Excited-state dynamics of all-trans-spheroidene was studied by time-resolved fluorescence up-conversion method. In order to completely remove fluorescent impurities, spheroidene was purified by two series of alternate alumina and silica-gel chromatography. We used TOPAS, whose repetition rate is 1KHz, as our laser source. The laser output was separated to two beams, one worked as gating pulse, the other was frequency doubled by BBO crystal and was used as pumping pulse. The fluorescence and the gating pulse mixed inside the BBO crystal to generate up-conversion signal. Single photon counting system was used to acquire data. The fluorescence kinetics at different wavelengths was different from each other. The lifetimes of different wavelengths were in between 0.18ps to 0.33ps. After doing dispersion correction and intensity calibration, time-resolved fluorescence up-conversion spectra of all-trans-spheroidene was reconstructed. Single value decomposition followed by global fitting will be used to analyse the spectra.
We previously reported isolation and characterization of an Arabidopsis freezing tolerance 1 (frt1) mutant that showed mature-leaf-specific enhancement of the degree of freezing tolerance due to soluble sugar accumulation. Here, we showed that this mutant shows "restricted sucrose export" phenotypes. Thus, we renamed this mutant rsx1. As reported previously, the rsx1 mutant showed mature-leaf-specific accumulation of transitory starch. We also showed that GUS expression in the rosettes of RSX1promoter:GUS plants occurs in a basipital mode along the leaf vein, suggesting the correlation between RSX1 expression and the expression of source leaf functions. In accordance with this, 14C-sucrose-feeding experiments revealed that rsx1 plants are restricted in the sucrose export out of mature leaves. We also present some transmission electron micrographs, which strongly supported our hypothesis that RSX1 is a genetic factor involved in the establishment of sucrose translocation pathway in the source leaves of A. thaliana.
本演題ではトランスポゾンタグラインから単離した表皮細胞のクチクラが欠損した変異体cof1 (cuticular defect and organ fusion)を報告する。cof1変異体は本葉で器官の融合を示し、また不稔であった。トルイジンブルーテストやSEM、TEMによる観察からこの変異体では茎や葉のクチクラが減少していることが明らかになった。さらに、表皮細胞のワックス成分をガスクロマトグラフィーを用いて成分分析したところ、野性株と比べてクチクラ層を構成する主要な脂質成分、特にアルカンが著しく減少していた。このcof1変異体の原因遺伝子はWBCサブファミリーに属するABCトランスポーターであり、クチクラ欠損変異体cer5の原因遺伝子AtWBC12と相同性が高い遺伝子AtWBC11であることが分った。CER5は茎の表皮細胞の細胞膜に局在し、ワックスの成分である脂質を細胞内から細胞外へと輸送するのではないかと考えられている。またCFPとAtWBC11の融合タンパク質を用いてAtWBC11の細胞内での局在を調べたところ、細胞膜に局在すると考えられた。これらの結果からCOF1/AtWBC11はクチクラのワックスの輸送に関与することが強く示唆された。
The SNF1/AMPK kinases are highly conserved in eukaryotes. Protein kinases of this subfamily exist as catalytically active hetero-trimeric complexes consisting of α, β and γ subunits. Previous reports indicate that interaction between α and γ subunits of SNF1 kinase are strongly in accordance with the deprivation of glucose in the growth medium. Our yeast two-hybrid experiments with the three subunits rice SnRK1 complex convincingly show that the interaction not only between α and γ, but also β and γ subunits is mediated by deprivation of glucose in the growth medium. Some of the experimental evidences also suggest that both dimeric and trimeric forms of protein complexes may exist in vivo .These findings suggest that the regulatory γ subunits of rice SnRK1 may recognize specific signals and interacts with the dimeric complexes comprising of α and β subunits and thus stimulate the catalytic activity of the enzyme complex.
Using a dynamic method which enabled simultaneous measurement of the cell length and turgidity of Characean internode, a rectilinear correlation was found between them, within 4 sec or so immediately after the step change in outer osmotic pressure. By studying the time dependency of these parameters, the velocity of the water flow V across the cell membrane can be observed instantaneously. Further, the absolute water conductivity Lp can also be estimated from V and the shift in water motive force across the membrane. Then the difference in Lp was accomplished by comparing the effluxing and influxing situations through changing πe from the holding osmotic pressure of 150 mM mannitol solution to either 200 mM or to 50 mM. There was no significant difference in Lp between them suggesting that the membrane itself is not a rectifier for the water flow.