Accumulation of TIP2;2 Aquaporin during Dark Adaptation Is Partially PhyA Dependent in Roots of Arabidopsis Seedlings

Light regulates the expression and function of aquaporins, which are involved in water and solute transport. In Arabidopsis thaliana, mRNA levels of one of the aquaporin genes, TIP2;2, increase during dark adaptation and decrease under far-red light illumination, but the effects of light at the protein level and on the mechanism of light regulation remain unknown. Numerous studies have described the light regulation of aquaporin genes, but none have identified the regulatory mechanisms behind this regulation via specific photoreceptor signaling. In this paper, we focus on the role of phytochrome A (phyA) signaling in the regulation of the TIP2;2 protein. We generated Arabidopsis transgenic plants expressing a TIP2;2-GFP fusion protein driven by its own promoter, and showed several differences in TIP2;2 behavior between wild type and the phyA mutant. Fluorescence of TIP2;2-GFP protein in the endodermis of roots in the wild-type seedlings increased during dark adaptation, but not in the phyA mutant. The amount of the TIP2;2-GFP protein in wild-type seedlings decreased rapidly under far-red light illumination, and a delay in reduction of TIP2;2-GFP was observed in the phyA mutant. Our results imply that phyA, cooperating with other photoreceptors, modulates the level of TIP2;2 in Arabidopsis roots

Gold(I)-Catalyzed Asymmetric Induction of Planar Chirality by Intramolecular Nucleophilic Addition to Chromium-Complexed Alkynylarenes: Asymmetric Synthesis of Planar Chiral (1<i>H</i>‑Isochromene and 1,2-Dihydroisoquinoline)chromium Complexes

Gold­(I)-catalyzed asymmetric intramolecular cyclization of prochiral 1,3-dihydroxymethyl-2-alkynylbenzene or 1,3-bis­(carbamate)-2-alkynylbenzene tricarbonylchromium complexes with axially chiral diphosphine ligand gave planar chiral tricarbonylchromium complexes of 1<i>H</i>-isochromene or 1,2-dihydroisoquinoline with high enantioselectivity. An enantiomeric excess of the planar chiral arene chromium complexes was largely affected by a combination of axially chiral diphosphine­(AuCl)₂ precatalysts and silver salts. In the case of 1,3-dihydroxymethyl-2-alkynylbenzene chromium complexes, a system of segphos­(AuCl)₂ with AgBF₄ resulted in the formation of the corresponding antipode