Genome-Wide Identification of Maize Protein Arginine Methyltransferase Genes and Functional Analysis of ZmPRMT1 Reveal Essential Roles in Arabidopsis Flowering Regulation and Abiotic Stress Tolerance.

Histone methylation, as one of the important epigenetic regulatory mechanisms, plays a significant role in growth and developmental processes and stress responses of plants, via altering the methylation status or ratio of arginine and lysine residues of histone tails, which can affect the regulation of gene expression. Protein arginine methyltransferases (PRMTs) have been revealed to be responsible for histone methylation of specific arginine residues in plants, which is important for maintaining pleiotropic development and adaptation to abiotic stresses in plants. Here, for the first time, a total of eight PRMT genes in maize have been identified and characterized in this study, named as ZmPRMT1-8. According to comparative analyses of phylogenetic relationship and structural characteristics among PRMT gene family members from several representative species, all maize 8 PRMT proteins were categorized into three distinct subfamilies. Further, schematic structure and chromosome location analyses displayed evolutionarily conserved structure features and an unevenly distribution on maize chromosomes of ZmPRMT genes, respectively. The expression patterns of ZmPRMT genes in different tissues and under various abiotic stresses (heat, drought, and salt) were determined. The expression patterns of ZmPRMT genes indicated that they play a role in regulating growth and development and responses to abiotic stress. Eventually, to verify the biological roles of ZmPRMT genes, the transgenic Arabidopsis plants overexpressing ZmPRMT1 gene was constructed as a typical representative. The results demonstrated that overexpression of ZmPRMT1 can promote earlier flowering time and confer enhanced heat tolerance in transgenic Arabidopsis. Taken together, our results are the first to report the roles of ZmPRMT1 gene in regulating flowering time and resisting heat stress response in plants and will provide a vital theoretical basis for further unraveling the functional roles and epigenetic regulatory mechanism of ZmPRMT genes in maize growth, development and responses to abiotic stresses.

Genome-wide identification and expression profiling analysis of maize AP2/ERF superfamily genes reveal essential roles in abiotic stress tolerance.

BACKGROUND: As one of the largest transcription factor families in plants, the APETALA2/Ethylene-Responsive Factor (AP2/ERF) superfamily is involved in various biological processes and plays significant roles in plant growth, development and responses to various stresses. Although identification and characterization of AP2/ERF superfamily genes have been accomplished in many plant species, very little is known regarding the structure and function of AP2/ERF genes in maize. RESULTS: In this study, a total of 214 genes encoding ZmAP2/ERF proteins with complete AP2/ERF domain were eventually identified according to the AGPv4 version of the maize B73 genome. Based on the number of AP2/ERF domain and similarities of amino acid sequences among AP2/ERF proteins from Arabidopsis, rice and maize, all 214 putative ZmAP2/ERF proteins were categorized into three distinct families, including the AP2 family (44), the ERF family (166) and the RAV family (4), respectively. Among them, the ERF family was further subdivided into two diverse subfamilies, including the DREB and ERF subfamilies with 61 and 105 members, respectively. Further, based on phylogenetic analysis, the members of DREB and ERF subfamilies were subdivided into four (Group I-IV) and eight (Group V-XII) groups, respectively. The characteristics of exon-intron structure of these putative ZmAP2/ERF genes and conserved protein motifs of their encoded ZmAP2/ERF proteins were also presented respectively, which was in accordance with the results of group classification. Promoter analysis suggested that ZmAP2/ERF genes shared many stress- and hormone-related cis-regulatory elements. Gene duplication and synteny analysis revealed that tandem or segmental duplication and purifying selection might play significant roles in evolution and functional differentiation of AP2/ERF superfamily genes among three various gramineous species (maize, rice and sorghum). Using RNA-seq data, transcriptome analysis indicated that the majority of ZmAP2/ERF genes displayed differential expression patterns at different developmental stages of maize. In addition, the following analyses of co-expression network among ZmAP2/ERF genes and protein protein interaction between ZmAP2 and ZmERF proteins further enabled us to understand the regulatory relationship among members of the AP2/ERF superfamily in maize. Furthermore, by quantitative real-time PCR analysis, twenty-seven selected ZmAP2/ERF genes were further confirmed to respond to three different abiotic stresses, suggesting their potential roles in various abiotic stress responses. Collectively, these results revealed that these ZmAP2/ERF genes play essential roles in abiotic stress tolerance. CONCLUSIONS: Taken together, the present study will serve to present an important theoretical basis for further exploring the function and regulatory mechanism of ZmAP2/ERF genes in the growth, development, and adaptation to abiotic stresses in maize.

The Dynamics of DNA methylation in the maize (Zea mays L.) inbred line B73 response to heat stress at the seedling stage.

High temperature stress has become a major concern for crop production worldwide because it greatly affects the growth, development, and productivity of plants. The mechanisms underlying the development of heat-tolerance need to be better understood for important agricultural crops. Recent research shows that DNA methylation is dynamic during plant development. However, the molecular mechanism regulating these dynamic DNA methylation patterns remains to be elucidated. In this study, six MethylRAD libraries were constructed using DNA isolated from leaves of maize. A total of 42,561,144 and 48,157,284 clean reads were generated from CK (Control condition) and HTP (Heat stress condition) treatments, respectively. The results showed that a total of 25,470 methylated genes were found in six tested samples, including 325 differentially methylated genes (200 in CCGG sites and 125 in CCWGG sites) between the CK and HTP samples. KEGG pathway enrichment analysis for DMGs indicated that Spliceosome, Homologous recombination, RNA transport, Ubiquitin mediated proteolysis and Carbon metabolism pathways play a central role in maize response to heat stress. Taken together, this research revealed the genome-wide DNA methylation pattern of maize leaves in response to heat exposure and identified candidate genes potentially involved in response to heat stress at the methylation level, which will facilitate future studies to elucidate the epigenetic mechanisms underlying the responses of maize to heat stress.

Retrospective analysis of risk factors associated with Kawasaki disease in China.

In order to provide early intervention for coronary artery lesion (CAL) caused by Kawasaki Disease (KD), we analyzed clinical characteristics of typical and incomplete KD cases from 1998 to 2008 in Northwest and Central China. A total of 383 patients included 298 cases of typical KD and 85 cases of incomplete KD. The morbidity of incomplete KD was 28.5%, a percentage significantly lower than that of typical KD. The occurrence of bulbar conjunctiva congestion, erythra, crissum red, film-like decrustation, lip red, rhagades, raspberry tongue, bilateral toe-end decrustation, limb sclerosis, cervical lymph nodes enlargement, agitation and irritability in incomplete KD group was lower than that in the group of typical KD (p < 0.05); however, the occurrence of unilateral toe-end decrustation, scar reappearance erythema, malaise, fatigue, liver incidence was significant higher in incomplete KD group (p < 0.05). Based on lab assays and inspection index comparisons, the incomplete KD cases whose C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were significantly increased, had significantly higher reduction in blood platelet (PLT). Interestingly, the KD patients with CPR higher than 30 mg/L, ESR higher than 40 mm/h, hepatomegaly and IVIG ineffectiveness, had higher incidence of CAL development. Altogether, our data have indicated differential clinical characteristics between incomplete KD and typical KD, and have identified several high risk factors of KD for CAL, such as hepatomegaly.

Anodic electrogenerated chemiluminescence behavior and the choline biosensing application of blue emitting conjugated polymer dots.

The anodic electrochemiluminescence (ECL) behavior of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots was studied and applied in oxidoreductase-based ECL biosensing using Chox as the model enzyme.

Novel electrochemical immunoassay for quantitative monitoring of biotoxin using target-responsive cargo release from mesoporous silica nanocontainers.

A novel homogeneous immunoassay protocol was designed for quantitative monitoring of small molecular biotoxin (brevetoxin B, PbTx-2, as a model) by using target-responsive cargo release from polystyrene microsphere-gated mesoporous silica nanocontainer (MSN). Initially, monoclonal mouse anti-PbTx-2 capture antibody was covalently conjugated onto the surface of MSN (mAb-MSN), and the electroactive cargo (methylene blue, MB) was then trapped in the pores of mAb-MSN by using aminated polystyrene microspheres (APSM) based on the electrostatic interaction. Upon addition of target PbTx-2, the positively charged APSM was displaced from the negatively charged mAb-MSN because of the specific antigen-antibody reaction. Thereafter, the molecular gate was opened, and the trapped methylene blue was released from the pores. The released methylene blue could be monitored by using a square wave voltammetry (SWV) in a homemade microelectrochemical detection cell. Under optimal conditions, the SWV peak current increased with the increasing of PbTx-2 concentration in the range from 0.01 to 3.5 ng mL(-1) with a detection limit (LOD) of 6 pg mL(-1) PbTx-2 at the 3Sblank criterion. Intra- and interassay coefficients of variation with identical batches were ≤6% and 9.5%, respectively. The specificity and sample matrix interfering effects were acceptable. The analysis in 12 spiked seafood samples showed good accordance between results obtained by the developed immunoassay and a commercialized enzyme-linked immunosorbent assay (ELISA) method. Importantly, the target-responsive controlled release system-based electrochemical immunoassay (CRECIA) offers a promising scheme for the development of advanced homogeneous immunoassay without the sample separation and washing procedure.

Detection of human chorionic gonadotrophin hormone using a label-free epoxysilane-modified capacitive immunosensor.

A new and label-free capacitive immunosensor based on antibody-functionalized epoxysilane on a glassy carbon electrode has been developed for quantitative detection of human chorionic gonadotropin (hCG). Monitoring the changes in the capacitance signals of antibodies before and after the binding of the antigen provides the basis for an immunoassay. The performance and factors influencing the immunosensor were also studied. Under the optimized conditions, the developed immunosensor quantitatively detected serum hCG in the range of 18-450 mIU/ml with a detection limit of 5.0 mIU/ml (at 3delta). Thirty-five patients' sera were assayed by the proposed immunosensor, and the results agreed with those given by the commercial radioimmunoassay test kit, with correlation coefficient of 0.998. Further research about the intrinsic electroactivity of antibodies and their target molecules would surely provide new and sensitive screening assays as well as extensive data regarding their interaction mechanisms.