Forward genetics is a powerful approach used to link genotypes and phenotypes, and mutant screening/analysis has provided deep insights into many aspects of plant physiology. Gravitropism is a tropistic response in plants, in which hypocotyls and stems sense the direction of gravity and grow upward. Previous studies of gravitropic mutants have suggested that shoot endodermal cells in Arabidopsis stems and hypocotyls are capable of sensing gravity (i.e., statocytes). In the present study, we report a new screening system using hypergravity conditions to isolate enhancers of gravitropism mutants, and we also describe a rapid and efficient genome mapping method, using next-generation sequencing (NGS) and single nucleotide polymorphism (SNP)-based markers. Using the endodermal-amyloplast less 1 (eal1) mutant, which exhibits defective development of endodermal cells and gravitropism, we found that hypergravity (10 g) restored the reduced gravity responsiveness in eal1 hypocotyls and could, therefore, be used to obtain mutants with further reduction in gravitropism in the eal1 background. Using the new screening system, we successfully isolated six ene (enhancer of eal1) mutants that exhibited little or no gravitropism under hypergravity conditions, and using NGS and map-based cloning with SNP markers, we narrowed down the potential causative genes, which revealed a new genetic network for shoot gravitropism in Arabidopsis.
(1 No.5 3 (EL.-50m) ACC ( ABSTRACT Topographic irregularities such as hills affect the amplification characteristics of strong ground motion. Due to the interference between direct waves and scattered waves, the behavior of seismic waves passing through irregular terrain is complex. In this study, records of seismic ground motion were compared to simulated seismic waves, calculated from 3-dimensional FEM. The study objectives were to build an analytical model capable of accurately reproducing the observed data and to evaluate the amplification characteristics of strong ground motion in areas characterized by irregular topography.
A series of our studies aim to investigate systematically the melt spinning of poly-xylylene adipamide and its fiber properties. This paper discusses the molecular orientation in a melt spinning process. Polyxylylene-adipamide is made of xylylene-diamine (meta-xylylenediamine 73 mole%/para-xylylenediamine 27 mole %) and adipic acid. Traditional theories concerning the molecular orientation in melt spinning say that (1) polymer chain is stretched by drafting in spinning, and (2) molecular orientation is caused by shearing stress. These theories cannot explain the experimental results obtained hitherto, while Takserman-Krozer's theory about the molecular orientation of dilute polymer solution containing rotating ellipsoid particles can only explain them. The microstructure of these ellipsoid particles seems to be the folding structure proposed by A. Keller.
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