Modulation of synaptic function in retinal amacrine cells

Amacrine cells are interneurons that have diverse functions in retinal signal processing. In order to study signaling and modulation in retinal amacrine cells, we employ a simplified culture system containing identifiable GABAergic amacrine cells. Immunocytochemistry experiments indicate that GABAergic amacrine cells express metabotropic glutamate receptor 5 (mGluR5), a group I mGluR usually linked to the IP3 signaling pathway. Ca2+ imaging experiments using an mGluR5-specific agonist indicate that these receptors are functional and when activated, can stimulate temporally diverse Ca2+ elevations. To begin to establish the role of these receptors in modulating amacrine cell function, we have used electrophysiological methods to ask whether ion channels are the targets of mGluR5-dependent modulation. Here we discuss our results indicating that activation of mGluR5 leads to enhancement of currents through GABAA receptors. This enhancement is dependent upon elevations in cytosolic Ca2+ and activation of protein kinase C (PKC). To explore the consequences of Ca2+ elevations in another context, we have used nitric oxide (NO) donors to mimic the effects of activating the Ca2+-dependent synthetic enzyme for NO, neuronal nitric oxide synthase. We find that exposure to NO donors also enhances the amplitude of currents through GABAA receptors. Together, these results indicate that glutamate from presynaptic bipolar cells has the potential to work through multiple mechanisms to regulate the function of amacrine-to-amacrine cell GABAergic synapses

Squash Bug, Squash Vine Borer, and Striped Cucumber Beetle on Butternut Squash and Muskmelon

Alternative agricultural schemes are gaining attention as the demand for organic and sustainable products continues to grow. Pest insects pose a sizeable challenge to agricultural production because their activities reduce crop fitness and productivity. Effective management of pest-insects is, therefore, crucial for successful management, and increasingly entails a multi-dimensional approach

Testing the Accuracy and Precision of Wetness Sensors in a Tomato Field and on Turfgrass

Measurements of dew-period duration by painted, flat-plate, electronic wetness sensors at the top of the plant canopy in a tomato field and on adjacent turfgrass were compared with visual observations. The response range of sensors during the onset of dew sometimes exceeded 5 hr. but was less than 1 hr. on other nights. Sensors in the tomato field indicated dew formation occurred as much as 2 hr. earlier or later than dew became visible on adjacent tomato leaflets at the top of the crop canopy. A calibration threshold for sensors derived from a drying curve resulted in the underestimation of dew-period duration by up to 3.8 hr. and was less accurate than an empirically chosen threshold. Dew duration measured by sensors at the top of the tomato canopy and on adjacent turfgrass deviated from visual observation of dew duration at the top of the tomato canopy by about the same amount of time (0.8-hr. difference). These findings emphasize the need to use properly calibrated sensors for dew-period measurements and to calibrate dew-period measurements in a crop canopy

Time of Arrival from Bohmian Flow

We develop a new conception for the quantum mechanical arrival time distribution from the perspective of Bohmian mechanics. A detection probability for detectors sensitive to quite arbitrary spacetime domains is formulated. Basic positivity and monotonicity properties are established. We show that our detection probability improves and generalises earlier proposals by Leavens and McKinnon. The difference between the two notions is illustrated through application to a free wave packet.Comment: 18 pages, 8 figures, to appear in Journ. Phys. A; representation of ref. 5 improved (thanks to Rick Leavens