Plant roots perceive heat stress (HS) and adapt their architecture accordingly, which in turn influence the yield in crops. Investigating their heterogeneity and cell type-specific response to HS is essential for improving crop resilience. Here, we generate single-cell transcriptional landscape of maize (Zea mays) roots in response to HS. We characterize 15 cell clusters corresponding to 9 major cell types and identify cortex as the main root cell type responsive to HS with the most differentially expressed genes and its trajectory being preferentially affected upon HS. We find that cortex size strongly correlated with heat tolerance that is experimentally validated by using inbred lines and genetic mutation analysis of one candidate gene in maize, providing potential HS tolerance indicator and targets for crop improvement. Moreover, interspecies comparison reveals conserved root cell types and core markers in response to HS in plants, which are experimentally validated. These results provide a universal atlas for unraveling the transcriptional programs that specify and maintain the cell identity of maize roots in response to HS at a cell type-specific level.
Root System Architecture (RSA) plays an essential role in influencing maize yield by enhancing anchorage and nutrient uptake. Analyzing maize RSA dynamics holds potential for ideotype-based breeding and prediction, given the limited understanding of the genetic basis of RSA in maize. Here, we obtained 16 root morphology-related traits (R-traits), 7 weight-related traits (W-traits), and 108 slice-related microphenotypic traits (S-traits) from the meristem, elongation, and mature zones by cross-sectioning primary, crown, and lateral roots from 316 maize lines. Significant differences were observed in some root traits between tropical/subtropical and temperate lines, such as primary and total root diameters, root lengths, and root area. Additionally, root anatomy data were integrated with genome-wide association study (GWAS) to elucidate the genetic architecture of complex root traits. GWAS identified 809 genes associated with R-traits, 261 genes linked to W-traits, and 2577 key genes related to 108 slice-related traits. We confirm the function of a candidate gene, fucosyltransferase5 (FUT5), in regulating root development and heat tolerance in maize. The different FUT5 haplotypes found in tropical/subtropical and temperate lines are associated with primary root features and hold promising applications in molecular breeding. Furthermore, we performed machine learning prediction models of RSA using root slice traits, achieving high prediction accuracy. Collectively, our study offers a valuable tool for dissecting the genetic architecture of RSA, along with resources and predictive models beneficial for molecular design breeding and genetic enhancement.
Plant organ size is an important agronomic trait that greatly determines plant yield. However, despite its central importance, the genetic and molecular mechanisms underlying organ size control remain elusive. Here, we report the trithorax group protein ULTRAPETALA1 (ULT1) interacts with TCP14/15 transcription factors (TFs) by antagonizing the LIM-peptidase DA1 to regulate organ size in Arabidopsis. Loss of ULT1 function significantly increases rosette leaf, petal, silique and seed size, while overexpression of ULT1 results in reduced organ size. ULT1 associates with TCP14 and TCP15 to co-regulate cell size by affecting cellular endoreduplication. Transcriptome analysis reveals that ULT1 and TCP14/15 regulate common target genes involved in endoreduplication and leaf development. ULT1 can be recruited by TCP14/15 to promote H3K4 trimethylation (H3K4me3) at target genes, thereby activating their expression to determine final cell sizes. Furthermore, we found that ULT1 influences the interaction of DA1 and TCP14/15 and antagonizes the effect of DA1’s degradation on TCP14/TCP15. Collectively, our findings uncover a novel epigenetic mechanism underlying the regulation of organ size in Arabidopsis.
Epigenetics-mediated breeding (Epibreeding) involves engineering crop traits and stress responses through the targeted manipulation of key epigenetic features to enhance agricultural productivity. While conventional breeding methods raise concerns about reduced genetic diversity, epibreeding propels crop improvement through epigenetic variations that regulate gene expression, ultimately impacting crop yield. Epigenetic regulation in crops encompasses various modes, including histone modification, DNA modification, RNA modification, non-coding RNA, and chromatin remodeling. This review summarizes the epigenetic mechanisms underlying major agronomic traits in maize and identifies candidate epigenetic landmarks in the maize breeding process. We propose a valuable strategy for improving maize yield through epibreeding, combining CRISPR/Cas-based epigenome editing technology and Synthetic Epigenetics (SynEpi). Finally, we discuss the challenges and opportunities associated with maize trait improvement through epibreeding.
Synthetic biology plays a pivotal role in improving crop traits and increasing bioproduction through the use of engineering principles that purposefully modify plants through "design, build, test, and learn"cycles, ultimately resulting in improved bioproduction based on an input genetic circuit (DNA, RNA, and proteins). Crop synthetic biology is a new tool that uses circular principles to redesign and create innovative biological components, devices, and systems to enhance yields, nutrient absorption, resilience, and nutritional quality. In the digital age, artificial intelligence (AI) has demonstrated great strengths in design and learning. The application of AI has become an irreversible trend, with particularly remarkable potential for use in crop breeding. However, there has not yet been a systematic review of AI-driven synthetic biology pathways for plant engineering. In this review, we explore the fundamental engineering principles used in crop synthetic biology and their applications for crop improvement. We discuss approaches to genetic circuit design, including gene editing, synthetic nucleic acid and protein technologies, multi-omics analysis, genomic selection, directed protein engineering, and AI. We then outline strategies for the development of crops with higher photosynthetic efficiency, reshaped plant architecture, modified metabolic pathways, and improved environmental adaptability and nutrient absorption; the establishment of trait networks; and the construction of crop factories. We propose the development of SMART (self-monitoring, adapted, and responsive technology) crops through AI-empowered synthetic biotechnology. Finally, we address challenges associated with the development of synthetic biology and offer potential solutions for crop improvement.
Polycomb(PcG)and trithorax(trxG)are two groups of conserved epigenetic complexes that maintain active and repressive states of target genes by altering their chromatin states to regulate plant development and stress responses.In the conventional view,PcG and trxG proteins often function antagonistically in transcrip-tional gene regulation,based on the observation that mutations in trxG and PcG genes can counteract each other's activity,whereas mutations of genes within each group have synergistic effects(Pu and Sung,2015).Despite this general tendency,a growing body of evidence suggests that there is no overall synergism or antagonism between and within the trxG and PcG proteins.Instead,there is a nuanced and intricate synergistic interaction,establishing a mutual regulatory relationship between PcG and trxG.
Plant organ size is an important agronomic trait that makes a significant contribution to plant yield. Despite its central importance, the genetic and molecular mechanisms underlying organ size control remain to be fully clarified. Here, we report that the trithorax group protein ULTRAPETALA1 (ULT1) interacts with the TEOSINTE BRANCHED1/CYCLOIDEA/PCF14/15 (TCP14/15) transcription factors by antagonizing the LIN-11, ISL-1, and MEC-3 (LIM) peptidase DA1, thereby regulating organ size in Arabidopsis. Loss of ULT1 function significantly increases rosette leaf, petal, silique, and seed size, whereas overexpression of ULT1 results in reduced organ size. ULT1 associates with TCP14 and TCP15 to co-regulate cell size by affecting cellular endoreduplication. Transcriptome analysis revealed that ULT1 and TCP14/15 regulate common target genes involved in endoreduplication and leaf development. ULT1 can be recruited by TCP14/15 to promote lysine 4 of histone H3 trimethylation at target genes, activating their expression to determine final cell size. Furthermore, we found that ULT1 influences the interaction of DA1 and TCP14/15 and antagonizes the effect of DA1 on TCP14/15 degradation. Collectively, our findings reveal a novel epigenetic mechanism underlying the regulation of organ size in Arabidopsis.
Plant height is an important agronomic trait that affects crop yield. Elucidating the molecular mechanism underlying plant height regulation is also an important question in developmental biology. Here, we report that a BELL transcription factor, ZmBELL10, positively regulates plant height in maize (Zea mays). Loss of ZmBELL10 function resulted in shorter internodes, fewer nodes, and smaller kernels, while ZmBELL10 overexpression increased plant height and hundred-kernel weight. Transcriptome analysis and chromatin immunoprecipitation followed by sequencing showed that ZmBELL10 recognizes specific sequences in the promoter of its target genes and activates cell division- and cell elongation-related gene expression, thereby influencing node number and internode length in maize. ZmBELL10 interacted with several other ZmBELL proteins via a spatial structure in its POX domain to form protein complexes involving ZmBELL10. All interacting proteins recognized the same DNA sequences, and their interaction with ZmBELL10 increased target gene expression. We identified the key residues in the POX domain of ZmBELL10 responsible for its protein-protein interactions, but these residues did not affect its transactivation activity. Collectively, our findings shed light on the functions of ZmBELL10 protein complexes and provide potential targets for improving plant architecture and yield in maize.
The many-banded krait, Bungarus multicinctus, has been recorded as the animal resource of JinQianBaiHuaShe in the Chinese Pharmacopoeia. Characterization of its venoms classified chief phyla of modern animal neurotoxins. However, the evolutionary origin and diversification of its neurotoxins as well as biosynthesis of its active compounds remain largely unknown due to the lack of its high-quality genome. Here, we present the 1.58 Gbp genome of B. multicinctus assembled into 18 chromosomes with contig/scaffold N50 of 7.53 Mbp/149.8 Mbp. Major bungarotoxin-coding genes were clustered within genome by family and found to be associated with ancient local duplications. The truncation of glycosylphosphatidylinositol anchor in the 3’-terminal of a LY6E paralog released modern three-finger toxins(3FTxs) from membrane tethering before the Colubroidea divergence. Subsequent expansion and mutations diversified and recruited these 3FTxs. After the cobra/krait divergence, the modern unit-B of β-bungarotoxin emerged with an extra cysteine residue. A subsequent point substitution in unit-A enabled theβ-bungarotoxin covalent linkage. The B. multicinctus gene expression, chromatin topological organization, and histone modification characteristics were featured by transcriptome, proteome, chromatin conformation capture sequencing, and ChIP-seq. The results highlighted that venom production was under a sophisticated regulation. Our findings provide new insights into snake neurotoxin research, meanwhile will facilitate antivenom development, toxin-driven drug discovery and the quality control of JinQianBaiHuaShe.
Maize (Zea mays) is an important cereal crop with suitable stalk formation which is beneficial for acquiring an ideal agronomic trait to resist lodging and higher planting density. The elongation pattern of stalks arises from the variable growth of individual internodes driven by cell division and cell expansion comprising the maize stalk. However, the spatiotemporal dynamics and regulatory network of the maize stalk development and differentiation process remain unclear. Here, we report spatiotemporally resolved transcriptomes using all internodes of the whole stalks from developing maize at the elongation and maturation stages. We identified four distinct groups corresponding to four developmental zones and nine specific clusters with diverse spatiotemporal expression patterns among individual internodes of the stalk. Through weighted gene coexpression network analysis, we constructed transcriptional regulatory networks at a fine spatiotemporal resolution and uncovered key modules and candidate genes involved in internode maintenance, elongation, and division that determine stalk length and thickness in maize. Further CRISPR/Cas9-mediated knockout validated the function of a cytochrome P450 gene, ZmD1, in the regulation of stalk length and thickness as predicted by the WGCN. Collectively, these results provide insights into the high genetic complexity of stalk development and the potentially valuable resources with ideal stalk lengths and widths for genetic improvements in maize.
Plant height (PH) is an essential trait in maize (Zea mays) that is tightly associated with planting density, biomass, lodging resistance, and grain yield in the field. Dissecting the dynamics of maize plant architecture will be beneficial for ideotype-based maize breeding and prediction, as the genetic basis controlling PH in maize remains largely unknown. In this study, we developed an automated high-throughput phenotyping platform (HTP) to systematically and noninvasively quantify 77 image-based traits (i-traits) and 20 field traits (f-traits) for 228 maize inbred lines across all developmental stages. Time-resolved i-traits with novel digital phenotypes and complex correlations with agronomic traits were characterized to reveal the dynamics of maize growth. An i-trait-based genome-wide association study identified 4945 trait-associated SNPs, 2603 genetic loci, and 1974 corresponding candidate genes. We found that rapid growth of maize plants occurs mainly at two developmental stages, stage 2 (S2) to S3 and S5 to S6, accounting for the final PH indicators. By integrating the PH-association network with the transcriptome profiles of specific internodes, we revealed 13 hub genes that may play vital roles during rapid growth. The candidate genes and novel i-traits identified at multiple growth stages may be used as potential indicators for final PH in maize. One candidate gene, ZmVATE, was functionally validated and shown to regulate PH-related traits in maize using genetic mutation. Furthermore, machine learning was used to build predictive models for final PH based on i-traits, and their performance was assessed across developmental stages. Moderate, strong, and very strong correlations between predictions and experimental datasets were achieved from the early S4 (tenth-leaf) stage. Colletively, our study provides a valuable tool for dissecting the spatiotemporal formation of specific internodes and the genetic architecture of PH, as well as resources and predictive models that are useful for molecular design breeding and predicting maize varieties with ideal plant architectures.
Methylating RNA post-transcriptionally is emerging as a significant mechanism of gene regulation in eukaryotes. The crosstalk between RNA methylation and histone modification is critical for chromatin state and gene expression in mammals. However, it is not well understood mechanistically in plants. Here, the authors report a genome-wide correlation between RNA 5-cytosine methylation (m5 C) and histone 3 lysine27 trimethylation (H3K27me3) in Arabidopsis. The plant-specific Polycomb group (PcG) protein EMBRYONIC FLOWER1 (EMF1) plays dual roles as activators or repressors. Transcriptome-wide RNA m5 C profiling revealed that m5 C peaks are mostly enriched in chromatin regions that lacked H3K27me3 in both wild type and emf1 mutants. EMF1 repressed the expression of m5 C methyltransferase tRNA specific methyltransferase 4B (TRM4B) through H3K4me3, independent of PcG-mediated H3K27me3 mechanism. The 5-Cytosine methylation on targets is increased in emf1 mutants, thereby decreased the mRNA transcripts of photosynthesis and chloroplast genes. In addition, impairing EMF1 activity reduced H3K27me3 levels of PcG targets, such as starch genes, which are de-repressed in emf1 mutants. Both EMF1-mediated promotion and repression of gene activities via m5 C and H3K27me3 are required for normal vegetative growth. Collectively, t study reveals a previously undescribed epigenetic mechanism of RNA m5 C modifications and histone modifications to regulate gene expression in eukaryotes.
Glaucoma is the leading cause of irreversible blindness with trabecular meshwork (TM) dysfunction resulting in elevated intraocular pressure and retinal ganglion cell (RGC) damage leading to vision loss. In this study, we discovered that secretome, derived from human TM stem cells, via minimal invasive periocular injection, can reduce intraocular pressure, restore TM homeostasis, protect RGC, and restore RGC function in both steroid-induced and genetic myocilin mutant mouse models of glaucoma. The secretome upregulated the COX2-PGE2 axis via mitochondrial TMEM177 and led to activation of endogenous stem cells and TM regeneration. Inhibition of COX2 abolished the protective effect of secretome on TM cells. Secretome treatment also enhanced RGC survival and function. Proteomic analysis revealed that the secretome is enriched with proteins involved in extracellular matrix modulation leading to the remodeling of TM to restore homeostasis. This study highlights the feasibility of stem cell-free therapy for glaucoma with minimal invasive administration and the involvement of multiple novel pathways for a cumulative regenerative effect on the TM to protect RGC. Brief summary This study describes a cell-free treatment using stem cell secretome in two animal models of glaucoma and explores the potential mechanisms ### Competing Interest Statement University of Pittsburgh has a competing interest with a patent trabecular meshwork stem cells with Yiqin Du and Joel S. Schuman as inventors. University of Pittsburgh has filed provisional patent compositions and methods for treating ocular disorders with Yiqin Du and Ajay Kumar as inventors. All other authors declare no competing interests.
The hypoglycaemic target of empagliflozin (EMP), as a novel inhibitor of sodium-glucose cotransporter (SGLT2), is clear. However, recent studies have shown that EMP also has an important role in lipid metabolism and cardiovascular diseases. The liver plays an important role in the development of type 2 diabetes (T2D), although whether EMP affects liver glucose metabolism is currently not reported. This study was designed to evaluate the effect of EMP on hepatic glucose metabolism in T2D and the underlying mechanism. A model of T2D was established by a high-fat and glucose diet (HFD) combined with streptozotocin (30 mg/kg) in male Wistar rats. Serum samples were collected to measure biochemical indicators, and liver samples were extracted for RNA-seq assay. Quantitative real-time PCR (qPCR) was used to further verify the gene expression levels detected by the RNA-seq assay. The EMP group showed significantly decreased blood glucose, triglyceride, cholesterol, non-esterified fatty acid and low-density lipoprotein cholesterol levels, and increased high-density lipoprotein cholesterol levels in serum compared with the type 2 diabetes model (MOD) group. Furthermore, EMP decreased the levels of inflammatory factors IL-1β, IL-6, and IL-8 in the serum compared to the MOD. Liver transcriptome analysis showed EMP affects a large number of upregulated and downregulated genes. Some of these genes are novel and involve in the metal ion binding pathway and the negative regulation of transcription from the RNA polymerase II promoter pathway, which are also closely related to glucolipid metabolism and insulin signaling. Our study provides new knowledge about the mechanism through which SGLT inhibitor can offer beneficial effects in T2D and especially in the hepatic metabolism. These genes found in this study also laid a solid foundation for further research on the new roles and mechanisms of EMP.
Objective: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by 13 mutations in MeCP2, a transcription factor. MeCP2 mutations cause abnormal expression of 14 downstream genes and eventually lead to brain dysfunction. The role of MeCP2 in brain neural 15 development remains unclear. To further elucidate this role, a MeCP2-null rat model was created 16 with the CRISPR/cas9 system. Method: A MeCP2-cas9 vector was constructed and then 17 microinjected into fertilized rat ova in vitro. Two mutations by CRISPR/cas9 were confirmed to 18 cause deletions in exon 2 of MeCP2 via DNA sequencing, and protein expression was measured by 19 Western blotting. Transcriptome data for three brain tissues, the cerebellum, cerebral cortex and 20 hippocampus, were obtained via next-generation sequencing. Results: MeCP2-null rats were 21 successfully obtained, and preliminary analysis showed that the MeCP2-null rats exhibited motor 22 dysfunction and anxious and depressed behaviour. In addition, differentially expressed genes 23 (DEGs) were identified in the three MeCP2-null brain tissues compared to wild-type rat brain 24 tissues. In the rat cerebellum, 388 downregulated DEGs were mainly involved in the calcium ion 25 signalling pathway and the PI3K-Akt signalling pathway. In the cerebral cortex, 386 upregulated 26 DEGs were primarily involved in intracellular signal transduction, protein phosphorylation and the 27 MAPK signalling pathway. In the hippocampus, the DEGs were related to the MAPK signalling 28 pathway. Conclusion: We constructed a MeCP2-null rat model with unique features with 29 CRISPR/cas9 technology to study RTT and analysed DEGs in three rat brain tissues to highlight 30 potential targets for the development of new medicines. 31
Objective: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in MeCP2, a transcription factor. MeCP2 mutations cause abnormal expression of downstream genes and eventually lead to brain dysfunction. The role of MeCP2 in brain neural development remains unclear. To further elucidate this role, a MeCP2-null rat model was created with the CRISPR/cas9 system. Method: A MeCP2-cas9 vector was constructed and then microinjected into fertilized rat ova in vitro. Two mutations by CRISPR/cas9 were confirmed to cause deletions in exon 2 of MeCP2 via DNA sequencing, and protein expression was measured by Western blotting. Transcriptome data for three brain tissues, the cerebellum, cerebral cortex and hippocampus, were obtained via next-generation sequencing. Results: MeCP2-null rats were successfully obtained, and preliminary analysis showed that the MeCP2-null rats exhibited motor dysfunction and anxious and depressed behaviour. In addition, differentially expressed genes (DEGs) were identified in the three MeCP2-null brain tissues compared to wild-type rat brain tissues. In the rat cerebellum, 388 downregulated DEGs were mainly involved in the calcium ion signalling pathway and the PI3K-Akt signalling pathway. In the cerebral cortex, 386 upregulated DEGs were primarily involved in intracellular signal transduction, protein phosphorylation and the MAPK signalling pathway. In the hippocampus, the DEGs were related to the MAPK signalling pathway. Conclusion: We constructed a MeCP2-null rat model with unique features with CRISPR/cas9 technology to study RTT and analysed DEGs in three rat brain tissues to highlight potential targets for the development of new medicines.
A traditional Chinese tea with many pharmacological effects, vine tea (VT) is considered a potential dietary supplement to improve type 2 diabetes (T2D). To investigate the effect and mechanism of VT on glucose and lipid metabolic disorders in T2D rats, Wistar rats fed a normal diet served as the normal control, while rats fed a high-fat diet combined with low-dose streptozotocin (STZ)-induced T2D were divided into three groups: The model group (MOD); the positive control group (MET, metformin at 200 mg/kg/d); and the VT-treated group (VT500, allowed to freely drink 500 mg/L VT). After four weeks of intervention, biochemical metrics indicated that VT significantly ameliorated hyperglycemia, hyperlipidemia and hyperinsulinemia in T2D rats. Metabolomics research indicated that VT regulated the levels of metabolites closely related to glucose and lipid metabolism and promoted glycogen synthesis. Furthermore, VT had a significant influence on the expression of key genes involved in the Akt signaling pathway, inhibited gluconeogenesis through the Akt/Foxo1/Pck2 signaling pathway, and reduced fatty acid synthesis via the SREBP1c/Fasn signaling pathways. In conclusion, VT has great potential as a dietary supplement to ameliorate glucose and lipid metabolic disorders via the Akt signaling pathway in T2D rats.
We aimed to ascertain the mechanism underlying the effects of acteoside (ACT) from Ligustrum robustum (Roxb.) Blume (Oleaceae) on lipid metabolism and synthesis. ACT, a water-soluble phenylpropanoid glycoside, is the most abundant and major active component of L. robustum; the leaves of L. robustum, known as kudingcha (bitter tea), have long been used in China as an herbal tea for weight loss. Recently, based on previous studies, our team reached a preliminary conclusion that phenylpropanoid glycosides from L. robustum most likely contribute substantially to reducing lipid levels, but the mechanism remains unclear. Here, we conducted an in silico screen of currently known phenylethanoid glycosides from L. robustum and attempted to explore the hypolipidemic mechanism of ACT, the representative component of phenylethanoid glycosides in L. robustum, using RNA-seq technology, quantitative real-time PCR (qPCR) and Western blotting. First, the screening results for six compounds were docked with 15 human protein targets, and 3 of 15 protein targets were related to cardiovascular diseases. Based on previous experimental data and docking results, we selected ACT, which exerted positive effects, for further study. We generated a lipid accumulation model using HepG2 cells treated with a high concentration of oleic acid and then extracted RNA from cells treated for 24 h with 50 μmol/L ACT. Subsequently, we performed a transcriptomic analysis of the RNA-seq results, which revealed a large number of differentially expressed genes. Finally, we randomly selected some genes and proteins for further validation using qPCR and Western blotting; the results agreed with the RNA-seq data and confirmed their reliability. In conclusion, our experiments proved that ACT from L. robustum alters lipid metabolism and synthesis by regulating the expression of multiple genes, including Scarb1, Scarb2, Srebf1, Dhcr7, Acat2, Hmgcr, Fdft1, and Lss, which are involved several pathways, such as the glycolytic, AMPK, and fatty acid degradation pathways.
Erectile dysfunction (ED) is a major complication of diabetes mellitus. Eucommia ulmoides Oliv. is used as a traditional medicine for male impotence, but no systematic study has examined its effect on diabetes-associated ED. In this study, we investigated the effects of Eucommia ulmoides Oliv. leaf extract (EULE) on restoring erectile function in streptozotocin (STZ)-induced diabetic rats model. After 16 weeks of treatment, EULE administration had significantly increased intracavernosal pressure, nitric oxide (NO) levels, and cyclic guanosine monophosphate (cGMP) concentrations. Serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels were markedly higher and serum malondialdehyde (MDA) levels were lower in the EULE-treated groups than in the diabetic model group. EULE restored NO biosynthesis by significantly increasing protein kinase B (Akt) and endothelial NO synthase (eNOS) activation. Furthermore, EULE is likely to benefit the hypothalamic-pituitary-gonadal (HPG) axis, as it increased gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) concentrations as well as hormone receptors Gnrhr, Fshr, and Lhr expression levels. Hence, EULE attenuates oxidative stress, increases NO production, and activates the Akt-eNOS pathway to restore endothelial function; moreover, EULE enhances the HPG axis to improve erectile function. These results suggest that EULE may represent a new therapeutic avenue for diabetes-associated ED.