A Real-Time Quantitative PCR Assay for the Detection of Sphaeropsis sapinea from Inoculated Pinus nigra Shoots

Pinus nigra (Austrian pine) is a tree widely planted in central and southern Europe in the reforestation of areas with poor soils. One of the major constrains of P. nigra is a fungal disease caused by Sphaeropsis sapinea which causes shoot tip dieback and tree mortality. This paper describes a real‐time quantitative PCR assay based on the partial sequence of the small subunit ribosomal RNA of S. sapinea to detect and quantify DNA of the fungal pathogen in S. sapinea inoculated shoots. The study found that real‐time quantitative PCR was a reliable technique to diagnose this disease and suggests that it can also be used to study fungal behaviour in host tissue and particularly to quantify fungal growth in the latent or endophytic phase.     

Seed supply, drought, and grazing determine spatio-temporal patterns of recruitment for native and introduced invasive pines in grasslands

Aim The rate of grassland invasion by trees depends on the ability of the species to invade, i.e. their invasiveness, and on the susceptibility of the environments to invasion, i.e. their invasibility. Knowledge of the invasiveness of native and introduced tree species and of the environmental factors that contribute to invasibility is necessary to understand landscape evolution and assess required management measures. Our main aim was to explore this by estimating the separate effects of propagule pressure and environmental factors on the spatio‐temporal patterns of sapling recruitment, a key stage in the tree life cycle. Location Causse Mejean calcareous plateau (southern France). Methods The effects of seed supply and environmental variables (grazing, geological substrate, and duration or intensity of drought) on the spatio‐temporal patterns of sapling recruitment were assessed for the native Scots pine (Pinus sylvestris L.) and the introduced black pine (Pinus nigra Arn. ssp. nigra). Estimates were derived by inverse modelling with data of locations and ages of 4‐ to 20‐year‐old saplings and seed‐bearing trees in 32 sites. Yearly indices of drought were derived from a soil–water content model. Results For both species, seed supply was as important as the whole set of environmental factors in explaining sapling recruitment rates. Grazing and the duration of drought from July to August decreased sapling recruitment rates, which were also lower on hard limestone than on dolomite. Dispersal distances and effective fecundities were higher for the introduced P. nigra, which was less susceptible to drought but more affected by grazing than the native P. sylvestris. In grazed grasslands, shrubs facilitated sapling establishment of both species. Main conclusions This study shows how seed supply and environmental factors shape spatio‐temporal patterns of sapling recruitment for trees invading grasslands. Implications for landscape evolution and management, of the difference in invasiveness of the two pine species and of the hierarchy of environmental factors in determining invasibility, are discussed.     

黄猄蚁对橡胶盔蚧种群消长的影响

调查西双版纳地区黄猄蚁OecophyllasmaragdinaFabricius对橡胶盔蚧Parasaissetianigra(Nietner)种群数量和寄生蜂的影响。结果表明:黄猄蚁对橡胶盔蚧种群消长及寄生蜂均有影响。"有蚂蚁"枝条上介壳虫种群数量显著高于"无蚂蚁"枝条。"有蚂蚁"枝条介壳虫死亡率和寄生蜂都显著低于"无蚂蚁"枝条。说明黄猄蚁的存在影响了橡胶树介壳虫的种群繁殖率和死亡率。建议在今后综合防治中,充分利用蚂蚁与橡胶树介壳虫关系。通过驱逐橡胶树上的蚂蚁来有效遏制介壳虫的发生。     

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.     

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     

Erythropoietin protects against 6-hydroxydopamine-induced dopaminergic cell death

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the death of midbrain dopaminergic neurons. In the present study, erythropoietin, a trophic factor that has both hematopoietic and neural protective characteristics, was investigated for its capacity to protect dopaminergic neurons in experimental Parkinson's disease. Using both the dopaminergic cell line, MN9D, and primary dopamine neurons, we show that erythropoietin (1-3 U/mL) is neuroprotective against the dopaminergic neurotoxin, 6-hydroxydopamine. Protection was mediated by the erythropoietin receptor, as neutralizing anti-erythropoietin receptor antibody abrogated the protection. Activation of Akt/protein kinase B (PKB), via the phosphoinositide 3-kinase pathway, is a critical mechanism in erythropoietin-induced protection, while activation of extracellular signal-regulated kinase (ERK)1/2 contributes only moderately. Indeed, transfection of constitutively active Akt/PKB into dopaminergic cells was sufficient to protect against cell death. Furthermore, erythropoietin diminished markers of apoptosis in MN9D cells, including caspase 9 and caspase 3 activation and internucleosomal DNA fragmentation, suggesting that erythropoietin interferes with the apoptosis-execution process. When erythropoietin was administered to mice unilaterally lesioned with 6-hydroxydopamine, it prevented the loss of nigral dopaminergic neurons and maintained striatal catecholamine levels for at least 8 weeks. Erythropoietin-treated mice also had significantly reduced behavioral asymmetries. These studies suggest that erythropoietin can be an effective neuroprotective agent for dopaminergic neurons, and may be useful in reversing behavioral deficits associated with Parkinson's disease.     

色钉菇粗多糖对小鼠DA能神经元MPTP损伤的保护作用

以C57BL/6J小鼠为实验材料,研究色钉菇粗多糖对多巴胺能神经元损伤的保护作用,并用体外实验方法测定其抗氧化活性。用MPTP（1-甲基-4-苯基-1,2,3,6-四氢吡啶）方法复制了帕金森病小鼠模型,模型复制前,预先给予小鼠100mg/kg、200mg/kg、400mg/kg不同剂量的色钉菇粗多糖,通过行为学检测方法和免疫组化技术观察小鼠的行为变化以及黑质中多巴胺能神经元的数量变化;用抑制小鼠肝脂质过氧化能力的方法测定色钉菇粗多糖的抗氧化活性。结果显示,预先给予200mg/kg和400mg/kg剂量的色钉菇粗多糖能显著地改善帕金森病模型小鼠的行为症状,并能显著地降低MPTP所致的小鼠多巴胺能神经元的凋亡,这可能与该多糖的抗氧化活性有关。提示色钉菇多糖有开发成防治帕金森病药物的应用前景。     

Androgens exacerbate motor asymmetry in male rats with unilateral 6-hydroxydopamine lesion

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopamine neuron loss in the nigrostriatal pathway that shows greater incidence in men than women. The mechanisms underlying this gender bias remain elusive, although one possibility is that androgens may increase dopamine neuronal vulnerability to oxidative stress. Motor impairment can be modeled in rats receiving a unilateral injection of 6-hydroxydopamine (6-OHDA), a neurotoxin producing nigrostriatal degeneration. To investigate the role of androgens in PD, we compared young (2 months) and aged (24 months) male rats receiving gonadectomy (GDX) and their corresponding intact controls. One month after GDX, rats were unilaterally injected with 6-OHDA, and their motor impairment and asymmetry were assessed 2 weeks later using the cylinder test and the amphetamine-induced rotation test. Plasma samples were also collected to assess the concentration of testosterone and advanced oxidation protein products, a product of oxidative stress. GDX decreased lesion-induced asymmetry along with oxidative stress and increased amphetamine-induced rotations. These results show that GDX improves motor behaviors by decreasing motor asymmetry in 6-OHDA-treated rats, an effect that may be ascribed to increased release of striatal dopamine and decreased oxidative stress. Collectively, the data support the hypothesis that androgens may underlie the gender bias observed in PD.     

The influence and the mechanism of docosahexaenoic acid on a mouse model of Parkinson's disease

This study aimed to investigate the effects of docosahexaenoic acid (DHA) on the oxidative stress that occurs in an experimental mouse model of Parkinson’s disease (PD). An experimental model of PD was created by four intraperitoneal injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (4 × 20 mg/kg, at 12 h intervals). Docosahexaenoic acid was given daily by gavage for 4 weeks (36 mg/kg/day). The motor activity of the mice was evaluated via the pole test, and the dopaminergic lesion was determined by immunohistochemical analysis for tyrosine hydroxylase (TH)-immunopositive cells. The activity of antioxidant enzymes in the brain were determined by spectrophotometric assays and the concentration of thiobarbituric acid-reactive substances (TBARS) were measured as an index of oxidative damage. The number of apoptotic dopaminergic cells significantly increased in MPTP-treated mice compared to controls. Although DHA significantly diminished the number of cell deaths in MPTP-treated mice, it did not improve the decreased motor activity observed in the experimental PD model. Docosahexaenoic acid significantly diminished the amount of cell death in the MPTP + DHA group as compared to the MPTP group. TBARS levels in the brain were significantly increased following MPTP treatment. Glutathione peroxidase (GPx) and catalase (CAT) activities of brain were unaltered in all groups. The activity of brain superoxide dismutase (SOD) was decreased in the MPTP-treated group compared to the control group, but DHA treatment did not have an effect on SOD activity in the MPTP + DHA group. Our current data show that DHA treatment exerts neuroprotective actions on an experimental mouse model of PD. There was a decrease tendency in brain lipid oxidation of MPTP mice but it did not significantly.