Tipepidine activates VTA dopamine neuron via inhibiting dopamine D2 receptor-mediated inward rectifying K⁺ current.

We previously reported that the novel antidepressant-like effect of tipepidine may be produced at least partly through the activation of mesolimbic dopamine (DA) neurons via inhibiting G protein-coupled inwardly rectifying potassium (GIRK) channels. In this study, we investigated the action of tipepidine on DA D2 receptor-mediated GIRK currents (IDA(GIRK)) and membrane excitability in DA neurons using the voltage clamp and current clamp modes of the patch-clamp techniques, respectively. DA neurons were acutely dissociated from the ventral tegmental area (VTA) in rats and identified by the presence of the hyperpolarization-activated currents. Tipepidine reversibly inhibited IDA(GIRK) with IC50 7.0 µM and also abolished IDA(GIRK) irreversibly activated in the presence of intracellular GTPγS. Then tipepidine depolarized membrane potential and generated action potentials in the neurons current-clamped. Furthermore, the drug at 40 mg/kg, i.p. increased the number of cells immunopositive both for c-Fos and tyrosine hydroxylase (TH) in the VTA. These results suggest that tipepidine may activate DA neurons in VTA through the inhibition of GIRK channel-activated currents.

First Report of Leaf Rust of Blueberry Caused by Pucciniastrum vaccinii in Hawaii.

Blueberries (Vaccinium corymbosum L.) are a potential high-value, niche market crop for Hawaii. In May of 2007, rust-like symptoms were observed on multiple blueberry plants in a private nursery in Waimea, HI. In September of 2007, a similar leaf rust was observed on one bush of V. corymbosum cv. Sharpblue in the corner of a 36.6 × 9.1-m experimental plot at Mealani Research Station in Waimea. Within a month, rust was observed throughout the plot on 'Biloxi', 'Emerald', 'Jewel', 'Misty', 'Sapphire', and 'Sharpblue'. Preliminary field observations suggest that 'Sharpblue' and 'Sapphire' are highly susceptible to the rust and 'Biloxi' shows some tolerance. Leaf lesions began as approximately 1-mm2 chlorotic flecks that expanded and developed into reddish brown, necrotic spots with a chlorotic halo. New lesions and uredinia kept appearing over the course of 4 months. Defoliation occurred on plants where infection was severe. Yellowish orange pustules containing urediniospores first appeared on the abaxial side of older leaves and later appeared on new leaves. Urediniospores were elliptical to obovate (19.4 to 24.8 × 15.2 to 19.8 µm) with a thick, slightly roughened wall and a well-developed pore. Urediniospore morphology and dimensions were consistent with the description of Pucciniastrum vaccinii (G. Wint.) (1). A pathogenicity test was conducted with two 18-month-old 'Sharpblue' plants. Fully expanded leaves were sprayed with freshly collected urediniospores (3.8 × 105 spores per ml) suspended in a 0.05% solution of Tween 20 in water. The control plant was sprayed with sterile distilled water (SDW). Plants were covered with plastic bags for 48 h and held in a growth chamber at 20 to 22°C under continuous fluorescent lighting. The plastic bags were then removed and the plants were maintained in the growth chamber. Yellowish orange pustules that were identical to the original symptoms developed on 100% of inoculated leaves after 10 days. The plant inoculated with SDW remained symptomless. While leaf rust caused by P. vaccinii has been reported on Ohelo berry (V. reticulatum) (2), it has not been reported on V. corymbosum in Hawaii. To our knowledge, this is the first report of P. vaccinii on blueberry plants in Hawaii. This rust disease may pose a threat to the potential blueberry industry in Hawaii. References: (1) P. R. Bristow and A. W. Stretch. Page 20 in: Compendium of Blueberry and Cranberry Diseases. F. L. Caruso and D. C. Ramsdell, eds. The American Phytopathological Society, St. Paul, MN, 1995. (2) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2008.

First Report of Phytoplasmas Infecting Watercress in Hawaii.

Symptoms of leaf yellowing, reduced leaf size, and witches'-brooms have recently been observed affecting watercress (Nasturtium microphyllum Boen. × Rcbh.) in Hawaii. These symptoms are followed by the collapse of affected plants. This condition has led to 80 to 90% losses for one of the largest watercress farms on Oahu and is now affecting other watercress farms in the area. Nutritional deficiencies or toxicities, water salinity, and insect or mite feeding damage were investigated but could not be implicated in the etiology of this syndrome. Eighteen watercress plants with early yellowing or advanced symptoms and nine symptomless plants were analyzed for phytoplasma infection using polymerase chain reaction (PCR) assays with primer pairs P1/Tint or P1/P7 (4). Amplicons of the expected sizes were produced from all symptomatic plants, whereas no products were amplified from symptomless plants. Sequence analysis of the cloned PCR products confirmed their phytoplasma origin and indicated that the watercress was infected with a phytoplasma most similar to SAY (2), a severe strain of western aster yellows phytoplasma previously classified as a 16SrI-B group member (3). Leafhoppers collected from an affected watercress planting have been identified as the aster leafhopper (Macrosteles quadrilineatus Fbs.) This species is the most efficient vector of the aster yellows phytoplasma and had not been previously recorded in Hawaii. The only other phytoplasma disease known in Hawaii prior to this report is Dodonaea yellows (1), which affects one of the most common native plants (Dodonaea viscosa (L.) Jacq.) in dry upland forests on all the islands. Dodonaea yellows, however, has been attributed to an X-disease (16SrIII) group phytoplasma. The occurrence of an aster yellows group phytoplasma in watercress, a previously unrecorded host, and the presence of a very efficient vector, M. quadrilineatus, poses a serious threat to the production of other vegetable and floral crops in Hawaii. References: (1) W. Borth et al. Plant Dis. 79:1094, 1995. (2) C. Kuske and B. Kirkpatrick. Int. J. Syst. Bacteriol. 42:226, 1992. (3) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (4) C. Smart et al. Appl. Environ. Microbiol. 62:2988, 1996.

Powerful Claisen condensation and Claisen-aldol tandem reaction of alpha,alpha-dialkylated esters promoted by ZrCl4-iPr2NEt.

Powerful Claisen ester condensations of alpha,alpha-dialkylated esters mediated by ZrCl4-iPr2NEt were performed to give the corresponding thermodynamically unfavorable alpha,alpha-dialkylated beta-ketoesters, and Claisen-aldol tandem reactions between an intermediary Zr-enolate of a alpha,alpha-dialkylated beta-ketoester and aldehydes also proceeded.