Perception of butenolides by Bacillus subtilis via the α/ß hydrolase RsbQ.

The regulation of behavioral and developmental decisions by small molecules is common to all domains of life. In plants, strigolactones and karrikins are butenolide growth regulators that influence several aspects of plant growth and development, as well as interactions with symbiotic fungi.1,2,3 DWARF14 (D14) and KARRIKIN INSENSITIVE2 (KAI2) are homologous enzyme-receptors that perceive strigolactones and karrikins, respectively, and that require hydrolase activity to effect signal transduction.4,5,6,7 RsbQ, a homolog of D14 and KAI2 from the gram-positive bacterium Bacillus subtilis, regulates growth responses to nutritional stress via the alternative transcription factor SigmaB (σB).8,9 However, the molecular function of RsbQ is unknown. Here, we show that RsbQ perceives butenolide compounds that are bioactive in plants. RsbQ is thermally destabilized by the synthetic strigolactone GR24 and its desmethyl butenolide equivalent dGR24. We show that, like D14 and KAI2, RsbQ is a functional butenolide hydrolase that undergoes covalent modification of the catalytic histidine residue. Exogenous application of both GR24 and dGR24 inhibited the endogenous signaling function of RsbQ in vivo, with dGR24 being 10-fold more potent. Application of dGR24 to B. subtilis phenocopied loss-of-function rsbQ mutations and led to a significant downregulation of σB-regulated transcripts. We also discovered that exogenous butenolides promoted the transition from planktonic to biofilm growth. Our results suggest that butenolides may serve as inter-kingdom signaling compounds between plants and bacteria to help shape rhizosphere communities.

A Google Trends Analysis of Interest in Nonbinary Identities.

Emerging research on stigma suggests that society's mistreatment of nonbinary individuals can, in part, be attributed to public uncertainty and a lack of knowledge about nonbinary identities. In response to this, this study drew upon the theoretical framework of uncertainty management to explore research questions related to nonbinary identity and information behaviors by investigating uncertainty management as evidenced by longitudinal Google Trends data related to nonbinary gender identities. If individuals were found to be engaging in information seeking, the result of this behavior may be that they become less likely to hold stigmatizing attitudes toward nonbinary people, and ultimately be less likely to engage in discrimination toward them. Results indicated that indeed there has been an increase in search volume interest related to nonbinary identities in the past decade. The study concludes by presenting the need for further research to clarify the nature of the relationship between stigma and information seeking, as well as presenting a quandary for researchers regarding the desire for more detailed demographic data, as balanced with concerns for privacy.