839 research outputs found

    Leaves of more cold hardy grapes have a higher density of small, sunken stomata

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    Leaf stomatal density, index and size are known to be affected by the growing conditions, presumably to provide a better function for plant development. The question was whether there is a difference in stomatal parameters between grape species with different cold hardiness: V. riparia and V. vinifera; and the V. vinifera cultivars 'Riesling', 'Chardonnay', 'Sauvignon Blanc' and 'Merlot'. Analysis by scanning electron microscopy allowed the observation of 3 types of stomata in developing and mature leaves of all examined grape leaves. Stomatal parameters were found to be significantly affected by species or cultivar and growing conditions but not rootstock. A higher stomatal density and index were determined for the more cold hardy V. riparia and V. vinifera 'Riesling', whereby the higher number of stomata in 'Riesling' was found to be due to a higher number of small, sunken stomata. These findings might indicate a strategy of grape plants to optimize growth under low temperatures by using fast-acting stomata whose gas and water exchange are less affected than for larger stomata

    Identification, analysis, and linkage mapping of expressed sequence tags from the Australian sheep blowfly

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    Background: The Australian sheep blowfly Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) is a destructive pest of the sheep, a model organism for insecticide resistance research, and a valuable tool for medical and forensic professionals. However, genomic information on L. cuprina is still sparse.Results: We report here the construction of an embryonic and 2 larval cDNA libraries for L. cuprina. A total of 29,816 expressed sequence tags (ESTs) were obtained and assembled into 7,464 unique clusters. The sequence collection captures a great diversity of genes, including those related to insecticide resistance (e.g., 12 cytochrome P450s, 2 glutathione S transferases, and 6 esterases). Compared to Drosophila melanogaster, codon preference is different in 13 of the 18 amino acids encoded by redundant codons, reflecting the lower overall GC content in L. cuprina. In addition, we demonstrated that the ESTs could be converted into informative gene markers by capitalizing on the known gene structures in the model organism D. melanogaster. We successfully assigned 41 genes to their respective chromosomes in L. cuprina. The relative locations of these loci revealed high but incomplete chromosomal synteny between L. cuprina and D. melanogaster.Conclusions: Our results represent the first major transcriptomic undertaking in L. cuprina. These new genetic resources could be useful for the blowfly and insect research community

    Enhanced firing of locus coeruleus neurons and SK channel dysfunction are conserved in distinct models of prodromal Parkinson's disease

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    Parkinson’s disease (PD) is clinically defined by the presence of the cardinal motor symptoms, which are associated with a loss of dopaminergic nigrostriatal neurons in the substantia nigra pars compacta (SNpc). While SNpc neurons serve as the prototypical cell-type to study cellular vulnerability in PD, there is an unmet need to extent our efforts to other neurons at risk. The noradrenergic locus coeruleus (LC) represents one of the first brain structures affected in Parkinson’s disease (PD) and plays not only a crucial role for the evolving non-motor symptomatology, but it is also believed to contribute to disease progression by efferent noradrenergic deficiency. Therefore, we sought to characterize the electrophysiological properties of LC neurons in two distinct PD models: (1) in an in vivo mouse model of focal α-synuclein overexpression; and (2) in an in vitro rotenone-induced PD model. Despite the fundamental differences of these two PD models, α-synuclein overexpression as well as rotenone exposure led to an accelerated autonomous pacemaker frequency of LC neurons, accompanied by severe alterations of the afterhyperpolarization amplitude. On the mechanistic side, we suggest that Ca(2+)-activated K(+) (SK) channels are mediators of the increased LC neuronal excitability, as pharmacological activation of these channels is sufficient to prevent increased LC pacemaking and subsequent neuronal loss in the LC following in vitro rotenone exposure. These findings suggest a role of SK channels in PD by linking α-synuclein- and rotenone-induced changes in LC firing rate to SK channel dysfunction
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