Spatial population genetic structure reveals strong natal site fidelity in Echinocladius martini (Diptera: Chironomidae) in northeast Queensland, Australia

1. A diverse array of patterns has been reported regarding the spatial extent of population genetic structure and effective dispersal in freshwater macroinvertebrates. In river systems, the movements of many taxa can be restricted to varying degrees by the natural stream channel hierarchy. 2. In this study, we sampled populations of the non-biting freshwater midge Echinocladius martini in the Paluma bioregion of tropical northeast Queensland to investigate fine scale patterns of within- and among-stream dispersal and gene flow within a purported historical refuge. We amplified a 639 bp fragment of mitochondrial COI and analysed genetic structure using pairwise ΦST, hierarchical AMOVA, Mantel tests and a parsimony network. Genetic variation was partitioned among stream sections using Streamtree to investigate the effect of potential instream dispersal barriers. 3. The data revealed strong natal site fidelity and significant differentiation among neighbouring, geographically proximate streams. We found evidence for only episodic adult flight among sites on separate stream reaches. Overall, however, our data suggested that both larval and adult dispersal was largely limited to within a stream channel. 4. This may arise from a combination of the high density of riparian vegetation physically restricting dispersal and from the joint effects of habitat stability and large population sizes. Together these may mitigate the requirement for movement among streams to avoid inbreeding and local extinction due to habitat change and may thus enable persistence of upstream populations in the absence of regular compensatory upstream flight. Taken together, these data suggest that dispersal of E. martini is highly restricted, to the scale of only a few kilometres, and hence occurs predominantly within the natal stream.

Alteraciones escolares de la lecto-escritura.

Construcción de las distintas etiopatologías que explican las alteraciones lecto-gráficas. Estudio de la dislexia desde una óptica eminentemente psicopedagógica. 205 niños de la primera etapa de la EGB (102 pertenecen a la clase media alta; 103 pertenecen a la clase baja). Población: niños de la primera etapa de EGB de Oviedo. Tipo muestreo: aleatorio estratificado. Diseño factorial. Factores estudiados: neurológicos (percepciones sensoriales - procesos analíticos y sintéticos); psicológicos (memoria visual y auditiva inteligencia - lenguaje oral - afectividad y personalidad psicomotricidad); sociales (reforzamiento social - clima motivacional familiar). Estudio de 38 casos seleccionados, por el porcentaje de faltas y por el tipo de faltas, que ofrecen rasgos típicos de alteraciones léxicas y que clasifica como niños con trastornos en los aprendizajes de lectura y escritura. Variables estudiadas: grado de madurez de la percepción viso-motora; problemas emocionales; variables aptitudinales (verbal, perceptivo - manipulativo, numérico, general cognoscitivo, memoria, motricidad). Tests de inteligencia general: test de Raven-matrices progresivas escala en color (para los dos primeros cursos de EGB) y test de aptitudes escolares-tea 1 (para los cursos tercero y cuarto de EGB). Test para las pruebas de lectura y escritura TALE, Test de análisis y síntesis de la lecto-escritura de Montserrat Cervera y José Toro. Escalas MC Carthy de aptitudes y psicomotricidad (permite obtener puntuaciones de diferentes conductas gnósicas y motoras). Test de Bender infantil (test guestaltico visomotor para niños). Los factores neurológicos (percepción sensorial auditivo-visual, madurez neurológica) y los factores psicológicos (memoria visual-auditiva, propiedades topológicas de espacio y tiempo, psicomotricidad, lenguaje oral, afectividad y personalidad) son, según el autor, los más fundamentales a la hora de explicar las alteraciones de lectura y escritura. La inteligencia es un factor importante e inserto en los aprendizajes de lecto-grafía pero no puede considerarse a la inteligencia como factor único en la explicación de ciertos problemas lecto-gráficos. Existe una mayor relación entre inteligencia y escritura que entre inteligencia y lectura. La procedencia o extracción social influye decisivamente en los aprendizajes lecto-gráficos. En la investigación experimental no se estudian los factores pedagógicos y su incidencia en las alteraciones de lectura-escritura, pero considera que por su importancia se merecen una investigación aparte. Los factores sociales son estudiados únicamente en base a la distinta extracción social de los grupos en que se divide la muestra, pero también precisan un estudio mucho más profundo debido a las relaciones que el factor social y familiar tienen con las alteraciones en la lecto-escritura.

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients

OBJECTIVE: The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients. METHODS: Twenty male chronic obstructive pulmonary disease patients (66.2 +/- 8.3 years old, FEV1: 49.3 +/- 19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion. ClinicalTrials.gov: NCT00500864 RESULTS: Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l). CONCLUSIONS: The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.