not understand how the level of buffering is controlled in natural populations. We exploit wild populations of the marine chordate Ciona intestinalis to show that levels of buffering are maternally inherited. Comparative transcriptomics show expression levels of genes encoding canonical chaperones such as Hsp70 and Hsp90 do not correlate with buffering. However the expression of genes encoding endoplasmic reticulum (ER) chaperones does correlate. We also show that ER chaperone genes are widely conserved amongst animals. Contrary to previous beliefs that expression level of Heat Shock Proteins (HSPs) can be used as a measurement of buffering levels, we propose that ER associated chaperones comprise a cellular basis for canalization. ER chaperones have been neglected by the fields of development, evolution and ecology, but their study will enhance understanding of both our evolutionary past and the impact of global environmental change.

The snail hosts of schistosomiasis: some evolutionary and ecological perspectives in relation to control

Despite opportunities for radiation provided by spatio-temporal isolation, the basic morphological plan of pulmonate snails has remained conservative. In consequence of the resulting dearth of morphological characters and their plasticity, there is a case for using biochemical characters such as exogenous chemicals released by the snails (e.g. amino acids) and their chemoreception niche as taxonomic aids to classify snails of medical importance. As these same chemicals are used by snails to distinguish conspecifics they could also be used as "environmental antibodies" in controlled release formulations (CRF's) designed to remove target snails in a specific, cost-effective and ecologically acceptable manner. The snails, surface-living bacteria, algae and macrophytic plants are considered as co-evolved, interactive modular systems with strong mutualistic elements. Recently, anthropogenic perturbations such as deforestation, and damming of flowing waters, have benefited these modules whereas others such as river canalization, acid deposition, accumulation of pesticide residues and eutrophication have harmed them. Research is needed to elucidate the factors which limit the growth of snails in primitive habitats, uninfluenced by man, as well as in those subject to harmful anthropogenic factors. The understanding thus gained could be applied to develop cost-effective primary health care strategies to reduce or prevent transmission of schistosomiasis and other water related diseases.

Genetics of colouration in birds.

Establishing the links between phenotype and genotype is of great importance for resolving key questions about the evolution, maintenance and adaptive function of phenotypic variation. Bird colouration is one of the most studied systems to investigate the role of natural and sexual selection in the evolution of phenotypic diversity. Given the recent advances in molecular tools that allow discovering genetic polymorphisms and measuring gene and protein expression levels, it is timely to review the literature on the genetics of bird colouration. The present study shows that melanin-based colour phenotypes are often associated with mutations at melanogenic genes. Differences in melanin-based colouration are caused by switches of eumelanin to pheomelanin production or by changes in feather keratin structure, melanoblast migration and differentiation, as well as melanosome structure. Similar associations with other types of colourations are difficult to establish, because our knowledge about the molecular genetics of carotenoid-based and structural colouration is quasi inexistent. This discrepancy stems from the fact that only melanin-based colouration shows pronounced heritability estimates, i.e. the resemblance between related individuals is usually mainly explained by genetic factors. In contrast, the expression of carotenoid-based colouration is phenotypically plastic with a high sensitivity to variation in environmental conditions. It therefore appears that melanin-based colour traits are prime systems to understand the genetic basis of phenotypic variation. In this context, birds have a great potential to bring us to new frontiers where many exciting discoveries will be made on the genetics of phenotypic traits, such as colouration. In this context, a major goal of our review is to suggest a number of exciting future avenues.

Efectividad en la canalización yugular guiada por ecografía usando tres diferentes técnicas. Experimento en modelos simulados.

Introducción: El desarrollo tecnológico permite efectuar procedimientos eficientes en pacientes críticos de urgencias como canalizar vasos centrales guiados por ecografía. Éste procedimiento comparado con la técnica a ciegas ofrece ventajas como disminución de complicaciones, mejor éxito y menor tiempo de procedimiento. Hay diferentes técnicas de abordaje: transversal, longitudinal y oblicua, lo que supone diferencias en la efectividad y éxito en cada una de ellas. Materiales y métodos: Se realizó un experimento en modelos simulados con especialistas y residentes de último año de medicina de emergencias. Posterior a estandarizar los conceptos y abordajes de cada una de las técnicas, se puncionaron los modelos para determinar cuál técnica presenta mayor éxito y efectividad para canalización yugular con guía ecográfica. Resultados: El procedimiento fue efectivo en 175 réplicas (97.2%) distribuidas así: éxito 133 (73.9%), redirección 37 (20.6%) y requerimiento de segunda punción en 5 (2.8%). En la técnica transversal la efectividad fue 96.7% (n=58), en longitudinal del 100% (n=60) y en oblicua del 95.0% (n=57), (p=0.377). En residentes la efectividad fue 95.6% (n=86) y en especialistas 98.9% (n=89), (p=0.184). La distribución de éxito mostró que en los especialistas fue mayor en un 18.9% que en los residentes (p=0.004), por género los hombres tienen un éxito mayor en un 18.7% que las mujeres (p=0.009, OR=3.12, IC 95%: 1.30, 7.52). Discusión: No se encontró diferencia significativa en el uso de cualquier técnica, pero la tendencia favorece la técnica longitudinal, quien obtuvo mayor porcentaje de efectividad y éxito.

Intrinsically Multivariate Predictive Genes

Canalizing genes possess such broad regulatory power, and their action sweeps across a such a wide swath of processes that the full set of affected genes are not highly correlated under normal conditions. When not active, the controlling gene will not be predictable to any significant degree by its subject genes, either alone or in groups, since their behavior will be highly varied relative to the inactive controlling gene. When the controlling gene is active, its behavior is not well predicted by any one of its targets, but can be very well predicted by groups of genes under its control. To investigate this question, we introduce in this paper the concept of intrinsically multivariate predictive (IMP) genes, and present a mathematical study of IMP in the context of binary genes with respect to the coefficient of determination (CoD), which measures the predictive power of a set of genes with respect to a target gene. A set of predictor genes is said to be IMP for a target gene if all properly contained subsets of the predictor set are bad predictors of the target but the full predictor set predicts the target with great accuracy. We show that logic of prediction, predictive power, covariance between predictors, and the entropy of the joint probability distribution of the predictors jointly affect the appearance of IMP genes. In particular, we show that high-predictive power, small covariance among predictors, a large entropy of the joint probability distribution of predictors, and certain logics, such as XOR in the 2-predictor case, are factors that favor the appearance of IMP. The IMP concept is applied to characterize the behavior of the gene DUSP1, which exhibits control over a central, process-integrating signaling pathway, thereby providing preliminary evidence that IMP can be used as a criterion for discovery of canalizing genes.

Genetic heterogeneity of within-family variance of body weight in Atlantic salmon (Salmo salar)

BACKGROUND: Canalization is defined as the stability of a genotype against minor variations in both environment and genetics. Genetic variation in degree of canalization causes heterogeneity of within-family variance. The aims of this study are twofold: (1) quantify genetic heterogeneity of (within-family) residual variance in Atlantic salmon and (2) test whether the observed heterogeneity of (within-family) residual variance can be explained by simple scaling effects. RESULTS: Analysis of body weight in Atlantic salmon using a double hierarchical generalized linear model (DHGLM) revealed substantial heterogeneity of within-family variance. The 95% prediction interval for within-family variance ranged from ~0.4 to 1.2 kg2, implying that the within-family variance of the most extreme high families is expected to be approximately three times larger than the extreme low families. For cross-sectional data, DHGLM with an animal mean sub-model resulted in severe bias, while a corresponding sire-dam model was appropriate. Heterogeneity of variance was not sensitive to Box-Cox transformations of phenotypes, which implies that heterogeneity of variance exists beyond what would be expected from simple scaling effects. CONCLUSIONS: Substantial heterogeneity of within-family variance was found for body weight in Atlantic salmon. A tendency towards higher variance with higher means (scaling effects) was observed, but heterogeneity of within-family variance existed beyond what could be explained by simple scaling effects. For cross-sectional data, using the animal mean sub-model in the DHGLM resulted in biased estimates of variance components, which differed substantially both from a standard linear mean animal model and a sire-dam DHGLM model. Although genetic differences in canalization were observed, selection for increased canalization is difficult, because there is limited individual information for the variance sub-model, especially when based on cross-sectional data. Furthermore, potential macro-environmental changes (diet, climatic region, etc.) may make genetic heterogeneity of variance a less stable trait over time and space.

Localized matrix metalloproteinase (MMP)-2 and MMP-9 activity in the rat ventral prostate during the first week of postnatal development

The initial events in prostatic morphogenesis involve cell proliferation, epithelial canalization and outgrowth toward the stroma. We have hypothesized that stromal rearrangement takes place at the sites of epithelial growth and branching and that this rearrangement involves the action of gelatinases matrix metalloproteinase (MMP)-2 and MMP-9. Thus, the purpose of the present study was to characterize structural aspects of epithelial growth during the first week of postnatal development of the rat ventral prostate and to investigate the expression, localization and activity of MMP-2 and MMP-9 during this period by histological, ultrastructural and immunocytochemical analysis, in addition to gel zymography, in situ zymography and Western blotting. An increasing complexity of prostatic architeture was observed within the first postnatal week. Concurrently, the stroma became more organized and some cells differentiated into smooth muscle cells. Reticulin fibers appeared in a basket-like arrangement around both growing tips and epithelial sprouts, associated with a fainter staining for laminin. MMP-2 and MMP-9 activities were detected. MMP-2/MMP-9 expression decreased during the first week. Developing epithelial cords showed strong and difuse gelatinolytic activity. This activity coincided with the distribution of MMP-2 as determined by immunocytochemistry. on the other hand, MMP-9 was rather concentrated at the epithelial tips. These results suggest that gelatinolytic activity (with contribution of both MMP-2 and MMP-9) in the epithelium and at the epithelium-stroma interface are at least in part responsible for the tissue remodeling that allows epithelial growth and its projection into the surrounding stroma.

Implante venosos homólogo conservado em glutaraldeído da veia jugular em eqüinos: avaliação clínica, ultra-sonográfica e histopatológica

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

Avaliação de biofilme de proteus mirabilis em modelo experimental de fluxo dinâmico

Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

Seasonal effects of wastewater to the water quality of the Caeté river estuary, Brazilian Amazon

A situação socioeconômica de Bragança depende principalmente dos recursos biológicos estuarinos e marinhos, que são influenciados pelos ciclos de marés e climatologia. Coletas oceanográficas (com medidas de variáveis hidrológicas, hidro-dinâmicas e microbiológicas) foram realizadas na área mais urbanizada do estuário do Caeté, para caracterizar a qualidade das águas no setor estudado. Durante o período seco, o estuário foi mais eutrófico e apresentou os maiores valores de temperatura (30,5°C em Out./06), salinidade (17 psu em Fev./07), pH (8,24 em Fev./07) e coliformes fecais (>1000 MNP/ 100 ml em Dez./06 e Fev./07). As espécies fitoplanctô-nicas Cyclotella meneghiniana, Coscinodiscus centralis e outras espécies r-estrategistas também foram observadas. A falta de saneamento básico foi responsável pela contaminação local, especialmente durante o período seco, quando o esgoto foi lançado mais concentrado no estuário, mostrando a influência humana na redução da qualidade da água estuarina estudada. A pesca é considerada uma das principais atividades econômicas do município de Bragança e, portanto, esta contaminação poderá afetar negativamente a qualidade ambiental deste ecossistema amazônico.

Spatial and functional relationships between air conduits and blood capillaries in the pulmonary gas exchange tissue of adult and developing chickens

The documented data regarding the three-dimensional structure of the air capillaries (ACs), the ultimate sites of gas exchange in the avian lung is contradictory. Further, the mode of gas exchange, described as cross-current has not been clearly elucidated. We studied the temporal and spatial arrangement of the terminal air conduits of the chicken lung and their relationship with the blood capillaries (BCs) in embryos as well as the definitive architecture in adults. Several visualization techniques that included corrosion casting, light microscopy as well as scanning and transmission electron microscopy were used. Two to six infundibulae extend from each atrium and give rise to numerous ACs that spread centrifugally. Majority of the ACs are tubular structures that give off branches, which anastomose with their neighboring cognates. Some ACs have globular shapes and a few are blind-ending tapering tubes. During inauguration, the luminal aspects of the ACs are characterized by numerous microvillus-like microplicae, which are formed during the complex processes of cell attenuation and canalization of the ACs. The parabronchial exchange BCs, initially inaugurated as disorganized meshworks, are reoriented via pillar formation to lie predominantly orthogonal to the long axes of the ACs. The remodeling of the retiform meshworks by intussusceptive angiogenesis essentially accomplishes a cross-current system at the gas exchange interface in the adults, where BCs form ring-like patterns around the ACs, thus establishing a cross-current system. Our findings clarify the mode of gas exchange in the parabronchial mantle and illuminate the basis for the functional efficiency of the avian lung.

Interaction between Meristem Tissue Layers Controls Phyllotaxis

Phyllotaxis and vein formation are among the most conspicuous patterning processes in plants. The expression and polarization of the auxin efflux carrier PIN1 is the earliest marker for both processes, with mathematical models indicating that PIN1 can respond to auxin gradients and/or auxin flux. Here, we use cell-layer-specific PIN1 knockouts and partial complementation of auxin transport mutants to examine the interaction between phyllotactic patterning, which occurs primarily in the L1 surface layer of the meristem, and midvein specification in the inner tissues. We show that PIN1 expression in the L1 is sufficient for correct organ positioning, as long as the L1-specific influx carriers are present. Thus, differentiation of inner tissues can proceed without PIN1 or any of the known polar transporters. On theoretical grounds, we suggest that canalization of auxin flux between an auxin source and an auxin sink may involve facilitated diffusion rather than polar transport.

Propagation of Dyakonon Wave-Packets at the Boundary of Metallodielectric Lattices

We rigorously analyze the propagation of localized surface waves that takes place at the boundary between a semi-infinite layered metal-dielectric (MD) nanostructure cut normally to the layers and a isotropic medium. It is demonstrated that Dyakonov-like surface waves (also coined dyakonons) with hybrid polarization may propagate in a wide angular range. As a consequence, dyakonon-based wave-packets (DWPs) may feature sub-wavelength beamwidths. Due to the hyperbolic-dispersion regime in plasmonic crystals, supported DWPs are still in the canalization regime. The apparent quadratic beam spreading, however, is driven by dissipation effects in metal.