RESUMO
Stem cell homeostasis in the shoot apical meristem involves a core regulatory feedback loop between the signalling peptide CLAVATA3 (CLV3), produced in stem cells, and the transcription factor WUSCHEL, expressed in the underlying organising centre. clv3 mutant meristems display massive overgrowth, which is thought to be caused by stem cell overproliferation, although it is unknown how uncontrolled stem cell divisions lead to this altered morphology. Here, we reveal local buckling defects in mutant meristems, and use analytical models to show how mechanical properties and growth rates may contribute to the phenotype. Indeed, clv3 mutant meristems are mechanically more heterogeneous than the wild type, and also display regional growth heterogeneities. Furthermore, stereotypical wild-type meristem organisation, in which cells simultaneously express distinct fate markers, is lost in mutants. Finally, cells in mutant meristems are auxin responsive, suggesting that they are functionally distinguishable from wild-type stem cells. Thus, all benchmarks show that clv3 mutant meristem cells are different from wild-type stem cells, suggesting that overgrowth is caused by the disruption of a more complex regulatory framework that maintains distinct genetic and functional domains in the meristem.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Ácidos Indolacéticos , Meristema , Mutação , Brotos de Planta , Células-Tronco , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Meristema/metabolismo , Meristema/citologia , Meristema/crescimento & desenvolvimento , Meristema/genética , Mutação/genética , Células-Tronco/metabolismo , Células-Tronco/citologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/genética , Brotos de Planta/metabolismo , Ácidos Indolacéticos/metabolismo , Regulação da Expressão Gênica de Plantas , Fenótipo , Proteínas de Homeodomínio/metabolismo , Proteínas de Homeodomínio/genéticaRESUMO
The generation of random numbers is a task of paramount importance in modern science. A central problem for both classical and quantum randomness generation is to estimate the entropy of the data generated by a given device. Here we present a protocol for self-testing quantum random number generation, in which the user can monitor the entropy in real time. Based on a few general assumptions, our protocol guarantees continuous generation of high quality randomness, without the need for a detailed characterization of the devices. Using a fully optical setup, we implement our protocol and illustrate its self-testing capacity. Our work thus provides a practical approach to quantum randomness generation in a scenario of trusted but error-prone devices.