14 research outputs found
Dysfunctional Light-Evoked Regulation of cAMP in Photoreceptors and Abnormal Retinal Adaptation in Mice Lacking Dopamine D4 Receptors
Dopamine is a retinal neuromodulator that has been implicated in many aspects of retinal physiology. Photoreceptor cells express dopamine D4 receptors that regulate cAMP metabolism. To assess the effects of dopamine on photoreceptor physiology, we examined the morphology, electrophysiology, and regulation of cAMP metabolism in mice with targeted disruption of the dopamine D4 receptor gene. Photoreceptor morphology and outer segment disc shedding after light onset were normal in D4 knock-out (D4KO) mice. Quinpirole, a dopamine D2/ D3/D4 receptor agonist, decreased cAMP synthesis in retinas of wild-type (WT) mice but not in retinas of D4KO mice. In WT retinas, the photoreceptors of which were functionally isolated by incubation in the presence of exogenous glutamate, light also suppressed cAMP synthesis. Despite the similar inhibition of cAMP synthesis, the effect of light is directly on the photoreceptors and independent of dopamine modulation, because it was unaffected by application of the D4 receptor antagonist L-745,870. Nevertheless, compared with WT retinas, basal cAMP formation was reduced in the photoreceptors of D4KO retinas, and light had no additional inhibitory effect. The results suggest that dopamine, via D4 receptors, normally modulates the cascade that couples light responses to adenylyl cyclase activity in photoreceptor cells, and the absence of this modulation results in dysfunction of the cascade. Dark-adapted electroretinogram (ERG) responses were normal in D4KO mice. However, ERG b-wave responses were greatly suppressed during both light adaptation and early stages of dark adaptation. Thus, the absence of D4 receptors affects adaptation, altering transmission of light responses from photoreceptors to inner retinal neurons. These findings indicate that dopamine D4 receptors normally play a major role in regulating photoreceptor cAMP metabolism and adaptive retinal responses to changing environmental illumination.Fil: Nir, Izhak. The University of Texas Health Science Center; Estados UnidosFil: Harrison, Joseph M.. The University of Texas Health Science Center; Estados UnidosFil: Haque, Rashidul. Emory University School of Medicine; Estados UnidosFil: Low, Malcolm J.. Oregon Health and Science University; Estados UnidosFil: Grandy, David K.. Oregon Health and Science University; Estados UnidosFil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Iuvone, P. Michael. Emory University School of Medicine; Estados Unido
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Three Decades of Satisfied Israeli Farmers: Barn Owls (Tyto alba) as Biological Pest Control of Rodents
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Three Decades of Satisfied Israeli Farmers: Barn Owls (Tyto alba) as Biological Pest Control of Rodents
Compared to the use of invertebrate as biological pest control of agents of invertebrate pests, the use of vertebrates as biological pest control agents against other vertebrates is less common due to difficulties in manipulating and increasing their populations. Barn owls have been used as biological control agents in different countries, including Israel, which initiated the project in 1982 and as of 2017 has a total of 3,250 nest boxes deployed in the country. Our aim here was to determine whether farmer satisfaction/dissatisfaction response to a survey on the effectiveness of the barn owl project is related to the number of nest boxes and breeding barn owl pairs that the farmers have in their fields; and whether farmers deploy nest boxes as a result of previous rodent damage in their fields. We found that farmers that had incurred rodent damage both used more rodenticides and also installed more nest-boxes (and consequently had more breeding barn owls) than those who reported a lack of damage. Farmers who were satisfied using barn owls had more nest boxes and hence more breeding barn owls, and reported that rodent damage had decreased during the project, as compared to farmers who were not satisfied with the project. The number of nest boxes added to agricultural fields is growing yearly, both due to scientific and national projects and because farmers in Israel purchase nest boxes independently, indicating their belief in the project