Functional diversity for body actions in the mesencephalic locomotor region

1. Download : Download high-res image (240KB)
2. Download : Download full-size image

     

Use of Heteroduplex Mobility Analysis (HMA) for Differentiating Phytoplasma Isolates Causing Witches' Broom Disease on Populus nigra cv Italica and Stolbur or Big Bud Symptoms on Tomato

Heteroduplex mobility analysis (HMA) was performed to distinguish French and German isolates of phytoplasmas from Populus nigra cv Italica witches broom. The French isolate was similar to the phytoplasma responsible for the European aster yellows while the German isolate was different but closely related to it. When phytoplasmas inducing similar "stolbur" symptoms in tomato were compared to HMA, a high degree of genetic differences was observed among the reference stolbur C (StC) isolate, the European aster yellows and the other phytoplasmas inducing stolbur or big bud symptoms in tomato. Pseudo-stolbur B and D from Brazil were differentiated from the reference St C using this method.     

First Characterization of 6-Hydroxytryptamine in the Rat Midbrain by Using Specific Antibodies

The visualization of serotonin, 5-methoxytryptamine, and tryptamine in the rat midbrain has been made possible by the development of antibodies raised against these conjugated molecules. It has been suggested that 6-hydroxytryptamine (6-HT) might also be a neurotransmitter in this region. To test this hypothesis, 6-HT was synthesized and antibodies were raised in the rabbit. The high avidity (IC50 = 5 x 10(-9) M) and specificity [cross-reactivity ratio between 6-HT-glutaraldehyde (G)-bovine serum albumin (BSA) and 5-HT-G-BSA, the most immunoreactive compound, was 1,500] rendered these antibodies reliable tools for specific molecular detection of 6-HT in the G-fixed tissues. In the dopaminergic region, 6-HT immunoreactivity was noted in the substantia nigra but was particularly intense in the red nuclei, where it seems to be localized in the magnocellular division in the form of large 6-HT neurons. In contrast, there were few 6-HT neurons in the raphe nuclei. Thus, 6-HT may be a new putative neurotransmitter existing in the red nuclei, in addition to the other neurotransmitters already described in this region, in the nigro-rubral pathway, and in the rubral projection from the dorsal raphe nuclei. 6-HT is possibly implicated in motor control and might exert hallucinogenic properties as do other 6-hydroxylated indoleamines.     

Submergence of black ash logs to control emerald ash borer and preserve wood for American Indian basketmaking

相似文献   

Progressive brain metabolic changes under deep brain stimulation of subthalamic nucleus in parkinsonian rats

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an efficient neurosurgical treatment for advanced Parkinson's disease. Non‐invasive metabolic neuroimaging during the course of DBS in animal models may contribute to our understanding of its action mechanisms. Here, DBS was adapted to in vivo proton magnetic resonance spectroscopy at 11.7 T in the rat to follow metabolic changes in main basal ganglia structures, the striatum, and the substantia nigra pars reticulata (SNr). Measurements were repeated OFF and ON acute and subchronic (7 days) STN‐DBS in control and parkinsonian (6‐hydroxydopamine lesion) conditions. Acute DBS reversed the increases in glutamate, glutamine, and GABA levels induced by the dopamine lesion in the striatum but not in the SNr. Subchronic DBS normalized GABA in both the striatum and SNr, and glutamate in the striatum. Taurine levels were markedly decreased under subchronic DBS in the striatum and SNr in both lesioned and unlesioned rats. Microdialysis in the striatum further showed that extracellular taurine was increased. These data reveal that STN‐DBS has duration‐dependent metabolic effects in the basal ganglia, consistent with development of adaptive mechanisms. In addition to counteracting defects induced by the dopamine lesion, prolonged DBS has proper effects independent of the pathological condition.

     

Ephrin‐A5 regulates the formation of the ascending midbrain dopaminergic pathways

Dopaminergic neurons from the substantia nigra and the ventral tegmental area of the midbrain project to the caudate/putamen and nucleus accumbens, respectively, establishing the mesostriatal and the mesolimbic pathways. However, the mechanisms underlying the development of these pathways are not well understood. In the current study, the EphA5 receptor and its corresponding ligand, ephrin‐A5, were shown to regulate dopaminergic axon outgrowth and influence the formation of the midbrain dopaminergic pathways. Using a strain of mutant mice in which the EphA5 cytoplasmic domain was replaced with β‐galactosidase, EphA5 protein expression was detected in both the ventral tegmental area and the substantia nigra of the midbrain. Ephrin‐A5 was found in both the dorsolateral and the ventromedial regions of the striatum, suggesting a role in mediating dopaminergic axon‐target interactions. In the presence of ephrin‐A5, dopaminergic neurons extended longer neurites in in vitro coculture assays. Furthermore, in mice lacking ephrin‐A5, retrograde tracing studies revealed that fewer neurons sent axons to the striatum. These observations indicate that the interactions between ephrin‐A ligands and EphA receptors promote growth and targeting of the midbrain dopaminergic axons to the striatum. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2009     

The value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean members of the genus Pinus

This study reports the value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean species of the genus Pinus (P. nigra subsp. salzmannii, P. pinaster, P. pinea and P. halepensis), with the aim of using these characters to identify isolated cuticles and stomata in palynology slides. Preparations were made of the cuticles of pine needles belonging to one natural Iberian population of each of the above species. A number of epidermal morphological characteristics were then recorded with the aim of distinguishing these species from one another. The structure of the stomatal complex (the shape and arrangement of the subsidiary cells) was different in each species. The aperture of the epistomatal chamber was significantly smaller in P. pinea than in the other species examined, and the variables recorded for the thickening of the guard cells provided relationships that clearly distinguished all four taxa. The width and length of the stomata and the upper woody lamellae, the central distance between the external limits of the medial lamellae borders and the length of the stem were the most useful variables in this respect. The present results contribute to the ongoing discussion regarding the taxonomic classification of the members of Pinus, and provide valuable clues for the identification of Iberian Mediterranean pine species from small pine needle fragments or isolated stomata. After validation of the present results for multiple populations, these results could also be used to help identify fossil leaf macroremains and the scattered/isolated stomata commonly observed in palaeopalynological samples. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 436–448.     

The DRD2 TaqIA polymorphism associated with changed midbrain volumes in healthy individuals

The human DRD2 gene is located on chromosome 11q22-q23 and contains one specific functional polymorphism called TaqIA, which characteristically presents two alleles referred to as A1 and A2. Evidence indicates that the A1 allele impacts brain dopaminergic function and may confer an increased risk of developing Parkinson's disease. However, possible morphological changes underlying such genetic variant remain to be clarified. The aim of this study was to provide an in vivo demonstration of changes in brain structures associated with the TaqIA polymorphism of the DRD2 gene. Optimized voxel-based morphometry (VBM) was applied to high-resolution MR brain images of 70 healthy controls divided into two groups according to their DRD2 genotype (A1/A2, n = 15; A2/A2, n = 55). Compared with individuals' homozygous for the A2 allele, the A1 carriers had significantly smaller areas of a specific part of the midbrain, encompassing the substantia nigra bilaterally. Our findings showed an association of the DRD2 TaqIA polymorphism with the changed volumes of a specific subcortical region strongly involved in the dopaminergic system.     

A single intramuscular injection of rAAV‐mediated mutant erythropoietin protects against MPTP‐induced parkinsonism

Erythropoietin (Epo) is neuroprotective in a number of preparations, but can lead to unacceptably high and even lethal hematocrit levels. Recent reports show that modified Epo variants confer neuroprotection in models of glaucoma and retinal degeneration without raising hematocrit. In this study, neuroprotective effects of two Epo variants (EpoR76E and EpoS71E) were assessed in a model of Parkinson's disease. The constructs were packaged in recombinant adeno‐associated viral (rAAV) vectors and injected intramuscularly. After 3 weeks, mice received five daily injections of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) and were killed 5 weeks later. The MPTP‐lesioned mice pretreated with rAAV.eGFP (negative control) exhibited a 7‐ to 9‐Hz tremor and slower latencies to move on a grid test (akinesia). Both of these symptomatic features were absent in mice pretreated with either modified Epo construct. The rAAV.eGFP‐treated mice lesioned with MPTP exhibited a 41% reduction in tyrosine hydroxylase (TH)‐positive neurons in the substantia nigra. The rAAV.EpoS71E construct did not protect nigral neurons, but neuronal loss in mice pretreated with rAAV.EpoR76E was only half that of rAAV.eGFP controls. Although dopamine levels were normal in all groups, 3,4‐dihydroxyphenylacetic acid (DOPAC) was significantly reduced only in MPTP‐lesioned mice pretreated with rAAV.eGFP, indicating reduced dopamine turnover. Analysis of TH‐positive fibers in the striatum showed normalized density in MPTP‐lesioned mice pretreated with rAAV.EpoS71E, suggesting that enhanced sprouting induced by EpoS71E may have been responsible for normal behavior and dopaminergic tone in these mice. These results show that systemically administered rAAV‐generated non‐erythropoietic Epo may protect against MPTP‐induced parkinsonism by a combination of neuroprotection and enhanced axonal sprouting.