AGAMOUS regulates various target genes via cell cycle-coupled H3K27me3 dilution in floral meristems and stamens.

The MADS domain transcription factor AGAMOUS (AG) regulates floral meristem termination by preventing maintenance of the histone modification lysine 27 of histone H3 (H3K27me3) along the KNUCKLES (KNU) coding sequence. At 2 d after AG binding, cell division has diluted the repressive mark H3K27me3, allowing activation of KNU transcription prior to floral meristem termination. However, how many other downstream genes are temporally regulated by this intrinsic epigenetic timer and what their functions are remain unknown. Here, we identify direct AG targets regulated through cell cycle-coupled H3K27me3 dilution in Arabidopsis thaliana. Expression of the targets KNU, AT HOOK MOTIF NUCLEAR LOCALIZED PROTEIN18 (AHL18), and PLATZ10 occurred later in plants with longer H3K27me3-marked regions. We established a mathematical model to predict timing of gene expression and manipulated temporal gene expression using the H3K27me3-marked del region from the KNU coding sequence. Increasing the number of del copies delayed and reduced KNU expression in a polycomb repressive complex 2- and cell cycle-dependent manner. Furthermore, AHL18 was specifically expressed in stamens and caused developmental defects when misexpressed. Finally, AHL18 bound to genes important for stamen growth. Our results suggest that AG controls the timing of expression of various target genes via cell cycle-coupled dilution of H3K27me3 for proper floral meristem termination and stamen development.

The Sequelae and Moderators of Influence of Dandruff on Mental Health Among Mainland Chinese Adults.

Introduction: The psychological impact of dandruff has been largely understudied. Methods: In this cross-sectional study (N = 2116), we examined the consequences of self-perception of dandruff severity on mental health, quality of life, and sleep quality among Chinese adults. Additionally, we examined the moderating factors that influence these associations. Results: Bivariate analyses revealed that greater self-perceived dandruff severity was associated with poorer mental health, lower quality of life, and reduced sleep quality. Furthermore, dandruff severity was positively correlated with appearance anxiety, feelings of helplessness, and perceived stigma. Individuals with more severe dandruff experienced increased teasing and ostracism and, subsequently, heightened psychological distress. Moderation analyses demonstrated that females were more adversely affected by dandruff than males, and those with comorbid skin conditions or a history of being teased and ostracized during adolescence due to dandruff experienced exacerbated negative outcomes. Discussion: This study highlights the need for further research on the psychological consequences of self-perceived severity of dandruff and potential interventions to mitigate its impact.

Timing mechanism dependent on cell division is invoked by Polycomb eviction in plant stem cells.

Plant floral stem cells divide a limited number of times before they stop and terminally differentiate, but the mechanisms that control this timing remain unclear. The precise temporal induction of the Arabidopsis zinc finger repressor KNUCKLES (KNU) is essential for the coordinated growth and differentiation of floral stem cells. We identify an epigenetic mechanism in which the floral homeotic protein AGAMOUS (AG) induces KNU at ~2 days of delay. AG binding sites colocalize with a Polycomb response element in the KNU upstream region. AG binding to the KNU promoter causes the eviction of the Polycomb group proteins from the locus, leading to cell division-dependent induction. These analyses demonstrate that floral stem cells measure developmental timing by a division-dependent epigenetic timer triggered by Polycomb eviction.