Membrane Stacks Research Articles

The effect of ion exchange membranes on the bipolar membrane electrodialysis of ammonium chloride wastewater

The different bipolar membranes and their configurations with monopolar ion exchange membranes from different manufacturers such as FAB-FBM-FKB, AHA-(BP-1E)- CMB, and JAM-(BMP-1)-JCM are used in the bipolar membrane electrodialysis (BMED) of simulated NH4Cl wastewater to examine the effect of membrane properties on the generation of HCl and NH3∙H2O. The results indicated that the configuration of AHA-(BP-1E)-CMB presented the promising performance among all the ion exchange membranes according to the generated acid and base concentration. And the configuration of FAB-FBM-FKB presented the expected performance on the membrane stack voltage, energy consumption, current efficiency of the BMED system. The stability of different ion exchange membranes in strong acid and base solution were investigated further by the analyses of SEM, contact angle and membrane resistance. It was found that the membranes AHA and FKB had better chemical stability than other membranes.

Comparative study on tartaric acid production by two-chamber and three-chamber electro-electrodialysis

Acidification is an essential step in organic acid production. In this work, an environmentally friendly electro-electrodialysis (EED) process was carried out to transform potassium tartrate (K2Tar) to tartaric acid (H2Tar) without additional waste salt generation. The characteristics of ions migration in the two-chamber EED and three-chamber EED processes were investigated, and the conversion ratio of tartaric acid and specific energy consumption of the two configurations were also compared. The competitive migration of K+ ions and H+ ions through cation exchange membrane was the key factor affecting the extent of acidification in the two-chamber EED process, while the selective transport of tartrate ions (Tar2−) and H+ ions through the anion exchange membrane influenced the three-chamber EED process significantly. The three-chamber process generated pure H2Tar solution with higher concentration than the two-chamber process and reached a conversion ratio of 99% after 120 min’s operation running at 7 mA/cm2. Owing to the lower resistance of the two-chamber membrane stack, the specific energy consumption in the two-chamber EED process was lower than that of three-chamber EED process. This work provides important knowledge for assessing the application of EED in the production of tartaric acid (H2Tar) from potassium tartrate (K2Tar) and a better understanding of the transport phenomena in the system with ionic organic compounds.

Ultrastructural modifications induced by SARS-CoV-2 in Vero cells: a kinetic analysis of viral factory formation, viral particle morphogenesis and virion release.

Many studies on SARS-CoV-2 have been performed over short-time scale, but few have focused on the ultrastructural characteristics of infected cells. We used TEM to perform kinetic analysis of the ultrastructure of SARS-CoV-2-infected cells. Early infection events were characterized by the presence of clusters of single-membrane vesicles and stacks of membrane containing nuclear pores called annulate lamellae (AL). A large network of host cell-derived organelles transformed into virus factories was subsequently observed in the cells. As previously described for other RNA viruses, these replication factories consisted of double-membrane vesicles (DMVs) located close to the nucleus. Viruses released at the cell surface by exocytosis harbored the typical crown of spike proteins, but viral particles without spikes were also observed in intracellular compartments, possibly reflecting incorrect assembly or a cell degradation process.

Effects of salt and gel network structures on purple membrane stacking in hydrogels immobilized with poly(vinyl alcohol)

The effects of a gel network structure on purple membrane (PM) spontaneous stacking are discussed, with particular emphasis on the relationship between the PM periodic pre-structures before gelation. Such peculiar intermembrane pre-structures with a periodic distance of ∼20 nm have recently been found to provide an important key to PM stacking, which is critical for the engineering applications of PM. Here, we investigated how the PM stacking differs depending on the gel network of a poly(vinyl alcohol) gel. On the basis of the results, we propose a plausible interplay between the PM periodic pre-structures and the type of gel network for PM stacking. The results indicate that a porous gel network, in addition to the PM periodic pre-structure in solutions, is necessary for PM stacking in immobilized gel samples.

Fine tuning the structural colours of photonic nanosheet suspensions by polymer doping.

Aqueous suspensions of nanosheets are readily obtained by exfoliating low-dimensional mineral compounds like H3Sb3P2O14. The nanosheets self-organize, at low concentration, into a periodic stack of membranes, i.e. a lamellar liquid-crystalline phase. Due to the dilution, this stack has a large period of a few hundred nanometres, it behaves as a 1-dimensional photonic material and displays structural colours. We experimentally investigated the dependence of the period on the nanosheet concentration. We theoretically showed that it cannot be explained by the usual DLVO interaction between uniform lamellae but that the particulate nature of nanosheet-laden membranes must be considered. Moreover, we observed that adding small amounts of 100 kDa poly(ethylene oxide) (PEO) decreases the period and allows tuning the colour throughout the visible range. PEO adsorbs on the nanosheets, inducing a strong reduction of the nanosheet charge. This is probably due to the Lewis-base character of the EO units of PEO that become protonated at the low pH of the system, an interpretation supported by theoretical modeling. Oddly enough, adding small amounts of 1 MDa PEO has the opposite effect of increasing the period, suggesting the presence of an additional intermembrane repulsion not yet identified. From an applied perspective, our work shows how the colours of these 1-dimensional photonic materials can easily be tuned not only by varying the nanosheet concentration (which might entail a phase transition) but also by adding PEO. From a theoretical perspective, our approach represents a necessary step towards establishing the phase diagram of aqueous suspensions of charged nanosheets.

Pomegranate juice supports therapeutic –treatment of atorvastatin against maternal hypercholesterolemia induced retinopathy of rat offspring

ABSTRACT Dietary consumption of processed high fat diet led to the development of metabolic diseases. This study aimed to demonstrate the retinopathy in a rat offspring maternally fed on high cholesterol and the improvement of pomegranate juice (PJ) administration and atorvastatin as potential treatment. Eighty pregnant Wistar albino rats were categorized into eight groups (n = 10); the control, PJ supplementation [0.4 m L (20%)]; atorvastatin-treatment (10 mg/kg); and hypercholesterolemia (fed on 3% cholesterol for 6 weeks prior to conception, during pregnancy and lactation period. Retinas of 21-day-old rat offspring were investigated. Offspring maternally fed on a hypercholesterolemic diet exhibited internal retinal hemorrhage at the interphase between the pigment epithelium and photoreceptors leading to retinal detachment. In addition, widespread of degenerated stacked membrane of the photoreceptor outer segment and the neovascularization within the nuclear layers were observed. Offspring retina of a hypercholesterolemic mother exhibited a significant depletion of assayed neurotransmitters coinciding with a significant increase of the vacuolar endothelial growth factor apoptotic markers expressing pressing damaging of retinal cells. Co-administration of pomegranate juice to hypercholesterolemic mother rats treated with atorvastatin significantly improved the retinal structure and the assayed biochemical markers of offspring than that with atorvastatin-treatment. In conclusion, PJ showed a potent antiapoptotic and ant- angiogenesis activity and improved the histocytological pictures of rat offspring maternally subjected to hypercholesterolemia.

Leaf photosynthetic and anatomical insights into mechanisms of acclimation in rice in response to long-term fluctuating light.

Long-term fluctuating light (FL) conditions are very common in natural environments. The physiological and biochemical mechanisms for acclimation to FL differ between species. However, most of the current conclusions regarding acclimation to FL were made based on studies in algae or Arabidopsis thaliana. It is still unclear how rice (Oryza sativa L.) integrate multiple physiological changes to acclimate to long-term FL. In this study, we found that rice growth was repressed under long-term FL. By systematically measuring phenotypes and physiological parameters, we revealed that: (a) under short-term FL, photosystem I (PSI) was inhibited, while after 1-7 days of long-term FL, both PSI and PSII were inhibited. Higher acceptor-side limitation in electron transport and higher overall nonphotochemical quenching (NPQ) explained the lower efficiencies of PSI and PSII, respectively. (b) An increase in pH differences across the thylakoid membrane and a decrease in thylakoid proton conductivity revealed a reduction of ATP synthase activity. (c) Using electron microscopy, we showed a decrease in membrane stacking and stomatal opening after 7 days of FL treatment. Taken together, our results show that electron flow, ATP synthase activity and NPQ regulation are the major processes determining the growth performance of rice under long-term FL conditions.

Ammonia oxidation at pH 2.5 by a new gammaproteobacterial ammonia-oxidizing bacterium

Ammonia oxidation was considered impossible under highly acidic conditions, as the protonation of ammonia leads to decreased substrate availability and formation of toxic nitrogenous compounds. Recently, some studies described archaeal and bacterial ammonia oxidizers growing at pH as low as 4, while environmental studies observed nitrification at even lower pH values. In this work, we report on the discovery, cultivation, and physiological, genomic, and transcriptomic characterization of a novel gammaproteobacterial ammonia-oxidizing bacterium enriched via continuous bioreactor cultivation from an acidic air biofilter that was able to grow and oxidize ammonia at pH 2.5. This microorganism has a chemolithoautotrophic lifestyle, using ammonia as energy source. The observed growth rate on ammonia was 0.196 day−1, with a doubling time of 3.5 days. The strain also displayed ureolytic activity and cultivation with urea as ammonia source resulted in a growth rate of 0.104 day−1 and a doubling time of 6.7 days. A high ammonia affinity (Km(app) = 147 ± 14 nM) and high tolerance to toxic nitric oxide could represent an adaptation to acidic environments. Electron microscopic analysis showed coccoid cell morphology with a large amount of intracytoplasmic membrane stacks, typical of gammaproteobacterial ammonia oxidizers. Furthermore, genome and transcriptome analysis showed the presence and expression of diagnostic genes for nitrifiers (amoCAB, hao, nor, ure, cbbLS), but no nirK was identified. Phylogenetic analysis revealed that this strain belonged to a novel bacterial genus, for which we propose the name “Candidatus Nitrosacidococcus tergens” sp. RJ19.

(Invited) Printed Built-in Power Sources with Dimensional Conformability

The ongoing surge in demand for flexible/wearable electronics, self-powered systems, soft robotics, and Internet of Things (IoT) has inspired the relentless pursuit of form factor-free, high-performance power sources that can be monolithically and seamlessly integrated with various electronics. To reach this challenging goal, a new class of advanced power sources with various form factors that are different from existing commercial ones are needed. From the viewpoint of power source design and architecture, traditional cell materials and fabrication have resulted in power sources that feature a lack of variety in form factors and flexibility. In specific, most of the current power sources are manufactured by winding or stacking of slurry-casted electrode sheets and separator membranes, followed by the injection of liquid electrolytes inside a fixed form of canisters or pouch packaging substances; these methods impose stringent restrictions on the unitization of power sources with electronic devices. Printed power sources have recently garnered considerable attention as a fresh and game-changing approach due to their design diversity, shape/performance compatibility with electronic devices, and scalable/low-cost processability. Printed power sources based on high-fidelity printing techniques and rationally designed material chemistry are fabricated directly on complex-shaped objects, thereby enabling monolithic integration and electrochemical coupling with target devices that lie far beyond those achievable with conventional power source technologies.Here, this talk introduces form factor-free, printed built-in power sources, with particular attention to their dimensional conformability and performance compatibility with newly emerging complex-structured electronic devices. A key-enabling technology for the printed power sources is the design of battery inks (specifically, electrode and electrolyte inks), with a focus on their rheology and electrochemistry. Our research interests are directed to discussing effects of the battery inks on printing processability, microstructure (focusing on bicontinuous ion/electron transport channels) and electrochemical performance of the resultant printed power sources. We envision that the printed power sources open a new avenue towards form factor-free/monolithic integrated power sources with object-tailored design versatility and dimensional conformability.

Ultra-thin pore-filling membranes with mirror-image wave patterns for improved power density and reduced pressure drops in stacks of reverse electrodialysis

Reverse electrodialysis (RED) emerged as a promising membrane-based technology due to an increased interest in salinity gradient energy. We report on the fabrication and characterization of ion-exchange membranes wave-patterned with non-conductive materials and supported by thin (16-μm-thick) pore-filling membranes. These membranes, which are double-sided or single-sided, are designed to secure stable electrolyte channels based on wave lines with mirror images. Cross-flow RED stacks were evaluated as functions of cell pairs and flow rates. The non-conductive material increases the membrane resistance for anion and cation exchange, maintaining permselectivity approximately constant. The gross power density of a flat stack is higher than that of a single-sided patterned membrane stack; however, the latter exhibits superior net power density, particularly at high flow rates. The pressure drop of the single-sided wave-patterned membrane is significantly lower (~3 × ) than that of the flat membrane. The maximum gross power density was 1.39 W/m2 for 10-cell pairs, and the optimum cell pairs were 30, with the highest net energy efficiency of 9.4%. The net energy efficiency can be maximized by optimizing the design and operating conditions of the RED stack and net power density, via the addition of an ionic conductivity function to the patterned structure.

Ammonium sulfate production from wastewater and low-grade sulfuric acid using bipolar- and cation-exchange membranes

Conventional electrodialysis can be used to recover ammonia from dewatering centrate (i.e., down-stream wastewater from digested sludge dewatering). However, ionic impurities of the recovered ammonia solution are still a limiting factor for broad applications of ion-exchange membranes (IEMs) in wastewater treatment and resource recovery. In this study, an electrodialysis stack with bipolar membranes (BPMs) and cation exchange membranes (CEMs) but without anion exchange membranes (AEMs) was examined under various operation conditions to demonstrate high-purity ammonium sulfate production using low-grade sulfuric acid and dewatering centrate. Two significant benefits of removing AEMs from the bipolar membrane electrodialysis (BMED) are no more membrane fouling problems on AEMs and complete exclusion of impurity anions (e.g., chloride ions) in the recovered ammonium sulfate solution. A higher applied voltage condition (30 V over 7 pairs of CEM and BPM) resulted in a substantially high ammonia recovery (88.4%) and concentration (4.34 g-N/L) in 90 min. The ammonia recovery and concentration were also improved by increasing the flow rate through the BMED stack. The lowest electric energy consumption in the membrane stack was 9.6 kW h/kg-N, indicating energy efficient production of high-purity ammonium sulfate from wastewater. The amount of divalent cation scales accumulated in the BMED stack was linearly proportional to the average electric current, implying that the scaling problem can be controlled by reducing the applied voltage. Even with the scale accumulation, the electric current generation (i.e., separation performance) was hardly affected during the experiment. These findings demonstrated the strong potential of AEM-lacking BMED for practical ammonia separation from wastewater with reduced impurities.

Functional analyses of STIM1 mutations reveal a common pathomechanism for tubular aggregate myopathy and Stormorken syndrome.

Tubular aggregate myopathy (TAM) is a progressive disorder characterized by muscle weakness, cramps, and myalgia. TAM clinically overlaps with Stormorken syndrome (STRMK), combining TAM with miosis, thrombocytopenia, hyposplenism, ichthyosis, short stature, and dyslexia. TAM and STRMK arise from gain-of-function mutations in STIM1 (stromal interaction molecule 1) or ORAI1, both encoding key regulators of Ca2+ homeostasis, and mutations in either gene result in excessive extracellular Ca2+ entry. The pathomechanistic similarities and differences between TAM and STRMK are only partially understood. Here we provide functional in vitro experiments demonstrating that STIM1 harboring the TAM D84G or the STRMK R304W mutation similarly cluster and exert a dominant effect on the wild-type protein. Both mutants recruit ORAI1 to the clusters, increase cytosolic Ca2+ levels, promote major nuclear import of the Ca2+ -dependent transcription factor NFAT (nuclear factor of activated T cells), and trigger the formation of circular membrane stacks. In conclusion, the analyzed TAM and STRMK mutations have a comparable impact on STIM1 protein function and downstream effects of excessive Ca2+ entry, highlighting that TAM and STRMK involve a common pathomechanism.

Achieving maximum recovery of latent heat in photothermally driven multi-layer stacked membrane distillation

Photothermal membrane distillation (PMD) has received increased attention for water desalination because it uses abundant sunlight as its main energy source. It can also be implemented in a modular configuration and work well for decentralized communities. Here we present a multi-layer stacked membrane module with airgaps that can reduce conductive heat loss and recover latent heat. The membrane is synthesized by a simple and scalable spray-coating method that prepared by graphene nanosheets deposition onto a hydrophobic polytetrafluoroethylene (PTFE) membrane with polymerized dopamine (PDA) and trichloro(1H,1H,2H,2H-perfluorooctyl) silane (FTCS). Graphene nanosheets are employed as a photothermal material because of its broad light absorption in the solar spectrum and efficient photothermal conversion. To maximize the water flux, the airgap thickness was optimized, and multiple heat recovery layers were stacked. Using the optimized airgap and four stacked layers, we achieved a high water flux of 1.17 kg/m 2 /h under 0.75 kW/m 2 , equivalent to 105% solar conversion efficiency, which is the highest efficiency reported among all PMD studies (20–70%). To predict the water flux, we further constructed a theoretical model to estimate the membrane surface temperatures that are photothermally heated, which will be helpful in understanding and optimizing future PMD systems. The high efficiency of the multi-layer stacked PMD module in this study bespeaks its great promise as a sustainable and off-grid desalination technique. With an efficient graphene nanosheet-based photothermal membrane, we demonstrate that the performance of the photothermal membrane distillation was largely improved by effectively recovering latent heat generated during condensation of vapor. Using the optimized airgap and four stacked layers, we achieved a high water flux of 1.17 kg/m 2 /h under 0.75 kW/m 2 , equivalent to 105% solar conversion efficiency. • Graphene-based photothermal membranes were fabricated with a simple spray coating. • In our novel multi-layer stacked module, latent heat was efficiently recovered. • With an optimal setting, we achieved the high solar-to-water efficiency (~ 105%). • Synthesized membranes were mechanically and chemically robust for long-term use.

Characterizations of Electrolyte–Insulator–Semiconductor Sensors With Array Wells and a Stack-Sensing Membrane

This study addressed the characteristics of electrolyte-insulator-semiconductor (EIS) pH sensors with array wells and sensing membrane stacks of 3-aminopropyltriethoxysilane (APTES)/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . The arrays of square wells were fabricated by nanoimprint lithography (NIL) and investigated using an atomic force microscope (AFM). The surface chemical properties of molecular APTES on SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> were investigated by water contact angle (WCA) studies and X-ray photoelectron spectroscopy (XPS). The sensitivity, hysteresis, and drift of EIS sensors were studied. All of the sensing properties were greatly enhanced by using the techniques we propose. With these improvements, high-performance sensors can be fabricated for future biochemical applications.

Effect of Elevated PEM Fuel Cell Operating Temperature (120°C and 140°C) and Membrane Thickness on Proton Conductivity for Combat Vehicle Use

Electrical power required to operate vehicles in the U.S. Army is increasing due to expanding mission requirements, such as silent watch, exportable power, and powerful onboard electronics. Proton Exchange Membrane Fuel Cells (PEMFCs) provide a solution, but stack thermal-cycling, electrocatalyst and membrane degradation losses need to be reduced before integration of PEMFCs can be realized. Membrane thermal degradation is exacerbated by poor heat rejection (as ballistic grills impede airflow) which can raise stack temperatures ≥140°C. Commercial PEMFCs operate ~65°C so elevated temperatures could degrade the membrane. Nafion 115 (127 μm), 117 (183 μm) and 1110 (254 μm) membranes submerged in 16 MΩ water were heated between 65-140°C to investigate elevated temperature and membrane thickness on proton conductivity. EIS results showed sample thickness did not statistically impact conductivity overall. Conductivity, however, was impacted for temperatures >100°C with each material. Overall, these materials are not suitable when operating PEMFCs above 100°C.

Direct Measurement of Crossover and Interfacial Resistance of Ion-Exchange Membranes in All-Vanadium Redox Flow Batteries.

Among various components commonly used in redox flow batteries (RFBs), the separator plays a significant role, influencing resistance to current as well as capacity decay via unintended crossover. It is well-established that the ohmic overpotential is dominated by the membrane and interfacial resistance in most aqueous RFBs. The ultimate goal of engineering membranes is to improve the ionic conductivity while keeping crossover at a minimum. One of the major issues yet to be addressed is the contribution of interfacial phenomena in the influence of ionic and water transport through the membrane. In this work, we have utilized a novel experimental system capable of measuring the ionic crossover in real-time to quantify the permeability of ionic species. Specifically, we have focused on quantifying the contributions from the interfacial resistance to ionic crossover. The trade-off between the mass and ionic transport impedance caused by the interface of the membranes has been addressed. The MacMullin number has been quantified for a series of electrolyte configurations and a correlation between the ionic conductivity of the contacting electrolyte and the Nafion® membrane has been established. The performance of individual ion-exchange membranes along with a stack of various separators have been explored. We have found that utilizing a stack of membranes is significantly beneficial in reducing the electroactive species crossover in redox flow batteries compared to a single membrane of the same fold thickness. For example, we have demonstrated that the utilization of five layers of Nafion® 211 membrane reduces the crossover by 37% while only increasing the area-specific resistance (ASR) by 15% compared to a single layer Nafion® 115 membrane. Therefore, the influence of interfacial impedance in reducing the vanadium ion crossover is substantially higher compared to a corresponding increase in ASR, indicating that mass and ohmic interfacial resistances are dissimilar. We have expanded our analysis to a combination of commercially available ion-exchange membranes and provided a design chart for membrane selection based on the application of interest (short duration/high-performance vs. long-term durability). The results of this study provide a deeper insight into the optimization of all-vanadium redox flow batteries (VRFBs).

Enhanced Stability of Lipid Structures by Dip-Pen Nanolithography on Block-Type MPC Copolymer.

Biomimetic lipid membranes on solid supports have been used in a plethora of applications, including as biosensors, in research on membrane proteins or as interfaces in cell experiments. For many of these applications, structured lipid membranes, e.g., in the form of arrays with features of different functionality, are highly desired. The stability of these features on a given substrate during storage and in incubation steps is key, while at the same time the substrate ideally should also exhibit antifouling properties. Here, we describe the highly beneficial properties of a 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer for the stability of supported lipid membrane structures generated by dip-pen nanolithography with phospholipids (L-DPN). The MPC copolymer substrates allow for more stable and higher membrane stack structures in comparison to other hydrophilic substrates, like glass or silicon oxide surfaces. The structures remain highly stable under immersion in liquid and subsequent incubation and washing steps. This allows multiplexed functionalization of lipid arrays with antibodies via microchannel cantilever spotting (µCS), without the need of orthogonal binding tags for each antibody type. The combined properties of the MPC copolymer substrate demonstrate a great potential for lipid-based biomedical sensing and diagnostic platforms.

Ultrathin dense double-walled carbon nanotube membrane for enhanced lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as next-generation technology for energy storage due to their high energy density. However, the rapid capacity fading resulted from the shuttle effect obstructs their practical application. Herein, ultrathin dense double-walled carbon nanotube (DWCNT) membrane has been designed to impede the shuttle effect. The outer wall of DWCNT helps to keep the integrity and conductivity for its inner wall. The defects on DWCNT are less than those on multi-walled CNT (MWCNT), which helps DWNCT to stack and form dense membrane. The tiny areal density of 0.00477 mg cm−2 of DWCNT membrane would not weaken the Li-S battery’s energy density too much. The electrochemical tests suggested that the DWCNT membrane improved the cycling performance effectively. A possible reason was discussed. The cathode electrolyte interphase (CEI) grown on the DWCNTs made the membrane further dense, which promoted the blocking effect on polysulfides.

Lattice Models for Protein Organization throughout Thylakoid Membrane Stacks

Proteins in photosynthetic membranes can organize into patterned arrays that span the membrane’s lateral size. Attractions between proteins in different layers of a membrane stack can play a key role in this ordering, as was suggested by microscopy and fluorescence spectroscopy and demonstrated by computer simulations of a coarse-grained model. The architecture of thylakoid membranes, however, also provides opportunities for interlayer interactions that instead disfavor the high protein densities of ordered arrangements. Here, we explore the interplay between these opposing driving forces and, in particular, the phase transitions that emerge in the periodic geometry of stacked thylakoid membrane disks. We propose a lattice model that roughly accounts for proteins’ attraction within a layer and across the stromal gap, steric repulsion across the lumenal gap, and regulation of protein density by exchange with the stroma lamellae. Mean-field analysis and computer simulation reveal rich phase behavior for this simple model, featuring a broken-symmetry striped phase that is disrupted at both high and low extremes of chemical potential. The resulting sensitivity of microscopic protein arrangement to the thylakoid’s mesoscale vertical structure raises intriguing possibilities for regulation of photosynthetic function.

Cellular Plasticity in Response to Suppression of Storage Proteins in the Brassica napus Embryo.

The tradeoff between protein and oil storage in oilseed crops has been tested here in oilseed rape (Brassica napus) by analyzing the effect of suppressing key genes encoding protein storage products (napin and cruciferin). The phenotypic outcomes were assessed using NMR and mass spectrometry imaging, microscopy, transcriptomics, proteomics, metabolomics, lipidomics, immunological assays, and flux balance analysis. Surprisingly, the profile of storage products was only moderately changed in RNA interference transgenics. However, embryonic cells had undergone remarkable architectural rearrangements. The suppression of storage proteins led to the elaboration of membrane stacks enriched with oleosin (sixfold higher protein abundance) and novel endoplasmic reticulum morphology. Protein rebalancing and amino acid metabolism were focal points of the metabolic adjustments to maintain embryonic carbon/nitrogen homeostasis. Flux balance analysis indicated a rather minor additional demand for cofactors (ATP and NADPH). Thus, cellular plasticity in seeds protects against perturbations to its storage capabilities and, hence, contributes materially to homeostasis. This study provides mechanistic insights into the intriguing link between lipid and protein storage, which have implications for biotechnological strategies directed at improving oilseed crops.