Evaluating spray drift from Uncrewed Aerial Spray Systems: A machine learning and variance-based sensitivity analysis of environmental and spray system parameters.

Uncrewed Aerial Spray Systems (UASS), commonly called drones, have become an important application technique for plant protection products in Asia and worldwide. As such, environmental variables and spray system parameters influencing spray drift deserve detailed investigations. This study presents the data analysis of 114 UASS drift trials conducted between December 2021 and December 2022 in China. Study design was based on the ISO 22866:2005 protocol for spray drift trials and considered different UASS platforms, nozzles, and release heights, and specifically continuously measured weather conditions. The relative importance of the environmental variables and spray system parameters was evaluated by a random forest (RF) feature importance analysis, a Sobol sensitivity analysis and partial dependence plots. This approach was preferred to linear ranking techniques such as ANOVA (analysis of variance) due to the non-linearity of the system. In addition, partial dependence plots are proposed to visualize the relationship between specific input parameters within the system. Drift deposition curves calculated from the 114 trials show good agreement with previous UASS trials reported in the literature. As reported in previous studies, spray drift following UASS applications is lower than for manned aerial vehicles, greater than for ground spray applications, and similar to drift observed from orchard air blast applications. In addition, 9 trials were conducted on corn fields in order to evaluate the potential effect of crop cover on spray drift. Spray drift was observed to be reduced over the cropped soil, suggesting that plant cover might possibly reduce spray drift. These findings could help supporting drift mitigation policies, stewardship advice and product labelling around the world.

Enhancer of zeste homolog 2 depletion induces cellular senescence via histone demethylation along the INK4/ARF locus.

Polycomb group proteins are epigenetic transcriptional repressors that function through recognition and modification of histone methylation and chromatin structure. As a member of PcG proteins, enhancer of zeste homolog 2 (EZH2) targets cell cycle regulatory proteins which govern cell cycle progression and cellular senescence. In previous work, we reported that EZH2 depletion functionally induced cellular senescence in human gastric cancer cells with mutant p53. However, whether EZH2 expression contributes to the change of key cell cycle regulators and the mechanism involved are still unclear. To address this issue, we investigated the effects of EZH2 depletion on alteration of histone methylation pattern. In gastric cancer cells, INK4/ARF locus was activated to certain extent in consequence of a decrease of H3K27me3 along it caused by EZH2 silence, which contributed substantially to an increase in the expression of p15(INK4b), p14(ARF) and p16(INK4a) and resulted in cellular senescence ultimately. Furthermore, MKN28 cells, which did not express p16(INK4a) and p21(cip), could be induced to senescence via p15(INK4b) activation and suppression of p15(INK4b) reversed senescence progression induced by EZH2 downregulated. These data unravel a crucial role of EZH2 in the regulation of INK4/ARF expression and senescence procedure in gastric cancer cells, and show that the cellular senescence could just depend on the activation of p15(INK4b)/Rb pathway, suggesting the cell-type and species specificity involved in the mechanisms of senescence inducement.

The overexpression of AP-4 as a prognostic indicator for gastric carcinoma.

As a transcription factor belonging to the basic helix-loop-helix leucine-zipper subgroup, AP-4 can control target gene expression by altering cell signal transduction, and regulate growth, development, and cell apoptosis. Under pathological circumstances, it is involved in tumorigenesis. Herein, immunohistochemistry and real-time PCR were used to detect the transcription factor AP-4 expression in gastric cancer, and these data were examined for correlation with histology, pTNM stage, and prognosis. The AP-4 expression rate was 83.67% in a total of 98 gastric cancer tissues, which was significantly higher than 40.91% in non-neoplastic tissues; AP-4 mRNA relative expression shows a significant difference between gastric cancer and normal tissues, and AP-4 expression has a significantly positive correlation with the depth of tumor invasion (P < 0.0001), degree of tumor differentiation (P = 0.0058), lymph node metastasis (P = 0.0255), and pTNM stage (P = 0.001). Survival analysis showed that AP-4-positive patients' median survival time (12.60 months) was significantly shorter than that (41.40 months) of AP-4-negative patients. AP-4 expression in gastric cancer is associated with clinicopathological parameters of gastric cancer, such as differentiation, lymph node metastasis, depth of invasion (P = 0.0010), and pTNM stage. What's more, AP-4 overexpression indicated a worse prognosis for patients. So AP-4 may be a molecular marker to predict the progression and prognosis of the tumor.