Host legumes control root nodule numbers by sensing external and internal cues. A major external cue is soil nitrate, whereas a feedback regulatory system in which earlier formed nodules suppress further nodulation through shoot-root communication is an important internal cue. The latter is known as autoregulation of nodulation (AUT), and is believed to consist of two long-distance signals: a root-derived signal that is generated in infected roots and transmitted to the shoot; and a shoot-derived signal that systemically inhibits nodulation. In Lotus japonicus, the leucine-rich repeat receptor-like kinase, HYPERNODULATION ABERRANT ROOT FORMATION 1 (HAR1), mediates AUT and nitrate inhibition of nodulation, and is hypothesized to recognize the root-derived signal. Here we identify L. japonicus CLE-Root Signal 1 (LjCLE-RS1) and LjCLE-RS2 as strong candidates for the root-derived signal. A hairy root transformation study shows that overexpressing LjCLE-RS1 and -RS2 inhibits nodulation systemically and, furthermore, that the systemic suppression depends on HAR1. Moreover, LjCLE-RS2 expression is strongly up-regulated in roots by nitrate addition. Based on these findings, we propose a simple model for AUT and nitrate inhibition of nodulation mediated by LjCLE-RS1, -RS2 peptides and the HAR1 receptor-like kinase.

13 C high-resolution solid-state NMR coupled with selective 13 C isotope-labeling of different Ala one methyl carbons was used to clarify the structure of (AG) 15 peptide in the silk II structure as a model for the crystalline domain of Bombyx mori silk fiber. At the inner part of the peptide, the fraction of the peak at 16.6 ppm of the Ala Cb resonance assigned to b-turn structure increased at 11th and 19th positions. These data indicate the appearance of the most probable lamellar structure having a turn structure at these two positions, although the position of turn was distributed along the chain.

Far-infrared (FIR) and low-frequency Raman bands in the 90–400 cm–1 region of crystalline nylon 6 in α form were assigned based on comparisons of experimental spectra and quantum mechanical calculations. A fragment methodology was applied in the calculations for explicit consideration of interchain interactions and crystal symmetry. The main features in both Raman and FIR spectra were reproduced well, which enabled the band assignments based on density functional theory and the significant improvement of the conventional assignments for which there had been a big dispute. Temperature dependence of the experimental FIR spectra has revealed that both bands at 222 and 111 cm–1 are characteristic of the α-form structure. Their intensities linearly decreased with increasing temperature with marked two transition points, which correspond to glass and Brill transitions. Both bands can be indicators of the lattice length of α-form nylon 6. On the basis of the calculations, the FIR and Raman bands at ∼100 cm–1 were successfully assigned to methylene torsion and transverse motion of amide groups in which NH and O atoms move out of the amide plane. Decomposition of the calculated spectra revealed that the intensities at ∼100 cm–1 in both spectra mainly originate from the amide groups and only secondarily from the methylene groups. Moreover, the FIR intensities at ∼100 cm–1 were nearly perfectly governed by the amide groups, which could be a reason why this FIR band is particularly sensitive to hydrogen bonds among the low-frequency bands. The FIR band at 222 cm–1 was assigned to methylene torsion and transverse motion of NH groups. Both FIR bands at 222 and 111 cm–1 contain perpendicular motions of methylene and amide groups. This will be a reason for their sensitivity to interchain interactions in α-form nylon 6. Contrarily, the FIR band at 294 cm–1 is in parallel polarization to the chain direction and assigned to a deformation of C–CH2–CH2 and bending motion of CO in the amide plane. This is the reason why this band is not sensitive to the structural transitions of nylon 6. Our previous works revealed that in regions of 125 and 70 cm–1, there are specific vibrational peaks of crystalline polyesters primarily arising from out-of-plane motion of ester groups. We can find a similarity in 125 and 70 cm–1 regions between crystalline polyesters and nylon 6 that both polymers show specific out-of-plane vibrational peaks around 100 cm–1, which are sensitive to the lattice length among polymer chains.

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Background Heat shock proteins (Hsps) are overexpressed in several tumors and contribute to cell proliferation, metastasis, and anticancer drug resistance. Therefore, Hsp inhibitors have enhanced cytotoxicity as chemotherapeutic agents and may be effective with a reduced dosage for tumor therapy to avoid side effects. Results Four new azaphilones, maximazaphilones I–IV (1–4), and three known compounds (5–7) have been isolated from the airborne-derived fungus Penicillium maximae. Inhibitory effects of isolated compounds against induction of Hsp105 were evaluated by the luciferase assay system using Hsp105 promoter. In this assay, 2–4, 6, and 7 significantly inhibited hsp105 promoter activity without cytotoxicity. In addition, all isolated compounds except for 5 significantly induced the death of Adriamycin (ADR)-treated HeLa cells. Interestingly, 1–4, 6, and 7 didn’t show anti-proliferative and cell death-inducing activity without ADR. Conclusion This study revealed the chemical structures of maximazaphilones I–IV (1–4) and the potency of azaphilones may be useful for cancer treatment and reducing the dose of anticancer agents. In addition, one of the mechanisms of cell death-inducing activity for 2–4, 6, and 7 was suggested to be inhibitory effects of Hsp105 expression.