Mapping oto-pharyngeal development in a human inner ear organoid model.

Inner ear development requires the coordination of cell types from distinct epithelial, mesenchymal and neuronal lineages. Although we have learned much from animal models, many details about human inner ear development remain elusive. We recently developed an in vitro model of human inner ear organogenesis using pluripotent stem cells in a 3D culture, fostering the growth of a sensorineural circuit, including hair cells and neurons. Despite previously characterizing some cell types, many remain undefined. This study aimed to chart the in vitro development timeline of the inner ear organoid to understand the mechanisms at play. Using single-cell RNA sequencing at ten stages during the first 36 days of differentiation, we tracked the evolution from pluripotency to various ear cell types after exposure to specific signaling modulators. Our findings showcase gene expression that influences differentiation, identifying a plethora of ectodermal and mesenchymal cell types. We also discern aspects of the organoid model consistent with in vivo development, while highlighting potential discrepancies. Our study establishes the Inner Ear Organoid Developmental Atlas (IODA), offering deeper insights into human biology and improving inner ear tissue differentiation.

Hair-bearing human skin generated entirely from pluripotent stem cells.

The skin is a multilayered organ, equipped with appendages (that is, follicles and glands), that is critical for regulating body temperature and the retention of bodily fluids, guarding against external stresses and mediating the sensation of touch and pain1,2. Reconstructing appendage-bearing skin in cultures and in bioengineered grafts is a biomedical challenge that has yet to be met3-9. Here we report an organoid culture system that generates complex skin from human pluripotent stem cells. We use stepwise modulation of the transforming growth factor ß (TGFß) and fibroblast growth factor (FGF) signalling pathways to co-induce cranial epithelial cells and neural crest cells within a spherical cell aggregate. During an incubation period of 4-5 months, we observe the emergence of a cyst-like skin organoid composed of stratified epidermis, fat-rich dermis and pigmented hair follicles that are equipped with sebaceous glands. A network of sensory neurons and Schwann cells form nerve-like bundles that target Merkel cells in organoid hair follicles, mimicking the neural circuitry associated with human touch. Single-cell RNA sequencing and direct comparison to fetal specimens suggest that the skin organoids are equivalent to the facial skin of human fetuses in the second trimester of development. Moreover, we show that skin organoids form planar hair-bearing skin when grafted onto nude mice. Together, our results demonstrate that nearly complete skin can self-assemble in vitro and be used to reconstitute skin in vivo. We anticipate that our skin organoids will provide a foundation for future studies of human skin development, disease modelling and reconstructive surgery.

A randomized, double-blind, phase III study assessing clinical similarity of SB17 (proposed ustekinumab biosimilar) to reference ustekinumab in subjects with moderate-to-severe plaque psoriasis.

BACKGROUND: Ustekinumab (UST) is a safe and effective treatment for moderate-to-severe psoriasis. OBJECTIVES: To compare efficacy, safety, pharmacokinetics (PK), and immunogenicity of the proposed UST biosimilar SB17 with reference UST in subjects with moderate-to-severe plaque psoriasis. METHODS: In this randomized double-blind study, subjects were randomized to receive 45 mg of SB17 or UST subcutaneously at week 0, 4, and every 12 weeks. The primary endpoint was the percent change from baseline in Psoriasis Area and Severity Index at week 12 with an equivalence margin of [-15%, 15%]. Other secondary efficacy, safety, PK, and immunogenicity endpoints were measured through week 28. RESULTS: Two hundred forty-nine subjects were randomized to SB17, 254 to UST. Adjusted difference of Psoriasis Area and Severity Index change from baseline at week 12 of -0.6% (95% confidence interval; -3.780, 2.579) was within the equivalence margin. Physician's Global Assessment and Dermatology Life Quality Index were also comparable. Overall treatment-emergent adverse events were comparable (SB17: 48.2%, UST: 48.8%). The overall incidence of antidrug antibodies up to Week 28 was 13.3% with SB17 and 39.4% with UST. LIMITATIONS: Data were only through week 28. CONCLUSION: SB17 was clinically biosimilar to UST up to week 28.

Multimodal-based machine learning approach to classify features of internet gaming disorder and alcohol use disorder: A sensor-level and source-level resting-state electroencephalography activity and neuropsychological study.

OBJECTIVES: Addictions have recently been classified as substance use disorder (SUD) and behavioral addiction (BA), but the concept of BA is still debatable. Therefore, it is necessary to conduct further neuroscientific research to understand the mechanisms of BA to the same extent as SUD. The present study used machine learning (ML) algorithms to investigate the neuropsychological and neurophysiological aspects of addictions in individuals with internet gaming disorder (IGD) and alcohol use disorder (AUD). METHODS: We developed three models for distinguishing individuals with IGD from those with AUD, individuals with IGD from healthy controls (HCs), and individuals with AUD from HCs using ML algorithms, including L1-norm support vector machine, random forest, and L1-norm logistic regression (LR). Three distinct feature sets were used for model training: a unimodal-electroencephalography (EEG) feature set combined with sensor- and source-level feature; a unimodal-neuropsychological feature (NF) set included sex, age, depression, anxiety, impulsivity, and general cognitive function, and a multimodal (EEG + NF) feature set. RESULTS: The LR model with the multimodal feature set used for the classification of IGD and AUD outperformed the other models (accuracy: 0.712). The important features selected by the model highlighted that the IGD group had differential delta and beta source connectivity between right intrahemispheric regions and distinct sensor-level EEG activities. Among the NFs, sex and age were the important features for good model performance. CONCLUSIONS: Using ML techniques, we demonstrated the neurophysiological and neuropsychological similarities and differences between IGD (a BA) and AUD (a SUD).

Comparison of SB17 and reference ustekinumab in healthy adults: A randomized, double-blind, single-dose, phase I study.

OBJECTIVE: This study compared the pharmacokinetic (PK) characteristics of SB17 (Samsung Bioepis, Incheon, Republic of Korea), a proposed biosimilar of ustekinumab (UST) against reference UST (Stelara, Janssen Biotech, Horsham, PA, USA). MATERIALS AND METHODS: This double-blind, three-arm, parallel-group, single-dose study randomized 201 healthy adult subjects 1 : 1 : 1 to receive 45 mg of SB17, European Union-sourced UST (EU-UST) or United States of America-sourced UST (US-UST) via subcutaneous (SC) injection. Primary endpoints were area under the concentration-time curve from time zero to infinity (AUCinf) and maximum serum concentration (Cmax). Safety, tolerability, and immunogenicity were investigated. RESULTS: All 90% confidence intervals (CIs) for the ratios of AUCinf and Cmax between groups were within the predefined bioequivalence margin of 0.8 - 1.25. The geometric LSMeans ratios of AUCinf and Cmax were 0.99 and 0.90 for SB17/EU-UST, 1.01 and 0.94 for SB17/US-UST, and 1.02 and 1.05 for EU-UST/US-UST, respectively. The proportion of subjects with treatment-emergent adverse events (TEAEs) was comparable between SB17, EU-UST, and US-UST (68.7, 58.2, and 65.7%). No deaths, serious adverse events (SAEs), or severe TEAEs were reported. The incidence of subjects testing positive for post-dose anti-drug antibodies (ADAs) was 26.9%, 34.3%, and 34.3% in the SB17, EU-UST, and US-UST groups, respectively. Among the subjects with a positive ADA result at day 99/end of study, 53.8% (SB17 n = 5, EU-UST n = 12, and US-UST n = 11) were positive for neutralizing antibodies (NAbs). CONCLUSION: This study demonstrated bioequivalence of SB17, EU-UST, and US-UST in terms of PK. Safety, tolerability, and immunogenicity were also comparable between all groups.

How people react to suicidal ideation: The effect of suicide literacy, suicide stigma, and expressive suppression.

INTRODUCTION: The purpose of this study is to understand the role of suicide literacy and suicide stigma in laypeople's intention to recommend professional help in Korea. Additionally, the study focuses on the role of expressive suppression as a sociocultural factor. METHODS: Participants read vignettes depicting either subclinical distress or suicidal ideation and answered questions measuring suicide literacy, stigma, and expressive suppression. Mediated moderation analyses were used to examine the interactions between these factors. RESULTS: The result found the significant effect of expressive suppression. The mediating effect of suicide stigma on the relationship between suicide literacy and recommendation of professional help was significant for those who do not suppress their emotions. This result indicates that when individuals were not hesitant to express negative emotions, high suicide literacy lowered suicide stigma and led to more willingness to recommend professional help. CONCLUSIONS: The results showed that expressive suppression acts as a barrier deterring Koreans from professional help for their mental health. The findings underscore the importance of sociocultural factors such as expressive suppression in developing suicide prevention strategies.

Genomic deletion of malic enzyme 2 confers collateral lethality in pancreatic cancer.

The genome of pancreatic ductal adenocarcinoma (PDAC) frequently contains deletions of tumour suppressor gene loci, most notably SMAD4, which is homozygously deleted in nearly one-third of cases. As loss of neighbouring housekeeping genes can confer collateral lethality, we sought to determine whether loss of the metabolic gene malic enzyme 2 (ME2) in the SMAD4 locus would create cancer-specific metabolic vulnerability upon targeting of its paralogous isoform ME3. The mitochondrial malic enzymes (ME2 and ME3) are oxidative decarboxylases that catalyse the conversion of malate to pyruvate and are essential for NADPH regeneration and reactive oxygen species homeostasis. Here we show that ME3 depletion selectively kills ME2-null PDAC cells in a manner consistent with an essential function for ME3 in ME2-null cancer cells. Mechanistically, integrated metabolomic and molecular investigation of cells deficient in mitochondrial malic enzymes revealed diminished NADPH production and consequent high levels of reactive oxygen species. These changes activate AMP activated protein kinase (AMPK), which in turn directly suppresses sterol regulatory element-binding protein 1 (SREBP1)-directed transcription of its direct targets including the BCAT2 branched-chain amino acid transaminase 2) gene. BCAT2 catalyses the transfer of the amino group from branched-chain amino acids to α-ketoglutarate (α-KG) thereby regenerating glutamate, which functions in part to support de novo nucleotide synthesis. Thus, mitochondrial malic enzyme deficiency, which results in impaired NADPH production, provides a prime 'collateral lethality' therapeutic strategy for the treatment of a substantial fraction of patients diagnosed with this intractable disease.

Identification of MYC as an antinecroptotic protein that stifles RIPK1-RIPK3 complex formation.

The underlying mechanism of necroptosis in relation to cancer is still unclear. Here, MYC, a potent oncogene, is an antinecroptotic factor that directly suppresses the formation of the RIPK1-RIPK3 complex. Gene set enrichment analyses reveal that the MYC pathway is the most prominently down-regulated signaling pathway during necroptosis. Depletion or deletion of MYC promotes the RIPK1-RIPK3 interaction, thereby stabilizing the RIPK1 and RIPK3 proteins and facilitating necroptosis. Interestingly, MYC binds to RIPK3 in the cytoplasm and inhibits the interaction between RIPK1 and RIPK3 in vitro. Furthermore, MYC-nick, a truncated form that is mainly localized in the cytoplasm, prevented TNF-induced necroptosis. Finally, down-regulation of MYC enhances necroptosis in leukemia cells and suppresses tumor growth in a xenograft model upon treatment with birinapant and emricasan. MYC-mediated suppression of necroptosis is a mechanism of necroptosis resistance in cancer, and approaches targeting MYC to induce necroptosis represent an attractive therapeutic strategy for cancer.

Polyunsaturated fatty acid biosynthesis pathway determines ferroptosis sensitivity in gastric cancer.

Ferroptosis is an iron-dependent regulated necrosis mediated by lipid peroxidation. Cancer cells survive under metabolic stress conditions by altering lipid metabolism, which may alter their sensitivity to ferroptosis. However, the association between lipid metabolism and ferroptosis is not completely understood. In this study, we found that the expression of elongation of very long-chain fatty acid protein 5 (ELOVL5) and fatty acid desaturase 1 (FADS1) is up-regulated in mesenchymal-type gastric cancer cells (GCs), leading to ferroptosis sensitization. In contrast, these enzymes are silenced by DNA methylation in intestinal-type GCs, rendering cells resistant to ferroptosis. Lipid profiling and isotope tracing analyses revealed that intestinal-type GCs are unable to generate arachidonic acid (AA) and adrenic acid (AdA) from linoleic acid. AA supplementation of intestinal-type GCs restores their sensitivity to ferroptosis. Based on these data, the polyunsaturated fatty acid (PUFA) biosynthesis pathway plays an essential role in ferroptosis; thus, this pathway potentially represents a marker for predicting the efficacy of ferroptosis-mediated cancer therapy.

Effect of heavy metals on the energy metabolism in the brackish water flea Diaphanosoma celebensis.

Heavy metals such as lead (Pb), cadmium (Cd), and arsenic (As) are of great concern in aquatic ecosystems because of their global distribution, persistence, and biomagnification via the food web. They can induce the expression of cellular protective systems (e.g., detoxification enzymes and antioxidant enzymes) to protect organisms from oxidative stress, which is a high-energy-consuming process. Thus, energy reserves (e.g., glycogen, lipids, and proteins) are utilized to maintain metabolic homeostasis. Although a few studies have suggested that heavy metal stress can modulate the metabolic cycle in crustaceans, information on changes in energy metabolism under metal pollution remains lacking in planktonic crustaceans. In the present study, the activity of digestive enzymes (amylase, trypsin, and lipase) and the contents of energy storage molecules (glycogen, lipid, and protein) were examined in the brackish water flea Diaphanosoma celebensis exposed to Cd, Pb, and As for 48 h. Transcriptional modulation of the three AMP-activated protein kinase (AMPK) and metabolic pathway-related genes was further investigated. Amylase activity was highly increased in all heavy metal-exposed groups, whereas trypsin activity was reduced in Cd- and As-exposed groups. While glycogen content was increased in all exposed groups in a concentration-dependent manner, lipid content was reduced at higher concentrations of heavy metals. The expression of AMPKs and metabolic pathway-related genes was distinct among heavy metals. In particular, Cd activated the transcription of AMPK-, glucose/lipid metabolism-, and protein synthesis-related genes. Our findings indicate that Cd can disrupt energy metabolism, and may be a potent metabolic toxicant in D. celebensis. This study provides insights into the molecular mode of action of heavy metal pollution on the energy metabolism in planktonic crustaceans.

Social stigma of suicide in South Korea: A cultural perspective.

This study examined suicide stigma in relation to Korean cultural characteristics, such as Collectivism, Chemyon sensitivity (concern about losing a socially acceptable face), the tendency toward conformity, and the emphasis on the interdependent self. We found that these characteristics were connected to suicide stigma in Korea. Those with high Chemyon sensitivity tended to perceive that suicidal people were incompetent, immoral, selfish, and deviated from society. Conformity tendency was positively associated with five stigma factors: incompetence, glorification, immorality, selfishness, and social exclusion. Those who perceived themselves as interdependent tended to consider suicidal people incompetent, lacking morality, self-centered, and deviant.

Enhanced resting-state EEG source functional connectivity within the default mode and reward-salience networks in internet gaming disorder.

BACKGROUND: The two key mechanisms affected by internet gaming disorder (IGD) are cognitive and reward processing. Despite their significance, little is known about neurophysiological features as determined using resting-state electroencephalography (EEG) source functional connectivity (FC). METHODS: We compared resting-state EEG source FC within the default mode network (DMN) and reward/salience network (RSN) between patients with IGD and healthy controls (HCs) to identify neurophysiological markers associated with cognitive and reward processing. A total of 158 young male adults (79 patients with IGD and 79 HCs) were included, and the source FC of the DMN and RSN in five spectral bands (delta, theta, alpha, beta, and gamma) were assessed. RESULTS: Patients with IGD showed increased theta, alpha, and beta connectivity within the DMN between the orbitofrontal cortex and parietal regions compared with HCs. In terms of RSN, patients with IGD exhibited elevated alpha and beta connectivity between the anterior cingulate gyrus and temporal regions compared with HCs. Furthermore, patients with IGD showed negative correlations between the severity of IGD symptoms and/or weekly gaming time and theta and alpha connectivity within the DMN and theta, alpha, and beta connectivity within the RSN. However, the duration of IGD was not associated with EEG source FC. CONCLUSIONS: Hyper-connectivities within the DMN and RSN may be considered potential state markers associated with symptom severity and gaming time in IGD.

Comparison of the efficacy and safety of LBAL, a candidate adalimumab biosimilar, and adalimumab reference product in patients with active rheumatoid arthritis inadequately responding to methotrexate: a 52-week phase III randomised study.

OBJECTIVES: To evaluate the similarities between LBAL (adalimumab biosimilar candidate) and the adalimumab reference product (ADL) in terms of efficacy and safety, including immunogenicity, in patients with active rheumatoid arthritis despite methotrexate treatment. METHODS: This phase III, multicentre, randomised, double-blind, parallel-group, 56-week study was conducted in Japan and Korea. During the first 24 weeks, patients subcutaneously received 40 mg of LBAL or ADL every two weeks (LBAL and ADL groups). During the subsequent 28 weeks, the LBAL group patients and half of the ADL group patients received LBAL (L-L and A-L arms). The remaining ADL group patients continued to receive ADL (A-A arm). The primary efficacy endpoint was the change from baseline in disease activity score 28-erythrocyte sedimentation rate (DAS28-ESR) at Week 24. American College of Rheumatology (ACR) response rates, adverse events (AEs), and anti-drug antibody (ADA) were also assessed. RESULTS: In total, 383 patients were randomised. The least squares (LS) mean changes from baseline in DAS28-ESR at Week 24 were -2.45 and -2.53 in the LBAL (n=191) and ADL (n=190) groups, respectively. The 95% confidence interval (CI; -0.139, 0.304) of the difference (0.08) was within the pre-specified equivalence margin (-0.6, 0.6). Up to Week 52, the decreases in DAS28-ESR were maintained in all three arms. No notable differences in ACR20/50/70 were observed. The AE and ADA incidences were comparable between the arms. CONCLUSIONS: LBAL was equivalent in efficacy and comparable in safety, including immunogenicity, to ADL. Switching from ADL to LBAL did not impact on efficacy and safety.

Differential resting-state neurophysiological activity associated with game usage patterns and genres in Internet gaming disorder.

We investigated differences in quantitative electroencephalogram (EEG) patterns associated with game usage patterns and genre among patients with Internet gaming disorder (IGD). Data from 140 participants (76 IGD patients and 64 healthy controls) were analysed. The IGD group was divided into subgroups based on game usage patterns (single game [SG] or multiple games [MGs]) and genre (multiplayer online battle arena, first-person shooter [FPS], or massively multiplayer online role-playing game [MMORPG; hereafter, MMG]). A resting-state, eye-closed quantitative EEG was recorded, and the absolute power and coherence of brain waves were analysed. IGD patients who played SGs showed increased beta activity compared with those who played MGs and controls. Increased absolute beta power was significantly associated with higher tendencies towards behavioural inhibition compared with controls. FPS gamers showed increased delta power in the frontal region compared with controls, which was related to the severity of IGD. Furthermore, decreased intrahemispheric coherence in the left frontoparietal region was observed in the MMG and FPS groups compared with controls. This decreased coherence was observed in the theta (MMG and FPS), delta (MMG), and beta (FPS) bands. These features were related to impairment in visuospatial working memory. Unique neurophysiological features related to preoccupation with an SG may be associated with the inhibition of behavioural changes. The present study suggests that the underlying neurophysiological networks in IGD differ according to game usage patterns and genre.

Mediating the effects of depression in the relationship between university students' attitude toward suicide, frustrated interpersonal needs, and non-suicidal self-injury during the COVID-19 pandemic.

OBJECTIVE: The study aimed to examine the relationship on attitudes toward suicide, frustrated interpersonal needs, and non-suicidal self-injury (NSSI) of the university students. METHODS: The participants included 175 university students. Data were analyzed using the SPSS PROCESS macro (Model 4). RESULTS: Depression showed a fully mediating effect on the relationship between one's attitude toward suicide and NSSI behaviors. Furthermore, depression showed a full mediating impact on the relationship between frustrated interpersonal needs and NSSI behaviors. CONCLUSIONS: These findings indicate that suicidal attitudes and frustrated interpersonal needs should be considered significant factors for developing NSSI preventions and intervention among university students.

Skin organoids: A new human model for developmental and translational research.

Culturing skin cells outside of the body has been a cornerstone of dermatological investigation for many years; however, human skin equivalent systems typically lack the full complexity of native skin. Notably, skin appendages, such as hair follicles and sweat glands, remain a challenge to generate or maintain in cell cultures and reconstruct in damaged skin. Recent work from our lab has demonstrated methods for generating appendage-bearing skin tissue-known as skin organoids-from pluripotent stem cells. Here, we will summarize this work and other related works, and then discuss the potential future applications of skin organoids in dermatological research.

Neurophysiological and Cognitive Correlates of Error Processing Deficits in Internet Gaming Disorder.

The ability to detect and correct errors is a critical aspect of human cognition. Neuronal dysfunction in error processing has been reported in addictive disorders. The aim of this study was to investigate neural systems underlying error processing using event-related potentials (ERPs) and current source localization as well as neurocognitive executive function tests in patients with Internet gaming disorder (IGD). A total of 68 individuals (34 patients with IGD and 34 healthy controls [HCs]) were included, and two ERP components, error-related negativity (ERN) and error positivity (Pe), were extracted during a GoNogo task. Patients with IGD exhibited significantly reduced ERN and Pe amplitudes compared with HCs. Standardized low-resolution brain electromagnetic tomography (sLORETA) in between-group comparisons revealed that patients with IGD had decreased source activations of the Pe component in the anterior cingulate cortex (ACC) under the Nogo condition. These ERP changes were associated with deficits in decision-making and response inhibition in IGD patients. The results suggest that IGD may be associated with functional abnormalities in the ACC and alterations in neural activity related to both the early unconscious and the later conscious stages of error processing, as well as deficits in area of decision-making.

The Application of Mass Spectrometry in Drug Metabolism and Pharmacokinetics.

Drug metabolism and pharmacokinetics (DMPK) are fundamental in drug discovery. New chemical entities (NCEs) are typically evaluated with various in vitro and in vivo assays, which are time-consuming and labor intensive. These experiments are essential in identifying potential new drugs. Recently, mass spectrometry (MS) has played a key role in examining the drug-like properties of NCEs. Quantitative and qualitative mass spectrometry approaches are routinely utilized to obtain high-quality data in an efficient, timely, and cost-effective manner. Especially, liquid chromatography (LC) coupled with MS technology has been refined for metabolite identification (Met ID), which is critical for lead optimization. These qualitative and quantitative MS approaches and their specific utility in DMPK characterization will be described in this chapter.

Effect of Dementia on Postoperative Mortality in Elderly Patients with Hip Fracture.

BACKGROUND: The aim of this study was to assess the prevalence of dementia as an underlying disease in elderly patients with hip fracture, to investigate the effect of dementia on postoperative mortality after surgery of hip fracture, and to analyze the differences in postoperative mortalities according to the severity of dementia through subgroup analysis. METHODS: This study selected 2,346 elderly patients who were diagnosed with unilateral intertrochanteric or femoral neck fractures who underwent surgery between January 2004 and December 2018. The patients were classified into the non-dementia group (2,196 patients) and dementia group (150 patients; no-medication [66 patients] and medication [84 patients] subgroups). The cumulative crude mortality rate was calculated, and 30-day, 60-day, 3-month, 6-month, and 1-year mortality rates were compared between the groups. A univariate regression test was performed using age, sex, diagnosis, surgery type, and Charlson's comorbidity index (CCI), as these variables had P values of < 0.10. Multivariate regression analysis was performed to identify independent risk factors associated with mortality. RESULTS: The 30-day, 60-day, 3-month, 6-month, and 1-year postoperative cumulative mortality rates were 1.8%, 3.8%, 5.6%, 8.9%, and 13.6%, respectively, in the non-dementia group, and 2%, 7.3%, 14%, 19.3%, and 24%, respectively, in the dementia group (P = 0.748, P = 0.048, P < 0.001, P < 0.001, and P = 0.001). The factors that affected the 1-year mortality were age (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.08; P < 0.001), sex (OR, 2.68; 95% CI, 2.07-3.47; P < 0.001), CCI (OR, 1.34; 95% CI, 1.23-1.47; P < 0.001), and dementia (OR, 1.70; 95% CI, 1.46-1.08; P = 0.016). In subgroup analysis, severity of dementia influenced the 6-month mortality (OR, 1.41; 95% CI, 1.70-2.01; P = 0.018), and 1-year mortality (OR, 1.30; 95% CI, 1.17-1.90; P = 0.027). CONCLUSION: In elderly hip fracture patients, the comparison between patients with and without dementia revealed that dementia was an independent risk factor for mortality at a minimum of 1 year of follow-up, and the severity of dementia in hip fracture patients was a risk factor for mortality within 6 months and 1 year, postoperatively.

RNA-Seq and Electrical Penetration Graph Revealed the Role of Grh1-Mediated Activation of Defense Mechanisms towards Green Rice Leafhopper (Nephotettix cincticeps Uhler) Resistance in Rice (Oryza sativa L.).

The green rice leafhopper (GRH, Nephotettix cincticeps Uhler) is one of the most important insect pests causing serious damage to rice production and yield loss in East Asia. Prior to performing RNA-Seq analysis, we conducted an electrical penetration graph (EPG) test to investigate the feeding behavior of GRH on Ilpum (recurrent parent, GRH-susceptible cultivar), a near-isogenic line (NIL carrying Grh1) compared to the Grh1 donor parent (Shingwang). Then, we conducted a transcriptome-wide analysis of GRH-responsive genes in Ilpum and NIL, which was followed by the validation of RNA-Seq data by qPCR. On the one hand, EPG results showed differential feeding behaviors of GRH between Ilpum and NIL. The phloem-like feeding pattern was detected in Ilpum, whereas the EPG test indicated a xylem-like feeding habit of GRH on NIL. In addition, we observed a high death rate of GRH on NIL (92%) compared to Ilpum (28%) 72 h post infestation, attributed to GRH failure to suck the phloem sap of NIL. On the other hand, RNA-Seq data revealed that Ilpum and NIL GRH-treated plants generated 1,766,347 and 3,676,765 counts per million mapped (CPM) reads, respectively. The alignment of reads indicated that more than 75% of reads were mapped to the reference genome, and 8859 genes and 15,815,400 transcripts were obtained. Of this number, 3424 differentially expressed genes (DEGs, 1605 upregulated in Ilpum and downregulated in NIL; 1819 genes upregulated in NIL and downregulated in Ilpum) were identified. According to the quantile normalization of the fragments per kilobase of transcript per million mapped reads (FPKM) values, followed by the Student's t-test (p < 0.05), we identified 3283 DEGs in Ilpum (1935 upregulated and 1348 downregulated) and 2599 DEGs in NIL (1621 upregulated and 978 downregulated) with at least a log2 (logarithm base 2) twofold change (Log2FC ≥2) in the expression level upon GRH infestation. Upregulated genes in NIL exceeded by 13.3% those recorded in Ilpum. The majority of genes associated with the metabolism of carbohydrates, amino acids, lipids, nucleotides, the activity of coenzymes, the action of phytohormones, protein modification, homeostasis, the transport of solutes, and the uptake of nutrients, among others, were abundantly upregulated in NIL (carrying Grh1). However, a high number of upregulated genes involved in photosynthesis, cellular respiration, secondary metabolism, redox homeostasis, protein biosynthesis, protein translocation, and external stimuli response related genes were found in Ilpum. Therefore, all data suggest that Grh1-mediated resistance against GRH in rice would involve a transcriptome-wide reprogramming, resulting in the activation of bZIP, MYB, NAC, bHLH, WRKY, and GRAS transcription factors, coupled with the induction of the pathogen-pattern triggered immunity (PTI), systemic acquired resistance (SAR), symbiotic signaling pathway, and the activation of genes associated with the response mechanisms against viruses. This comprehensive transcriptome profile of GRH-responsive genes gives new insights into the molecular response mechanisms underlying GRH (insect pest)-rice (plant) interaction.