Development of "personality" in the domestic cat: A longitudinal study.

Although individual differences in the behavior of animals, sometimes referred to as personality, have recently received considerable attention, the development of such differences remains understudied. We previously found consistent individual differences in behavior in four tests simulating everyday contexts in 74 preweaning age kittens from 16 litters of the domestic cat. To study the development of consistent among-individual differences in four behavioral traits in cats, we followed a subset of these same individuals and repeated the same tests at 6 and 12 months of age. Some individual differences in behavior became increasingly repeatable with age due to a combination of decreased individual-level variance (canalization) and increased among-individual variance; these changes in variance and repeatability continued into adulthood (12 months). We did not observe behavioral syndromes at any age, in contrast to our previous reports in a different population of adult cats. The mechanisms that underlie increased repeatability with age and the possibility of personality structure differing between populations in this species remain to be studied.

Canalización del crecimiento entre los 2 y los 5 años en niños aparentemente sanos con talla baja a los 2 años / Canalization of growth between 2 and 5 years of age in apparently healthy children with short stature at age 2 years

Introducción. El tamaño del recién nacido se asocia a condiciones intrauterinas. El potencial genético se expresa más tarde; la canalización del crecimiento se describe clásicamente hasta los 24 meses. Objetivo. Describir la canalización del crecimiento entre los 2 y los 5 años en niños aparentemente sanos con talla baja a los 2 años. Población y métodos. Estudio de cohorte retrospectiva. Se incluyeron niños seguidos en un hospital universitario de comunidad entre 2003 y 2019, con puntaje Z de talla menor a -2 DE para edad y sexo a los 2 años. Se excluyeron los nacidos prematuros, con bajo peso y con enfermedades crónicas. Se evaluó la trayectoria de crecimiento. Se definió canalización como la adquisición de talla normal para la población general. Resultados. Se incluyeron 64 niños, de los cuales 37 (58 %) presentaron canalización del crecimiento a los 5 años (20 a los 3 años, 8 a los 4 años, y 9 a los 5 años). La velocidad de crecimiento a los 3 y a los 5 años fue significativamente mayor en los que canalizaron en comparación con los que no lo hicieron; hubo una tendencia similar a los 4 años. De los 27 niños con talla baja a los 5 años, 25 tuvieron al menos un registro de velocidad de crecimiento anual menor al percentil 25. Conclusiones. La mayoría de los niños aparentemente sanos con baja talla a los 2 años alcanzan una talla normal a los 5 años. La velocidad de crecimiento anual permite detectar a los niños con riesgo de no canalizar.

Introduction. Newborn size is associated with intrauterine conditions. Genetic potential is expressed later; the canalization of growth is typically described up to 24 months of age. Objective. To describe the canalization of growth between 2 and 5 years of age in apparently healthy children with short stature at age 2 years. Population and methods. Retrospective, cohort study. Children seen at a community teaching hospital between 2003 and 2019, who had a Z-score for height below -2 SDs for age and sex at age 2 years were included. Infants born preterm, with a low birth weight, and chronic conditions were excluded. Growth patterns were assessed. Canalization was defined as reaching a normal stature for the general population. Results. Sixty-four children were included; 37 (58%) showed canalization of growth at 5 years old (20 at 3 years, 8 at 4 years, and 9 at 5 years). The growth rate at 3 and 5 years of age was significantly higher among those who showed canalization compared to those who did not; a similar trend was observed at 4 years of age. Among 27 children with short stature at 5 years of age, 25 had at least 1 annual growth velocity below the 25th centile. Conclusions. Most apparently healthy children with short stature at 2 years old reached a normal stature at 5 years old. The annual growth velocity allows to detect children at risk of not showing canalization.

Canalization of growth between 2 and 5 years of age in apparently healthy children with short stature at age 2 years. / Canalización del crecimiento entre los 2 y los 5 años en niños aparentemente sanos con talla baja a los 2 años.

Introduction. Newborn size is associated with intrauterine conditions. Genetic potential is expressed later; the canalization of growth is typically described up to 24 months of age. Objective. To describe the canalization of growth between 2 and 5 years of age in apparently healthy children with short stature at age 2 years. Population and methods. Retrospective, cohort study. Children seen at a community teaching hospital between 2003 and 2019, who had a Z-score for height below -2 SDs for age and sex at age 2 years were included. Infants born preterm, with a low birth weight, and chronic conditions were excluded. Growth patterns were assessed. Canalization was defined as reaching a normal stature for the general population. Results. Sixty-four children were included; 37 (58%) showed canalization of growth at 5 years old (20 at 3 years, 8 at 4 years, and 9 at 5 years). The growth rate at 3 and 5 years of age was significantly higher among those who showed canalization compared to those who did not; a similar trend was observed at 4 years of age. Among 27 children with short stature at 5 years of age, 25 had at least 1 annual growth velocity below the 25th centile. Conclusions. Most apparently healthy children with short stature at 2 years old reached a normal stature at 5 years old. The annual growth velocity allows to detect children at risk of not showing canalization.

Introducción. El tamaño del recién nacido se asocia a condiciones intrauterinas. El potencial genético se expresa más tarde; la canalización del crecimiento se describe clásicamente hasta los 24 meses. Objetivo. Describir la canalización del crecimiento entre los 2 y los 5 años en niños aparentemente sanos con talla baja a los 2 años. Población y métodos. Estudio de cohorte retrospectiva. Se incluyeron niños seguidos en un hospital universitario de comunidad entre 2003 y 2019, con puntaje Z de talla menor a -2 DE para edad y sexo a los 2 años. Se excluyeron los nacidos prematuros, con bajo peso y con enfermedades crónicas. Se evaluó la trayectoria de crecimiento. Se definió canalización como la adquisición de talla normal para la población general. Resultados. Se incluyeron 64 niños, de los cuales 37 (58 %) presentaron canalización del crecimiento a los 5 años (20 a los 3 años, 8 a los 4 años, y 9 a los 5 años). La velocidad de crecimiento a los 3 y a los 5 años fue significativamente mayor en los que canalizaron en comparación con los que no lo hicieron; hubo una tendencia similar a los 4 años. De los 27 niños con talla baja a los 5 años, 25 tuvieron al menos un registro de velocidad de crecimiento anual menor al percentil 25. Conclusiones. La mayoría de los niños aparentemente sanos con baja talla a los 2 años alcanzan una talla normal a los 5 años. La velocidad de crecimiento anual permite detectar a los niños con riesgo de no canalizar.

Evolvability in the Cephalothoracic Structural Complexity of Aegla araucaniensis (Crustacea: Decapoda) Determined by a Developmental System with Low Covariational Constraint.

The integration of complex structures is proportional to the intensity of the structural fusion; its consequences are better known than the covariational effects under less restrictive mechanisms. The synthesis of a palimpsest model based on two early parallel pathways and a later direct pathway explains the cephalothoracic complexity of decapod crustaceans. Using this model, we tested the evolvability of the developmental modularity in Aegla araucaniensis, an anomuran crab with an evident adaptive sexual dimorphism. The asymmetric patterns found on the landmark configurations suggest independent perturbations of the parallel pathways in each module and a stable asymmetry variance near the fusion by canalization of the direct pathway, which was more intense in males. The greater covariational flexibility imposed by the parallel pathways promotes the expression of gonadic modularity that favors the reproductive output in females and agonistic modularity that contributes to mating success in males. Under these divergent expressions of evolvability, the smaller difference between developmental modularity and agonistic modularity in males suggests higher levels of canalization due to a relatively more intense structural fusion. We conclude that: (1) the cephalothorax of A. araucaniensis is an evolvable structure, where parallel pathways promote sexual disruptions in the expressions of functional modularity, which are more restricted in males, and (2) the cephalothoracic palimpsest of decapods has empirical advantages in studying the developmental causes of evolution of complex structures.

Sex differences in the canalization of child growth and development: An example of genetic regulation. / Diferencias de sexo en la canalización del crecimiento y del desarrollo infantil: un ejemplo de regulación genética.

In case of a disease or nutritional deficit, the growth curve may show deviations from the percentile it was depicting, and once damage is removed, a strong regulatory force tends to restore its path. Such phenomenon is known as catch-up growth and is an example of canalization of growth. Girls are more favored than boys because, when faced with the same damage, their growth (and also their psychomotor development) shows less deviation than that of boys. Such difference is also shown in a higher prevalence among boys of growth retardation in general and some developmental disorders, including autism spectrum disorder and cerebral palsy. Infant mortality is lower in girls at all ages and life expectancy is several years longer in women from all countries. The cause of such differences in favor of girls has a strong genetic component and is enriching for the interpretation of clinical and epidemiological studies.

Ante una enfermedad o carencia nutricional, la curva de crecimiento puede desviarse del percentil que recorría, y cuando el daño es neutralizado, hay una fuerza regulatoria que tiende a restaurar su trayectoria. Este fenómeno, llamado crecimiento compensatorio o catch-up, es un ejemplo de canalización del crecimiento. Las niñas se ven favorecidas respecto de los niños porque, ante un mismo daño, su crecimiento (y también su desarrollo psicomotor) se desvía menos que el de los niños. Esta diferencia también se expresa en una mayor prevalencia masculina de retraso del desarrollo en general y de algunos trastornos del desarrollo, como trastorno del espectro autista y parálisis cerebral, entre otros. La mortalidad infantil es menor en niñas a todas las edades y la esperanza de vida es varios años mayor en mujeres en todos los países. La causa de estas diferencias a favor de las niñas tiene un fuerte componente genético y enriquece la interpretación de estudios clínicos y epidemiológicos.

Diferencias de sexo en la canalización del crecimiento y del desarrollo infantil: un ejemplo de regulación genética / Sex differences in the canalization of child growth and development: An example of genetic regulation

Ante una enfermedad o carencia nutricional, la curva de crecimiento puede desviarse del percentil que recorría, y cuando el daño es neutralizado, hay una fuerza regulatoria que tiende a restaurar su trayectoria. Este fenómeno, llamado crecimiento compensatorio o catch-up, es un ejemplo de canalización del crecimiento. Las niñas se ven favorecidas respecto de los niños porque, ante un mismo daño, su crecimiento (y también su desarrollo psicomotor) se desvía menos que el de los niños. Esta diferencia también se expresa en una mayor prevalencia masculina de retraso del desarrollo en general y de algunos trastornos del desarrollo, como trastorno del espectro autista y parálisis cerebral, entre otros. La mortalidad infantil es menor en niñas a todas las edades y la esperanza de vida es varios años mayor en mujeres en todos los países. La causa de estas diferencias a favor de las niñas tiene un fuerte componente genético y enriquece la interpretación de estudios clínicos y epidemiológico

In case of a disease or nutritional deficit, the growth curve may show deviations from the percentile it was depicting, and once damage is removed, a strong regulatory force tends to restore its path. Such phenomenon is known as catch-up growth and is an example of canalization of growth. Girls are more favored than boys because, when faced with the same damage, their growth (and also their psychomotor development) shows less deviation than that of boys. Such difference is also shown in a higher prevalence among boys of growth retardation in general and some developmental disorders, including autism spectrum disorder and cerebral palsy. Infant mortality is lower in girls at all ages and life expectancy is several years longer in women from all countries. The cause of such differences in favor of girls has a strong genetic component and is enriching for the interpretation of clinical and epidemiological studies.

Stage- and thermal-specific genetic architecture for preadult viability in natural populations of Drosophila melanogaster.

Studying the processes affecting variation for preadult viability is essential to understand the evolutionary trajectories followed by natural populations. This task requires focusing on the complex nature of the phenotype-genotype relationship by taking into account usually neglected aspects of the phenotype and recognizing the modularity between different ontogenetic stages. Here, we describe phenotypic variability for viability during the larval and pupal stages in lines derived from three natural populations of Drosophila melanogaster, as well as the variability for phenotypic plasticity and canalization at two different rearing temperatures. The results indicate that the three populations present significant phenotypic differences for preadult viability. Furthermore, distinct aspects of the phenotype (means, plasticity, canalization, plasticity of canalization) are affected by different genetic bases underlying changes in viability in a stage- and environment-specific manner. These findings explain the generalized maintenance of genetic variability for this fitness trait.

The role of SDF1 in prostate epithelial morphogenesis.

Androgens induce rat prostate induction from the urogenital sinus epithelium at embryonic day 17.5. Subsequent morphogenesis, including epithelial cord growth, branching, and canalization, results from concerted paracrine interactions with the stroma. A significant number of paracrine factors bind heparan sulfate (HS). We hypothesized that interfering with overall sulfation could disrupt the signaling mediated by HS-binding factors and that the undersulfated environment would allow investigation of individual exogenous morphogens. First, we investigated whether acinar morphogenesis involved HS-proteoglycan expression and found that syndecans 1 and 3 were upregulated in RWPE1 cells in the transition from two- to three-dimensional (3D) Matrigel, capable of promoting spheroid formation. We then investigated whether sodium chlorate, a general sulfation inhibitor, interfered with spheroid formation by RWPE1 cells and acinar morphogenesis in ex vivo ventral prostate (VP) organ culture. As expected, treatment with sodium chlorate inhibited spheroid formation by RWPE1 cells in 3D culture. Chlorate also inhibited ex vivo VP epithelial branching and canalization, resulting in long branchless epithelial structures. We then investigated whether the HS-binding factors, FGF10, TGFß1, and SDF1, could reverse the effect of sodium chlorate. Although no effect was seen in the FGF10- and TGFß1-treated samples, SDF1 promoted epithelial canalization in the low sulfated environment, highlighting its specific role in lumen formation. Altogether, the results show that sodium chlorate perturbed prostate morphogenesis and allowed investigation of factors involved in branching and/or canalization, implicating SDF1 signaling in epithelial canalization.

La arquitectura genética como herramienta de análisis del mapa genotipo-fenotipo / Genetic architecture as an analysis tool of the genotype-phenotype map

El estudio de la relación entre el genotipo y el fenotipo es de gran importancia para las investigaciones en genética y en las ciencias de la vida en general. A diferencia de la concepción tradicional de esta relación como un conjunto invariante de parámetros, el enfoque actual utiliza la arquitectura genética, una herramienta realista y dinámica que permite elucidar el mapa genotipo-fenotipo, ahora considerado una estructura en evolución. De las complejas relaciones entre los elementos del mapa genotipo-fenotipo surgen diversas propiedades emergentes que pueden explicar distintos fenómenos evolutivos. Además, algunas de estas propiedades promueven la acumulación de variabilidad genética en poblaciones naturales, la cual constituye el sustrato de procesos evolutivos como la selección natural. La caracterización y análisis de la arquitectura genética de caracteres adaptativos constituye una herramienta eficaz para comprender los procesos genéticos subyacentes al cambio evolutivo.

Studying the relationship between genotype and phenotype is of great importance for genetics and life science studies in general. In contrast with the traditional view of this relationship as an invariant set of parameters, the current approach incorporates the concept of genetic architecture, a realistic and dynamic tool that allows to elucidate the genotype-phenotype map, which is now regarded as an evolving structure. From the complex relationships between the elements in the genotype-phenotype map several emergent properties arise that can explain different evolutionary phenomena. Moreover, some of these properties promote the accumulation of genetic variability in natural populations, which constitutes the substrate to evolutionary processes such as natural selection. The characterization and analysis of the genetic architecture of adaptive traits constitutes a powerful tool to understand the genetics underpinnings of evolution.

The influence of developmental environment on courtship song in cactophilic Drosophila.

Closely related species often differ in the signals involved in sexual communication and mate recognition. Determining the factors influencing signal quality (i.e. signal's content and conspicuousness) provides an important insight into the potential pathways by which these interspecific differences evolve. Host specificity could bias the direction of the evolution of sexual communication and the mate recognition system, favouring sensory channels that work best in the different host conditions. In this study, we focus on the cactophilic sibling species Drosophila buzzatii and D. koepferae that have diverged not only in the sensory channel used for sexual communication and mate recognition but also in the cactus species that use as primary hosts. We evaluate the role of the developmental environment in generating courtship song variation using an isofemale line design. Our results show that host environment during development induces changes in the courtship song of D. koepferae males, but not in D. buzzatii males. Moreover, we report for the first time that host rearing environment affects the conspicuousness of courtship song (i.e. song volume). Our results are mainly discussed in the context of the sensory drive hypothesis.

PATELLINS are regulators of auxin-mediated PIN1 relocation and plant development in Arabidopsis thaliana.

Coordinated cell polarization in developing tissues is a recurrent theme in multicellular organisms. In plants, a directional distribution of the plant hormone auxin is at the core of many developmental programs. A feedback regulation of auxin on the polarized localization of PIN auxin transporters in individual cells has been proposed as a self-organizing mechanism for coordinated tissue polarization, but the molecular mechanisms linking auxin signalling to PIN-dependent auxin transport remain unknown. We used a microarray-based approach to find regulators of the auxin-induced PIN relocation in Arabidopsis thaliana root, and identified a subset of a family of phosphatidylinositol transfer proteins (PITPs), the PATELLINs (PATLs). Here, we show that PATLs are expressed in partially overlapping cell types in different tissues going through mitosis or initiating differentiation programs. PATLs are plasma membrane-associated proteins accumulated in Arabidopsis embryos, primary roots, lateral root primordia and developing stomata. Higher order patl mutants display reduced PIN1 repolarization in response to auxin, shorter root apical meristem, and drastic defects in embryo and seedling development. This suggests that PATLs play a redundant and crucial role in polarity and patterning in Arabidopsis.

Evolución clínica y ultrasonográfica del síndrome postrombótico en su primer año de evolución / Clinical and ultrasonographic progression of posthrombotic syndrome in its first year

Introduccións: La insuficiencia venosa crónica es característica principal del síndrome postrombótico donde el estasis venoso es típico.Objetivos: Describir la evolución clínica y ultrasonográfica del síndrome postrombótico durante su primer año.Métodos: Estudio descriptivo prospectivo en 20 hombres (55,6 por ciento) y 16 mujeres (44,4 por ciento) con una edad promedio de 55,8 ± 14,2 años (IC95 por ciento: 41,6 70 años), ingresados en el Servicio de Flebolinfología del Instituto Nacional de Angiología y Cirugía Vascular con el diagnóstico de trombosis venosa profunda de los miembros inferiores. Las variables estudiadas fueron: tipos de síntomas clínicos, tipo de evolución ultrasonográfica por ecodoppler, estadios clínicos del síndrome postrombótico, tiempo y porcentaje de recanalización.Resultadoss: A los seis meses de evolución predominó la sintomatología severa (47,2 por ciento); en el sector fémoro–poplíteo la clasificación de buena. Al año, fue más frecuente la clasificación de moderada (52,8 por ciento) y de muy buena en el sector poplíteo; el edema pretibial fue el signo que predominó. En los sectores ocluidos fémoro-poplíteo el porcentaje de recanalización promedio aumentó al año y fue superior (p < 0,05) al obtenido a los seis meses. Se encontró asociación significativa entre el porcentaje de recanalización y el período de evolución(X2= 41,41; p= 0,0000); y entre el estadio clínico y el porcentaje de recanalización (X2= 32,95; p= 0,0000).Conclusións: durante el primer año de presentarse el síndrome postrombótico pueden ocurrir cambios clínicos y evolución favorable en la recanalización del sistema venoso profundo (AU)

Introduction: Chronic venous insufficiency is the main characteristic of the posthrombotic syndrome where the vein stasis is typical.Objective: to describe the clinical and ultrasonographic progression of the post-thrombotic syndrome in its first year.Methods: A descriptive prospective study was conducted in 20 men (55.6 percent) and 16 women (44.4 percent), with average age of 55.8 ± 14.2 years (IC95 percent: 41.6 70 years) diagnosed as deep venous thrombosis of the lower limb patients and hospitalized in the phlebolymphology service of the National Institute of Angiology and Vascular Surgery. The studied variables were types of clinical symptoms, type of ultrasonographic progression using Echodoppler device, clinical stagings of the posthrombotic syndrome, and time and percentage of re-canalization.Results: After six months of progression, severe symptoms predominated (47.2 percent); and in the femoral-popliteal area the classification was good. After a year, the moderate classification was more frequent (52.8 percent) and extremely good in the popliteal sector; the pretibial edema was the predominant sign (50 percent). In the occluded popliteal-femoral sector, the percentage of average re-canalization increased after a year, being higher (p< 0.05) than that of six months. A significant association was found between the percentage of re-channeling and the period of progression (X2= 41.41; p= 0.0000); and between the clinical staging and the percentage of re-canalization (X2= 32.95, p= 0.0000).Conclusions: During the first year of existence of the posthrombotic syndrome, clinical changes and favorable progression may occur in the re-canalization of the deep venous system

Evolución clínica y ultrasonográfica del síndrome postrombótico en su primer año de evolución / Clinical and ultrasonographic progression of posthrombotic syndrome in its first year

Introduccións: La insuficiencia venosa crónica es característica principal del síndrome postrombótico donde el estasis venoso es típico. Objetivos: Describir la evolución clínica y ultrasonográfica del síndrome postrombótico durante su primer año. Métodos: Estudio descriptivo prospectivo en 20 hombres (55,6 por ciento) y 16 mujeres (44,4 por ciento) con una edad promedio de 55,8 ± 14,2 años (IC95 por ciento : 41,6 ­ 70 años), ingresados en el Servicio de Flebolinfología del Instituto Nacional de Angiología y Cirugía Vascular con el diagnóstico de trombosis venosa profunda de los miembros inferiores. Las variables estudiadas fueron: tipos de síntomas clínicos, tipo de evolución ultrasonográfica por ecodoppler, estadios clínicos del síndrome postrombótico, tiempo y porcentaje de recanalización. Resultadoss: A los seis meses de evolución predominó la sintomatología severa (47,2 por ciento); en el sector fémoro­poplíteo la clasificación de buena. Al año, fue más frecuente la clasificación de moderada (52,8 por ciento) y de muy buena en el sector poplíteo; el edema pretibial fue el signo que predominó. En los sectores ocluidos fémoro-poplíteo el porcentaje de recanalización promedio aumentó al año y fue superior (p < 0,05) al obtenido a los seis meses. Se encontró asociación significativa entre el porcentaje de recanalización y el período de evolución (X2= 41,41; p= 0,0000); y entre el estadio clínico y el porcentaje de recanalización (X2= 32,95; p= 0,0000). Conclusións: durante el primer año de presentarse el síndrome postrombótico pueden ocurrir cambios clínicos y evolución favorable en la recanalización del sistema venoso profundo(AU)

Introduction: Chronic venous insufficiency is the main characteristic of the posthrombotic syndrome where the vein stasis is typical. Objective: to describe the clinical and ultrasonographic progression of the post-thrombotic syndrome in its first year. Methods: A descriptive prospective study was conducted in 20 men (55.6 percent) and 16 women (44.4 percent), with average age of 55.8 ± 14.2 years (IC95 percent : 41.6 ­ 70 years) diagnosed as deep venous thrombosis of the lower limb patients and hospitalized in the phlebolymphology service of the National Institute of Angiology and Vascular Surgery. The studied variables were types of clinical symptoms, type of ultrasonographic progression using Echodoppler device, clinical stagings of the posthrombotic syndrome, and time and percentage of re-canalization. Results: After six months of progression, severe symptoms predominated (47.2 percent); and in the femoral-popliteal area the classification was good. After a year, the moderate classification was more frequent (52.8 percent) and extremely good in the popliteal sector; the pretibial edema was the predominant sign (50 percent). In the occluded popliteal-femoral sector, the percentage of average re-canalization increased after a year, being higher (p< 0.05) than that of six months. A significant association was found between the percentage of re-channeling and the period of progression (X2= 41.41; p= 0.0000); and between the clinical staging and the percentage of re-canalization (X2= 32.95, p= 0.0000). Conclusions: During the first year of existence of the posthrombotic syndrome, clinical changes and favorable progression may occur in the re-canalization of the deep venous system(AU)

Genetic structure of phenotypic robustness in the collaborative cross mouse diallel panel.

Developmental stability and canalization describe the ability of developmental systems to minimize phenotypic variation in the face of stochastic micro-environmental effects, genetic variation and environmental influences. Canalization is the ability to minimize the effects of genetic or environmental effects, whereas developmental stability is the ability to minimize the effects of micro-environmental effects within individuals. Despite much attention, the mechanisms that underlie these two components of phenotypic robustness remain unknown. We investigated the genetic structure of phenotypic robustness in the collaborative cross (CC) mouse reference population. We analysed the magnitude of fluctuating asymmetry (FA) and among-individual variation of cranial shape in reciprocal crosses among the eight parental strains, using geometric morphometrics and a diallel analysis based on a Bayesian approach. Significant differences among genotypes were found for both measures, although they were poorly correlated at the level of individuals. An overall positive effect of inbreeding was found for both components of variation. The strain CAST/EiJ exerted a positive additive effect on FA and, to a lesser extent, among-individual variance. Sex- and other strain-specific effects were not significant. Neither FA nor among-individual variation was associated with phenotypic extremeness. Our results support the existence of genetic variation for both developmental stability and canalization. This finding is important because robustness is a key feature of developmental systems. Our finding that robustness is not related to phenotypic extremeness is consistent with theoretical work that suggests that its relationship to stabilizing selection is not straightforward.

Ontogenia y fisoonomía del paisaje epigenético:un modelo general para explicarr sistemas en desarroloo / Ontogeny and Physiognomy of the Epigenetic Landscape: A General Model to Explain Developmental Systems

El paisaje epigenético es una metáfora gráfica propuesta por Conrad H. Waddington para explicar el desarrollo de los organismos mediante la imagen de un paisaje compuesto por una superficie ondulante con cimas y valles, que representan las vías por las cuales se desplazan las células del organismo en su proceso de diferenciación. C.H. Waddington, considerado como el padre de la epigenética, es notable por sus aportes teóricos, que incluyen las nociones de asimilación genética, la canalización del desarrollo y el epigenotipo. Estas ideas surgieron a partir de estudios experimentales en biología del desarrollo, los cuales resultaron en el descubrimiento del "organizador" en embriones de aves y, posteriormente, de fenocopias inducidas por factores ambientales en Drosophila. En el presente artículo se presenta una interpretación del paisaje epigenético y conceptos relacionados, que ponen en evidencia el poder heurístico de este modelo y su importancia para la biología contemporánea. Este trabajo es un homenaje a la vida de C. H. Waddington, cuya obra continúa siendo de gran actualidad.

The epigenetic landscape is a graphic metaphor proposed by Conrad H. Waddington to explain the development of organisms and their parts. It is depicted as a wavy surface with summits and descending valleys, representing the paths followed by cells along their differentiation process, as part of organismal development. Conrad H. Waddington, regarded as the father of epigenetics, stands out for his theoretical contributions, that include the notions of genetic assimilation, canalization of development and epigenotype. These ideas were inspired by experimental works in developmental biology, that lead to the discovery of the organizer in bird embryos, as well as environmentallyinduced phenocopies in Drosophila. In the current essay, I present an interpretation of the epigenetic landscape and related concepts that highlight the heuristic power of this model and its importance for contemporary biology. This work is a tribute to the life of C. H. Waddington, whose work is still of great significance.

Efectividad del alcohol absoluto para canalizar los tumores irrresecables de esófago / Effectiveness of absolute alcohol to canalize the esophageal non-resectable tumors

INTRODUCCIÓN. En más del 75 por ciento de los pacientes con cáncer de esófago, los procedimientos que se realizan son paliativos y existe un dilema ético sobre la forma de solucionar el problema fundamental: la alimentación. El objetivo de esta investigación fue señalar la importancia de las infiltraciones con alcohol absoluto para lograr la implantación de prótesis esofágicas artesanales por el método de tracción. MÉTODOS. Se realizó un estudio prospectivo y lineal con pacientes con cáncer de esófago irresecable, ingresados entre 1995 y 2009. Fueron evaluados 112 pacientes, de los cuales 65 fueron tratados con métodos paliativos. Se colocaron 55 prótesis esofágicas y en 10 de estos casos fue necesario canalizar previamente el tumor con infiltraciones de alcohol absoluto. RESULTADOS. Se consiguió pasar la sonda nasogástrica en el 90 por ciento de los pacientes que necesitaron infiltraciones de alcohol absoluto. Fueron necesarias entre 1 y 2 sesiones, pero uno de los pacientes necesitó 3 sesiones de infiltración. No hubo complicaciones. CONCLUSIONES. La combinación de alcohol absoluto y prótesis permite eliminar la disfagia en el cáncer avanzado de esófago y cardias. Cuando existe estenosis total, el alcohol absoluto es un método adecuado para canalizar la estenosis tumoral de esófago antes de colocar la prótesis. En la mayoría de los casos son suficientes 1 o 2 sesiones de infiltración(AU)

INTRODUCTION. In more than 75 percent of patients presenting with esophageal cancer the procedures performed are of type palliative and there is a ethical dilemma on the way to solve the major problem: the feeding. The objective of present paper was to emphasize the significance of infiltrations with absolute alcohol to achieve the implantation of handmade esophageal prostheses using the traction method. METHODS. A linear and prospective study was performed in patients presenting with non-resectable esophageal cancer admitted between 1995 and 2009. A total of 112 patients were assessed with 65 of them treated using palliative methods. Fifty five esophageal prostheses were placed and in 10 of these cases it was necessary to tunnelled previously the tumor with absolute alcohol infiltrations. RESULTS.The nasogastric tube was passed in the 90 percent of patients needing infiltrations of absolute alcohol. One or two sessions were necessary but one of them need three sessions of infiltrations without complications. CONCLUSIONS.The combination of absolute alcohol and prosthesis allows to eliminate the dysphagia in cases of advanced cancer and cardias. When there is a total stenosis, the absolute alcohol is a appropriate method to canalize the esophageal tumoral stenosis before to place the prosthesis. In most of cases are enough 1 or 2 sessions of infiltrations(AU)