Multivariate analysis of electrophysiological diversity of Xenopus visual neurons during development and plasticity

Abstract Biophysical properties of neurons become increasingly diverse over development, but mechanisms underlying and constraining this diversity are not fully understood. Here we investigate electrophysiological characteristics of Xenopus tadpole midbrain neurons across development and during homeostatic plasticity induced by patterned visual stimulation. We show that in development tectal neuron properties not only change on average, but also become increasingly diverse. After sensory stimulation, both electrophysiological diversity and functional differentiation of cells are reduced. At the same time, the amount of cross-correlations between cell properties increase after patterned stimulation as a result of homeostatic plasticity. We show that tectal neurons with similar spiking profiles often have strikingly different electrophysiological properties, and demonstrate that changes in intrinsic excitability during development and in response to sensory stimulation are mediated by different underlying mechanisms. Overall, this analysis and the accompanying dataset provide a unique framework for further studies of network maturation in Xenopus tadpoles

Divergent Effects of Human Cytomegalovirus and Herpes Simplex Virus-1 on Cellular Metabolism

Viruses rely on the metabolic network of the host cell to provide energy and macromolecular precursors to fuel viral replication. Here we used mass spectrometry to examine the impact of two related herpesviruses, human cytomegalovirus (HCMV) and herpes simplex virus type-1 (HSV-1), on the metabolism of fibroblast and epithelial host cells. Each virus triggered strong metabolic changes that were conserved across different host cell types. The metabolic effects of the two viruses were, however, largely distinct. HCMV but not HSV-1 increased glycolytic flux. HCMV profoundly increased TCA compound levels and flow of two carbon units required for TCA cycle turning and fatty acid synthesis. HSV-1 increased anapleurotic influx to the TCA cycle through pyruvate carboxylase, feeding pyrimidine biosynthesis. Thus, these two related herpesviruses drive diverse host cells to execute distinct, virus-specific metabolic programs. Current drugs target nucleotide metabolism for treatment of both viruses. Although our results confirm that this is a robust target for HSV-1, therapeutic interventions at other points in metabolism might prove more effective for treatment of HCMV

New Venture Internationalization: The Role of Venture Capital Types and Reputation

This study examines how different types of venture capital relate to new venture internationalization. Using a sample of 646 U.S. new ventures that executed IPOs between 1995 and 2010, we find that ventures with foreign or corporate venture capital have higher levels of international intensity. We also investigate the moderating role of VC reputation on the relationship between foreign venture capital and international intensity and corporate venture capital and international intensity. Our results suggest that VC reputation weakens the positive relationship between corporate VC and international intensity

Data from: Multivariate analysis of electrophysiological diversity of Xenopus visual neurons during development and plasticity

Biophysical properties of neurons become increasingly diverse over development, but mechanisms underlying and constraining this diversity are not fully understood. Here we investigate electrophysiological characteristics of Xenopus tadpole midbrain neurons across development and during homeostatic plasticity induced by patterned visual stimulation. We show that in development tectal neuron properties not only change on average, but also become increasingly diverse. After sensory stimulation, both electrophysiological diversity and functional differentiation of cells are reduced. At the same time, the amount of cross-correlations between cell properties increase after patterned stimulation as a result of homeostatic plasticity. We show that tectal neurons with similar spiking profiles often have strikingly different electrophysiological properties, and demonstrate that changes in intrinsic excitability during development and in response to sensory stimulation are mediated by different underlying mechanisms. Overall, this analysis and the accompanying dataset provide a unique framework for further studies of network maturation in Xenopus tadpoles

Raw Electrophysiological Data, and extracted parameters from Optic Tectum Neurons of Xenopus tadpoles

This dataset contains the raw electrophysiological recording data that was used to quantify cell diversity in the Optic Tectum of premetamorphic Xenopus tadpoles. The recordings were performed in pClamp, and are stored here as Matlab MAT-files. The raw data is accompanied by a summary table of measurements presented in the paper, and a "master file" that matches raw data files to cell ids from the summary table. The ZIP archive contains several folders that separately store: (1) Voltage gated current traces in response to voltage steps that were used to build Na and K IV-curves (folder "01 IV curve"); (2) Active changes in membrane potential (spiking) in response to step current injections (folder "02 Current step injections"); (3) Spiking in response to cosine current injections (folder "03 Current cosine injections"); (4) Synaptic currents recorded in voltage clamp after synaptic stimulation of the optic nerve with equally spaced impulses and with different inter-stimulus intervals (folder "04 Synaptic bursts"); (5) Miniature spontaneous excitatory postsynaptic currents (folder "05 Minis")