Variety-dependent accumulation of glucomannan in the starchy endosperm and aleurone cell walls of rice grains and its possible genetic basis.

Plant cell wall plays important roles in the regulation of plant growth/development and affects the quality of plant-derived food and industrial materials. On the other hand, genetic variability of cell wall structure within a plant species has not been well understood. Here we show that the endosperm cell walls, including both starchy endosperm and aleurone layer, of rice grains with various genetic backgrounds are clearly classified into two groups depending on the presence/absence of ß-1,4-linked glucomannan. All-or-none distribution of the glucomannan accumulation among rice varieties is very different from the varietal differences of arabinoxylan content in wheat and barley, which showed continuous distributions. Immunoelectron microscopic observation suggested that the glucomannan was synthesized in the early stage of endosperm development, but the synthesis was down-regulated during the secondary thickening process associated with the differentiation of aleurone layer. Significant amount of glucomannan in the cell walls of the glucomannan-positive varieties, i.e., 10% or more of the starchy endosperm cell walls, and its close association with the cellulose microfibril suggested possible effects on the physicochemical/biochemical properties of these cell walls. Comparative genomic analysis indicated the presence of striking differences between OsCslA12 genes of glucomannan-positive and negative rice varieties, Kitaake and Nipponbare, which seems to explain the all-or-none glucomannan cell wall trait in the rice varieties. Identification of the gene responsible for the glucomannan accumulation could lead the way to clarify the effect of the accumulation of glucomannan on the agronomic traits of rice by using genetic approaches.

Fluorescence and nonradiative processes of dioxin vapors.

Fluorescence, fluorescence excitation, biacetyl-sensitized phosphorescence excitation and absorption spectra of five dioxins (dibenzofuran, 2-chlirodibenzofuran, 2,8-dichlorodibenzofuran, dibenzo-p-dioxin and 2-chlorodibenzo-p-dioxin) have been measured in the vapor phase. The intersystem crossing yields of dioxin vapors have been determined by means of a biacetyl sensitized phosphorescence method. It is shown that the nonradiative rates from the S1 state of dibenzo-p-dioxins increase significantly with increasing excitation energy, while those of dibenzofurans are almost unchanged. It is also shown that the main nonradiative process from S1 for dibenzofurans is both the intersystem crossing to T1 and internal conversion to S0 which includes possible photodecomposition, while that for dibenzo-p-dioxins is the internal conversion to S0, which also may include possible photochemical decomposition processes.

Excited electronic states and spectroscopy of unsymmetrically substituted polyenes.

α-Methyl-ω-phenylpolyenes, Me-(CH=CH)N-Ph, (MPPNs) with N = 2, 3, and 4 were synthesized. Fluorescence, absorption, and excitation spectra of MPPNs have been measured under different conditions along with those of ß-methylstyrene. It is shown that there is a forbidden singlet (π, π∗) excited state located at energies below the absorbing state for MPPNs with N = 3 and 4. Excitation energies of these polyenes are determined as a function of N. Quantitative analysis of the temperature dependence of the relative intensity of the fluorescence spectrum and its solvent shift behavior extract estimates of the various physical parameters that characterize excitation energies and excited-state dynamical behavior of MPPN with N = 3. The singlet excited states of the MPPNs were compared with those of the α,ω-diphenylpolyenes and α,ω-dimethylpolyenes.

Two lactones in the androconial scent of the lycaenid butterfly Celastrina argiolus ladonides.

Male adult butterflies of many species have characteristic odors originating from the disseminating organs known as androconia. Despite the fact that androconia exist in several species, there have been few investigations on adult scents from the lycaenid species. Celastrina argiolus ladonides (Lycaenidae) is a common species in Eurasia. We have reported that male adults of this species emit a faint odor, and the major components causing this odor have been newly found in the Insecta. By using field-caught individuals, we determined the chemical nature and location of this odor in the butterfly. Gas chromatography-mass spectrometry (GC-MS) analyses revealed that two lactone compounds, lavender lactone and δ-decalactone, are present in the extracts of males but absent in those of the females. On an average, approximately 50 ng of each compound was found per male. Chiral GC analyses performed using enantiomerically pure standards revealed that the natural lavender lactone was a mixture of two enantiomers with an R/S ratio of 32:68, whereas the natural δ-decalactone contained only the R-enantiomer. When the analyses were conducted using different parts-forewings, hindwings, and body-of three males, the lactones were more abundantly found on the forewings and hindwings than on the body. Microscopic observation of the wings demonstrated that battledore scales known as androconia are scattered on the upper surface of both the wings of C. argiolus ladonides males. These results indicate that the specialized scales on the wings of males serve as scent-disseminating organs.

Absorption spectra of α,ω-diphenylhexadecaoctaene and shorter diphenylpolyenes.

Absorption spectrum of α,ω-diphenylhexadecaoctaene has been measured along with those of α,ω-diphenylpolyenes with one to seven double bonds in the polyene chain in carbon tetrachloride at room temperature. Extrapolation of the observed vibrational frequencies in the 1(1)Bu state measured as a function of polyene double bond number provides the CC and CC stretching frequencies of 1520±20 and 1080±20 cm(-1), respectively, for diphenylpolyenes with infinite polyene chain length.

Ab initio study of the excited singlet states of all-trans alpha,omega-diphenylpolyenes with one to seven polyene double bonds: Simulation of the spectral data within Franck-Condon approximation.

Computational simulations of the electronic spectra with ab initio electronic structure calculations are presented for all-trans alpha,omega-diphenylpolyenes with the polyene double bond number (N) from 1 to 7. A direct comparison of the fluorescence spectra of diphenylpolyenes was made between the results of highly accurate calculations and the experimental data for the systems with various chain lengths. For the realistic simulation of the emission, the total vibrational wave function was described approximately as a direct product of one-dimensional (1D) vibrational wave functions along the normal coordinates that are determined from the vibrational analysis of the ground state. The observed spectra can be reproduced in a computationally efficient way by selecting effective C-C and C=C stretching modes for the constructions of the 1D vibrational Hamiltonians. The electronic structure calculations were performed using the multireference Moller-Plesset perturbation theory with complete active space configuration interaction reference functions. Based on the vertical excitation energies computed, the lowest singlet excited state of diphenylbutadiene is shown to be the optically forbidden 2 (1)A(g) state. The simulations of fluorescence spectra involving vibronic coupling effects reveal that the observed strong single C=C band consists of two major degenerate vibrational C=C modes for the shorter diphenylpolyenes with N=3 and 5. Further, the relative intensities of the C-C stretching modes in the fluorescence spectra tend to be larger than those of the C=C stretching modes for the systems with N over 5. This indicates that the geometric differences of the energy minima between the ground (1 (1)A(g)) and 2 (1)A(g) states grow larger towards the direction of the C-C stretching mode with increasing N.

Spectroscopy and photophysics of low-lying excited singlet states of alpha,omega-dithienylbutadiene and alpha,omega-dithienylethylene vapors.

Fluorescence and excitation spectra and fluorescence lifetimes have been measured for alpha,omega-dithienylbutadiene (DTB) and alpha,omega-dithienylethylene (DTE) in a jet-cooled He expansion and in the static vapor phase. It is shown that the emission of DTB in the static vapor phase consists of the S1(2(1)A(g)) and S2(1(1)B(u)) fluorescence, while the emission in a jet consists of solely the S1 fluorescence. The fluorescence quantum yields of DTB and DTE vapors decrease significantly with increasing excitation energy. The conformer-specific fluorescence was measured for DTB and DTE in a jet. The false S1 (2(1)A(g)) origin of the most stable conformer of DTB was observed at 25470.5 cm(-1) in a jet, which is located approximately 2800 cm(-1) below the S2 (1(1)B(u)) origin. The S1 origins of the two conformers of DTE were observed at 28648 and 28966 cm(-1) in a jet, and the S1 state of the most stable conformer is assigned as 1(1)B(u).

1(1)B(u) (S2) and 2(1)A(g) (S1) fluorescence and the 2(1)A(g) state of alpha,omega-dithienylbutadiene and alpha,omega-dithienylethylene.

Fluorescence and absorption spectra and fluorescence lifetimes have been measured for alpha,omega-dithenylbutadiene (DTB) and alpha,omega-dithenylethylene (DTE) in different solvents and at different temperatures as well as in the vapor phase. It is shown that the emission of DTB consists of the S(2) (1(1)B(u)) and S(1) (2(1)A(g)) fluorescence, while the emission of DTE consists of solely the S(1) (1(1)B(u)) fluorescence. The 2(1)A(g) and 1(1)Bu state levels of DTB are found to invert in solvents with the polarizability of near 0.32. All the available data for DTB on temperature and solvent dependence of the absorption and fluorescence spectra and the fluorescence lifetime support the presence of the lowest excited singlet state, 2(1)A(g), located below the strongly allowed 1(1)B(u) state. Quantitative analyses of the spectral data provide the physical parameters that characterize the excited state dynamical behavior of DTB.

Excitation-energy dependence of the phosphorescence quantum yields of pyridinecarboxaldehyde vapors.

Emission and excitation spectra of 3- and 4-pyridinecarboxaldehyde vapors have been measured at different pressures down to 10(-2)Torr. The phosphorescence quantum yield measured at low pressure as a function of excitation energy is nearly constant in the range of excitation energy corresponding to the S1(n, pi*) state, but it decreases abruptly at the S2(pi, pi*) threshold. The onset of the abrupt decrease of the yield corresponds to the location of the S2 absorption origin of each molecule, indicating that the nonradiative pathway depends on the type of the excited singlet state to which the molecule is initially excited. The relaxation processes are discussed based on the pressure and excitation-energy dependence of the phosphorescence quantum yield.

Ground-state, excited-singlet-state, and excited-triplet-state energy levels and photophysics of the three rotational isomers of isophthalaldehyde vapor.

Emission, excitation, and absorption spectra of isophthalaldehyde (benzene-1,3-dicarboxaldehyde) vapor have been measured at different temperatures, along with the UV-vis and IR absorption spectra in solution. Analyses of the temperature dependence of the phosphorescence and excitation spectra of isophthalaldehyde vapor revealed the energetic relationships among the three rotational isomers in the T1(n, pi*), S1(n, pi*), and ground states. This appears to be the first example of the system where the S0, T1, and S1 energy levels are determined for the three rotational isomers. The phosphorescence, fluorescence, and excitation origins of the three rotamers were assigned on the basis of the results of the density functional theory (DFT) and semiempirical SCF-MO calculations and infrared data as well as on the basis of the temperature dependence of the emission and excitation spectra.

Matrix-isolation infrared spectroscopy of the rotational isomers of 1,2-, 1,3-, and 1,4-benzenedicarboxaldehyde.

Rotational isomers (rotamers) of the three structural isomers of benzenedicarboxaldehydes (1,2-, 1,3-, and 1,4-derivatives) have been investigated in detail using matrix-isolation infrared spectroscopy in the 600-4000 cm-1 region, combined with UV photoexcitation and density-functional theory (DFT) calculations. Two rotamers were identified for 1,2- and 1,4-benzenedicarboxaldehyde (1,2- and 1,4-BDA, respectively), while three rotamers were identified for 1,3-benzenedicarboxaldehyde (1,3-BDA) in infrared spectra upon UV-irradiation. Most of the observed infrared bands of each rotamer have been assigned. The energetic relationships among the rotamers were revealed based on the infrared data and the DFT calculations. It is shown that the intramolecular C-H...H-C interaction in the H-syn rotamer or the C-H...O=C hydrogen bonding in the anti rotamer of 1,2-BDA results in the blue-shift of the aldehyde C-H stretching band and the shortening of the aldehyde C-H bond length. Both photoinduced rotational isomerization and rearrangement were observed upon UV irradiation for 1,2-BDA. The structure of the major enol isomer formed as the result of the photochemical rearrangement of 1,2-BDA is determined.

Photophysics of alpha,omega-diphenyloctatetraene in the vapor phase.

Fluorescence and fluorescence excitation spectra of diphenyloctatetraene vapor have been measured at different temperatures from 98 to 136 degrees C and at different buffer gas pressures from 0 to 300 Torr. The fluorescence quantum yields were determined as functions of the excitation energy and buffer gas pressure. It is shown that diphenyloctatetraene vapor exhibits weak fluorescence from the S2 (1(1)Bu) state in addition to the fluorescence from the S1 (2(1)Ag) state. The quantum yield of the S1 fluorescence is shown to decrease with decreasing pressure and with increasing excitation energy. The electronic relaxation processes of diphenyloctatetraene vapor are discussed based on the pressure and excitation-energy dependence of the fluorescence quantum yield.

Intensification of the emission signals using the reflection mirrors mounted to the sample holder of a fluorimeter.

Effects of the reflection mirrors mounted to the sample holder of a fluorimeter have been investigated. Analytical expressions are given for the emission intensity measured as a function of the concentration or optical density of the sample, in case one or two reflection mirrors are attached beside the sample holder to intensify the emission signals. The emission intensity calculated as a function of the sample concentration agreed well with the experimental data. By mounting two reflection mirrors, the emission signal was intensified by a factor of near 3.5. However, the degree of intensification depended strongly on the sample concentration and the linearity between the sample concentration and the emission intensity deviated significantly with increasing the sample concentration.

Emission spectra and electronic energy levels of the rotational isomers of pyridinecarboxaldehyde vapors.

Emission and excitation spectra of 2-, 3- and 4-pyridinecarboxaldehyde (2-, 3- and 4-PCA, respectively) vapors have been measured at different temperatures and compared to one another. The emission spectra of these vapors are shown to consist of the T(1)(n, pi) --> S(0) phosphorescence accompanied by the weak thermally activated S(1)(n, pi) --> S(0) delayed fluorescence. Two peaks originating from the two rotamers (syn and anti) have been identified in the fluorescence, phosphorescence and excitation spectra of 3-PCA vapor. Analyses of the temperature dependence and vibrational structure of the spectra of 3-PCA vapor provide the syn-anti energy difference of 190 +/- 30 cm(-1) in the T(1) (n, pi) state, 200 +/- 30 cm(-1) in the S(1)(n, pi) state, and 290 +/- 35 cm(-1) in the ground state. The ground-state energy difference is in agreement with the result of density functional theory (DFT) calculation for 3-PCA vapor. DFT calculation demonstrated also that the syn rotamer exists as a less stable isomer in the ground state for 2- and 3-PCA vapors.

Franck-Condon analysis of the absorption and fluorescence spectra of all trans alpha,omega-diphenylpolyenes with one to seven polyene double bonds.

Fluorescence and absorption spectra have been measured for all-trans alpha,omega-diphenylpolyenes with one to seven polyene double bonds in room-temperature solution, along with the fluorescence spectra of those with one to six polyene double bonds in n-alkane matrices at 77 K. All the spectral data were fitted by sums of Gaussians to treat the Franck-Condon envelopes of the measured spectra quantitatively. The Franck-Condon analyses of the spectra in the harmonic limit revealed that the displacements of the C=C and C-C stretching vibrational modes in the 2 Ag state relative to those in the ground state, 1 1Ag(S0), increase, while those in the 1 1Bu state show a slight decrease with the increase of the polyene chain length. It is also shown that the bandwidths of the absorption and fluorescence spectra exhibit a monotonic decrease with the increase of the chain length.

Evidence for the coexistence of two different mechanisms for the occurrence of anti-Kasha S2 (1 (1)Bu) fluorescence from alpha,omega-diphenylpolyenes.

Fluorescence, fluorescence excitation, and absorption spectra have been measured for diphenylpolyenes with the polyene double bond number (n) from three to seven in solvents with different polarizabilities at room temperature. These polyenes exhibit anti-Kasha S(2) (1 (1)B(u)) fluorescence beside conventional S(1) (2 (1)A(g)) fluorescence in room temperature solution. It is shown that there are two different mechanisms for occurrence of the S(2) (1 (1)B(u)) fluorescence of diphenylpolyenes. S(2) fluorescence occurs through the thermal population of the S(1) state for the shorter diphenylpolyenes (n=3 and 4), while it occurs as prompt S(2) fluorescence due to inefficient S(2)-->S(1) internal conversion for the longer diphenylpolyenes (n=6 and 7). With diphenyldecapentaene (n=5), S(2) fluorescence based on both mechanisms is observed depending on the polarizability of the solvent used. The present results provide deeper insight into the mechanism for the occurrence of anti-Kasha S(2) fluorescence of polyenes.

Geographical distribution of two haplotypes of chloroplast DNA in four oak species (Quercus) in Japan.

Chloroplast DNA polymorphism in four oak species (Quercus serrata, Q. mongolica var. crispula, Q. dentata and Q. aliena) was studied using collections from a total of 127 localities in Japan and South Korea on the basis of five intergenic spacers (trnD-trnT, trnT-trnL, rps14-psaB, trnS-trnT and trnQ-trnS). Although no variation existed in sequences among the four species, a single nucleotide (T/C) substitution in the trnQ-trnS intergenic spacer was found in all the four species, resulting in two haplotypes (T- and C-type). Phylogenetic analyses of the four species and related species showed that the C-type is derived and even likely of monophyletic origin, while the T-type is ancestral. Geographically, the T-type is widespread from South Korea to Japan, whereas the C-type is restricted to eastern Japan with rare exceptions. "Eastern Japan" approximately coincides with the distribution range of the boreal conifer forest during the last glacial maximum. Overall evidence suggests that the mutation from T- to C-type occurred in an individual of one of the four oak species and then was transferred to all the species by hybridization in eastern Japan, and that the Kanto District provided individuals with the C-type with a refugium during the last glacial maximum.

Photophysical processes in quinoxaline vapor at low pressure.

Excitation and pressure dependence of fluorescence and phosphorescence quantum yields has been reinvestigated in detail for quinoxaline in the static vapor phase at pressure range from 10(-3) to 10(-1) Torr. It is shown that the ratio of the nonradiative rate from T(1)(pi, pi*) to the rate of the S(1)(n, pi*) approximately -->T(1)(pi, pi*) intersystem crossing decreases with increasing the excitation energy in the S(0)-->S(1) excitation region. The phosphorescence quantum yield measured as a function of the excitation energy at low pressure shows an abrupt decrease on going the excitation from S(0)-->S(1) to S(0)-->S(2), indicating the slow vibrational energy redistribution between the S(1) levels optically populated and those populated through the internal conversion from S(2) to S(1).

Novel plasmodesmata association of dehydrin-like proteins in cold- acclimated Red-osier dogwood (Cornus sericea).

Dehydrins are proteins associated with conditions affecting the water status of plant cells, such as drought, salinity, freezing and seed maturation. Although the function of dehydrins remains unknown, it is hypothesized that they stabilize membranes and macromolecules during cellular dehydration. Red-osier dogwood (Cornus sericea L.), an extremely freeze-tolerant woody plant, accumulates dehydrin-like proteins during cold acclimation and the presence of these proteins is correlated with increased freeze tolerance (Karlson 2001, Sarnighausen et al. 2002, Karlson et al. 2003). Our objective was to determine the location of dehydrins in cold-acclimated C. sericea stems in an effort to provide insight into their potential role in the freeze tolerance of this extremely cold hardy species. Abundant labeling was observed in the nucleus and cytoplasm of cold-acclimated C. sericea stem cells. In addition, labeling was observed in association with plasmodesmata of cold-acclimated vascular cambium cells. The unique association of dehydrin-like proteins with plasmodesmata has not been reported previously.