The type-B response regulators ARR10, ARR12, and ARR18 specify the central cell in Arabidopsis.

In Arabidopsis thaliana, the female gametophyte consists of two synergid cells, an egg cell, a diploid central cell, and three antipodal cells. CYTOKININ INDEPENDENT 1 (CKI1), a histidine kinase constitutively activating the cytokinin signaling pathway, specifies the central cell and restricts the egg cell. However, the mechanism regulating CKI1-dependent central cell specification is largely unknown. Here, we showed that the type-B ARABIDOPSIS RESPONSE REGULATORS10, 12, and 18 (ARR10/12/18) localize at the chalazal pole of the female gametophyte. Phenotypic analysis showed that the arr10 12 18 triple mutant is female sterile. We examined the expression patterns of embryo sac marker genes and found that the embryo sac of arr10 12 18 plants had lost central cell identity, a phenotype similar to that of the Arabidopsis cki1 mutant. Genetic analyses demonstrated that ARR10/12/18, CKI1, and ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN2, 3, and 5 (AHP2/3/5) function in a common pathway to regulate female gametophyte development. In addition, constitutively activated ARR10/12/18 in the cki1 embryo sac partially restored the fertility of cki1. Results of transcriptomic analysis supported the conclusion that ARR10/12/18 and CKI1 function together to regulate the identity of the central cell. Our results demonstrated that ARR10/12/18 function downstream of CKI1-AHP2/3/5 as core factors to determine cell fate of the female gametophyte.

PPCP Degradation by Chlorine-UV Processes in Ammoniacal Water: New Reaction Insights, Kinetic Modeling, and DBP Formation.

The combination of chlorine and UV (i.e., chlorine-UV process) has been attracting more attention in recent years due to its ready incorporation into existing water treatment facilities to remove PPCPs. However, limited information is available on the impact of total ammonia nitrogen (TAN). This study investigated two model PPCPs, N,N-diethyl-3-toluamide (DEET) and caffeine (CAF), in the two stages of the chlorine-UV process (i.e., chlorination and UV/chlor(am)ine) to elucidate the impact of TAN. During chlorination, the degradation of DEET and CAF was positively correlated with the overall consumption of total chlorine by TAN. Reactive nitrogen intermediates, including HNO/NO- and ONOOH/ONOO-, along with •OH were identified as major contributors to the removal of DEET and CAF. During UV irradiation, DEET and CAF were degraded under UV/chlorine or UV/NH2Cl conditions. •OH and •Cl were the major reactive species to degrade DEET and CAF under UV/NH2Cl conditions, whereas •OCl played a major role for degrading CAF under UV/chlorine conditions. Numerical models were developed to predict the removal of DEET and CAF under chlorination-UV process. Chlorinated disinfection byproducts were detected. Overall, this study presented kinetic features and mechanistic insights on the degradation of PPCPs under the chlorine-UV process in ammoniacal water.

Controlled solvothermal synthesis of nanosheets, nanobelts, and ultralong nanobelt arrays with honeycomb-like micropatterns of ZnSe on zinc substrate.

Nanosheets, nanobelts, and ultralong nanobelt arrays with honeycomb-like micropatterns of ZnSe were synthesized via a solvothermal reaction of Zn with Se and KBH(4) in ethylenediamine at 200 degrees C for 24 h and subsequent annealing. The control over these nanostructures with different morphologies was achieved by adjusting the KBH(4)/Se molar ratio. The role of KBH(4) in the formation of ZnSe(en)(0.5) nanobelts with different length-to-width ratios was investigated, and a possible mechanism was also proposed to account for the growth and conversion of these precursor nanostructures into ZnSe nanostructures. Current-voltage behaviors of the ultralong nanobelt arrays with honeycomb-like micropatterns were investigated. In addition, variable-aspect ratio ZnS nanosheets and nanowires were also synthesized by adjusting the KBH(4)/thiourea molar ratio in the Zn-thiourea-KBH(4)-ethylenediamine solvothermal system. The results suggest that this method may be employed for the controllable synthesis of other II-VI semiconductor nanostructures such as ZnTe, NiS, MnS, and so forth and provides opportunities for both fundamental research and technological applications.