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Excitatory amino acid transporters (EAATs) control visual signal transmission in the retina by rapidly removing glutamate released from photoreceptors and bipolar cells (BCs). Although it has been reported that EAAT2 and EAAT5 are expressed at presynaptic terminals of photoreceptors and some BCs in mammals, the distinct functions of these two glutamate transporters in retinal synaptic transmission, especially at a single synapse, remain elusive. In this study, we found that EAAT2 was expressed in all BC types while coexisting with EAAT5 in rod bipolar (RB) cells and several types of cone BCs from mice of either sex. Our immunohistochemical study, together with a recently published literature ( Gehlen et al., 2021 ), showed that EAAT2 and EAAT5 were both located in RB axon terminals near release sites. Optogenetic, electrophysiological and pharmacological analyses, however, demonstrated that EAAT2 and EAAT5 regulated neurotransmission at RB→AII amacrine cell synapses in significantly different ways: EAAT5 dramatically affected both the peak amplitude and kinetics of postsynaptic responses in AIIs, whereas EAAT2 had either relatively small or opposite effects. By contrast, blockade of EAAT1/GLAST, which was exclusively expressed in Müller cells, showed no obvious effect on AII responses, indicating that glutamate uptake by Müller cells did not influence synaptic transmission from RB terminals. Furthermore, we found that temporal resolution at RB→AII synapses was reduced substantially by blockade of EAAT5 but not EAAT2. Taken together, our work reveals the distinct functions of EAAT2 and EAAT5 in signal transmission at RB ribbon synapses.

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The on-surface discretized bouudary equation (OS-DBE) method for two-dimensioual scattering problems achieves high accuracy for the current solution, primarily due to the features of the method itself, but also due to higher order analytical evaluation of the integrals concerned. In this paper, we provide detailed formulation of higher order analytical integral evaluation and show its effects on the solution accuracy. In view of the fast multiple method (FMM) applied to the solution of the OS-DBE matrices, the higher order approximations to far interactions are also derived. The method of moments without or with FMM implementation is incideutally addressed regarding this subject. Abnormal phenomena associated with higher order evaluation that may appear in the magnetic field expressions or magnetic field integral equations are discussed.Index Terms---on-surface discretized boundary equation method, method of moments, fast multiple method, higher order integral evaluation, two dimensional scattering problems.