Aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is a polyphagous insect species that migrates into the upper Midwest of the United States and the Western Canadian Prairies. Populations of this insect are associated with the transmission of a plant pathogen (Candidatus Phytoplasma asteris, 16SrI) to several annual crops and perennial plant species. Previous studies suggest that aster leafhoppers can sometimes prefer less suitable hosts for their development and survival, yet it is unclear if this lower performance on certain plant species is associated with reduced or impaired probing behaviors due to characteristics of the plants.
View Article and Find Full Text PDFIn plant-microbe-insect systems, plant-mediated responses involve the regulation and interactions of plant defense signaling pathways of phytohormones jasmonic acid (JA), ethylene (ET), and salicylic acid (SA). Phytoplasma subgroup 16SrI is the causal agent of Aster Yellows (AY) disease and is primarily transmitted by populations of aster leafhoppers (Macrosteles quadrilineatus Forbes). Aster Yellows infection in plants is associated with the downregulation of the JA pathway and increased leafhopper oviposition.
View Article and Find Full Text PDFPolyphagous insects are characterized by a broad diet comprising plant species from different taxonomic groups. Within these insects, migratory species are of particular interest, given that they encounter unpredictable environments, with abrupt spatial and temporal changes in plant availability and density. Aster leafhoppers (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) arrive in the Canadian Prairies in spring and early summer and are the main vector of a prokaryotic plant pathogen known as Aster Yellows Phytoplasma (AYp) (Candidatus Phytoplasma asteris).
View Article and Find Full Text PDFSome plant pathogens are capable of manipulating their insect vectors and plant hosts in a way that disease transmission is enhanced. Aster leafhopper (Macrosteles quadrilineatus Forbes) (Hemiptera: Cicadellidae) is the main vector of Aster Yellows Phytoplasma (Candidatus Phytoplasma asteris) in the Canadian Prairies, which causes Aster Yellows (AY) disease in over 300 plant species including cereals and oilseeds. However, little is known about the host range of Aster leafhoppers or their host-choice selection behavior in this geographical region.
View Article and Find Full Text PDFBrain imaging studies with PET, SPECT, functional magnetic resonance imaging, and spectroscopy provide evidence of prefrontal dysfunction in schizophrenia. Dysfunction of the prefrontal cortex is associated with cognitive impairment and negative symptoms. Combined multimodal imaging shows that a developmentally early disturbance of frontotemporal-limbic neuronal networks is associated with a disinhibition of subcortical dopaminergic neurotransmission.
View Article and Find Full Text PDFBackground And Purpose: Using perfusion- and diffusion-weighted MR imaging in acute ischemic stroke of the middle cerebral artery (MCA), previous studies have shown a typical pathophysiologic pattern that is characterized by a perfusion deficit larger than the diffusion lesion (mismatch), with the final lesion usually comprising the initial diffusion lesion (core) plus parts of the initial mismatch area. Little is known about underlying pathophysiology in small ischemic stroke. In this study, we used perfusion- and diffusion-weighted MR imaging to investigate the underlying pathophysiology of small subcortical ischemia.
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