Meta-analysis of the effect of expression of MYB transcription factor genes on abiotic stress

Background MYB proteins are a large group of transcription factors. The overexpression of MYB genes has been reported to improve abiotic stress tolerance in plant. However, due to the variety of plant species studied and the types of gene donors/recipients, along with different experimental conditions, it is difficult to interpret the roles of MYB in abiotic stress tolerance from published data. Methods Using meta-analysis approach, we investigated the plant characteristics involved in cold, drought, and salt stress in MYB-overexpressing plants and analyzed the degrees of influence on plant performance by experimental variables. Results The results show that two of the four measured plant parameters in cold-stressed plants, two of the six in drought-stressed, and four of the 13 in salt-stressed were significantly impacted by MYB overexpression by 22% or more, and the treatment medium, donor/recipient species, and donor type significantly influence the effects of MYB-overexpression on drought stress tolerance. Also, the donor/recipient species, donor type, and stress duration all significantly affected the extent of MYB-mediated salt stress tolerance. In summary, this study compiles and analyzes the data across studies to help us understand the complex interactions that dictate the efficacy of heterologous MYB expression designed for improved abiotic stress tolerance in plants

Sensitivity analysis of thermal factors affecting the nonlinear freezing process of soil

In the construction of artificial freezing methods and cold region engineering, the determination of the accurate temperature field is the demand of both ensuring the stability of frozen soil and reducing the project investment. Affected by the external environment, phase change latent heat, non-linear thermal parameters, etc., the temperature evolution of the soil freezing process is a non-linear form, and the temperature field evolution will be more complex with the change of different influencing factors. Scientific control and utilization of the influencing factors of the frozen soil temperature field play a vital role in improving the freezing efficiency and accuracy of the soil temperature field. This study aims to analyze the sensitivity of thermal factors on the nonlinear formation process of frozen soil temperature field, and to provide the results for the control of various factors in frozen soil engineering. A freezing model test was designed and implemented, the boundary conditions and temperature evolution in the model were monitored. Meanwhile, the thermal parameters and unfrozen water content of the model soil were tested indoor. Then the theoretical relationship between unfrozen water content and parameters was deduced to determine the variation range of unfrozen water content. The boundary condition values (including the maximum, minimum and average values) and thermal parameters were used in the orthogonal simulation of the freezing model, respectively. The temperature simulation values were compared with the model test values, and the factors affecting the nonlinear heat transfer of frozen soils were analyzed quantitatively by both the range method and variance analysis method. Several suggestions of the vital factors in the soil freezing construction were offered based on this research

Plaque removal efficacy of a compacted dual-head power toothbrush: A split-mouth randomized clinical trial

PURPOSE: To evaluate the plaque removal efficacy of a compacted dual-head power toothbrush (DH) in comparison with a single-head power toothbrush (SH). METHODS: 24 healthy university students were included in this split-mouth and single-center clinical trial. The DH and SH were randomly assigned to brush the left/right half mouth in the first visit. Testing time points were 30 and 60 seconds. Additionally, 15 and 45 seconds were set for the DH period. The overall, buccal, lingual, gingival marginal, and proximal plaque scores at different time points were recorded and determined by Rustogi Modification of the Navy Plaque Index. To avoid the influence of the right handedness, subjects were brushed in the second visit after 4 weeks, and the SH and the DH were assigned to the right/left half mouth in an opposite period to that of the first visit. RESULTS: 21 participants completed this study. Overall plaque score reductions of the SH and DH were 29% and 59% (P< 0.05) at 30 seconds, and the reductions were 47% and 77% respectively (P< 0.05) at 60 seconds. Using the DH for 45 seconds reduced significantly more overall, buccal, lingual, and gingival marginal plaque than that of using SH for 60 seconds (P< 0.05). The SH reduced plaque scores significantly less in the right and lower dentitions than left and upper dentitions respectively, while DH reduced comparable plaque scores between these dentitions. The DH is more effective in removing overall, buccal, lingual, gingival marginal, and proximal plaque in healthy university students than the SH, meanwhile DH showed comparable overall plaque reduction rates between different regions of the dentitions. CLINICAL SIGNIFICANCE: This compact dual-head power toothbrush provides a new option to carry out daily plaque control effectively