Barley TAPETAL DEVELOPMENT and FUNCTION1 (HvTDF1) gene reveals conserved and unique roles in controlling anther tapetum development in dicot and monocot plants.

The anther tapetum helps control microspore release and essential components for pollen wall formation. TAPETAL DEVELOPMENT and FUNCTION1 (TDF1) is an essential R2R3 MYB tapetum transcription factor in Arabidopsis thaliana; however, little is known about pollen development in the temperate monocot barley. Here, we characterize the barley (Hordeum vulgare L.) TDF1 ortholog using reverse genetics and transcriptomics. Spatial/temporal expression analysis indicates HvTDF1 has tapetum-specific expression during anther stage 7/8. Homozygous barley hvtdf1 mutants exhibit male sterility with retarded tapetum development, delayed tapetum endomitosis and cell wall degeneration, resulting in enlarged, vacuolated tapetum surrounding collapsing microspores. Transient protein expression and dual-luciferase assays show TDF1 is a nuclear-localized, transcription activator, that directly activates osmotin proteins. Comparison of hvtdf1 transcriptome data revealed several pathways were delayed, endorsing the observed retarded anther morphology. Arabidopsis tdf1 mutant fertility was recovered by HvTDF1, supporting a conserved role for TDF1 in monocots and dicots. This indicates that tapetum development shares similarity between monocot and dicots; however, barley HvTDF1 appears to uniquely act as a modifier to activate tapetum gene expression pathways, which are subsequently also induced by other factors. Therefore, the absence of HvTDF1 results in delayed developmental progression rather than pathway failure, although inevitably still results in pollen degeneration.

A randomized controlled study on color stability of tetracycline teeth restored with ceramic veneer.

OBJECTIVES: This study aimed to evaluate the color stability of tetracycline teeth restored with ceramic veneers of different thicknesses combined with different resin cement systems after aging. METHODS: Twenty patients with tetracycline teeth, including two maxillary central incisors, were selected clinically. The patients were randomly divided into four groups and restored with 0.5 and 0.75 mm ceramic veneers by using a veneer adhesive system, either with light-cured or dual-cured reaction. The color difference (ΔE) values after cementation and 1, 6, 12, and 24 months of use were obtained by quantification of L*, a*, and b* values with a colorimeter. The results were analyzed statistically with two-way ANOVA and Student's t test. RESULTS: The ΔE values of ceramic veneers detected after aging were less than 2.25. The 0.5 mm groups exhibited greater color change than the 0.75 mm-thick veneers (P<0.05). No significant difference was found on the color change of dual- or light-cured resin cements. CONCLUSIONS: Resin cements and veneer thickness influence the color of ceramic veneers after aging. Cementation of veneers with either dual- or light-cured resin cements does not affect the long-term color stability of tetracycline teeth differently.

Remineralising effect of 45S5 bioactive glass on artificial caries in dentine.

BACKGROUND: This study investigated the remineralisation effect of bioactive glass on artificial dentine caries. METHODS: Dentine disks with artificial caries were treated with bioactive glass (group BAG), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (group CPP-ACP), sodium fluoride glycerol (group F) or deionized water (group W). All disks were subjected to pH cycling for 28 days subsequently. The topography, microhardness and remineralisation depth of the dentine carious lesion were assessed by atomic force microscopy (AFM), microhardness testing and confocal laser scanning microscope (CLSM), respectively. RESULTS: AFM images indicated mineral depositions on the surface of the carious lesion in group BAG. The changes of Vickers hardness number (ΔVHN, mean ± SD) after pH cycling were 9.67 ± 3.60, 6.06 ± 3.83, 5.00 ± 2.19 and - 1.90 ± 2.09 (p < 0.001) in group BAG, group CPP-ACP, group F and group W, respectively. The remineralisation depth (mean ± SD) of the carious lesion in group BAG, group CPP-ACP, group F and group W were 165 ± 11 µm, 111 ± 11 µm, 75 ± 6 µm and 0 µm (p < 0.001), respectively. CONCLUSION: Bioactive glass possessed a promising remineralisation effect on artificial dentine caries and could be a therapeutic choice for caries management.

TaZFP1, a C2H2 type-ZFP gene of T. aestivum, mediates salt stress tolerance of plants by modulating diverse stress-defensive physiological processes.

Salt stress suppresses plant growth, development, and crop productivity. In this study, we characterized the role of TaZFP1, a C2H2 type-zinc finger protein family member of T. aestivum, in salt stress tolerance. TaZFP1 possesses a conserved C2H2 motif (CX2-4CX12HX3-5H) shared by plant ZFP proteins, translocates to the nucleus after endoplasmic reticulum (ER) assortment, and displays a ZF 3-D structure similar to its eukaryote homologs. The transcripts of TaZFP1 were upregulated during salt stress condition and this effect was restored under normal conditions. Compared to wild type (WT), the transgenic lines of TaZFP1 overexpression or knockdown displayed improved phenotypes, biomass, photosynthesis parameters (Pn, ΨPSII, and NPQ), osmolytes contents (i.e. proline and soluble sugar), and enhanced antioxidant enzyme (AE) activity following salt stress treatment. A set of genes associated with proline synthesis (i.e., NtP5CS1 and NtP5CS2) and encoding AEs (i.e., NtSOD2, NtCAT1, and NtPOD4) were upregulated in the salt-challenged transgenic lines of TaZFP1 expression. Additionally, the transgenic lines exhibited similar stomata movement patterns and leaf water retention properties under salinity conditions compared to those induced by exogenous abscisic acid (ABA) treatment, suggesting that the TaZFP1-mediated salt response is dependent on the ABA signaling. High throughput RNAseq analysis revealed significant alteration of gene transcription in transgenic lines upon salt stress. Among them, the differentially expressed genes (DEGs) represented by the gene ontology (GO) terms were associated with organic acid, carboxylic acid, carbohydrate, and coenzyme as well as organonitrogen compounds, translation, peptide metabolism, and peptide biosynthesis. A set of upregulated DEGs were found to be thylakoid- and photosystem-associated, which is consistent with the TaZFP1-mediated improvement in photosynthesis in salt-stressed transgenic lines. Our investigation indicated that the TaZFP1-mediated salt tolerance is ascribed to the regulation of gene functions related to photosynthesis, osmolytes metabolism and ROS homeostasis mediated by ABA signaling.

Antimicrobial effects of a bioactive glass combined with fluoride or triclosan on Streptococcus mutans biofilm.

OBJECTIVE: The objective of this study was to investigate the antibacterial effects on a cariogenic biofilm of a bioactive glass (BAG) combined with either sodium fluoride (NaF) or triclosan (TCS). DESIGN: According to minimal bactericidal concentrations, 37.5mg/ml of BAG, 4.69 mg/ml of NaF, and 15.53 µg/ml of TCS solutions were prepared. When used alone, the three antimicrobial solutions were increased to double-dosage strength (2 MBC). The study contained the following experimental groups: group 1, BAG (2 MBC); group 2, NaF (2 MBC); group 3, TCS (2 MBC); group 4, BAG+NaF; group 5, BAG+TCS; group 6, control (saline). Streptococcus mutans biofilm was cultured with 0.1% sucrose anaerobically on 66 sterilized coverslips (1 × 1 cm(2)) for 24h uninterrupted. After 10 min of exposure to the experimental groups, the microbial kinetics, morphology, and viability of the S. mutans biofilms were assessed by evaluation of colony-forming units (CFUs), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). RESULTS: BAG (2 MBC) used alone showed significantly stronger antibacterial effects than the other two antimicrobials used alone. The combination groups also displayed the same or greater biofilm inactivation effects as BAG (2 MBC) in the plate count test. SEM showed smaller stacks (towers) and fewer surrounding bacteria in groups BAG (2 MBC), BAG+NaF, and BAG+TCS. Confocal microscopy also determined higher live/dead ratios in groups NaF (2 MBC), TCS (2 MBC), and control than in groups BAG (2 MBC), BAG+NaF, and BAG+TCS. CONCLUSIONS: The combinations of BAG with either NaF or TCS enhanced the inactivation effects of BAG (2 MBC) on S. mutans biofilm, and these findings should be further investigated clinically for the control of dental biofilms.