Transcriptomic Profiling of Two Rice Thermo-Sensitive Genic Male Sterile Lines with Contrasting Seed Storability after Artificial Accelerated Aging Treatment

Seed storability has a significant impact on seed vitality and is a crucial genetic factor in maintaining seed value during storage. In this study, RNA sequencing was used to analyze the seed transcriptomes of two rice thermo-sensitive genic male sterile (TGMS) lines, S1146S (storage-tolerant) and SD26S (storage-susceptible), with 0 and 7 days of artificial accelerated aging treatment. In total, 2658 and 1523 differentially expressed genes (DEGs) were identified in S1146S and SD26S, respectively. Among these DEGs, 729 (G1) exhibited similar regulation patterns in both lines, while 1924 DEGs (G2) were specific to S1146S, 789 DEGs (G3) were specific to SD26S, and 5 DEGs (G4) were specific to contrary differential expression levels. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that "translation", "ribosome", "oxidative phosphorylation", "ATP-dependent activity", "intracellular protein transport", and "regulation of DNA-templated transcription" were significantly enriched during seed aging. Several genes, like Os01g0971400, Os01g0937200, Os03g0276500, Os05g0328632, and Os07g0214300, associated with seed storability were identified in G4. Core genes Os03g0100100 (OsPMEI12), Os03g0320900 (V2), Os02g0494000, Os02g0152800, and Os03g0710500 (OsBiP2) were identified in protein-protein interaction (PPI) networks. Seed vitality genes, MKKK62 (Os01g0699600), OsFbx352 (Os10g0127900), FSE6 (Os05g0540000), and RAmy3E (Os08g0473600), related to seed storability were identified. Overall, these results provide novel perspectives for studying the molecular response and related genes of different-storability rice TGMS lines under artificial aging conditions. They also provide new ideas for studying the storability of hybrid rice.

OsVPE2, a Member of Vacuolar Processing Enzyme Family, Decreases Chilling Tolerance of Rice

Chilling is a major abiotic stress affecting rice growth, development and geographical distribution. Plant vacuolar processing enzymes (VPEs) contribute to the seed storage protein processing and mediate the programmed cell death by abiotic and biotic stresses. However, little is known about the roles of plant VPEs in cold stress responses and tolerance regulation. Here, we found that OsVPE2 was a chilling-responsive gene. The early-indica rice variety Xiangzaoxian31 overexpressing OsVPE2 was more sensitive to chilling stress, whereas the OsVPE2-knockout mutants generated by the CRISPR-Cas9 technology exhibited significantly enhanced chilling tolerance at the seedling stage without causing yield loss. Deficiency of OsVPE2 reduces relative electrolyte leakage, accumulation of toxic compounds such as reactive oxygen species and malondialdehyde, and promotes antioxidant enzyme activities under chilling stress conditions. It was indicated that OsVPE2 mediated the disintegration of vacuoles under chilling stress, accompanied by the entry of swollen mitochondria into vacuoles. OsVPE2 suppressed the expression of genes that have a positive regulatory role in antioxidant process. Moreover, haplotype analysis suggested that the natural variation in the OsVPE2 non-coding region may endow OsVPE2 with different expression levels, thereby probably conferring differences in cold tolerance between japonica and indica sub-population. Our results thus reveal a new biological function of the VPE family in regulating cold resistance, and suggest that the gene editing or natural variations of OsVPE2 can be used to create cold tolerant rice varieties with stable yield.

Integrative transcriptomic analysis deciphering the role of rice bHLH transcription factor Os04g0301500 in mediating responses to biotic and abiotic stresses

Understanding the signaling pathways activated in response to these combined stresses and their crosstalk is crucial to breeding crop varieties with dual or multiple tolerances. However, most studies to date have predominantly focused on individual stress factors, leaving a significant gap in understanding plant responses to combined biotic and abiotic stresses. The bHLH family plays a multifaceted regulatory role in plant response to both abiotic and biotic stresses. In order to comprehensively identify and analyze the bHLH gene family in rice, we identified putative OsbHLHs by multi-step homolog search, and phylogenic analysis, molecular weights, isoelectric points, conserved domain screening were processed using MEGAX version 10.2.6. Following, integrative transcriptome analysis using 6 RNA-seq data including Xoo infection, heat, and cold stress was processed. The results showed that 106 OsbHLHs were identified and clustered into 17 clades. Os04g0301500 and Os04g0489600 are potential negative regulators of Xoo resistance in rice. In addition, Os04g0301500 was involved in non-freezing temperatures (around 4°C) but not to 10°C cold stresses, suggesting a complex interplay with temperature signaling pathways. The study concludes that Os04g0301500 may play a crucial role in integrating biotic and abiotic stress responses in rice, potentially serving as a key regulator of plant resilience under changing environmental conditions, which could be important for further multiple stresses enhancement and molecular breeding through genetic engineering in rice.

CRISPR/Cas9-mediated simultaneous mutation of three salicylic acid 5-hydroxylase (OsS5H) genes confers broad-spectrum disease resistance in rice

Salicylic acid (SA) is an essential plant hormone that plays critical roles in basal defence and amplification of local immune responses and establishes resistance against various pathogens. However, the comprehensive knowledge of the salicylic acid 5-hydroxylase (S5H) in rice-pathogen interaction is still elusive. Here, we reported that three OsS5H homologues displayed salicylic acid 5-hydroxylase activity, converting SA into 2,5-dihydroxybenzoic acid (2,5-DHBA). OsS5H1, OsS5H2, and OsS5H3 were preferentially expressed in rice leaves at heading stage and responded quickly to exogenous SA treatment. We found that bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo) strongly induced the expression of OsS5H1, OsS5H2, and OsS5H3. Rice plants overexpressing OsS5H1, OsS5H2, and OsS5H3 showed significantly decreased SA contents and increased 2,5-DHBA levels, and were more susceptible to bacterial blight and rice blast. A simple single guide RNA (sgRNA) was designed to create oss5h1oss5h2oss5h3 triple mutants through CRISPR/Cas9-mediated gene mutagenesis. The oss5h1oss5h2oss5h3 exhibited stronger resistance to Xoo than single oss5h mutants. And oss5h1oss5h2oss5h3 plants displayed enhanced rice blast resistance. The conferred pathogen resistance in oss5h1oss5h2oss5h3 was attributed to the significantly upregulation of OsWRKY45 and pathogenesis-related (PR) genes. Besides, flg22-induced reactive oxygen species (ROS) burst was enhanced in oss5h1oss5h2oss5h3. Collectively, our study provides a fast and effective approach to generate rice varieties with broad-spectrum disease resistance through OsS5H gene editing.

Transcriptomic Profiling of Cold Stress-Induced Differentially Expressed Genes in Seedling Stage of Indica Rice

Cold stress significantly constrains the growth, development, productivity, and distribution of rice, particularly the indica cultivar, known for its susceptibility to cold, limiting its cultivation to specific regions. This study investigated the genes associated with cold responsiveness in the roots of two indica cultivars, SQSL (cold-tolerant) and XZX45 (cold-susceptible), through transcriptome dynamics analysis during the seedling stage. The analysis identified 8144 and 6427 differentially expressed genes (DEGs) in XZX45 and SQSL, respectively. Among these DEGs, 4672 (G2) were shared by both cultivars, while 3472 DEGs (G1) were specific to XZX45, and 1755 DEGs (G3) were specific to SQSL. Additionally, 572 differentially expressed transcription factors (TFs) from 48 TF families, including WRKY, NAC, bHLH, ERF, bZIP, MYB, C2H2, and GRAS, were identified. Gene Ontology (GO) enrichment analysis revealed significant enrichment of DEGs in the G3 group, particularly in the "response to cold" category, highlighting the crucial role of these specific genes in response to cold stress in SQSL. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated pronounced enrichment of DEGs in the G3 group in metabolic pathways such as "Pyruvate metabolism", "Glycolysis/Gluconeogenesis", and "Starch and sucrose metabolism", contributing to cold tolerance mechanisms in SQSL. Overall, this study provides comprehensive insights into the molecular mechanisms underlying cold responses in the indica cultivar, informing future genetic improvement strategies to enhance cold tolerance in susceptible indica rice cultivars.

Exogenous Abscisic Acid Affects the Heat Tolerance of Rice Seedlings by Influencing the Accumulation of ROS

Heat stress (HS) has become one of the major abiotic stresses that severely constrain rice growth. Abscisic acid (ABA) plays an important role in plant development and stress response. However, the effect of different concentrations of exogenous ABA on HS tolerance in rice still needs to be further elucidated. Here, we found that high concentrations of exogenous ABA increased HS damage in seedlings, whereas 10^-12 M ABA treatment increased fresh and dry weight under HS relative to mock seedlings. Our further data showed that, in response to HS, 10^-5 M, ABA-treated seedlings exhibited a lower chlorophyll content, as well as transcript levels of chlorophyll biosynthesis and antioxidant genes, and increased the accumulation of reactive oxygen species (ROS). In addition, the transcript abundance of some heat-, defense-, and ABA-related genes was downregulated on 10^-5 M ABA-treated seedlings under HS. In conclusion, high concentrations of exogenous ABA reduced the HS tolerance of rice seedlings, and this negative effect could be achieved by regulating the accumulation of ROS, chlorophyll biosynthesis, and the transcription levels of key genes in seedlings under HS.

Exogenous Kinetin Modulates ROS Homeostasis to Affect Heat Tolerance in Rice Seedlings

Heat stress caused by rapidly changing climate warming has become a serious threat to crop growth worldwide. Exogenous cytokinin (CK) kinetin (KT) has been shown to have positive effects in improving salt and drought tolerance in plants. However, the mechanism of KT in heat tolerance in rice is poorly understood. Here, we found that exogenously adequate application of KT improved the heat stress tolerance of rice seedlings, with the best effect observed when the application concentration was 10−9 M. In addition, exogenous application of 10−9 M KT promoted the expression of CK-responsive OsRR genes, reduced membrane damage and reactive oxygen species (ROS) accumulation in rice, and increased the activity of antioxidant enzymes. Meanwhile, exogenous 10−9 M KT treatment significantly enhanced the expression of antioxidant enzymes, heat activation, and defense-related genes. In conclusion, exogenous KT treatment regulates heat tolerance in rice seedlings by modulating the dynamic balance of ROS in plants under heat stress.

Identification of subspecies-divergent genetic loci responsible for mineral accumulation in rice grains

Rice (Oryza sativa L.) is a major staple food that provides not only dietary calories but also trace elements for the global inhabitants. The insufficiency of mineral nutrients and the potential accumulation of excessive toxic elements in grains pose risks to human health. The substantial natural variations in mineral accumulation in rice grains presents potentials for genetic improvements of rice via biofortifications of essential mineral nutrients and eliminations of toxic elements in grains. However, the genetic mechanisms underlying the natural variations in mineral accumulation have not been fully explored to date owing to unstable phenotypic variations, which are attributed to poor genetic performance and strong environmental effects. In this study, we first compared the genetic performance of different normalization approaches in determining the grain-Cd, grain-Mn, and grain-Zn variations in rice in different genetic populations. Then through quantitative trait loci (QTLs) identification in two rice inter-ectype populations, three QTLs, including qCd7, qMn3, and qZn7, were identified and the QTLs were found to exhibit allelic differentiation in the different ecotypes. Our results were expected to broaden our understanding for mineral accumulation in rice and propose the potential functional alleles that can be explored for further genetic improvement of rice.

Comparative transcriptome analysis of the mechanism difference in heat stress response between indica rice cultivar "IR64" and japonica cultivar "Koshihikari" at the seedling stage

Heat stress (HS) has become a major abiotic stress in rice, considering the frequency and intensity of extreme hot weather. There is an urgent need to explore the differences in molecular mechanisms of HS tolerance in different cultivars, especially in indica and japonica. In this study, we investigated the transcriptome information of IR64 (indica, IR) and Koshihikari (japonica, Kos) in response to HS at the seedling stage. From the differentially expressed genes (DEGs) consistently expressed at six time points, 599 DEGs were identified that were co-expressed in both cultivars, as well as 945 and 1,180 DEGs that were specifically expressed in IR and Kos, respectively. The results of GO and KEGG analysis showed two different HS response pathways for IR and Kos. IR specifically expressed DEGs were mainly enriched in chloroplast-related pathways, whereas Kos specifically expressed DEGs were mainly enriched in endoplasmic reticulum and mitochondria-related pathways. Meanwhile, we highlighted the importance of NO biosynthesis genes, especially nitrate reductase genes, in the HS response of IR based on protein-protein interaction networks. In addition, we found that heat shock proteins and heat shock factors play very important roles in both cultivars. This study not only provides new insights into the differences in HS responses between different subspecies of rice, but also lays the foundation for future research on molecular mechanisms and breeding of heat-tolerant cultivars.

9-cis-epoxycarotenoid dioxygenase 1 confers heat stress tolerance in rice seedling plants

High temperature is one of the main constraints affecting plant growth and development. It has been reported that abscisic acid (ABA) synthesis gene 9-cis-epoxycarotenoid dioxygenase (NCED) positively regulates plant resistance to salt, cold, and drought stresses. However, little is known about the function of the NCED gene in heat tolerance of rice. Here, we found that OsNCED1 was a heat stress inducible gene. Rice seedlings overexpressing OsNCED1 showed enhanced heat tolerance with more abundant ABA content, whereas the knockout mutant osnced1 accumulated less ABA and showed more sensitive to heat stress. Under heat stress, increased expression of OsNCED1 could reduce membrane damage and reactive oxygen species (ROS) level of plants, and elevate the activity of antioxidant enzymes. Moreover, real time-quantitative PCR (RT-qPCR) analysis showed that overexpression of OsNCED1 significantly activated the expression of genes involved in antioxidant enzymes, ABA signaling pathway, heat response, and defense. Together, our results indicate that OsNCED1 positively regulates heat tolerance of rice seedling by raising endogenous ABA contents, which leads to the improved antioxidant capacity and activated expression of heat and ABA related genes.

Grain Quality Characterization of Hybrid Rice Restorer Lines with Resilience to Suboptimal Temperatures during Filling Stage

Rice (Oryza sativa L.) is a staple food that is consumed worldwide, and hybrid rice has been widely employed in many countries to greatly increase yield. However, the frequency of extreme temperature events is increasing, presenting a serious challenge to rice grain quality. Improving hybrid rice grain quality has become crucial for ensuring consumer acceptance. This study compared the differences in milling quality, appearance quality, and physical and chemical starch properties of rice grains of five restorer lines (the male parent of hybrid rice) when they encountered naturally unfavorable temperatures during the filling period under field conditions. High temperatures (HTs) and low temperatures (LTs) had opposite effects on grain quality, and the effect was correlated with rice variety. Notably, R751, R313, and Yuewangsimiao (YWSM) were shown to be superior restorer lines with good resistance to both HT and LT according to traits such as head rice rate, chalkiness degree, chalky rice rate, amylose content, alkali spreading value, and pasting properties. However, Huazhan and 8XR274 were susceptible to sub-optimal temperatures at the grain-filling stage. Breeding hybrid rice with adverse-temperature-tolerant restorer lines can not only ensure high yield via heterosis but also produce superior grain quality. This could ensure the quantity and taste of rice as a staple food in the future, when extreme temperatures will occur increasingly frequently.

The view of Hong Kong parents on secondary use of dried blood spots in newborn screening program

Background

Residual dried blood spots (rDBS) from newborn screening programmes represent a valuable resource for medical research, from basic sciences, through clinical to public health. In Hong Kong, there is no legislation for biobanking. Parents’ view on the retention and use of residual newborn blood samples could be cultural-specific and is important to consider for biobanking of rDBS.

Objective

To study the views and concerns on long-term storage and secondary use of rDBS from newborn screening programmes among Hong Kong Chinese parents.

Methods

A mixed-method approach was used to study the views and concerns on long-term storage and secondary use of rDBS from newborn screening programmes among Hong Kong Chinese parents of children 0–3 years or expecting parents through focus groups (8 groups; 33 participants) and a survey (n = 1012, 85% mothers) designed with insights obtained from the focus groups. We used framework analysis to summarise the themes as supportive factors, concerns and critical arguments for retention and secondary use of rDBS from focus group discussion. We used multiple logistic regression to assess factors associated with support for retention and secondary use of rDBS in the survey.

Results

Both in focus groups and survey, majority of parents were not aware of the potential secondary use of rDBS. Overall secondary use of rDBS in medical research was well accepted by a large proportion of Hong Kong parents, even if all potential future research could not be specified in a broad consent. However parents were concerned about potential risks of biobanking rDBS including leaking of data and mis-use of genetic information. Parents wanted to be asked for permission before rDBS are stored and mainly did not accept an “opt-out” approach. The survey showed that parents born in mainland China, compared to Hong Kong born parents, had lower awareness of newborn screening but higher support in biobanking rDBS. Higher education was associated with support in rDBS biobanking only among fathers.

Conclusion

Long-term storage and secondary use of rDBS from newborn screening for biomedical research and a broad consent for biobanking of rDBS are generally acceptable to Hong Kong parents given their autonomy is respected and their privacy is protected, highlighting the importance of an accountable governance and a transparent access policy for rDBS biobanks.

Rice cellulose synthase-like protein OsCSLD4 coordinates the trade-off between plant growth and defense

Plant cell wall is a complex and changeable structure, which is very important for plant growth and development. It is clear that cell wall polysaccharide synthases have critical functions in rice growth and abiotic stress, yet their role in plant response to pathogen invasion is poorly understood. Here, we describe a dwarf and narrowed leaf in Hejiang 19 (dnl19) mutant in rice, which shows multiple growth defects such as reduced plant height, enlarged lamina joint angle, curled leaf morphology, and a decrease in panicle length and seed setting. MutMap analysis, genetic complementation and gene knockout mutant show that cellulose synthase-like D4 (OsCSLD4) is the causal gene for DNL19. Loss function of OsCSLD4 leads to a constitutive activation of defense response in rice. After inoculation with rice blast and bacterial blight, dnl19 displays an enhanced disease resistance. Widely targeted metabolomics analysis reveals that disruption of OsCSLD4 in dnl19 resulted in significant increase of L-valine, L-asparagine, L-histidine, L-alanine, gentisic acid, but significant decrease of L-aspartic acid, malic acid, 6-phosphogluconic acid, glucose 6-phosphate, galactose 1-phosphate, gluconic acid, D-aspartic acid. Collectively, our data reveals the importance of OsCSLD4 in balancing the trade-off between rice growth and defense.

WGCNA Analysis Identifies the Hub Genes Related to Heat Stress in Seedling of Rice (Oryza sativa L.)

Frequent high temperature weather affects the growth and development of rice, resulting in the decline of seed–setting rate, deterioration of rice quality and reduction of yield. Although some high temperature tolerance genes have been cloned, there is still little success in solving the effects of high temperature stress in rice (Oryza sativa L.). Based on the transcriptional data of seven time points, the weighted correlation network analysis (WGCNA) method was used to construct a co–expression network of differentially expressed genes (DEGs) between the rice genotypes IR64 (tolerant to heat stress) and Koshihikari (susceptible to heat stress). There were four modules in both genotypes that were highly correlated with the time points after heat stress in the seedling. We further identified candidate hub genes through clustering and analysis of protein interaction network with known–core genes. The results showed that the ribosome and protein processing in the endoplasmic reticulum were the common pathways in response to heat stress between the two genotypes. The changes of starch and sucrose metabolism and the biosynthesis of secondary metabolites pathways are possible reasons for the sensitivity to heat stress for Koshihikari. Our findings provide an important reference for the understanding of high temperature response mechanisms and the cultivation of high temperature resistant materials.

Comparative Analysis of Heat-Tolerant and Heat-Susceptible Rice Highlights the Role of OsNCED1 Gene in Heat Stress Tolerance

To elucidate the mechanism underlying the response of rice to heat stress (HS), the transcriptome profile of panicles was comparatively analyzed between the heat-tolerant line 252 (HTL252) and heat-susceptible line 082 (HSL082), two rice recombinant inbred lines (RILs). Our differentially expressed gene (DEG) analysis revealed that the DEGs are mainly associated with protein binding, catalysis, stress response, and cellular process. The MapMan analysis demonstrated that the heat-responsive (HR) genes for heat shock proteins, transcription factors, development, and phytohormones are specifically induced in HTL252 under HS. Based on the DEG analysis, the key gene OsNCED1 (Os02g0704000), which was induced under HS, was selected for further functional validation. Moreover, 9-cis-epoxycarotenoid dioxygenase (NCED) is a key rate-limiting enzyme in the ABA biosynthetic pathway. Overexpression of OsNCED1 improved the HS tolerance of rice at the heading and flowering stage. OsNCED1-overexpression plants exhibited significant increases in pollen viability, seed setting rate, superoxide dismutase (SOD) and peroxidase (POD) activities, while significantly lower electrolyte leakage and malondialdehyde (MDA) content relative to the wild type (WT). These results suggested that OsNCED1 overexpression can improve the heat tolerance of rice by enhancing the antioxidant capacity. Overall, this study lays a foundation for revealing the molecular regulatory mechanism underlying the response of rice to prolonged HS.

[Analysis of local reactions and efficacy of CD19 chimeric antigen receptor-modified T cells therapy in recurrent/refractory B-cell lymphoma with >7.5 cm lesions]

目的

观察病灶>7.5 cm的复发/难治B细胞非霍奇金淋巴瘤（R/R NHL）患者CD19嵌合抗原受体T细胞（CAR-T细胞）治疗的肿瘤局部反应及疗效。

方法

以2018年8月至2020年5月接受CD19 CAR-T细胞治疗的病灶>7.5 cm的32例R/R NHL患者为研究对象，流式细胞仪检测CD19CAR-T细胞的体内扩增情况；酶联免疫吸附测定法检测患者外周血中细胞因子水平；观察全身不良反应及肿瘤局部反应，分析总有效率（ORR）及总生存（OS）情况。

结果

① 32例患者CAR-T细胞治疗后，13例获得完全缓解（CR）（40.63％），10例获得部分缓解（PR）（31.25％），ORR为71.88％。② 23例有效患者均发生细胞因子释放综合征（CRS），其中1～2级13例，3～4级10例；而疾病稳定+疾病进展（SD+PD）组9例患者CRS均为1～2级（P＝0.030）。③共15例（46.9％）患者发生肿瘤局部反应，其中CR 9例、PR 5例、SD 1例，肿瘤局部反应包括：浅表肿物直径增大且伴红肿热痛；深部肿物表现为腹痛、腹胀、憋气以及肿瘤局部疼痛、烧灼，瘤体增大或伴局部水肿；肿瘤局部出现渗出性病变，可见于腹腔、胸膜腔等。④有效组CD19 CAR-T细胞峰值高于SD+PD组［16.8％（5.3％～48.2％）对2.9％（1.5％～5.7％），z＝−4.297，P<0.001］，有效组中出现肿瘤局部反应患者CD19 CAR-T细胞峰值高于未出现肿瘤局部反应患者［22.2％（10.5％～48.2％）对12.6％（5.3％～21.6％），z＝−3.213，P＝0.001］，多发肿块组CD19 CAR-T细胞峰值高于单发肿块组［35.8％（1.5％～48.2％）对16.8％（10.5％～18.5％），z＝−2.023，P＝0.040］。⑤肿瘤局部反应出现和瘤体缩小时间，均较全身不良反应时间延迟。⑥有效患者中出现肿瘤局部反应者OS率高于未出现肿瘤局部反应者，但差异无统计学意义（75.0％对34.6％，P＝0.169）。

结论

病灶>7.5 cm的R/R NHL患者CD19 CAR-T细胞治疗，近一半出现肿瘤局部反应，发生时间迟于全身不良反应开始的时间。临床试验注册：中国临床试验注册中心（ChiCTR1800018059）

Genetic Control Diversity Drives Differences Between Cadmium Distribution and Tolerance in Rice

Rice, a staple crop for nearly half the planet's population, tends to absorb and accumulate excessive cadmium (Cd) when grown in Cd-contaminated fields. Low levels of Cd can degrade the quality of rice grains, while high levels can inhibit the growth of rice plants. There is genotypic diversity in Cd distribution and Cd tolerance in different rice varieties, but their underlying genetic mechanisms are far from elucidated, which hinders genetic improvements. In this study, a joint study of phenotypic investigation with quantitative trait loci (QTLs) analyses of genetic patterns of Cd distribution and Cd tolerance was performed using a biparent population derived from japonica and indica rice varieties. We identified multiple QTLs for each trait and revealed that additive effects from various loci drive the inheritance of Cd distribution, while epistatic effects between various loci contribute to differences in Cd tolerance. One pleiotropic locus, qCddis8, was found to affect the Cd distribution from both roots to shoots and from leaf sheaths to leaf blades. The results expand our understanding of the diversity of genetic control over Cd distribution and Cd tolerance in rice. The findings provide information on potential QTLs for genetic improvement of Cd distribution in rice varieties.

[Mechanism of lncRNA-SRLR induced invasion and metastasis in U2OS osteosarcoma cells]

Objective: To explore the potential mechanism of sorafenib resistance associated long non-coding RNA (lncRNA-SRLR) promoted invasion and metastasis in U2OS osteosarcoma cells. Methods: We transfected U2OS cells with negative control lentivirus (LV-NC) or lncRNA-SRLR overexpressed lentivirus (LV-over/SRLR) particles. LV-NC and LV-over/SRLR stable transfected cells (U20S/NC and U20S/SRLR) were selected by primary cell culture medium containing puromycin. The mRNA expressions of lncRNA-SRLR and procollagen-lysine, procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (PLOD2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The effect of lncRNA-SRLR on the invasion of U2OS cells were determined by wound-healing assay and Transwell migration assay. The effect of SRLR on the interleukin-6 (IL-6) secretion of U2OS cells was evaluated by enzyme-linked immunosorbent assay (ELISA) analysis. The subcellular distribution of SRLR in U2OS cells was detected by fluorescence in situ hybridization (FISH) analysis.The expression of PLOD2 in cells was detected by immunofluorescence (IF). The expressions of PLOD2 and focal adhesion kinase (FAK)/signal transducer and activator of transcription 3 (STAT3) signal pathway related proteins in U2OS/NC and U2OS/SRLR cells were detected by western blotting. Results: qRT-PCR assay showed that mRNA expressions of lncRNA-SRLR and PLOD2 in U2OS/SRLR cells were (3 964.97±0.05) and (2.77±0.11), respectively, significantly higher than those in U2OS/NC cells (P<0.001 or P<0.01). The results of wound-healing and Transwell migration assay showed that over-expression of SRLR markedly promoted the invasion ability of U2OS cells (P<0.05). The result of ELISA analysis showed that the IL-6 secretions in U2OS/NC or U2OS/SRLR cells were (125.38±11.22) pg/ml or (119.97±13.43) pg/ml, without statistical significance (P>0.05). The subcellular distribution assay revealed that lncRNA-SRLR is predominately located in the nucleus. The result of IF showed that compared with U2OS/NC cells, the expression of PLOD2 was up-regulated in U2OS/SRLR cells. The result of western blotting showed that over-expression of SRLR significantly increased the expression levels of PLOD2, phosphorylation (p)-FAK and p-STAT3 in U2OS cells (P<0.01). Conclusion: lncRNA-SRLR promotes invasion and metastasis of osteosarcoma by activating PLOD2-FAK/STAT3 signal axis.

Endoplasmic Reticulum-Localized PURINE PERMEASE1 Regulates Plant Height and Grain Weight by Modulating Cytokinin Distribution in Rice

Cytokinins (CKs) are a class of phytohormones playing essential roles in various biological processes. However, the mechanisms underlying CK transport as well as its function in plant growth and development are far from being fully elucidated. Here, we characterize the function of PURINE PERMEASE1 (OsPUP1) in rice (Oryza sativa L.). OsPUP1 was predominantly expressed in the root, particularly in vascular cells, and CK treatment can induce its expression. Subcellular localization analysis showed that OsPUP1 was predominantly localized to the endoplasmic reticulum (ER). Overexpression of OsPUP1 resulted in growth defect of various aerial tissues, including decreased leaf length, plant height, grain weight, panicle length, and grain number. Hormone profiling revealed that the CK content was decreased in the shoot of OsPUP1-overexpressing seedling, but increased in the root, compared with the wild type. The CK content in the panicle was also decreased. Quantitative reverse transcription-PCR (qRT-PCR) analysis using several CK type-A response regulators (OsRRs) as the marker genes suggested that the CK response in the shoot of OsPUP1-overexpressing seedling is decreased compared to the wild type when CKs are applied to the root. Genetic analysis revealed that BG3/OsPUP4, a putative plasma membrane-localized CK transporter, overcomes the function of OsPUP1. We hypothesize that OsPUP1 might be involved in importing CKs into ER to unload CKs from the vascular tissues by cell-to-cell transport.

Characterization and identification of the candidate gene of rice thermo-sensitive genic male sterile gene tms5 by mapping

Previous research has demonstrated that the thermo-sensitive genic male-sterile (TGMS) gene in rice was regulated by temperature. TGMS rice is important to hybrid rice production because the application of the TGMS system in two-line breeding is cost-effective, simple, efficient and overcomes the limitations of the cytoplasmic male sterility (CMS) system. AnnongS is the first discovered and deeply studied TGMS rice line in China. Previous studies have suggested that AnnongS-1 and Y58S, two derivative TGMS lines of AnnongS, were both controlled by a single recessive gene named tms5, which was genetically mapped on chromosome 2. In the current study, three populations (AnnongS-1 x Nanjing11, Y58S x Q611, and Y58S x Guanghui122) were developed to investigate the tms5 gene molecular map. Analysis of recombination events of sterile samples, utilizing 125 probes covering the tms5 region, suggested that the tms5 gene was physically mapped to a 19 kb DNA fragment between two markers, 4039-1 and 4039-2, located on the BAC clone AP004039. Following the construction of a physical map between the two markers, ONAC023, a member of the NAC (NAM-ATAF-CUC-related) gene family, was identified as the candidate of the tms5 gene.

Agonist-induced mu opioid receptor phosphorylation and functional desensitization in rat thalamus

By metabolically labeling tissue slices from striatum and thalamus with [32P]orthophosphoric acid and immunoprecipitating the receptor with mu receptor-specific antiserum, we found that the endogenous mu receptor in the brain tissue did undergo phosphorylation. The phosphorylation occurred at basal level (no drug treatment) and was enhanced with DAMGO-treatment. The enhancement of the phosphorylation was blocked by naloxone. Morphine stimulation also increased the phosphorylation, but the amount of enhancement was less than that caused by DAMGO-treatment. Mu receptor phosphorylation in the thalamus was much greater than the striatum, while no phosphorylation of the mu receptor in the cerebellum was detected, even with DAMGO treatment. The extent of mu receptor phosphorylation identified in the thalamus, striatum and cerebellum is consistent with the previous studies of mu receptor distribution. The time course and dose-response studies demonstrated that mu receptor phosphorylation was a rapid event, exhibited a positive dose-dependent response, and was similar to that observed in the cloned mu receptor in CHO cells. Furthermore, we correlated the change of mu receptor phosphorylation with the desensitization of the mu receptor function, specifically, inhibition of adenylyl cyclase activity in the thalamus of morphine-tolerant rats. We found that in the thalamus of rats chronically treated with morphine, the enhancement of mu receptor phosphorylation in basal and DAMGO-treated samples paralleled the desensitization of DAMGO-mediated inhibition of adenylyl cyclase. Our results suggest that mu receptor phosphorylation in vivo may play an important role in the modulation of mu receptor function following both acute exposure to morphine and during the development of morphine tolerance.

Role for the C-terminus in agonist-induced mu opioid receptor phosphorylation and desensitization

Determining which domains and amino acid residues of the mu opioid receptor are phosphorylated is critical for understanding the mechanism of mu opioid receptor phosphorylation. The role of the C-terminus of the receptor was investigated by examining the C-terminally truncated or point-mutated mu opioid receptors in receptor phosphorylation and desensitization. Both wild-type and mutated receptors were stably expressed in Chinese hamster ovary (CHO) cells. The receptor expression was confirmed by receptor radioligand binding and immunoblottting. After exposure to 5 microM of DAMGO, phosphorylation of the C-terminally truncated receptor and the mutant receptor T394A was reduced to 40 and 10% of that of the wild-type receptor, respectively. Mutation effects on agonist-induced desensitization were studied using adenylyl cyclase inhibition assays. The C-terminally truncated receptor and mutant receptor T394A both showed complete loss of DAMGO-induced desensitization, while the mutant T/S-7A receptor only lost part of its ability to desensitize. Taken together, these results suggest that the C-terminus of the mu opioid receptor participates in receptor phosphorylation and desensitization with threonine 394, a crucial residue for both features. DAMGO-induced mu opioid receptor phosphorylation and desensitization are associated and appear to involve both the mu opioid receptor C-terminus and other domains of the receptor.

Selected cysteine residues in transmembrane domains of mu-opioid receptor are critical for effects of sulfhydryl reagents

The effects of sulfhydryl-specific methanethiosulfonate (MTS) derivatives on mu-opioid receptor binding were examined in Chinese hamster ovary (CHO) cells that stably express mu-opioid receptors (HmuCHO). Three charged MTS derivatives inhibited the binding of [(3)H][D-Ala(2),N-MePhe(4),Gly-ol(5)]-enkephalin to mu-opioid receptors with IC(50) values ranging from 0.12 to 13 mM. Further characterization of the mu-opioid receptor interactions with ethylammonium MTS (the most potent among tested MTS reagents) revealed that ethylammonium MTS inhibition of ligand binding to the receptor was irreversible, with both the maximal receptor binding (B(max)) and the binding affinity (K(d)) being changed. Preincubation of HmuCHO cells with [D-Ala(2),N-MePhe(4), Gly-ol(5)]-enkephalin or naloxone prevented the receptor inactivation normally caused by MTS derivatives, indicating that the reactions may occur within or near the ligand-binding pocket on the receptor. To identify the susceptible sulfhydryl groups, each of the cysteine residues in the mu-receptor transmembrane domains were substituted with serine by site-directed mutagenesis. All of the mutant receptors transiently expressed in COS cells had receptor binding properties similar to the wild-type receptors. However, four mutant receptors with a serine substitution in transmembrane domain III (C161S), IV (C192S), V (C237S), or VII (C332S) displayed significant resistance against MTS inhibition compared with the wild-type receptor. We conclude that these four cysteine residues react with MTS reagents and are responsible for the effect of the MTS reagents on mu-opioid receptor binding.