Under pressure: phenotypic divergence and convergence associated with microhabitat adaptations in Triatominae.

BACKGROUND: Triatomine bugs, the vectors of Chagas disease, associate with vertebrate hosts in highly diverse ecotopes. It has been proposed that occupation of new microhabitats may trigger selection for distinct phenotypic variants in these blood-sucking bugs. Although understanding phenotypic variation is key to the study of adaptive evolution and central to phenotype-based taxonomy, the drivers of phenotypic change and diversity in triatomines remain poorly understood. METHODS/RESULTS: We combined a detailed phenotypic appraisal (including morphology and morphometrics) with mitochondrial cytb and nuclear ITS2 DNA sequence analyses to study Rhodnius ecuadoriensis populations from across the species' range. We found three major, naked-eye phenotypic variants. Southern-Andean bugs primarily from vertebrate-nest microhabitats (Ecuador/Peru) are typical, light-colored, small bugs with short heads/wings. Northern-Andean bugs from wet-forest palms (Ecuador) are dark, large bugs with long heads/wings. Finally, northern-lowland bugs primarily from dry-forest palms (Ecuador) are light-colored and medium-sized. Wing and (size-free) head shapes are similar across Ecuadorian populations, regardless of habitat or phenotype, but distinct in Peruvian bugs. Bayesian phylogenetic and multispecies-coalescent DNA sequence analyses strongly suggest that Ecuadorian and Peruvian populations are two independently evolving lineages, with little within-lineage phylogeographic structuring or differentiation. CONCLUSIONS: We report sharp naked-eye phenotypic divergence of genetically similar Ecuadorian R. ecuadoriensis (nest-dwelling southern-Andean vs palm-dwelling northern bugs; and palm-dwelling Andean vs lowland), and sharp naked-eye phenotypic similarity of typical, yet genetically distinct, southern-Andean bugs primarily from vertebrate-nest (but not palm) microhabitats. This remarkable phenotypic diversity within a single nominal species likely stems from microhabitat adaptations possibly involving predator-driven selection (yielding substrate-matching camouflage coloration) and a shift from palm-crown to vertebrate-nest microhabitats (yielding smaller bodies and shorter and stouter heads). These findings shed new light on the origins of phenotypic diversity in triatomines, warn against excess reliance on phenotype-based triatomine-bug taxonomy, and confirm the Triatominae as an informative model system for the study of phenotypic change under ecological pressure .

Orientational relaxations in solid (1,1,2,2)tetrachloroethane.

We employ dielectric spectroscopy and molecular dynamic simulations to investigate the dipolar dynamics in the orientationally disordered solid phase of (1,1,2,2)tetrachloroethane. Three distinct orientational dynamics are observed as separate dielectric loss features, all characterized by a simply activated temperature dependence. The slower process, associated to a glassy transition at 156 ± 1 K, corresponds to a cooperative motion by which each molecule rotates by 180° around the molecular symmetry axis through an intermediate state in which the symmetry axis is oriented roughly orthogonally to the initial and final states. Of the other two dipolar relaxations, the intermediate one is the Johari-Goldstein precursor relaxation of the cooperative dynamics, while the fastest process corresponds to an orientational fluctuation of single molecules into a higher-energy orientation. The Kirkwood correlation factor of the cooperative relaxation is of the order of one tenth, indicating that the molecular dipoles maintain on average a strong antiparallel alignment during their collective motion. These findings show that the combination of dielectric spectroscopy and molecular simulations allows studying in great detail the orientational dynamics in molecular solids.

Nuclear rDNA pseudogenes in Chagas disease vectors: evolutionary implications of a new 5.8S+ITS-2 paralogous sequence marker in triatomines of North, Central and northern South America.

A pseudogene, paralogous to rDNA 5.8S and ITS-2, is described in Meccus dimidiata dimidiata, M. d. capitata, M. d. maculippenis, M. d. hegneri, M. sp. aff. dimidiata, M. p. phyllosoma, M. p. longipennis, M. p. pallidipennis, M. p. picturata, M. p. mazzottii, Triatoma mexicana, Triatoma nitida and Triatoma sanguisuga, covering North America, Central America and northern South America. Such a nuclear rDNA pseudogene is very rare. In the 5.8S gene, criteria for pseudogene identification included length variability, lower GC content, mutations regarding the functional uniform sequence, and relatively high base substitutions in evolutionary conserved sites. At ITS-2 level, criteria were the shorter sequence and large proportion of insertions and deletions (indels). Pseudogenic 5.8S and ITS-2 secondary structures were different from the functional foldings, different one another, showing less negative values for minimum free energy (mfe) and centroid predictions, and lower fit between mfe, partition function, and centroid structures. A complete characterization indicated a processed pseudogenic unit of the ghost type, escaping from rDNA concerted evolution and with functionality subject to constraints instead of evolving free by neutral drift. Despite a high indel number, low mutation number and an evolutionary rate similar to the functional ITS-2, that pseudogene distinguishes different taxa and furnishes coherent phylogenetic topologies with resolution similar to the functional ITS-2. The discovery of a pseudogene in many phylogenetically related species is unique in animals and allowed for an estimation of its palaeobiogeographical origin based on molecular clock data, inheritance pathways, evolutionary rate and pattern, and geographical spread. Additional to the technical risk to be considered henceforth, this relict pseudogene, designated as "ps(5.8S+ITS-2)", proves to be a valuable marker for specimen classification, phylogenetic analyses, and systematic/taxonomic studies. It opens a new research field, Chagas disease epidemiology and control included, given its potential relationships with triatomine fitness, behaviour and adaptability.

Dynamic heterogeneity in the glass-like monoclinic phases of CBr(n)Cl(4-n), n = 0,1,2.

Glassy dynamics of rigid molecules is still a matter of controversy: the physics behind the relaxation process at time scales faster than that ruled by the viscosity, the so called Johari-Goldstein process, is not known. In this work we unravel the mechanism of such a process by using a simple molecular model in which the centers of mass of the molecules are forming an ordered lattice, and molecular reorientation is performed by jumps between equilibrium orientations. We have studied the dynamics of simple quasi-tetrahedral molecules CBr(n)Cl(4-n), n = 0, 1, 2, in their monoclinic phases by means of dielectric spectroscopy and nuclear quadrupole resonance: the first technique allows to measure in a broad time scale but it is insensitive to molecular particularities, while the second has a restricted time window but senses the movement of each chlorine atom separately. The dynamic picture emerging from these techniques is that the secondary relaxation process is related to the different molecular surroundings around each nonequivalent atom of the molecule. Dynamical heterogeneities thus seem to be the cause of the secondary relaxation in this simple model of glass.

Systematics of Mepraia (Hemiptera-Reduviidae): cytogenetic and molecular variation.

The haematophagous insects of the subfamily Triatominae (Hemiptera-Reduviidae) have great epidemiological importance as vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Mepraia was originally described as a monotypic genus comprised of Mepraia spinolai, distributed along coastal areas of northern Chile (from Region I to the Metropolitan Region). Recently, some M. spinolai populations have been ranked as a new species named Mepraia gajardoi. Several populations along the distribution range of the genus were sampled, and genetic differentiation was studied based upon the analysis of three molecular markers: cytogenetics (karyotype and chromosome behaviour during meiosis using the C-banding technique), mitochondrial DNA (a cytochrome oxidase I gene fragment), and nuclear ribosomal DNA (intergenic region including the two internal transcribed spacers ITS-1 and ITS-2 and the 5.8S rRNA gene). The data here presented indicate that populations within the Mepraia genus (excluding Region II specimens) can be divided into two separate lineages. One lineage is comprised of specimens from the northernmost Region I and represents M. gajardoi. The other includes samples from the southern III, IV and the Metropolitan Regions, and represents M. spinolai. Region II individuals deserve particular attention as their relationship to the two identified lineages is not clear-cut. While they appear to belong to M. spinolai based on cytogenetics and rDNA markers, COI results indicate a closer relationship to M. gajardoi. This disagreement can be due to mitochondrial DNA introgression or the retention of ancestral polymorphisms.

New microscopic mechanism for secondary relaxation in glasses.

The dynamics of simple molecular systems showing glassy properties has been explored by dielectric spectroscopy and nuclear quadrupole resonance (NQR) on the halogenomethanes CBr2Cl2 and CBrCl3 in their low-temperature monoclinic phases. The dielectric spectra display features which correspond to alpha- and beta-relaxation processes, commonly observed in canonical glass formers. NQR experiments, also performed in the ergodic monoclinic phase of CCl4, enable the determination of the microscopic mechanism underlying the beta dynamics in these simple model glasses: Molecules that are nonequivalent with respect to their molecular environment perform reorientational jumps at different time scales. Thus our findings reveal another mechanism that can give rise to typical beta-relaxation behavior, raising some doubt about the existence of a universal explanation of this phenomenon.

Utilidad de la serología rutinaria para el diagnóstico de la infección VIH / How useful is the routine HIV screening?

No disponible

Neuroartropatía diabética / No disponible

No disponible

[Epidemiological study of colorectal cancer in Zamora (Spain): a comparison between the years 1996 and 2003]. / Estudio epidemiológico del cáncer colorrectal en la provincia de Zamora: comparación entre los años 1996 y 2003.

INTRODUCTION: Colorectal cancer (CRC) is one of the most frequent tumors in Western countries. In Spain, widely different rates have been reported for distinct regions. AIM: To determine the epidemiological characteristics of CRC in the province of Zamora in 1996 and 2003 and to identify possible variations in these characteristics in each of these two years. MATERIAL AND METHODS: We performed a descriptive, retrospective study of all cases of CRC diagnosed in the Complejo Asistencial de Zamora in 1996 and 2003. RESULTS: In 1996, 146 patients were diagnosed with CRC, representing an unadjusted and adjusted incidence of 70.85 and 49.40 cases per 10(5) inhabitants. In 2003, 173 patients were diagnosed, representing an unadjusted and adjusted incidence of 86.89 and 58.12 cases per 105 inhabitants. The mean age at diagnosis was 72.08 years in 1996 and 71.15 years in 2003. The mean time to diagnosis was 3.37 months in 1996 and 4.11 in 2003. The mean time to diagnosis in 1996 was 4.35 months in rectal tumors and 2.87 months in colon tumors (p = 0.013). In 2003, the mean time to diagnosis was 4.70 months in rectal tumors and 3.84 months in colon tumors (p = 0.0749). The mean time to diagnosis was 3.56 and 3.83 months in patients living in urban areas and was 3.24 and 4.35 months in those living in rural areas in 1996 and 2003, respectively. More than 65% of the neoplasms were located in the rectum and sigmoid colon, with no differences between the two years. In 1996, 46.1% of the tumors were stage III or IV at diagnosis while in 2003, this percentage increased to 50.9%. In both years, the four basic health areas with the highest rates within the province were Aliste, Carbajales, Carballeda and Corrales. CONCLUSION: CRC is a highly frequent disease in the province of Zamora, especially in some of the western regions. The incidence of CRC was higher in 2003 than in 1996. Most of the tumors were located in the rectum and sigmoid colon. The time from symptom onset to diagnosis was prolonged. A high percentage of tumors were diagnosed in advanced stages.

Estudio epidemiológico del cáncer colorrectal en la provincia de Zamora: comparación entre los años 1996 y 2003 / Epidemiological study of colorectal cancer in Zamora (Spain): a comparison between the years 1996 and 2003

Introducción: El cáncer colorrectal (CCR) es uno de los tumores más frecuentes en los países occidentales. En España se han comunicado tasas muy diferentes en distintas regiones. El objetivo del presente estudio ha sido conocer las características del CCR en la provincia de Zamora en los años 1996 y 2003, evaluando si existen variaciones en las características epidemiológicas en estos 2 años. Material y métodos: Se ha realizado un estudio descriptivo, retrospectivo, de todos los casos diagnosticados en el Complejo Asistencial de Zamora en los años 1996 y 2003. Resultados: En el año 1996, se diagnosticó de CCR a 146 pacientes, con una tasa bruta de 70,85 casos/105 habitantes. En el año 2003, se diagnosticó a 173 enfermos, con una tasa bruta de 86,89 casos/105 habitantes. Las tasas ajustadas fueron de 49,40 casos/105 habitantes en 1996 y de 58,12 casos/105 habitantes en 2003. La edad media en el momento del diagnóstico fue de 72,08 años en 1996 y de 71,15 en 2003. En el año 1996, el tiempo medio de diagnóstico fue de 3,37 meses, que ascendió hasta 4,11 meses en 2003. El tiempo medio de diagnóstico de los tumores rectales en el año 1996 fue de 4,35 meses, y el de los tumores de colon, de 2,87 meses (p = 0,013). En 2003, las neoplasias rectales se diagnostican en 4,70 meses de media y las de colon, en 3,84 meses (p = 0,0749). En el año 1996, el tiempo medio de diagnóstico fue de 3,56 meses en pacientes que vivían en medio urbano y de 3,24 meses en los del medio rural, mientras que en 2003 fue de 3,83 meses en el primer caso y de 4,35 en el segundo. Más del 65% de las neoplasias se asentó en el recto y el sigma, situación que ocurrió por igual en ambos años estudiados. El 46,1% de los tumores se diagnosticó en estadios III y IV en el año 1996, porcentaje que amumentó en el año 2003 hasta el 50,9%. Aliste, Carbajales, Carballeda y Corrales son las 4 zonas básicas de salud con tasas más altas dentro de la provincia en ambos años. Conclusión: El CCR es muy frecuente en nuestra provincia, fundamentalmente en algunas comarcas de la franja oeste. Su incidencia aumentó en el año 2003 en comparación con 1996. La mayoría de las neoplasias se asientan en el recto y elsigma. El tiempo que transcurre desde el comienzo de los síntomas hasta su diagnóstico es muy prolongado. En un gran porcentaje de tumores, el diagnóstico se realiza en estadios avanzados

Introduction: Colorectal cancer (CRC) is one of the most frequent tumors in Western countries. In Spain, widely different rates have been reported for distinct regions. Aim: To determine the epidemiological characteristics of CRC in the province of Zamora in 1996 and 2003 and to identify possible variations in these characteristics in each of these two years. Material and methods: We performed a descriptive, retrospective study of all cases of CRC diagnosed in the Complejo Asistencial de Zamora in 1996 and 2003. Results: In 1996, 146 patients were diagnosed with CRC, representing an unadjusted and adjusted incidence of 70.85 and 49.40 cases per 105 inhabitants. In 2003, 173 patients were diagnosed, representing an unadjusted and adjusted incidence of 86.89 and 58.12 cases per 105 inhabitants. The mean age at diagnosis was 72.08 years in 1996 and 71.15 years in 2003. The mean time to diagnosis was 3.37 months in 1996 and 4.11 in 2003. The mean time to diagnosis in 1996 was 4.35 months in rectal tumors and 2.87 months in colon tumors (p = 0.013). In 2003, the mean time to diagnosis was 4.70 months in rectal tumors and 3.84 months in colon tumors (p = 0.0749). The mean time to diagnosis was 3.56 and 3.83 months in patients living in urban areas and was 3.24 and 4.35 months in those living in rural areas in 1996 and 2003, respectively. More than 65% of the neoplasms were located in the rectum and sigmoid colon, with no differences between the two years. In 1996, 46.1% of the tumors were stage III or IV at diagnosis while in 2003, this percentage increased to 50.9%. In both years, the four basic health areas with the highest rates within the province were Aliste, Carbajales, Carballeda and Corrales. Conclusion: CRC is a highly frequent disease in the province of Zamora, especially in some of the western regions. The incidence of CRC was higher in 2003 than in 1996. Most of the tumors were located in the rectum and sigmoid colon. The time from symptom onset to diagnosis was prolonged. A high percentage of tumors were diagnosed in advanced stages