Most plants do poorly when flooded. Certain rice varieties, known as deepwater rice, survive periodic flooding and consequent oxygen deficiency by activating internode growth of stems to keep above the water. Here, we identify the gibberellin biosynthesis gene, (), whose loss-of-function allele catapulted the rice Green Revolution, as being responsible for submergence-induced internode elongation. When submerged, plants carrying the deepwater rice-specific haplotype amplify a signaling relay in which the gene is transcriptionally activated by an ethylene-responsive transcription factor, OsEIL1a. The SD1 protein directs increased synthesis of gibberellins, largely GA, which promote internode elongation. Evolutionary analysis shows that the deepwater rice-specific haplotype was derived from standing variation in wild rice and selected for deepwater rice cultivation in Bangladesh.
Structural evolution from monomer to fibril of amyloid β peptide is related to pathogenic mechanism of Alzheimer disease, and its acceleration is a long-running problem in drug development. This study reveals that ultrasonic cavitation bubbles behave as catalysts for nucleation of the peptide: The nucleation reaction is highly dependent on frequency and pressure of acoustic wave, and we discover an optimum acoustical condition, at which the reaction-rate constant for nucleation is increased by three-orders-of magnitudes. A theoretical model is proposed for explaining highly frequency and pressure dependent nucleation reaction, where monomers are captured on the bubble surface during its growth and highly condensed by subsequent bubble collapse, so that they are transiently exposed to high temperatures. Thus, the dual effects of local condensation and local heating contribute to dramatically enhance the nucleation reaction. Our model consistently reproduces the frequency and pressure dependences, supporting its essential applicability.
Novel metal-complex assemblies constructed from the flexible hinge-like ligand H(2)bhnq (H(2)bhnq=2,2'-bi(3-hydroxy-1,4-naphthoquinone)) have been synthesized. The X-ray crystal structures of these compounds reveal that four types of architectures are accessible by variation of the metal ions. In copper(II) compounds 1-3, the chelating bhnq(2-) ions bridge copper(II) centers to form one-dimensional zigzag chains. The chains of 1-3 are arranged by hydrogen-bonding interactions and stacking interactions to produce porous structures. Cobalt(II) and zinc(II) compounds 4 and 5 form one-dimensional helical chains. In 4 and 5, the crystal packing induces spontaneous resolution of the helical chains with chiral cavities formed perpendicular to the helices. Nickel(II) compounds 6 and 7 form cyclic tetramers. The fourth architecture, a dimer (compound 8), is obtained by the reaction of zinc(II) and bhnq(2-) in MeOH. In these compounds, changes of the dihedral angles and the metal-coordination mode of the bhnq(2-) ion induce the structural versatility. The assemblies of the zigzag chains of the copper(II) compounds exhibit reversible vapochromic behavior. UV/Vis, powder X-ray diffraction, EPR, and adsorption isotherm measurements indicate that this vapochromic behavior is based on the hinge-like flexibility of the bhnq(2-) ion.
The spontaneous self-organization of coordination compounds has been studied intensively over the last few decades.[1] One area of particular interest is the assembly of multistranded helicates. [2][3][4][5] As most strategies for the synthesis of helicates with high nuclearities make use of long and flexible organic ligands, many linear helicates have been prepared. [3, 5] Because of their unique physical and chemical properties, helicates have been used as components of functional materials and devices. [6, 7] These applications could experience remarkable development if clusters with novel properties were introduced into the helicates.There are few examples of cluster helicates, in which metal clusters define the helical axis.[ [9] The Mössbauer spectrum of 1 at 78 K consists of three quadrupole doublets with relative peak areas of 2:1:2, which correspond to two types of high-spin iron(II) ions (isomer shift (IS) = 1.03 mm s À1 , quadrupole splitting (QS) = 3.34 mm s À1 ; IS = 1.03 mm s À1 , QS = 2.81 mm s À1 ) and one type of low-spin iron(II) ion (IS = 0.46 mm s À1 , QS= 0.26 mm s À1 ), respectively (Figure 1).[10] These Mössbauer data are consistent with the structure determined by X-ray diffraction.
The variable temperature magnetic susceptibility, X-ray crystallography, and Mössbauer and Raman spectra of a new dinuclear complex-based one-dimensional coordination polymer [[Fe(II)2(NCS)2(mu-bpypz)2](micro-4,4'-bpy)].MeOH demonstrated a steep one-step [HS-HS] to [LS-LS] spin transition.
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