RGA1 regulates grain size, rice quality and seed germination in the small and round grain mutant srg5

BACKGROUND

Generating elite rice varieties with high yield and superior quality is the main goal of rice breeding programs. Key agronomic traits, including grain size and seed germination characteristics, affect the final yield and quality of rice. The RGA1 gene, which encodes the α-subunit of rice G-protein, plays an important role in regulating rice architecture, seed size and abiotic stress responses. However, whether RGA1 is involved in the regulation of rice quality and seed germination traits is still unclear.

RESULTS

In this study, a rice mutant small and round grain 5 (srg5), was identified in an EMS-induced rice mutant library. Systematic analysis of its major agronomic traits revealed that the srg5 mutant exhibited a semi-dwarf plant height with small and round grain and reduced panicle length. Analysis of the physicochemical properties of rice showed that the difference in rice eating and cooking quality (ECQ) between the srg5 mutant and its wild-type control was small, but the appearance quality was significantly improved. Interestingly, a significant suppression of rice seed germination and shoot growth was observed in the srg5 mutant, which was mainly related to the regulation of ABA metabolism. RGA1 was identified as the candidate gene for the srg5 mutant by BSA analysis. A SNP at the splice site of the first intron disrupted the normal splicing of the RGA1 transcript precursor, resulting in a premature stop codon. Additional linkage analysis confirmed that the target gene causing the srg5 mutant phenotype was RGA1. Finally, the introduction of the RGA1 mutant allele into two indica rice varieties also resulted in small and round rice grains with less chalkiness.

CONCLUSIONS

These results indicate that RGA1 is not only involved in the control of rice architecture and grain size, but also in the regulation of rice quality and seed germination. This study sheds new light on the biological functions of RGA1, thereby providing valuable information for future systematic analysis of the G-protein pathway and its potential application in rice breeding programs.

Lysine-rich rice partially enhanced the growth and development of skeletal system with better skeletal microarchitecture in young rats

Rice is the primary staple food for half of the world's population but is low in lysine content. Previously, we developed transgenic rice with enhanced free lysine content in rice seeds (lysine-rich rice), which was shown safe for consumption and improved the growth in rats. However, the effects of lysine-rich rice on skeletal growth and development remained unknown. In this study, we hypothesized that lysine-rich rice improved skeletal growth and development in weaning rats. Male weaning Sprague-Dawley rats received lysine-rich rice (HFL) diet, wild-type rice (WT) diet, or wild-type rice with various contents of lysine supplementation diet for 70 days. Bone microarchitectures were examined by microcomputed tomography, bone strength was investigated by mechanical test, and dynamics of bone growth were examined by histomorphometric analysis. In addition, we explored the molecular mechanism of lysine and skeletal growth through biochemical testing of growth hormone, bone turnover marker, and amino acid content of rat serum analysis, as well as in a cell culture system. Results indicated that the HFL diet improved rats' bone growth, strength, and microarchitecture compared with the WT diet group. In addition, the HFL diet increased the serum essential amino acids, growth hormone (insulin-like growth factor-1), and bone formation marker concentrations. The cell culture model showed that lysine deficiency reduced insulin-like growth factor-1 and Osterix expression, Akt/mammalian target of rapamycin signaling, and matrix mineralization, and inhibited osteoblast differentiation associated with bone growth. Our findings showed that lysine-rich rice improved skeletal growth and development in weaning rats. A further increase of rice lysine content is highly desirable to fully optimize bone growth and development.

Effect of melting combined with ice recrystallization on porous starch preparation: Pore-forming properties, granular morphology, functionality, and multi-scale structures

In this work, critical melting (CM) combined with freeze-thawing treatment (FT, freezing at -20 ℃ and -80 ℃, respectively) was used to prepare porous starch. The results showed that CM combined with the slow freezing rate (-20 ℃) can prepare porous starch with characteristics of grooves and cavities, while combined with the rapid freezing rate (-80 ℃) can prepare with holes and channels, especially after repeating FT cycles. Compared with the native counterpart, the specific surface area, pore volume, and average diameter of CMFT-prepared porous starch were significantly increased to 4.07 m2/g, 7.29 cm3/g × 10-3, and 3.57 nm, respectively. CMFT significantly increased the thermal stability of starch, in which the To, Tp, and Tc significantly increased from 63.32, 69.62, and 72.90 (native) to ∼69, 72, and 76 °C, respectively. CMFT significantly increased water and oil absorption of porous starch from 91.20 % and 72.00 % (native) up to ∼163 % and 94 %, respectively. Moreover, CMFT-prepared porous starch had a more ordered double-helical structure, which showed in the significantly increased relative crystallinity, semi-crystalline lamellae structure, and the proportion of the double helix structure of starch. The synergistic effect of melting combined with ice recrystallization can be used as an effective way to prepare structure-stabilized porous starch.

The OsNAC24-OsNAP protein complex activates OsGBSSI and OsSBEI expression to fine-tune starch biosynthesis in rice endosperm

Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch-synthesis enzyme-coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI, OsSBEI, OsAGPS2, OsSSI, OsSSIIIa and OsSSIVb. Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC-binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss-of-function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24-OsNAP complex plays key roles in fine-tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24-OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality.

[Safety of double and a half layered esophagojejunal anastomosis in radical gastrectomy: A prospective, multi-center, single arm trial]

Objective: To evaluate the safety of double and a half layered esophagojejunal anastomosis in radical gastrectomy. Methods: This prospective, multi-center, single-arm study was initiated by the Affiliated Cancer Hospital of Zhengzhou University in June 2021 (CRAFT Study, NCT05282563). Participating institutions included Nanyang Central Hospital, Zhumadian Central Hospital, Luoyang Central Hospital, First Affiliated Hospital of Henan Polytechnic University, First Affiliated Hospital of Henan University, Luohe Central Hospital, the People's Hospital of Hebi, First People's Hospital of Shangqiu, Anyang Tumor Hospital, First People's Hospital of Pingdingshan, and Zhengzhou Central Hospital Affiliated to Zhengzhou University. Inclusion criteria were as follows: (1) gastric adenocarcinoma confirmed by preoperative gastroscopy;(2) preoperative imaging assessment indicated that R0 resection was feasible; (3) preoperative assessment showed no contraindications to surgery;(4) esophagojejunostomy planned during the procedure; (5) patients volunteered to participate in this study and gave their written informed consent; (6) ECOG score 0-1; and (7) ASA score I-III. Exclusion criteria were as follows: (1) history of upper abdominal surgery (except laparoscopic cholecystectomy);(2) history of gastric surgery (except endoscopic submucosal dissection and endoscopic mucosal resection); (3) pregnancy or lactation;(4) emergency surgery for gastric cancer-related complications (perforation, hemorrhage, obstruction); (5) other malignant tumors within 5 years or coexisting malignant tumors;(6) arterial embolism within 6 months, such as angina pectoris, myocardial infarction, and cerebrovascular accident; and (7) comorbidities or mental health abnormalities that could affect patients' participation in the study. Patients were eliminated from the study if: (1) radical gastrectomy could not be completed; (2) end-to-side esophagojejunal anastomosis was not performed during the procedure; or (3) esophagojejunal anastomosis reinforcement was not possible. Double and a half layered esophagojejunal anastomosis was performed as follows: (1) Open surgery: the full thickness of the anastomosis is continuously sutured, followed by embedding the seromuscular layer with barbed or 3-0 absorbable sutures. The anastomosis is sutured with an average of six to eight stitches. (2) Laparoscopic surgery: the anastomosis is strengthened by counterclockwise full-layer sutures. Once the anastomosis has been sutured to the right posterior aspect of the anastomosis, the jejunum stump is pulled to the right and the anastomosis turned over to continue to complete reinforcement of the posterior wall. The suture interval is approximately 5 mm. After completing the full-thickness suture, the anastomosis is embedded in the seromuscular layer. Relevant data of patients who had undergone radical gastrectomy in the above 12 centers from June 2021 were collected and analyzed. The primary outcome was safety (e.g., postoperative complications, and treatment). Other studied variables included details of surgery (e.g., surgery time, intraoperative bleeding), postoperative recovery (postoperative time to passing flatus and oral intake, length of hospital stay), and follow-up conditions (quality of life as assessed by Visick scores). Result: [1] From June 2021 to September 2022,457 patients were enrolled, including 355 men and 102 women of median age 60.8±10.1 years and BMI 23.7±3.2 kg/m2. The tumors were located in the upper stomach in 294 patients, mid stomach in 139; and lower stomach in 24. The surgical procedures comprised 48 proximal gastrectomies and 409 total gastrectomies. Neoadjuvant chemotherapy was administered to 85 patients. Other organs were resected in 85 patients. The maximum tumor diameter was 4.3±2.2 cm, number of excised lymph nodes 28.3±15.2, and number of positive lymph nodes five (range one to four. As to pathological stage,83 patients had Stage I disease, 128 Stage II, 237 Stage III, and nine Stage IV. [2] The studied surgery-related variables were as follows: The operation was successfully completed in all patients, 352 via a transabdominal approach, 25 via a transhiatus approach, and 80 via a transthoracoabdominal approach. The whole procedure was performed laparoscopically in 53 patients (11.6%), 189 (41.4%) underwent laparoscopic-assisted surgery, and 215 (47.0%) underwent open surgery. The median intraoperative blood loss was 200 (range, 10-1 350) mL, and the operating time 215.6±66.7 minutes. The anastomotic reinforcement time was 2 (7.3±3.9) minutes for laparoscopic-assisted surgery, 17.6±1.7 minutes for total laparoscopy, and 6.0±1.2 minutes for open surgery. [3] The studied postoperative variables were as follows: The median time to postoperative passage of flatus was 3.1±1.1 days and the postoperative gastrointestinal angiography time 6 (range, 4-13) days. The median time to postoperative oral intake was 7 (range, 2-14) days, and the postoperative hospitalization time 15.8±6.7 days. [4] The safety-related variables were as follows: In total, there were 184 (40.3%) postoperative complications. These comprised esophagojejunal anastomosis complications in 10 patients (2.2%), four (0.9%) being anastomotic leakage (including two cases of subclinical leakage and two of clinical leakage; all resolved with conservative treatment); and six patients (1.3%) with anastomotic stenosis (two who underwent endoscopic balloon dilation 21 and 46 days after surgery, the others improved after a change in diet). There was no anastomotic bleeding. Non-anastomotic complications occurred in 174 patients (38.1%). All patients attended for follow-up at least once, the median follow-up time being 10 (3-18) months. Visick grades were as follows: Class I, 89.1% (407/457); Class II, 7.9% (36/457); Class III, 2.6% (12/457); and Class IV 0.4% (2/457). Conclusion: Double and a half layered esophagojejunal anastomosis in radical gastrectomy is safe and feasible.

Gene editing of non-coding regulatory DNA and its application in crop improvement

The development of the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) system has provided precise and efficient strategies to edit target genes and generate transgene-free crops. Significant progress has been made in the editing of protein-coding genes; however, studies on the editing of non-coding DNA with regulatory roles lags far behind. Non-coding regulatory DNAs, including those which can be transcribed into long non-coding RNAs (lncRNAs), and miRNAs, together with cis-regulatory elements (CREs), play crucial roles in regulating plant growth and development. Therefore, the combination of CRISPR/Cas technology and non-coding regulatory DNA has great potential to generate novel alleles that affect various agronomic traits of crops, thus providing valuable genetic resources for crop breeding. Herein, we review recent advances in the roles of non-coding regulatory DNA, attempts to edit non-coding regulatory DNA for crop improvement, and potential application of novel editing tools in modulating non-coding regulatory DNA. Finally, the existing problems, possible solutions, and future applications of gene editing of non-coding regulatory DNA in modern crop breeding practice are also discussed.

Revelation of rice molecular design breeding: the blend of tradition and modernity

As one of the major staple crops, rice feeds more than one half of the world population. Due to increasing population and dramatic climate change, the rice varieties with higher yield performance and excellent overall agronomic performance should be developed. The raise of molecular design breeding concept provides opportunity to get new breakthrough for variety development, and it is important to clarify the efficient gene combination during actual breeding. In this review, we summarize the recent advances about rice variety improvement either by marker assisted selection (MAS) breeding or popular gene editing technique, which will be beneficial to understand different aspects of the molecular design breeding. We provide genetic views for the classical MAS application, including the genetic effect of key genes and their combinations, the recurrent genome recovery rate at different backcross generations, linkage drag and recombination selection. Moreover, we compare the breeding value of recently-developed molecular techniques, including the advantage of high-throughput genotyping and the way and effect of gene editing in creating useful traits. Considering the current status and actual demands of rice breeding, we raise the strategy to take advantages of both traditional breeding resources and popular molecular techniques, which might pave the way to optimize the process of molecular design breeding in future.

Effects of enhanced starch-xanthan gum synergism on their physicochemical properties, functionalities, structural characteristics, and digestibility

The limited and unstable interactions between potato starch (PS) and xanthan gum (XG) by simple mixing (SM) lead it difficult to induce substantial changes in starchy products. Structural unwinding and rearrangement of PS and XG by critical melting and freeze-thawing (CMFT) were used to promote PS/XG synergism, and the physicochemical, functionalities, and structural properties were investigated. Compared to "Native" and SM, CMFT promoted the formation of large clusters with a rough granular surface and wrapped by a matrix composed of released soluble starches and XG (SEM), thus making the composite more compact to thermal processes, such as the significantly decreased WSI and SP, and increased the melting temperatures. The enhanced synergism of PS/XG after CMFT effectively decreased the breakdown viscosity from ~3600 (Native) to ~300 mPa·s and increased the final viscosity from ~2800 (Native) to ~4800. CMFT significantly increased the functional properties of PS/XG composite, including water/oil absorptions and resistant starch content. CMFT caused the partial melting and loss of large packaged structures in starch (XRD, FTIR, and NMR), and the melting and the loss of crystalline structure controlled at approximately 20 % and 30 %, respectively, are the most effective for promoting PS/XG interaction.

Co-Overexpression of Two Key Source Genes, OsBMY4 and OsISA3, Improves Multiple Key Traits of Rice Seeds

Optimized source-sink interactions are determinants of both rice yield and quality. However, most source genes have not been well studied in rice, a major grain crop. In this study, OsBMY4 and OsISA3, the key β-amylase and debranching enzymes that control transient starch degradation in rice leaves, were co-overexpressed in rice in order to accelerate starch degradation efficiency and increase the sugar supply for sink organs. Systematic analyses of the transgenic rice indicated that co-overexpression of OsBMY4 and OsISA3 not only promoted rice yield and quality, but also improved seed germination and stress tolerance. Moreover, since the OsBMY4 gene has not been characterized, we generated osbmy4 mutants using CRIPSR/Cas9 gene editing, which helped to reveal the roles of β-amylase in rice yield and quality. This study demonstrated that specific modulation of the expression of some key source genes improves the source-sink balance and leads to improvements in multiple key traits of rice seeds.

[Study on the consistency of IGF-1 and IGFBP-3 of peripheral whole blood and venous serum in children]

This study aimed to explore the consistency of insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-binding protein-3 (IGFBP-3) by detecting peripheral whole blood and venous serum among children. As a cross-sectional study, children who were aged 0-14 as well as received physical examinations in the Child Healthcare Department of the Children's Hospital of Nanjing Medical University during January 2022 to April 2022 were enrolled in this study. Meanwhile, both of peripheral whole blood and venous serum samples were collected, and the levels of IGF-1 and IGFBP-3 were assayed individually via chemiluminescence immunoassay (CLIA). Additionally, linear regression equation was used to analyze the correlation of results between two categories of samples, while Inter-class Correlation Coefficient (ICC) was used to evaluate the consistency of test results among two types of samples. The change trends of IGF-1 and IGFBP-3 with age were analyzed at the same time. A total of 203 valid matched samples were collected, including 117 boys and 86 girls. Peripheral whole blood was well correlated with serum IGF-1 (r=0.986, P<0.001) and IGFBP-3 (r=0.974, P<0.001), and the linear regression equation is shown as follows: (IGF-1) _{venous serum} =1.047×(IGF-1) _{peripheral whole blood}-6.840; (IGFBP-3) _{venous serum}=0.924×(IGFBP-3) _{peripheral whole blood}+0.396. The correlation and consistency were still persisted after being stratified by sex and age. ICC of IGF-1 and IGFBP-3 were 0.983 and 0.967, respectively which provided an excellent strength of agreement. The levels of IGF-1 or IGFBP-3 in boys' and girls' peripheral whole blood and serum showed significant statistical differences among various age groups (all P<0.001), and also increased significantly with age (all P _trend<0.001). In conclusion, the results of IGF-1 and IGFBP-3 in peripheral whole blood and venous serum had positive comparability that could be mutually recognized. The detection of IGF-1 and IGFBP-3 in peripheral whole blood had great potential for young age children by providing guidance for nutritional intervention, growth and development assessment.

[The correlations of abdominal adipose tissue with anthropometric and metabolic parameters in obese children by magnetic resonance imaging]

Objective: To explore abdominal fat mass distribution and contents among obese children via magnetic resonance imaging (MRI), and analyze the correlations of abdominal adipose tissue with anthropometric and metabolic parameters. Methods: Cross-sectional study. There were 60 obese children admitted to the Children's Health Care Department and Endocrinology Department at Children's Hospital of Nanjing Medical University from July 2016 to December 2018. Children's gender, age, height, weight, body composition, waist circumference and blood pressure were recorded. The levels of fasting blood glucose, lipids, insulin were measured, and liver ultrasound was performed, and the body mass index Z score (BMI-Z), waist-to-height ratio (WHtR) and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. In addition, contents of subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT) and total abdominal adipose tissue (TAAT) were calculated according to feedback of abdominal MRI scan images. The associations between the contents of abdominal adipose tissue, physical examination status and metabolic disorders among obese children were analyzed through correlation analysis and regression analysis. Receiver operating characteristic (ROC) curve was used to compare the accuracy of fat mass in different parts of the abdomen in predicting their metabolic disorders. Results: A total of 60 children were enrolled in the study, included 44 boys and 16 girls, with age of (9.2±1.4) years. The contents of SAT, VAT and TAAT among the 60 children were positively associated with BMI-Z (r=0.60, 0.46, 0.59), body fat percentage (r=0.64, 0.67, 0.68) and waist-to-height ratio (r=0.60, 0.57, 0.61) (all P<0.01). Meanwhile, contents of SAT and TAAT were also positively correlated with systolic blood pressure (r=0.47, 0.49), triglyceride (r=0.33, 0.35) and HOMA-IR (r=0.33, 0.28)(all P<0.05). In order to adjust the confounding effects among various variables, regression analysis was applied and the result showed that the body fat percentage (β=0.59, 0.66, 0.65) and waist-to-height ratio (β=0.53, 0.63, 0.59) were most related to abdominal fat contents (all P<0.01), including SAT, VAT and TAAT among obese children. According to ROC, SAT had outstanding evaluation performances for the diagnosis of insulin resistance and metabolic syndrome, while VAT had excellent evaluation performances for non-alcoholic fatty liver disease (area under curve=0.68, 0.69, 0.69, 95%CI 0.54-0.82, 0.55-0.84, 0.53-0.85, P=0.017, 0.014, 0.019). Conclusions: As one of the best indexes, body fat percentage and WHtR can be used to predict the contents of SAT, VAT and TAAT among obese children. With the increase of abdominal SAT or VAT, the risks for insulin resistance, metabolic syndrome and non-alcoholic fatty liver disease would increase. Assessment of abdominal fat and metabolic risks in obese children should combine BMI-Z with waist circumference and body composition analysis.

Brassinosteroids regulate rice seed germination through the BZR1-RAmy3D transcriptional module

Seed dormancy and germination, two physiological processes unique to seed-bearing plants, are critical for plant growth and crop production. The phytohormone brassinosteroid (BR) regulates many aspects of plant growth and development, including seed germination. The molecular mechanisms underlying BR control of rice (Oryza sativa) seed germination are mostly unknown. We investigated the molecular regulatory cascade of BR in promoting rice seed germination and post-germination growth. Physiological assays indicated that blocking BR signaling, including introducing defects into the BR-insensitive 1 (BRI1) receptor or overexpressing the glycogen synthase kinase 2 (GSK2) kinase delayed seed germination and suppressed embryo growth. Our results also indicated that brassinazole-resistant 1 (BZR1) is the key downstream transcription factor that mediates BR regulation of seed germination by binding to the alpha-Amylase 3D (RAmy3D) promoter, which affects α-amylase expression and activity and the degradation of starch in the endosperm. The BZR1-RAmy3D module functions independently from the established Gibberellin MYB-alpha-amylase 1A (RAmy1A) module of the gibberellin (GA) pathway. We demonstrate that the BZR1-RAmy3D module also functions in embryo-related tissues. Moreover, RNA-sequencing (RNA-seq) analysis identified more potential BZR1-responsive genes, including those involved in starch and sucrose metabolism. Our study successfully identified the role of the BZR1-RAmy3D transcriptional module in regulating rice seed germination.

Genes and Their Molecular Functions Determining Seed Structure, Components, and Quality of Rice

With the improvement of people's living standards and rice trade worldwide, the demand for high-quality rice is increasing. Therefore, breeding high quality rice is critical to meet the market demand. However, progress in improving rice grain quality lags far behind that of rice yield. This might be because of the complexity of rice grain quality research, and the lack of consensus definition and evaluation standards for high quality rice. In general, the main components of rice grain quality are milling quality (MQ), appearance quality (AQ), eating and cooking quality (ECQ), and nutritional quality (NQ). Importantly, all these quality traits are determined directly or indirectly by the structure and composition of the rice seeds. Structurally, rice seeds mainly comprise the spikelet hull, seed coat, aleurone layer, embryo, and endosperm. Among them, the size of spikelet hull is the key determinant of rice grain size, which usually affects rice AQ, MQ, and ECQ. The endosperm, mainly composed of starch and protein, is the major edible part of the rice seed. Therefore, the content, constitution, and physicochemical properties of starch and protein are crucial for multiple rice grain quality traits. Moreover, the other substances, such as lipids, minerals, vitamins, and phytochemicals, included in different parts of the rice seed, also contribute significantly to rice grain quality, especially the NQ. Rice seed growth and development are precisely controlled by many genes; therefore, cloning and dissecting these quality-related genes will enhance our knowledge of rice grain quality and will assist with the breeding of high quality rice. This review focuses on summarizing the recent progress on cloning key genes and their functions in regulating rice seed structure and composition, and their corresponding contributions to rice grain quality. This information will facilitate and advance future high quality rice breeding programs.

Improvement of pasting and gelling behaviors of waxy maize starch by partial gelatinization and freeze-thawing treatment with xanthan gum

To improve the pasting and gelling behaviors of waxy maize starch, an aqueous dispersion with or without xanthan gum was subjected to partial gelatinization (5 ℃ above the onset melting temperature of starch) and freeze-thawing treatment. After the treatments, starch granules were slightly deformed, with partial loss of birefringence, and tended to aggregate. The relative crystallinity and thermal stability of waxy maize starch crystals decreased by the treatments. These changes indicated that the treatment affected the inner structure and chain arrangement of the granules. The treated waxy maize starches, however, showed a higher overall pasting viscosity with shorter and more cohesive pastes than that of the native starch. The treated starches formed rigid gels with increased stability against freeze-thawing. The addition of small amounts of xanthan gum enhanced the effects of the treatments.

Progress on inheritance and gene cloning for rice grain quality in Jiangsu province

In China, rice (Oryza sativa L.) is a major cereal crop of great importance maintaining the food security and sustainable agricultural development. Jiangsu is one of the main provinces for rice production. After more than 40 years of development, the yield and quality of rice grain have made great progress. Rice grain quality is a complex trait involving production, processing, marketing and consumption of the grain. In this review, we summarize the progress on the genetic basis of main grain quality traits in the rice variety breeding in Jiangsu province and point out the achievement of each milestone. With a focus on the genetic regulation of grain appearance, eating and cooking quality and nutritional quality, we describe the classic genetic rules and molecular basis of rice grain quality traits and review the function of major genes that regulate corresponding traits. The genetics and improvement of grain quality achieved in Jiangsu province was highlighted on the domestic and international rice breeding programs. In particular, with the advance of breeding conception in terms of functional genomics and genetic regulatory networks, the specific molecular design for grain quality improvement will be the future direction of rice genetic breeding program of Jiangsu Province.

Gibberellin recovers seed germination in rice with impaired brassinosteroid signalling

Seed germination is essential for ensuring grain yield and quality. Germination rate, uniformity, and post-germination growth all contribute to cultivation. Although the phytohormones gibberellin (GA) and brassinosteroid (BR) are known to regulate germination, the underlying mechanism of their crosstalk in co-regulating rice seed germination remains unclear. In this study, the isobaric tags for relative and absolute quantitation (iTRAQ) proteomic approach was employed to identify target proteins responsive to GA during recovery of germination in BR-deficient and BR-insensitive rice. A total of 42 differentially abundant proteins were identified in both BR-deficient and BR-insensitive plants, and most were altered consistently in the two groups. Gene Ontology (GO) analysis revealed enrichment in proteins with binding and catalytic activity. A potential protein-protein interaction network was constructed using STRING analysis, and five Late Embryogenesis Abundant (LEA) family members were markedly down-regulated at both mRNA transcript and protein levels. These LEA genes were specifically expressed in rice seeds, especially during the latter stages of seed development. Mutation of LEA33 affected rice grain size and seed germination, possibly by reducing BR accumulation and enhancing GA biosynthesis. The findings improve our knowledge of the mechanisms by which GA and BR coordinate seed germination.

Superconductivity in a unique type of copper oxide

The mechanism of superconductivity in cuprates remains one of the big challenges of condensed matter physics. High-T c cuprates crystallize into a layered perovskite structure featuring copper oxygen octahedral coordination. Due to the Jahn Teller effect in combination with the strong static Coulomb interaction, the octahedra in high-T c cuprates are elongated along the c axis, leading to a 3dx 2-y 2 orbital at the top of the band structure wherein the doped holes reside. This scenario gives rise to 2D characteristics in high-T c cuprates that favor d-wave pairing symmetry. Here, we report superconductivity in a cuprate Ba2CuO4-y , wherein the local octahedron is in a very exceptional compressed version. The Ba2CuO4-y compound was synthesized at high pressure at high temperatures and shows bulk superconductivity with critical temperature (T c ) above 70 K at ambient conditions. This superconducting transition temperature is more than 30 K higher than the T c for the isostructural counterparts based on classical La2CuO4 X-ray absorption measurements indicate the heavily doped nature of the Ba2CuO4-y superconductor. In compressed octahedron, the 3d3z 2-r 2 orbital will be lifted above the 3dx 2-y 2 orbital, leading to significant 3D nature in addition to the conventional 3dx 2-y 2 orbital. This work sheds important light on advancing our comprehensive understanding of the superconducting mechanism of high T c in cuprate materials.

Wound Age Estimation by Neutrophil Migration Distance

Abstract

Objective To explore the application of neutrophil migration distance for wound age estimation of skeletal muscles in rats, and to provide methodological basis for follow-up study in future. Methods The skeletal muscle contusion model was established in rats, and the control group and the 2, 4, 6 h post-traumatic groups were set. The law of response of neutrophils that participated in the inflammation after injury was detected by immunohistochemical staining, and the relationship between neutrophil migration distance and injury time was detected by TissueFAXS PLUS software. Results The skeletal muscle was obviously infiltrated with neutrophils 2-6 h after injury. The positive rate of neutrophil was （28.75±0.94）% at 2 h post-traumatic, and reached the peak （45.50±3.63）% at 4 h post-traumatic, then decreased to （31.92±1.56）% at 6 h post-traumatic. The neutrophil migration distances increased with the progress of inflammation, and reached （124.80±12.32） μm, （229.03±21.45） μm and （335.04±16.75） μm at 2 h, 4 h and 6 h, respectively. Conclusion There is a relationship of neutrophil infiltrated number and migration distance and wound age within the 2-6 h after skeletal muscle injury, which could be used for the inference of skeletal muscle wound age.

Li(Cd,Mn)P: a new cadmium based diluted ferromagnetic semiconductor with independent spin & charge doping

We report a new diluted ferromagnetic semiconductor Li_1+y(Cd,Mn)P, wherein carrier is doped via excess Li while spin is doped by isovalence substitution of Mn²⁺ into Cd²⁺. The extended Cd 4d-orbitals lead to more itinerant characters of Li_1+y(Cd,Mn)P than that of analogous Li_1+y(Zn,Mn)P. A higher Curie temperature of 45 K than that for Li_1+y(Zn,Mn)P is obtained in Li_1+y(Cd,Mn)P polycrystalline samples by Arrott plot technique. The p-type carriers are determined by Hall effect measurements. The first principle calculations and X-ray diffraction measurements indicate that occupation of excess Li is at Cd sites rather than the interstitial site. Consequently holes are doped by excess Li substitution. More interestingly Li_1+y(Cd,Mn)P shows a very low coercive field (<100 Oe) and giant negative magnetoresistance (~80%) in ferromagnetic state that will benefit potential spintronics applications.

iTRAQ-Based Analysis of Proteins Co-Regulated by Brassinosteroids and Gibberellins in Rice Embryos during Seed Germination

Seed germination, a pivotal process in higher plants, is precisely regulated by various external and internal stimuli, including brassinosteroid (BR) and gibberellin (GA) phytohormones. The molecular mechanisms of crosstalk between BRs and GAs in regulating plant growth are well established. However, whether BRs interact with GAs to coordinate seed germination remains unknown, as do their common downstream targets. In the present study, 45 differentially expressed proteins responding to both BR and GA deficiency were identified using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis during seed germination. The results indicate that crosstalk between BRs and GAs participates in seed germination, at least in part, by modulating the same set of responsive proteins. Moreover, most targets exhibited concordant changes in response to BR and GA deficiency, and gene ontology (GO) indicated that most possess catalytic activity and are involved in various metabolic processes. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis was used to construct a regulatory network of downstream proteins mediating BR- and GA-regulated seed germination. The mutation of GRP, one representative target, notably suppressed seed germination. Our findings not only provide critical clues for validating BR–GA crosstalk during rice seed germination, but also help to optimise molecular regulatory networks.

[Guidelines for diagnosis and treatment of dengue in China]

Dengue is the most prevalent and rapidly spreading mosquito-borne viral disease. As a dengue non-endemic country, China has experienced several dengue outbreaks in recent years. However, dengue patients in China displayed distinct clinical characteristics compared to patients in endemic countries. To standardize the diagnosis and treatment of dengue fever, the experts of the Society of Infectious Diseases, Society of Tropical Medicine and Parasitology of Chinese Medical Association, and the Society of Emergency Medicine, China Association of Chinese Medicine have reached this guideline based on guidelines for diagnosis, treatment, prevention and control of dengue (World Health Organization, 2009); guidelines for diagnosis and treatment of dengue (National Health and Family Planning Commission of the People's Republic of China, 2014, Edition 2), health industry standard of the People's Republic of China "diagnosis for dengue fever (WS216-2018)" and systemic reports on dengue. The guideline includes 8 aspects: introduction, terminology, epidemiology and prevention, etiology and pathogenesis, clinical features, diagnosis, treatment and problems to be solved.

Down-Regulation of SSSII-2 Gene Expression Results in Novel Low-Amylose Rice with Soft, Transparent Grains

Although soft rice, with low amylose content (AC), has high eating and cooking quality (ECQ), its appearance is poor due to the opaque endosperm. Here, a novel soft rice with low AC but a transparent appearance was generated by knocking-down the expression of SSSII-2, a gene encoding one isoform of soluble starch synthase (SSS). The physicochemical properties of the SSSII-2 RNAi rice are quite different from the control but more like the popular soft rice "Nanjing 46". The taste value assay further demonstrated that the ECQ of SSSII-2 RNAi rice was as high as "Nanjing 46", but only SSSII-2 RNAi rice retained the transparent endosperm under low moisture conditions. Further examination showed that the different morphologies and fine structures of the starch granules may contribute to the specific properties of SSSII-2 RNAi rice. Therefore, SSSII-2 has potential application in future high quality rice breeding programs.

[Prognostic significance of combined TERT and IDH gene mutation analysis in diffusely infiltrating gliomas]

Objective: To investigate the status and prognostic significance of TERT and IDH1/2 genes mutations in diffusely infiltrating gliomas. Methods: Hot spot mutations of TERT and IDH1/2 genes were detected by DNA sequencing in 236 cases of gliomas at West China Hospital from 2012 to 2016, including pilocytic astrocytoma (WHO grade Ⅰ, 16 cases), diffuse astrocytoma and oligodendroglioma (WHO grade Ⅱ, 89 cases), anaplastic astrocytoma and oligodendroglioma (WHO grade Ⅲ, 72 cases) and glioblastoma (WHO grade Ⅳ, 59 cases). The prognostic significance of TERT and IDH1/2 hot spot mutations was evaluated. Results: No IDH or TERT mutations were detected in pilocytic gliomas. TERT promoter mutation frequency was higher in patients aged ≥40 years(60.8%, 93/153) than in patients aged <40 years (32.8%, 22/67; P<0.01). TERT promoter mutation rate was also significantly higher in oligodendroglioma (87.5% , 56/64) than that in astrocytoma(37.8%, 59/156; P<0.01). Young age (<40 years), oligodendroglioma and IDH1 mutation were favorable prognostic factors for diffusely infiltrating astrocytic and oligodendroglial tumors. TERT mutation alone was not of prognostic significance. Diffusely infiltrating astrocytic and oligodendroglial tumors were divided into four molecular subtypes according to TERT and IDH1 mutation status: IDH(+ )/TERT(+ ), IDH(+ )/TERT(-), IDH(-)/TERT(-) and IDH(-)/TERT(+ ). There was significant prognostic difference among the 4 subtypes. Conclusions: Combined IDH and TERT gene mutation analysis may be useful for prognostic subgrouping. Notably, IDH1 wild-type cases can be further subdivided into TERT(+ ) or (-) subgroups with significant prognostic difference.

Characterization of Imprinted Genes in Rice Reveals Conservation of Regulation and Imprinting with Other Plant Species

Genomic imprinting is an epigenetic phenomenon by which certain genes display differential expression in a parent-of-origin-dependent manner. Hundreds of imprinted genes have been identified from several plant species. Here, we identified, with a high level of confidence, 208 imprinted gene candidates from rice (Oryza sativa). Imprinted genes of rice showed limited association with the transposable elements, which contrasts with findings from Arabidopsis (Arabidopsis thaliana). Generally, imprinting in rice is conserved within a species, but intraspecific variation also was detected. The imprinted rice genes do not show signatures of selection, which suggests that domestication has had a limited evolutionary consequence on genomic imprinting. Although conservation of imprinting in plants is limited, we show that some loci are imprinted in several different species. Moreover, our results suggest that different types of epigenetic regulation can be established either before or after fertilization. Imprinted 24-nucleotide small RNAs and their neighboring genes tend to express alleles from different parents. This association was not observed between 21-nucleotide small RNAs and their neighboring genes. Together, our findings suggest that the regulation of imprinting can be diverse, and genomic imprinting has evolutionary and biological significance.

[The expression of long non-coding RNA LINC00261 in laryngeal carcinoma tissue and their clinical significance]

Objective:To investigate the expression of LINC00261 in laryngeal carcinoma and to discuss their relevance and the roles in carcinogenesis and development of laryngeal carcinoma. Method:The expressions of LINC00261 in laryngeal carcinoma tissue and paired adjacent normal tissue was determined by real-time PCR. The relationship between the expressions of LINC00261 and the clinic pathological characteristics including clinical stage, pathological type, histological grade and lymph node metastasis in LSCC was analysed according to the clinical data. Result:①The expression of LINC00261 was significantly decreased in the LSCC tissue compared with the normal laryngeal tissue(P<0.01).②In clinical stage grouping, there were no statistical differences of the quantity of LINC00261 expression among supraglottic, glottic and subglottic LSCC(P>0.05).In histological differentiation grouping, LINC00261 had no significant changes in poorly differentiated LSCC compared with the well and moderately differentiated LSCC(P>0.05). In histological grade grouping, the expression of LINC00261 in T1+T2 stages was significantly higher than T3+T4 stages(P<0.05). Moreover, the expression of LINC00261 in LSCC with lymph node metastasis was significantly lower than that without of lymph node metastasis(P<0.05). Conclusion:Down regulation of LINC00261 in laryngeal carcinoma may contribute to the carcinogenesis and development of laryngeal carcinoma. The decreased expression of LINC00261 maybe relative to T term degree and lymphamatic metastasis of laryngeal carcinoma.

Seed-Specific Expression of OsDWF4, a Rate-Limiting Gene Involved in Brassinosteroids Biosynthesis, Improves Both Grain Yield and Quality in Rice

Brassinosteroids (BRs) are essential plant-specific steroidal hormones that regulate diverse growth and developmental processes in plants. We evaluated the effects of OsDWF4, a gene that encodes a rate-limiting enzyme in BR biosynthesis, on both rice yield and quality when driven by the Gt1 or Ubi promoter, which correspond to seed-specific or constitutive expression, respectively. Generally, transgenic plants expressing OsDWF4 showed increased grain yield with more tillers and longer and heavier seeds. Moreover, the starch physicochemical properties of the transgenic rice were also improved. Interestingly, OsDWF4 was found to exert different effects on either rice yield or quality when driven by the different promoters. The overall performance of the pGt1::OsDWF4 lines was better than that of the pUbi::OsDWF4 lines. Our data not only demonstrate the effects of OsDWF4 overexpression on both rice yield and quality but also suggest that a seed-specific promoter is a good choice in BR-mediated rice breeding programs.

A Connection between Lysine and Serotonin Metabolism in Rice Endosperm

Cereal endosperms produce a vast array of metabolites, including the essential amino acid lysine (Lys). Enhanced accumulation of Lys has been achieved via metabolic engineering in cereals, but the potential connection between metabolic engineering and Lys fortification is unclear. In mature seeds of engineered High Free Lysine (HFL) rice (Oryza sativa), the endosperm takes on a characteristic dark-brown appearance. In this study, we use an integrated metabolomic and transcriptomic approach combined with functional validation to elucidate the key metabolites responsible for the dark-brown phenotype. Importantly, we found that serotonin biosynthesis was elevated dramatically and closely linked with dark-brown endosperm color in HFL rice. A functional connection between serotonin and endosperm color was confirmed via overexpression of TDC3, a key enzyme of serotonin biosynthesis. Furthermore, we show that both the jasmonate signaling pathway and TDC expression were strongly induced in the late stage of endosperm development of HFL rice, coinciding with serotonin accumulation and dark-brown pigmentation. We propose a model for the metabolic connection between Lys and serotonin metabolism in which elevated 2-aminoadipate from Lys catabolism may play a key role in the connection between the jasmonate signaling pathway, serotonin accumulation, and the brown phenotype in rice endosperm. Our data provide a deeper understanding of amino acid metabolism in rice. In addition, the finding that both Lys and serotonin accumulate in HFL rice grains should promote efforts to create a nutritionally favorable crop.

Subchronic feeding study of high-free-lysine transgenic rice in Sprague-Dawley rats

Lysine is considered to be the first essential amino acid in rice. An elite High-Free-Lysine transgenic line HFL1 was previously produced by metabolic engineering to regulate lysine metabolism. In this study, a 90-day toxicology experiment was undertaken to investigate the potential health effect of feeding different doses of HFL1 rice to Sprague-Dawley rats. During the trial, body weight gain, food consumption and food efficiency were recorded, and no adverse effect was observed in rats fed transgenic (T) rice diets compared with non-transgenic (N) or control diets. At both midterm and final assessments, hematological parameters and serum chemistry were measured, and organ weights and histopathology were examined at the end of the trial. There was no diet-related difference in most hematological or serum chemistry parameters or organ weights between rats fed the T diets and those fed the N or control diets. Some parameters were found to differ between T groups and their corresponding N and/or control groups, but no adverse histological effect was observed. Taken together, the data from the current trial demonstrates that high lysine transgenic rice led to no adverse effect in Sprague-Dawley rats given a diet containing up to 70% HFL1 rice in 90 days.

Superconductivity in HfTe5 across weak to strong topological insulator transition induced via pressures

Recently, theoretical studies show that layered HfTe₅ is at the boundary of weak & strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice parameters. The topological properties of 3D stacked HfTe₅ are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic & crystal structures for HfTe₅ with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe₅ crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe₅ transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe₅ is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.

Association between TXNRD1 polymorphisms and anti-tuberculosis drug-induced hepatotoxicity in a prospective study

Anti-tuberculosis drug-induced hepatotoxicity (ATDH) is a serious adverse reaction to anti-tuberculosis (TB) treatment. Thioredoxin reductase 1 (TXNRD1), encoded by the TXNRD1 gene, is an important enzyme involved in oxidant challenge. TXNRD1 plays a key role in regulating cell growth and transformation, and protects cells against oxidative damage. We investigated the association between TXNRD1 polymorphisms and ATDH susceptibility. In this prospective study, 280 newly diagnosed TB patients were followed-up for 3 months after beginning anti-TB therapy. Tag single-nucleotide polymorphisms (tag-SNPs) of TXNRD1 were selected using Haploview 4.2 based on the HapMap database of the Chinese Han in Beijing (CHB) panel. Genotyping was performed using the MassARRAY platform. Of the 280 patients enrolled in this study, 33 were lost to follow-up, 24 had ATDH, and 223 were free from ATDH. After adjusting for sex, age, smoking status, and body mass index, there were no significant differences in the allele and genotype frequency distributions of TXNRD1 SNPs between the ATDH and non-ATDH groups (all P > 0.05). The haplotype analysis showed that haplotype TCAGCC was associated with an increased risk of ATDH susceptibility [P = 0.024, OR (95%CI) = 6.273 (1.023-38.485)]. Further stratified analyses showed that the haplotype TCAGCC was associated with ATDH susceptibility in female subjects [P = 0.036, OR (95%CI) = 5.711 (0.917-35.560)] and non-smokers [P = 0.029, OR (95%CI) = 6.008 (0.971-37.158)]. Our results suggest that TXNRD1 variants may favor ATDH susceptibility in females and non-smokers. Further studies are required to verify this association.

Biofortification of rice with the essential amino acid lysine: molecular characterization, nutritional evaluation, and field performance

Rice (Oryza sativa L.), a major staple crop worldwide, has limited levels of the essential amino acid lysine. We previously produced engineered rice with increased lysine content by expressing bacterial aspartate kinase and dihydrodipicolinate synthase and inhibiting rice lysine ketoglutarate reductase/saccharopine dehydrogenase activity. However, the grain quality, field performance, and integration patterns of the transgenes in these lysine-enriched lines remain unclear. In the present study, we selected several elite transgenic lines with endosperm-specific or constitutive regulation of the above key enzymes but lacking the selectable marker gene. All target transgenes were integrated into the intragenic region in the rice genome. Two pyramid transgenic lines (High Free Lysine; HFL1 and HFL2) with free lysine levels in seeds up to 25-fold that of wild type were obtained via a combination of the above two transgenic events. We observed a dramatic increase in total free amino acids and a slight increase in total protein content in both pyramid lines. Moreover, the general physicochemical properties were improved in pyramid transgenic rice, but the starch composition was not affected. Field trials indicated that the growth of HFL transgenic rice was normal, except for a slight difference in plant height and grain colour. Taken together, these findings will be useful for the potential commercialization of high-lysine transgenic rice.

A residue substitution in the plastid ribosomal protein L12/AL1 produces defective plastid ribosome and causes early seedling lethality in rice

The plastid ribosome is essential for chloroplast biogenesis as well as seedling formation. As the plastid ribosome closely resembles the prokaryotic 70S ribosome, many plastid ribosomal proteins (PRPs) have been identified in higher plants. However, their assembly in the chloroplast ribosome in rice remains unclear. In the present study, we identified a novel rice mutant, albino lethal 1 (al1), from a chromosome segment substitution line population. The al1 mutant displayed an albino phenotype at the seedling stage and did not survive past the three-leaf stage. No other apparent differences in plant morphology were observed in the al1 mutant. The albino phenotype of the al1 mutant was associated with decreased chlorophyll content and abnormal chloroplast morphology. Using fine mapping, AL1 was shown to encode the PRPL12, a protein localized in the chloroplasts of rice, and a spontaneous single-nucleotide mutation (C/T), resulting in a residue substitution from leucine in AL1 to phenylalanine in al1, was found to be responsible for the early seedling lethality. This point mutation is located at the L10 interface feature of the L12/AL1 protein. Yeast two-hybrid analysis showed that there was no physical interaction between al1 and PRPL10. In addition, the mutation had little effect on the transcript abundance of al1, but had a remarkable effect on the protein abundance of al1 and transcript abundance of chloroplast biogenesis-related and photosynthesis-related genes. These results provide a first glimpse into the molecular details of L12's function in rice.

Riga-Fede disease in a child

Riga-Fede disease (RFD) was initially described as a benign ulceration of the lingual frenum or tongue of infants, most commonly resulting from repetitive trauma by natal teeth. However, similar clinical manifestations can also be found in children with repetitive tongue-thrusting habits or certain neurological disorders. This report describes an unusual case of RFD in a 6-year-old Chinese boy. The lesion appeared as an ulcer on the anterior ventral surface of the child's tongue, and was caused by a repetitive tongue-thrusting habit. After eliminating the source of repetitive trauma and starting concurrent use of therapeutic drugs for 1 week, the lesion healed completely.

Manipulation of the rice L-galactose pathway: evaluation of the effects of transgene overexpression on ascorbate accumulation and abiotic stress tolerance

Ascorbic acid (AsA) is the most abundant water-soluble antioxidant in plants, and it plays a crucial role in plant growth, development and abiotic stress tolerance. In the present study, six key Arabidopsis or rapeseed genes involved in AsA biosynthesis were constitutively overexpressed in an elite Japonica rice cultivar. These genes encoded the GDP-mannose pyrophosphorylase (GMP), GDP-mannose-3',5'-epimerase (GME), GDP-L-galactose phosphorylase (GGP), L-galactose-1-phosphate phosphatase (GPP), L-galactose dehydrogenase (GDH), and L-galactono-1,4-lactone dehydrogenase (GalLDH). The effects of transgene expression on rice leaf AsA accumulation were carefully evaluated. In homozygous transgenic seedlings, AtGGP transgenic lines had the highest AsA contents (2.55-fold greater than the empty vector transgenic control), followed by the AtGME and AtGDH transgenic lines. Moreover, with the exception of the AtGPP lines, the increased AsA content also provoked an increase in the redox state (AsA/DHA ratio). To evaluate salt tolerance, AtGGP and AtGME transgenic seedlings were exposed to salt stress for one week. The relative plant height, root length and fresh weight growth rates were significantly higher for the transgenic lines compared with the control plants. Altogether, our results suggest that GGP may be a key rate-limiting step in rice AsA biosynthesis, and the plants with elevated AsA contents demonstrated enhanced tolerance for salt stress.

The anomaly Cu doping effects on LiFeAs superconductors

The Cu substitution effect on the superconductivity of LiFeAs has been studied in comparison with Co/Ni substitution. It is found that the shrinking rate of the lattice parameter c for Cu substitution is much smaller than that of Co/Ni substitution. This is in conjugation with the observation of ARPES that shows almost the same electron and hole Fermi surfaces (FSs) size for undoped and Cu substituted LiFeAs sample, except for a very small hole band sinking below Fermi level with doping. This indicates that there is little doping effect at Fermi surface by Cu substitution, in sharp contrast to the more effective carrier doping effect by Ni or Co.

Superconductivity in topological insulator Sb2Te3 induced by pressure

Topological superconductivity is one of most fascinating properties of topological quantum matters that was theoretically proposed and can support Majorana Fermions at the edge state. Superconductivity was previously realized in a Cu-intercalated Bi₂Se₃ topological compound or a Bi₂Te₃ topological compound at high pressure. Here we report the discovery of superconductivity in the topological compound Sb₂Te₃ when pressure was applied. The crystal structure analysis results reveal that superconductivity at a low-pressure range occurs at the ambient phase. The Hall coefficient measurements indicate the change of p-type carriers at a low-pressure range within the ambient phase, into n-type at higher pressures, showing intimate relation to superconducting transition temperature. The first principle calculations based on experimental measurements of the crystal lattice show that Sb₂Te₃ retains its Dirac surface states within the low-pressure ambient phase where superconductivity was observed, which indicates a strong relationship between superconductivity and topology nature.

Major QTLs reduce the deleterious effects of high temperature on rice amylose content by increasing splicing efficiency of Wx pre-mRNA

We discovered four QTLs that maintain proper rice amylose content at high temperature by increasing the splicing efficiency of Wx gene. Amylose content mainly controlled by Wx gene is a key physicochemical property for eating and cooking quality in rice. During the grain filling stage, high temperature can harm rice grain quality by significantly reducing the amylose content in many rice varieties. Here, we provide genetic evidences between Wx gene expression and rice amylose content at high temperature, and identified several quantitative trait loci (QTLs) in this pathway. We performed a genome-wide survey on a set of chromosome segment substitution lines (CSSLs) which carried chromosomal segments from the heat resistant indica 9311 in the heat-sensitive japonica Nipponbare background. Four QTLs, qHAC4, qHAC8a, qHAC8b and qHAC10, which can reduce the deleterious effects of amylose content at high temperature, were identified and mapped to chromosome 4, 8, 8 and 10, respectively. The major QTL qHAC8a, with the highest LOD score of 6.196, was physically mapped to a small chromosome segment (~300 kb). The CSSLs carrying the qHAC8a, qHAC8b and/or qHAC4 from 9311 have the high pre-mRNA splicing efficiency of Wx gene and likely lead to stable amylose content at high temperature. Thus, increasing pre-mRNA processing efficiency of Wx gene could be an important regulation mechanism for maintaining stable amylose content in rice seeds at high temperature. In addition, our results provide a theoretical basis for breeding heat-stable grain in rice.

Magnetic and structural transitions of SrFe2As2 at high pressure and low temperature

One of key issues in studying iron based superconductors is to understand how the magnetic phase of the parent compounds evolves. Here we report the systematic investigation of paramagnetic to antiferromagnetic and tetragonal to orthorhombic structural transitions of “122” SrFe₂As₂ parent compound using combined high resolution synchrotron Mössbauer spectroscopy and x-ray diffraction techniques in a cryogenically cooled high pressure diamond anvil cell. It is found that although the two transitions are coupled at 205 K at ambient pressure, they are concurrently suppressed to much lower temperatures near a quantum critical pressure of approximately 4.8 GPa where the antiferromagnetic state transforms into bulk superconducting state. Our results indicate that the lattice distortions and magnetism jointly play a critical role in inducing superconductivity in iron based compounds.

Characterization of the spatial and temporal expression of the OsSSII-3 gene encoding a key soluble starch synthase in rice

BACKGROUND

Starch, the major component of rice grain, consists of amylose and amylopectin. SSIIa, a key soluble starch synthase involved in the biosynthesis of rice amylopectin, is a major factor that controls the gelatinization temperature of rice grain. Extensive work has been done and impressive progress has been made in elaborating the function of the gene encoding SSIIa (OsSSII-3). However, the systematic expression analysis of OsSSII-3 is still rare.

RESULTS

In the present study, we performed a comprehensive expression analysis of OsSSII-3 in both the developing seeds and other tissues of indica rice 9311 by using quantitative real-time PCR. The results showed that the gene was dominantly expressed in the developing seeds. In addition, the promoter sequence of OsSSII-3 was cloned and fused with the GUS reporter gene and its expression was carefully monitored in the transgenic rice. The data from both histochemical and fluorometric analyses showed that the OsSSII-3 promoter was capable of driving the target gene to have an endosperm-specific expression, which may be due to the existing of several endosperm-specific motifs in the promoter, including the -300 elements, AACA motifs and GCN4 motifs. This result was quite consistent with that of the endogenous transcription analysis of OsSSII-3.

CONCLUSION

This study not only advanced our understanding of the spatial and temporal expression characteristics of OsSSII-3, but also provided a valuable promoter for future application in generating elite rice varieties with high nutritional or medicinal value.

Superconductivity of the topological insulator Bi2Se3 at high pressure

The pressure-induced superconductivity and structural evolution of Bi2Se3 single crystals are studied. The emergence of superconductivity at an onset transition temperature (Tc) of about 4.4 K is observed at around 12 GPa. Tc increases rapidly to a maximum of 8.2 K at 17.2 GPa, decreases to around 6.5 K at 23 GPa, and then remains almost constant with further increases in pressure. Variations in Tc with respect to pressure are closely related to the carrier density, which increases by over two orders of magnitude from 2 to 23 GPa. High-pressure synchrotron radiation measurements reveal structural transitions at around 12, 20, and above 29 GPa. A phase diagram of superconductivity versus pressure is also constructed.

OsbZIP58, a basic leucine zipper transcription factor, regulates starch biosynthesis in rice endosperm

Starch composition and the amount in endosperm, both of which contribute dramatically to seed yield, cooking quality, and taste in cereals, are determined by a series of complex biochemical reactions. However, the mechanism regulating starch biosynthesis in cereal seeds is not well understood. This study showed that OsbZIP58, a bZIP transcription factor, is a key transcriptional regulator controlling starch synthesis in rice endosperm. OsbZIP58 was expressed mainly in endosperm during active starch synthesis. osbzip58 null mutants displayed abnormal seed morphology with altered starch accumulation in the white belly region and decreased amounts of total starch and amylose. Moreover, osbzip58 had a higher proportion of short chains and a lower proportion of intermediate chains of amylopectin. Furthermore, OsbZIP58 was shown to bind directly to the promoters of six starch-synthesizing genes, OsAGPL3, Wx, OsSSIIa, SBE1, OsBEIIb, and ISA2, and to regulate their expression. These findings indicate that OsbZIP58 functions as a key regulator of starch synthesis in rice seeds and provide new insights into seed quality control.

Increased α-tocotrienol content in seeds of transgenic rice overexpressing Arabidopsis γ-tocopherol methyltransferase

Vitamin E comprises a group of eight lipid soluble antioxidant compounds that are an essential part of the human diet. The α-isomers of both tocopherol and tocotrienol are generally considered to have the highest antioxidant activities. γ-tocopherol methyltransferase (γ-TMT) catalyzes the final step in vitamin E biosynthesis, the methylation of γ- and δ-isomers to α- and β-isomers. In present study, the Arabidopsis γ-TMT (AtTMT) cDNA was overexpressed constitutively or in the endosperm of the elite japonica rice cultivar Wuyujing 3 (WY3) by Agrobacterium-mediated transformation. HPLC analysis showed that, in brown rice of the wild type or transgenic controls with empty vector, the α-/γ-tocotrienol ratio was only 0.7, much lower than that for tocopherol (~19.0). In transgenic rice overexpressing AtTMT driven by the constitutive Ubi promoter, most of the γ-isomers were converted to α-isomers, especially the γ- and δ-tocotrienol levels were dramatically decreased. As a result, the α-tocotrienol content was greatly increased in the transgenic seeds. Similarly, over-expression of AtTMT in the endosperm also resulted in an increase in the α-tocotrienol content. The results showed that the α-/γ-tocopherol ratio also increased in the transgenic seeds, but there was no significant effect on α-tocopherol level, which may reflect the fact that γ-tocopherol is present in very small amounts in wild type rice seeds. AtTMT overexpression had no effect on the absolute total content of either tocopherols or tocotrienols. Taken together, these results are the first demonstration that the overexpression of a foreign γ-TMT significantly shift the tocotrienol synthesis in rice, which is one of the world's most important food crops.

Core/shell structured NaYF4:Yb3+/Er3+/Gd+3 nanorods with Au nanoparticles or shells for flexible amorphous silicon solar cells

A simple approach for preparing near-infrared (NIR) to visible upconversion (UC) NaYF4:Yb/Er/Gd nanorods in combination with gold nanostructures has been reported. The grown UC nanomaterials with Au nanostructures have been applied to flexible amorphous silicon solar cells on the steel substrates to investigate their responses to sub-bandgap infrared irradiation. Photocurrent–voltage measurements were performed on the solar cells. It was demonstrated that UC of NIR light led to a 16-fold to 72-fold improvement of the short-circuit current under 980 nm illumination compared to a cell without upconverters. A maximum current of 1.16 mA was obtained for the cell using UC nanorods coated with Au nanoparticles under 980 nm laser illumination. This result corresponds to an external quantum efficiency of 0.14% of the solar cell. Mechanisms of erbium luminescence in the grown UC nanorods were analyzed and discussed.

Transformation of LRP gene into Brassica napus mediated by Agrobacterium tumefaciens to enhance lysine content in seeds

Lysine rich protein (LRP) gene derived from the seed of Psophocarpus tetragonolobus was transformed into Brassica napus, employing cotyledon petiole as explants and by using the Agrobacterium tumefaciens strain LBA4404. Transformation efficiency was found to be closely related with phytohormone concentration, infection incubation, and co-cultured time. A medium containing 4 mg/l 6-benzyladenine (6-BA) and 0.3 mg/l naphthalene acetic acid (NAA) was used for plant regeneration. With infection incubation of A. tumefaciens (OD600 = 0.4) for 20 min and co-culture of infected cotyledon petiole for 3 days, the highest transformation efficiency of 8.5% was obtained. To confirm LRP gene expression, PCR and Southern blot analysis were performed on leaf-isolated DNA from regenerated plants resistant to kanamycin. All transgenic plants of the generation T0 formed fertile seeds, which were sowed for the inheritance study of generational T1 and amino acid analysis. It was found that the lysine content of seeds from T1 generation increased by 16.7% compared with non-transgenic lines.

Development and high-throughput genotyping of substitution lines carring the chromosome segments of indica 9311 in the background of japonica Nipponbare

Chromosome segment substitution lines (CSSLs) are useful for the precise mapping of quantitative trait loci (QTLs) and dissection of the genetic basis of complex traits. In this study, two whole-genome sequenced rice cultivars, the japonica Nipponbare and indica 9311 were used as recipient and donor, respectively. A population with 57 CSSLs was developed after crossing and back-crossing assisted by molecular markers, and genotypes were identified using a high-throughput resequencing strategy. Detailed graphical genotypes of 38 lines were constructed based on resequencing data. These CSSLs had a total of 95 substituted segments derived from indica 9311, with an average of about 2.5 segments per CSSL and eight segments per chromosome, and covered about 87.4% of the rice whole genome. A multiple linear regression QTL analysis mapped four QTLs for 1000-grain weight. The largest-effect QTL was located in a region on chromosome 5 that contained a cloned major QTL GW5/qSW5 for grain size in rice. These CSSLs with a background of Nipponbare may provide powerful tools for future whole-genome discovery and functional study of essential genes/QTLs in rice, and offer ideal materials and foundations for japonica breeding.

A major locus qS12, located in a duplicated segment of chromosome 12, causes spikelet sterility in an indica-japonica rice hybrid

Chromosome segment duplications are integral in genome evolution by providing a source for the origin of new genes. In the rice genome, besides an ancient polyploidy event known in the rice common ancestor, it had been identified that there was a special segmental duplication involving chromosomes 11 and 12, but the biological role of this duplication remains unknown. In this study, by using a set of chromosome segment substitution lines (CSSLs) and near isogenic lines (NILs) derived from the indica cultivar 9311 and japonica cultivar Nipponbare, a major QTL (qS12) resulting in hybrid male sterility was mapped within ~400 kb region adjacent to the special duplicated segment on the short arm of chromosome 12. Compared to the japonica cultivar Nipponbare, the two sides of the qS12 candidate region were inverted in the indica cultivar 9311. Among 47 of the 111 rice genotypes evaluated by molecular markers, the inverted sides were detected, and found completely homologous to indica cultivar 9311. These results suggested that the two inverted sides protect the sequence in the qS12 regions from recombination. On the short-arm of chromosome 12, two QTLs S-e and S25, in addition to qS12, were previously detected as a distinct segregation distortion and pollen semi-sterility loci. We propose these three hybrid sterility loci are the same locus, and the duplicated segment on chromosome 12 may play a prominent role in diversification, i.e., sub-speciation of cultivated rice.