Effective dopamine (DA) neuron differentiation from neural precursor cells (NPCs) is prerequisite for precursor/ stem cell-based therapy of Parkinson's disease (PD). Nurr1, an orphan nuclear receptor, has been reported as a transcription factor that can drive DA neuron differentiation from non-dopaminergic NPCs in vitro. However, Nurr1 alone neither induces full neuronal maturation nor expression of proteins found specifically in midbrain DA neurons. In addition, Nurr1 expression is inefficient in inducing DA phenotype expression in NPCs derived from certain species such as mouse and human. We show here that Foxa2, a forkhead transcription factor whose role in midbrain DA neuron development was recently revealed, synergistically cooperates with Nurr1 to induce DA phenotype acquisition, midbrain-specific gene expression, and neuronal maturation. Thus, the combinatorial expression of Nurr1 and Foxa2 in NPCs efficiently yielded fully differentiated nigral (A9)-type midbrain neurons with clearly detectable DA neuronal activities. The effects of Foxa2 in DA neuron generation were observed regardless of the brain regions or species from which NPCs were derived. Furthermore, DA neurons generated by ectopic Foxa2 expression were more resistant to toxins. Importantly, Foxa2 expression resulted in a rapid cell cycle exit and reduced cell proliferation. Consistently, transplantation of NPCs transduced with Nurr1 and Foxa2 generated grafts enriched with midbrain-type DA neurons but reduced number of proliferating cells, and significantly reversed motor deficits in a rat PD model. Our findings can be applied to ongoing attempts to develop an efficient and safe precursor/stem cell-based therapy for PD. STEM CELLS 2010;28:501-512

SummarySix species belonging to the Criconematina, including a morphologically cryptic population within the Mesocriconema curvatum-group, are characterised based on integrative taxonomy based on morphological and molecular phylogenetic inferences from analyses of the 28S-rRNA, ITS-rRNA and COI gene sequences. Mesocriconema sp. 1 is morphologically similar to M. nebraskense and M. curvatum, differing from M. curvatum by the occasional presence of 1-2 anastomoses and a relatively higher R value, and from M. nebraskense by only a narrowed first lip annulus. However, based on COI gene sequence analysis, significant differences among the three species are evident. The sequence information in the COI gene among Mesocriconema spp. continues to reveal the existence of cryptic species within well-established species designations, and the concept of Molecular Operational Taxonomic Units might be helpful in grouping the different lineages according to sequence identities. Mesocriconema nebraskense is detailed herein for the first time outside the USA. DNA sequences of Hemicycliophora labiata were similar to those in GenBank while the existence in Korea of M. curvatum, Hemicriconemoides brachyurus and Paratylenchus nanus is molecularly confirmed.

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Drought is an important environmental stress that adversely affects plant growth and causes a reduction in growth. Despite the expanded areas of use and the increasing usefulness of the turfgrass, research on the drought stress on turfgrass is still insufficient, and there have only been few studies that investigated the effects of silicon on the drought resistance of turfgrass. This study was performed to determine the effects of silicon on Kentucky bluegrass (Poa pratensis L.) after the application of drought stress. The daily amount of water or silicon solution was 250 mL per a pot. For 14 d, plants were treated with 0, 0.1, and 1.0 mM silicon solution for silicon treatments and with distilled water for the control. Afterward, the plants were exposed to a 21‐d drought treatment, but the control received water as usual. Compared with the control, application of silicon increased the fresh weight of shoots and roots, as well as water content. The silicon pretreatments before drought significantly decreased chlorophyll contents, electrolyte leakage, and the concentrations of malondialdehyde (MDA) and H2O2. However, the α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) radical scavenging and glutathione (GSH) activities were significantly increased. Also, the responsive activities of the antioxidant enzymes encompassing superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase, and peroxidase were significantly enhanced. Our results suggest that silicon could help Kentucky bluegrass perform better under drought stress by increasing their antioxidant activities while decreasing lipid peroxidation.