Two-cell System Research Articles

Defining the cell and molecular origins of the primate ovarian reserve.

The primate ovarian reserve is established during late fetal development and consists of quiescent primordial follicles in the ovarian cortex, each composed of granulosa cells surrounding an oocyte in dictate. As late stages of fetal development are not routinely accessible for study with human tissue, we exploited the evolutionary proximity of the rhesus macaque to investigate primate follicle formation. Similar to human prenatal ovaries, the rhesus also develops multiple types of pre-granulosa (PG) cells, with the majority of primordial follicles derived from PG2 with small variable contributions from PG1. We observed that activated medullary follicles recruit fetal theca cells to establish a two-cell system for sex-steroid hormone production prior to birth, providing a cell-based explanation for mini puberty.

Eccentric orbits may enhance the habitability of Earth-like exoplanets

ABSTRACT The detection and characterization of Earth-like planets around Sun-like stars is an important goal of exoplanetary research, given their promise for hosting potentially habitable conditions. Key orbital parameters, such as eccentricity, can influence a planet’s climate response and, as a consequence, affect its potential habitability. Utilizing the Earth System Model – the Whole Atmosphere Community Climate Model (WACCM6), we simulated Earth-like exoplanets with two different orbital parameters: one circular ($e = 0$) and another highly eccentric ($e = 0.4$), both with zero obliquity but fixing the annual mean insolation. The highly eccentric case exhibits a 1.9 K warmer surface temperature due to lower surface and cloud albedo and a weaker longwave cloud forcing. Exploring the annual global mean climate difference, we analysed latitudinal and seasonal variations in hydrological cycle variables, such as sea ice, land snow, and clouds. Land habitability metrics based on temperature and precipitation reveal that the $e=0.4$ case has over 25 per cent more habitable land area for more than 80 per cent of its orbit, compared with the $e=0$ case. Additionally, the global circulation pattern shifts from a three-cell to a two-cell system in the $e=0.4$ case, expanding the Hadley cell to higher latitudes, enhancing meridional latent heat transport, and improving land habitability at higher latitudes. Our study suggests that Earth-like exoplanets with high eccentricity orbiting Sun-like stars may have greater land habitability than their circular counterparts, due to seasonally warmer surface temperatures and more evenly distributed precipitation over land.

Ammonia coverage ratio control of a novel two-cell SCR-DeNOX system configuration based on IA-ISMC

To respond the China’s “14th Five-Year Plan” on the control of nitrogen oxides (NOX) emission, urea-based selective catalytic reduction (SCR) system has been widely applied to reduce the NOX emission from the diesel engine. NO2 is no longer a factor to be ignored while refining the SCR-DeNOX system model because of the ship diesel engine's long-term low temperature and oxygen-rich condition, which provides abundant conditions for the creation of NO2. Therefore, a refined eight-state two-cell SCR-DeNOX model is established in this paper. Meanwhile, the trade-off between NOX emission and tailpipe ammonia (NH3) slip is one of the major challenges which SCR-DeNOX system is facing. While meeting NOX emission standards, the requirement of limiting NH3 slip to prevent secondary pollution is becoming increasingly urgent, which needs a better structure or controller. Therefore, a two-cell SCR-DeNOX system with a by-pass valve in front of the NH3 injection is designed, integral sliding mode control based on inversion algorithm (IA_ISMC) is proposed for each cell. Based on the FTP-75 test cycle, there are three points of view are presented. Firstly, compared with the traditional six-state model, simulation results from the refined eight-state SCR-DeNOX model are closer to the experimental data. Secondly, the introduction of the by-pass structure has a mild impact on the NOX conversion efficiency, but can largely limit the NH3 slip. Finally, the controller based on IA_ISMC effectively improves the tracking performance of NH3 coverage ratio and reduces the cost of NH3 injection. To sum up, the refined two-cell SCR-DeNOX system with a by-pass valve based on IA_ISMC can enhance SCR performance and lower costs.

Establishment of efficient 5-hydroxyvaleric acid production system by regenerating alpha-ketoglutaric acid and its application in poly(5-hydroxyvaleric acid) production

5-hydroxyvaleric acid (5-HV) is a versatile C5 intermediate of bio-based high-value chemical synthesis pathways. However, 5-HV production faces a few shortcomings involving the supply of cofactors, especially α-ketoglutaric acid (α-KG). Herein, we established a two-cell biotransformation system by introducing L-glutamate oxidase (GOX) to regenerate α-KG. Additionally, the catalase KatE was adapted to inhibit α-KG degradation by the H2O2 produced during GOX reaction. We searched for the best combination of genes and vectors and optimized the biotransformation conditions to maximize GOX effectiveness. Under the optimized conditions, 5-HV pathway with GOX showed 1.60-fold higher productivity than that of without GOX, showing 11.3 g/L titer. Further, the two-cell system with GOX and KatE was expanded to produce poly(5-hydroxyvaleric acid) (P(5HV)), and it reached at 412 mg/L of P(5HV) production and 20.5% PHA contents when using the biotransformation supernatant. Thus, the two-cell biotransformation system with GOX can potentially give the practical and economic alternative of 5-HV production using bio-based methods. We also propose direct utilization of 5-HV from bioconversion for P(5HV) production.

Comparative study on the performance of a two-cell system of Flow Electrode Capacitive Mixing (F-CapMix) for continuous energy production

In recent years, Capacitive Mixing (CapMix) has garnered growing interest as a novel method for harnessing energy from the salinity gradient between seawater and freshwater. However, the challenge of extracting energy in a continuous way remains to be solved in traditional CapMix system. In this study, we demonstrate the feasibility of achieving continuous energy extraction through the use of a two-cell flow electrode Capacitive Mixing (F-CapMix) system. The performance of the F-CapMix system is evaluated under various experimental conditions including the activated carbon loading, carbon black additives, velocity of the flow electrode and feed water and external resistance in the circuit. The results suggest that the power density of the system can be significantly increased by approximately 800 % or 400 % with an increase in the carbon loading or the addition of carbon black additives, respectively. Meanwhile, reducing the flow rate of the flow electrode and feedwater from 20 mL/s to 5 mL/s was found to improve the system's performance. In addition, it is crucial that the external resistance is matched to the internal resistance of the cell for achieving a maximum power density. These results highlight the potential of F-CapMix and provide guidance for its further optimization.

Spatial expression patterns of genes encoding sugar sensors in leaves of C4 and C3 grasses.

The mechanisms of sugar sensing in grasses remain elusive, especially those using C4 photosynthesis even though a large proportion of the world's agricultural crops utilize this pathway. We addressed this gap by comparing the expression of genes encoding components of sugar sensors in C3 and C4 grasses, with a focus on source tissues of C4 grasses. Given C4 plants evolved into a two-cell carbon fixation system, it was hypothesized this may have also changed how sugars were sensed. For six C3 and eight C4 grasses, putative sugar sensor genes were identified for target of rapamycin (TOR), SNF1-related kinase 1 (SnRK1), hexokinase (HXK) and those involved in the metabolism of the sugar sensing metabolite trehalose-6-phosphate (T6P) using publicly available RNA deep sequencing data. For several of these grasses, expression was compared in three ways: source (leaf) versus sink (seed), along the gradient of the leaf, and bundle sheath versus mesophyll cells. No positive selection of codons associated with the evolution of C4 photosynthesis was identified in sugar sensor proteins here. Expressions of genes encoding sugar sensors were relatively ubiquitous between source and sink tissues as well as along the leaf gradient of both C4 and C3 grasses. Across C4 grasses, SnRK1β1 and TPS1 were preferentially expressed in the mesophyll and bundle sheath cells, respectively. Species-specific differences of gene expression between the two cell types were also apparent. This comprehensive transcriptomic study provides an initial foundation for elucidating sugar-sensing genes within major C4 and C3 crops. This study provides some evidence that C4 and C3 grasses do not differ in how sugars are sensed. While sugar sensor gene expression has a degree of stability along the leaf, there are some contrasts between the mesophyll and bundle sheath cells.

Organic pollutants degradation using plasma with simultaneous ammonification assisted by electrolytic two-cell system

Atmospheric non-thermal dielectric barrier discharge (DBD) plasma has gained considerable attention due to its cost-efficiency, environmental friendliness, and simplicity. However, certain deficiencies restrict its broad application. Herein, the DBD plasma was used to disrupt three model pharmaceutically active compounds (PhACs), sulfamethoxazole (SMX), ibuprofen (IBP), and norfloxacin (NFX), by varying parameters, such as gas type (Ar, N2, O2, and air) and flow rate (1–4 L min−1). The air plasma discharge had the highest degradation efficiency, and the air flow rate was optimized at 2 L min−1. However, only 10% of IBP was removed by the sole plasma, whereas NFX and SMX were entirely removed after 30 min. Since the air plasma discharge generates reactive oxygen and nitrogen species in a chained reaction, the remaining NO2− and NO3− in the aqueous phase were problematic. Therefore, by coupling plasma with electrolysis using Cu/reduced Cu nanowire (R-CuNw) as the anode/cathode, all three PhACs were removed within 30 min, and NO2− and NO3− were completely reduced to NH3 with cathodic reduction. Moreover, the electrical energy per order (EEO, 0.04 kWh L−1) and treatment cost (0.003 USD L−1) were much lower than those of the single system. This system demonstrates great potential for water remediation, and the production of NH3 as a value-added by-product remarkably improves its practicality and is of great importance in agriculture and energy-related industries.

Numerical Simulation of a Periodic Quasi-Switching Mode of Flow around a Conical Dimple with a Slope Angle of 10 Degrees on the Wall of a Narrow Channel Using URANS

The applicability of the solution of the unsteady Reynolds-averaged Navier–Stokes equations (URANS) for the numerical simulation of the periodic quasi-switching regime of vortex generation and heat transfer in a deep conical dimple with a slope angle of 10∘ on the wall of a narrow channel is substantiated. To calculate the turbulent regime, the model of shear stress transfer by Menter 2003, modified taking into account the influence of the curvature of streamlines within the framework of the Rodi-Leshziner-Isaev approach, is used. At Reynolds number Re=104, the oscillation period of the transverse Rz and longitudinal forces Rx, as well as the total heat transfer Numm to the control section of the heated channel wall with a dimple, is set equal to 60, which corresponds to the Strouhal number St=0.0167. Computer visualization of swirling jet-vortex flows demonstrates focus-type sources on the side faces of the dimple. In the self-oscillating mode, a two-cell vortex system is formed with different intensities at the oscillation period Rz. Periodic changes in friction, Nusselt numbers and temperature are recorded in the longitudinal and transverse median sections of the dimple and reflect the oscillations of the vortex structure from left to right and from right to left. The formation of a fan jet is shown, which oscillates relative to the plane of longitudinal symmetry, causing a redistribution of power and thermal loads.

Photoenhanced Water Electrolysis in Separate O2 and H2 Cells Using Pseudocapacitive Electrodes.

Water electrolysis has received much attention in recent years as a means of sustainable H2 production. However, many challenges remain in obtaining high-purity H2 and making large-scale production cost-effective. This study provides a strategy for integrating a two-cell water electrolysis system with solar energy storage. In our proposed system, CuO-Cu(OH)2/Cu2O was used as a redox mediator between oxygen and hydrogen evolution components. The system not only overcame the gas-mixing issue but also showed high gas generation performance. The redox reaction (charge/discharge) of CuO-Cu(OH)2/Cu2O led to a significant increase (51%) in the initial rate of H2 production from 111.7 μmol h–1 cm–2 in the dark to 168.9 μmol h–1 cm–2 under solar irradiation. The effects of light on the redox reaction of CuO-Cu(OH)2/Cu2O during water electrolysis were investigated by in situ X-ray absorption and photoemission spectroscopy. These results suggest that surface oxygen vacancies are created under irradiation and play an important role in increased capacitance and gas generation. These findings provide a new path to direct storage of abundant solar energy and low-cost sustainable hydrogen production.

Metagenomic and metatranscriptomic analysis reveals enrichment for xenobiotic-degrading bacterial specialists and xenobiotic-degrading genes in a Canadian Prairie two-cell biobed system.

Biobeds are agriculture-based bioremediation tools used to safely contain and microbially degrade on-farm pesticide waste and rinsate, thereby reducing the negative environmental impacts associated with pesticide use. While these engineered ecosystems demonstrate efficient pesticide removal, the microbiomes in these environments remain largely understudied both taxonomically and functionally. This study used metagenomic and metatranscriptomic techniques to characterize the microbial community in a two-cell Canadian biobed system before and after a field season of pesticide application. These culture-independent approaches identified an enrichment of xenobiotic-degrading bacteria, such as Afipia, Sphingopyxis and Pseudomonas, and enrichment and transcription of xenobiotic-degrading genes, such as peroxidases, oxygenases, and hydroxylases, among others; we were able to directly link the transcription of these genes to Pseudomonas, Oligotropha, Mesorhizobium, Rhodopseudomonas, and Stenotrophomonas taxa.

On the Design of High Power Efficiency Uplink MIMO-NOMA Systems: A STBC and Joint Detection Perspective

The explosive growth of innovative applications imposes great challenges for future wireless communication systems with respect to ultra-high spectrum and power efficiency. Non-orthogonal multiple access (NOMA) and multiple-input-multiple-output (MIMO) have been acknowledged as two promising spectral-enhancing techniques to address the aforementioned issues. Orthogonal space-time block code (STBC), on the other hand, is capable of exploiting the full diversity gain of MIMO system. In this work, we explore how STBC can be utilized to enhance the performance of two-cell MIMO-NOMA networks. To this end, an uplink power minimization problem for the two-cell STBC-aided MIMO-NOMA system is investigated, wherein the joint detection technique is adopted to boost the cell-edge user's performance. The formulated optimization problem is non-convex and is intractable to be solved directly. A two-tier methodology is applied to decompose the original problem into two sub-problems, namely the beamforming design and the power allocation. Specifically, for the beamforming design, a closed-form expression is derived based on the Gram matrix of channel matrix. In the meanwhile, an efficient iterative method is developed to determine the power allocation coefficients for both the cell-center and the cell-edge users. Simulation results reveal that the proposed scheme outperforms several golden baselines in terms of total power consumption.

Design principles for enhanced up-scaling of flow-through capacitive deionization for water desalination

To develop efficient and cost-effective desalination technologies is crucial for addressing the globally increasing needs for drinking water. One such desalination technology that is growing is capacitive deionization (CDI), wherein ions are electrically removed from water passing through or between two porous conducting electrodes. As the CDI field grows, design principles for scaling from small CDI cells to larger units and modules will become increasingly important. Thus, we have investigated the flow distribution in single flow-through CDI cells and interconnected modules to determine architectural principles that can feasibly reduce the pressure drop with good throughput, thus increasing energy efficiency. The most important principles found include massive parallelism, open regions to symmetrically distribute flow, and tailoring the permeability of the electrodes and spacers. Crucially, we demonstrate how simply rerouting the flow reduces the pressure drop through the cell by a factor of four in a two-cell system. Finally, we leverage the found principles to a cylindrical CDI cell well-adapted to modular up-scaling. In conclusion, implementing the design principles leads to a significant reduction in pressure drop and energy consumption of a CDI system, which is essential for upscaling to larger modular systems for practical use.

Production of Tyrian purple indigoid dye from tryptophan in Escherichia coli.

Tyrian purple, mainly composed of 6,6'-dibromoindigo (6BrIG), is an ancient dye extracted from sea snails and was recently demonstrated as a biocompatible semiconductor material. However, its synthesis remains limited due to uncharacterized biosynthetic pathways and the difficulty of regiospecific bromination. Here, we introduce an effective 6BrIG production strategy in Escherichia coli using tryptophan 6-halogenase SttH, tryptophanase TnaA and flavin-containing monooxygenase MaFMO. Since tryptophan halogenases are expressed in highly insoluble forms in E. coli, a flavin reductase (Fre) that regenerates FADH2 for the halogenase reaction was used as an N-terminal soluble tag of SttH. A consecutive two-cell reaction system was designed to overproduce regiospecifically brominated precursors of 6BrIG by spatiotemporal separation of bromination and bromotryptophan degradation. These approaches led to 315.0 mg l-1 6BrIG production from tryptophan and successful synthesis of regiospecifically dihalogenated indigos. Furthermore, it was demonstrated that 6BrIG overproducing cells can be directly used as a bacterial dye.

Single Alkali Metal Ion-Activated Porous Carbon With Heteroatom Doping for Supercapacitor Electrode.

A single alkali metal ion activation method was used to prepare sulfur-doped microporous carbons. A series of alkali metal ions such as Li+, Na+, K+, and Cs+ was used in the polymerization process of 3-hydroxythiophenol and formaldehyde to obtain metal ion anchored in the sulfur-containing resin, which was further treated to obtain xerogel and carbonized to obtain microporous carbon with sulfur doping. In this case, the monodispersed alkali metal ions could realize highly effective activation with low activating agent dosage. Intensive material characterizations show that the alkali metal ions determine the pore structure and surface properties of as-prepared carbons. C-Cs prepared by Cs+ ion possesses a high Brunauer–Emmett–Teller specific surface area of 1,037 m2 g−1 with interconnected microporosity and sulfur doping. The specific capacitance of C-Cs can reach up to 270.9 F g−1 in a two-cell electrode measurement system, whereas C-Cs-based supercapacitors can deliver an energy density of 7.6 Wh kg−1, which is much larger than that of other samples due to its surface functionalities and well-interconnected porosities.

Abstract PR08: Discovery of immune regulators in primary human T cells using genome-wide CRISPR screens

Abstract The incredible success of cancer immunotherapies is still only limited to subsets of patients, which has motivated efforts to discover novel therapeutic targets to boost tumor killing by effector T cells. However, the translational potential of these discoveries may be limited by suboptimal correlation between cell line and animal models with human disease. Further, the majority of unbiased screening approaches are performed in cancer cells lines, rather than in the effector T cells themselves. We have developed a novel and flexible screening platform using sgRNA lentiviral infection with Cas9 protein electroporation (SLICE), to perform genome-wide CRISPR screens in primary human T cells at genome-wide scale. We have used this platform to survey the response of primary human CD8+ T cells to TCR stimulation. This screen revealed essential components of TCR signaling and inhibitors/agonists of T-cell proliferation. Targeted deletion of top candidate genes from the screen led to increased proliferation, increased expression of activation markers, and improved tumor killing in in vitro co-culture models. Coupling our screening platform with single-cell RNA-seq identified functional clustering of cell states across perturbations and showed that pooled screens in primary cells can now be analyzed at a single-cell level. In addition to finding ways to boost intrinsic T-cell activation, we also sought to adapt the SLICE screening platform to identify mediators of resistance to immunosuppressive forces in the tumor microenvironment. To model one such suppressive factor, we performed the screen in the presence of a potent adenosine agonist and found known and novel regulators of adenosine signaling in T cells. We are further integrating this platform with a two-cell co-culture system to attempt to find mechanisms of resistance to immunosuppressive cells in the tumor microenvironment. This novel platform provides the framework for unbiased, large-scale discovery of immune regulators as potential therapeutic targets in primary human T cells. This abstract is also being presented as Poster A90. Citation Format: Julia Carnevale, Eric Shifrut, Victoria Tobin, Theodore Roth, Jonathan Woo, Christina Bui, Jonathan Li, Morgan Diolaiti, Alan Ashworth, Alexander Marson. Discovery of immune regulators in primary human T cells using genome-wide CRISPR screens [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr PR08.

Simultaneous Signal-and-Interference Alignment for Two-Cell Over-the-Air Computation

The next-generation wireless -20mm]Our records show Qiao Lan is a Graduate Student Member, IEEE. Please verify. networks are envisioned to support large-scale sensing and distributed machine learning, thereby enabling new intelligent mobile applications. One common network operation will be the aggregation of distributed data (such as sensor observations or AI-model updates) for functional computation (e.g., averaging) so as to support large-scale sensing and distributed machine learning. An efficient solution for data aggregation, called over-the-air computation (AirComp), embeds functional computation into simultaneous access by many edge devices. Such schemes exploit the waveform superposition of a multi-access channel to allow an access point to receive a desired function of simultaneous signals. In this letter, we aim at realizing AirComp in a two-cell multi-antenna system. To this end, a novel scheme of simultaneous signal-and-interference alignment (SIA) is proposed that builds on classic IA to manage interference for multi-cell AirComp. The principle of SIA is to divide the spatial channel space into two subspaces with equal dimensions: one for signal alignment required by AirComp and the other for inter-cell IA. As a result, the number of interference-free spatially multiplexed functional streams received by each AP is maximized (equal to half of the available spatial degrees-of-freedom). Furthermore, the number is independent of the population of devices in each cell. In addition, the extension to SIA for more than two cells is discussed.

Analysis of Drone Placement Strategies for Complete Interference Cancellation in Two-Cell NOMA CoMP Systems

The use of unmanned aerial vehicles (UAV) as flying base stations is rapidly growing in the field of wireless communications to leverage the capacity of congested cells. This study considers a two-cell system where one of the cells is saturated, i.e. can no longer serve its users, and is supported by a UAV. The UAV positioning problem is investigated specifically to benefit from the interference cancellation properties available through the introduction of power-domain non-orthogonal multiple access (NOMA) techniques in coordinated multipoint (CoMP) systems. Indeed, adequate placement of the UAV can enable triple mutual successive interference cancellation (TMSIC) between a triplet of users, including a cell-edge and a cell-center user in each cell, to maximize system throughput or a mixture of throughput and TMSIC probability. The random line-of-sight/non-line-of-sight realizations of air-to-ground links between users and UAV are taken into account in the problem modeling, showing a significant improvement in performance compared to the conventional mean path loss model. The performance evaluation highlights the existing trade-offs between system capacity, fairness, and computational complexity of the investigated approaches.

Electrochemical recovery of hydrogen and elemental sulfur from hydrogen sulfide gas by two-cell system

ABSTRACT In spite of industries making huge investments, for a viable energy saving, still the methods for conservation of energy are lagging and the industries are still in search for alternatives. The major concern that persists with the oil and gas operations is emission of hydrogen sulfide, frequently or inadvertently, during the initial or later stages of the process. Hence, this study focuses on the indirect electrolysis toward the recovery of sulfur and hydrogen from hydrogen sulfide using graphite as both anode and cathode with calomel as reference electrode. The recovered sulfur was analyzed using high-resolution scanning electron microscope was in range of few microns that was in agreement with the X-ray diffraction analysis confirming the crystalline orthorhombic structure of sulfur (JCPDS Card no.89–2600). The cyclic voltammetry experiment was carried out by sweeping the potential between −1.2 and +1.2 V at a scan rate of 50 mVs−1 obtaining a maximum current density of 0.41 A/cm2. Maximum deposition of sulfur observed at pH 13 with a current density of 0.23 A/cm2 and temperature 80°C. The quantity of sulfur recovered by indirect electrolysis was in the range of 2.9 mg with efficiency of 90.44%.Thus an effective method using indirect electrolysis method was successfully used to achieve crystalline sulfur and hydrogen from H2S.

Antioxidant and antimicrobial assessment of licorice supercritical extracts

Licorice (Glycyrrhiza glabra L.) is a plant used widely in herbal medicines due to their several biological potentials. The supercritical extraction of licorice roots was investigated to assess the antioxidant and antimicrobial activity of the extracts. Extraction conditions were pressures from 15 to 40 MPa, 313.15 and 333.15 K, and ethanol cosolvent in the range of 0 to 20% mass. In the case of high-pressure extractions using pure carbon dioxide (CO2) fractionation of the supercritical extract was accomplished in a two-cell decompression system. Fractionation was carried out with the aim to examine the potential separation of the antioxidant and antimicrobial licorice compounds and thus increase the bioactive properties of the fractions obtained in each separation cell. Main licorice bioactive compounds, liquiritin, liquiritigenin, glycyrrhizin, isoliquiritigenin and glabridin, were identified by HPLC and quantified using standards. Extracts obtained with supercritical CO2 and ethanol cosolvent contain the higher amounts of phenolic compounds and also the higher antioxidant activity but exhibit low or even no antimicrobial activity. Using pure CO2 at high pressure coupled with the on-line fractionation of the extract, two samples were obtained which showed, respectively, lower phenolic compounds content and good antimicrobial capacity (first fraction) and higher phenolic compounds content and antioxidant capacity (second fraction). Thus, the advantages of supercritical on-line fractionation are demonstrated in the extraction of Licorice roots.

Analysis of a long-lived, two-cell lightning storm on Saturn

Lightning storms in Saturn’s atmosphere can last for a few days up to several months. In this paper we analyze a lightning storm that raged for seven and a half months at a planetocentric latitude of 35° south from the end of November 2007 until mid-July 2008. Thunderstorms observed by the Cassini spacecraft before this time were characterized by a single convective storm region of ~2000 km in size, but this storm developed two distinct convective storm cells at the same latitude separated by ~25° in longitude. The second storm cell developed in March 2008, and the entire two-cell convective system was moving with a westward drift velocity of about 0.35 deg per day, which differs from the zonal wind speed. An exhaustive data analysis shows that the storm system produced ~277000 lightning events termed Saturn electrostatic discharges (SEDs) that were detected by Cassini’s Radio and Plasma Wave Science (RPWS) instrument, and they occurred in 439 storm episodes. We analyzed the SED intensity distributions, the SED polarization, the burst rates, and the burst and episode durations. During this storm Cassini made several orbits around Saturn and observed the SEDs from all local times. A comparison with optical observations shows that SEDs can be detected when the storm is still beyond the visible horizon. We qualitatively describe this so-called over-the-horizon effect which is thought to be due to a temporary trapping of SED radio waves below Saturn’s ionosphere. We also describe the first occurrence of so-called SED pre- and post-episodes, which occur in a limited frequency range around 4 MHz separated from the main episode. Pre- and post-episodes were mostly observed by Cassini located at local noon, and should be a manifestation of an extreme over-the-horizon effect. Combined radio and imaging observations suggest that some decreases in SED activity are caused by splitting of the thunderstorm into a bright cloud and a dark oval.