Involvement of Cell Wall-Bound Diferulic Acid in Light-Induced Decrease in Growth Rate and Cell Wall Extensibility of Oryza Coleoptiles

Irradiation of white fluorescent light (5 W m^–2) inhibitedthe growth of Oryza coleoptiles. Light irradiation increasedstress-relaxation parameters of coleoptile cell walls, minimumstressrelaxationtime and relaxation rate, and decreased cellwall extensibility (strain/load). Under light conditions, thecontents of ferulic and diferulic acids ester-linked to thehemicellulosic arabinose residue in cell walls increased andcorrelated with the modification of the cell wall mechanicalproperties. These results suggest that light irradiation enhancesthe formation of diferulic acid bridges in hemicelluloses, makingcell walls mechanically rigid and thus inhibits cell elongationin rice coleoptiles. Also, irrespective of coleoptile age orthe presence of light, the ratio of diferulic acid to ferulicacid was almost constant, suggesting that the rate limitingstep in the formation of diferulic acid bridges in Oryza cellwalls is in the step of feruloylation. (Received September 24, 1991; Accepted December 3, 1991)     

How is autonomic nervous system activity in subjects who are sleepy but are unable to sleep in the daytime?

We investigated changes in the activity of the autonomic nervous system (ANS) in the relaxed condition in subjects who felt sleepy, but were unable to sleep. A total of 1021 subjects underwent daytime polysomnography. The sleep latency (SL) and the visual analog scale (VAS) were used to assess “immediate” objective and subjective sleepiness, respectively. The subjects were assigned to an “Alert-Alert” group (VAS ≤ 25 mm, SL ≥ 8 min), a “Sleepy-Alert” group (VAS ≥ 75 mm, SL ≥ 8 min), or a “Sleepy-Sleepy” group (VAS ≥ 75 mm, SL ≤ 4 min). In order to assess the ANS, the spectral analysis and the geometric method were used. The ANS data collected during the relaxed condition (after lights off, post-LO) was compared to that obtained during the control condition (before lights off, pre-LO). From the spectral analysis, a significant decrease of sympathetic function and an increase of parasympathetic function at post-LO in the Sleepy-Sleepy group, a tendency for sympathetic function decrease at post-LO in the Alert-Alert group, and no significant changes to sympathetic and parasympathetic function in the Sleepy-Alert group were observed. The results from the geometric method supported the results of the spectral analysis in the Alert-Alert group and the Sleepy-Sleepy group. The results of this study suggest that the ANS plays a role in individuals who are unable to sleep even though they feel sleepy and are given the opportunity to sleep.

     

Home-field advantage in decomposition of leaf litter and insect frass

Home-field advantage (HFA) hypothesis regarding litter decomposition states that litter is decomposed more rapidly in the habitat from which it is derived (i.e., home) than in other habitat (i.e., away) due to local adaptation of soil decomposers. We tested the HFA hypothesis regarding decomposition of leaf litter, insect frass, and their mixtures, using laboratory incubation of leaf litter from an evergreen (Pinus densiflora) and a deciduous (Quercus acutissima) tree species, frass excreted by two insect herbivores (Dendrolimus spectabilis and Lymantria dispar) fed on one of the two trees, and soil collected underneath the two trees. We found evidence that decomposers in each soil were specialized to decompose the litter derived from the tree species above them, indicating that the HFA occurred in litter decomposition. In contrast, the HFA was not detected in the decomposition of insect frass or litter-frass mixtures. Mixing with D. spectabilis frass non-additively decelerated, while mixing with L. dispar frass non-additively accelerated, decomposition of the mixtures, independent of soil and litter types. These indicate that the presence of insect herbivores may make it difficult to form and maintain a decomposer community specialized to a certain leaf litter, and that it may consequently cancel or weaken HFA in litter decomposition.     

Two lignan dimers from bamboo stems (Phyllostachys edulis)

Phyllostadimers A and B, two bis-lignans in which the two lignan units are directly connected by a C-C bond, were isolated from stems of bamboo, Phyllostachys edulis. Their structures were determined on the basis of spectral evidence. In addition, 14 known compounds were also obtained throughout the investigation. Phyllostadimer A significantly inhibited liposomal lipid peroxidation.     

Rapid establishment of introgression lines using cytoplasmic male sterility and a restorer gene in Oryza sativa cv. Nipponbare

Quantitative trait locus (QTL) analyses have greatly enhanced our understanding of complex traits in rice (Oryza sativa). In parallel, the development of introgression lines has provided a powerful tool for elucidation of complicated genetic networks and identification of QTL. We recently developed a biotron breeding system that allows rapid indoor cultivation of rice plants. The system, however, has two relatively weak points in its application to marker-assisted breeding in rice: first, variation in generation times among cultivars; second, the low number of seeds produced by crosses. To compensate for these weaknesses, we propose utilizing cytoplasmic male sterility (CMS) and restorer (Rf) lines with a cv. Nipponbare genetic background. Through use of the Nipponbare genetic background, rice generation times of 2 months can be achieved regardless of any differences in the genetic background of the donor rice plant. This CMS–Rf system confers a high yield of hybrid seeds, avoids the need for emasculation and precludes accidental crosses. Our results demonstrate that this new methodology can markedly accelerate many different aspects of rice research, especially in functional genomics. The combination of biotron breeding system, early flowering habit and CMS will be of great value for screening candidate genes associated with QTL and for introducing useful QTL into elite cultivars.     

Isolation and characterization of a halotolerant <Emphasis Type="Italic">Bacillus</Emphasis><Emphasis Type="Italic">subtilis</Emphasis> BBK-1 which produces three kinds of lipopeptides: bacillomycin L,plipastatin, and surfactin

Twenty-three halotolerant and biosurfactant producing strains were collected from salty conditions in central Thailand. One of the strains designated BBK-1 produced the biosurfactants with the highest activity. BBK-1 was isolated from fermented foods and was identified as B. subtilis based on its physiological characteristics and 16S rRNA gene sequence. We show that the strain grows in media containing NaCl up to 16% (w/v) and produces biosurfactants in NaCl up to 8%. We found that B. subtilis BBK-1 produces three kinds of surface-active lipopeptides simultaneously. By their respective molecular weights and amino acid compositions, it is indicated that these lipopeptides are bacillomycin L, plipastatin, and surfactin. In order to analyze the production mechanism of lipopeptides further in the strain, a generally important biosynthetic gene encoding 4'-phosphopantetheinyl transferase was cloned and sequenced. The gene existed in a single copy in the genome and the deduced amino acid sequence was almost identical to that of Lpa-14 from B. subtilis strain RB14, which co-produces iturin A and surfactin.     

Occurrence of a novel cardiac natriuretic peptide in rats

We established a specific radioimmunoassay for the ring structure of "iso-ANP" and detected iso-ANP[23-46]-like immunoreactivity (-LI) in the rat atrium (2.76 +/- 0.5 micrograms/g) and ventricle (13.9 +/- 5.7 ng/g). High performance-gel permeation chromatography revealed that iso-ANP[23-46]-LI in the rat heart was composed of two components with molecular weights of 10K and 5K. In reverse phase-high performance liquid chromatography, the retention times of these components were clearly different from that of synthetic iso-ANP. The 5K peptide was demonstrated to be present in the perfusate from isolated rat hearts and possessed binding ability to ANP receptors. This natriuretic peptide was, however, not detectable in other tissues including the brain. We conclude that the novel cardiac natriuretic peptide distinct from iso-ANP and ANP occurs in the rat heart and is secreted from the heart.