Hironori Takasaki

<jats:title>ABSTRACT</jats:title><jats:p>Pesticide contamination in freshwater ecosystems poses a significant threat to water quality and aquatic life, potentially disrupting entire food webs. Fluxametamide (FMT), a novel insecticide regarded as safe for nontarget species, has not been extensively studied in aquatic environments, raising concerns about its potential toxicity to organisms such as <jats:italic>Daphnia magna</jats:italic> (<jats:italic>D. magna</jats:italic>). This study investigates the acute toxicity of FMT, the potential of ultrafine bubbles (UFB), and the associated morphological alterations on <jats:italic>D. magna</jats:italic>. This result revealed that acute toxicity tests showed FMT is very toxic to <jats:italic>D. magna</jats:italic>, with LC<jats:sub>50</jats:sub> 24–48 h values of 0.051 and 0.013 µg/L, respectively. However, UFB has the potential to reduce the toxicity of FMT by twofold compared to control water in <jats:italic>D. magna</jats:italic>. Morphological analysis in the presence of UFB revealed carapace and body damage at high concentrations and prolonged exposure. In contrast, control water resulted in pesticide accumulation throughout the body, leading to more rapid tissue destruction even at lower concentrations and shorter exposure durations. In conclusion, UFB has the potential to alleviate the toxic effects of FMT by modifying its chemical structure, enhancing detoxification mechanisms, and minimizing its overall detrimental effect on <jats:italic>D. magna</jats:italic>. These findings represent an initial report on the effect of UFB on FMT toxicity in <jats:italic>D. magna</jats:italic>, providing essential theoretical foundations for the application of FMT in ecotoxicology.</jats:p>

Drought is one of the most devastating causes of yield losses in crops like maize, and the anticipated increases in severity and duration of drought spells due to climate change pose an imminent threat to agricultural productivity. To understand the drought response, phenotypic and molecular studies are typically performed at a given time point after drought onset, representing a steady-state adaptation response. Because growth is a dynamic process, we monitored the drought response with high temporal resolution and examined cellular and transcriptomic changes after rehydration at 4 and 6 days after leaf four appearance. These data showed that division zone activity is a determinant for full organ growth recovery upon rehydration. Moreover, a prolonged maintenance of cell division by the ectopic expression of PLASTOCHRON1 extends the ability to resume growth after rehydration. The transcriptome analysis indicated that GROWTH-REGULATING FACTORS (GRFs) affect leaf growth by impacting cell division duration, which was confirmed by a prolonged recovery potential of the GRF1-overexpression line after rehydration. Finally, we used a multiplex genome editing approach to evaluate the most promising differentially expressed genes from the transcriptome study and as such narrowed down the gene space from 40 to seven genes for future functional characterization.