920 resultados para Colectivos juveniles


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La “red de encierre activada por buzos” o “bolichito de fondo” es un arte de pesca que por sus características técnicas y de operación es clasificado como no determinado y no reglamentado. Se realizó una evaluación técnica de este arte de pesca, que indica que su cobertura espacial está limitada a la capacidad de buceo, restringida a zonas muy someras, presenta baja respuesta de selectividad y alto poder de pesca al compararla con otras artes de pesca artesanales utilizadas en la misma área costera; tiene elevada extracción de juveniles y de fauna acompañante los que generalmente están en mayores porcentajes de estadios inmaduros (II) y maduración inicial (III). Se recomienda prohibir su uso.

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The sugar beet cyst nematode, Heterodera schachtii, is a major agricultural pest. The disruption of the mating behaviour of this plant parasite in the field may provide a means of biological control, and a subsequent increase in crop yield. The H. schachtii female sex pheromone, which attracts homospecific males, was collected in an aqueous medium and isolated using high performance liquid chromatography. Characterization of the male-attractive material revealed that it was heat stable and water soluble. The aqueous medium conditioned by female H. schachtii was found to be biologically active and stimulated male behaviour in a concentration dependent manner. The activity of the crude pheromone was specific to males of H. schachtii and did not attract second stage juveniles. Results indicated that vanillic acid, a putative nematode pheromone, is not an active component of the H. schachtii sex pheromone. Male H. schachtii exhibited stylet thrusting, a poorly understood behaviour of the male, upon exposure to the female sex pheromone. This behaviour appeared to be associated with mate-finding and was used as a novel indicator of biological activity in bioassays. Serotonin, thought to be involved in the neural control of copulatory behaviour in nematodes, stimulated stylet thrusting. However, the relationship between stylet thrusting induced by the sex pheromone and stylet thrusting induced by serotonin is not clear. Extracellular electrical activity was recorded fi-om the anterior region of H. schachtii males during stylet thrusting, and appeared to be associated with this behaviour. The isolation of the female sex pheromone of H. schachtii may, ultimately, lead to the structural identification and synthesis of the active substance for use in a novel biological control strategy.

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Tesis ( Maestría en Derecho Laboral ) U.A.N.L.

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Tesis ( Maestro en Ciencias de la Administración con Especialidad en Producción y Calidad) - U.A.N.L., 2002

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Tesis (Maestría en Derecho del Trabajo ) U.A.N.L.

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Tesis (Maestría en Derecho Laboral) U.A.N.L.

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Tesis ( Maestría en Derecho Laboral ) U.A.N.L.

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[Tesis] ( Maestría en Derecho Laboral ) U.A.N.L.

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[Tesis] ( Maestría en Derecho Laboral ) U.A.N.L.

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Tesis (Maestría en Derecho Laboral) U.A.N.L.

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Tesis (Maestro en Derecho Laboral) U.A.N.L.

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UANL

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UANL

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UANL