Type I interferons (IFN-α/β) were originally identified as humoral factors, which are secreted in virally infected cells and confer an antiviral state in uninfected cells. Subsequently, their multifunctional roles have also been demonstrated, which include antitumor actions. More recently, the IFN system has been the focus of much attention in the context of the regulation of the innate and adaptive immune systems. Indeed, the IFN genes are induced in antigen-presenting cells (APCs) via the activation of distinct Toll-like receptors (TLRs), and accumulating evidence indicates the importance of TLR-induced IFN-α/ β for the induction of both innate and adaptive immune responses. Two members of the interferon regulatory factor (IRF) family of transcription factors, IRF-3 and IRF-7, play mutually nonredundant functions in IFN-α/β gene induction in response to viral infection or TLR stimulation. Another unique facet of the IFN-α/β system is that IFN-α/β are produced at low levels in normally growing cells. Although seemingly futile, a weak signal by these IFNs is critical to eliciting from cells strong responses to other stimuli, thereby providing a foundation for an efficient operation of the immune system. In the context of the antitumor action of IFNs, p53 gene transcription is induced by IFN-α/β, accompanied by an increase in p53 protein level for boosting p53 responses in tumor suppression. Furthermore, a new link was discovered between p53 and IFN-α/β in antiviral immunity. In this review, we focus on recent studies on the type I IFN (IFN-α/β) system and IRF-family transcription factors with respect to immunity and oncogenesis.


(Communicated by Tadamitsu KISHIMOTO, M.J.A.)

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Dunite and related rocks from the Moho transition zone of the East Pacific Rise (EPR) and the Mid-Cayman Trough (MCT) are examined to know the spreading-rate dependence of their compositions. The rocks from both ridges are basically a reaction product between peridotite and primitive MORB. Despite the large difference of prevalent peridotite chemistry, depleted harzburgite for EPR and lherzolite for MCT, the dunite has less different compositional ranges. The Al₂O₃ content of spinel differs only by 5 wt%, which may be equivalent to the difference of about 1 wt% of Al₂O₃ in the melt. This is almost equal to the possible spreading-rate dependent compositional difference of observed Mg-rich MORB. The relatively unfractionated MORBs erupted are in equilibrium with the oceanic dunite of which composition is independent of or only slightly dependent on spreading rate. Dunite is calculated to be about half of the total oceanic mafic crust by weight. The dunite is concentrated as the Moho transition zone, and is sparsely distributed as small lenses within the uppermost mantle peridotite.


(Communicated by Ikuo KUSHIRO, M.J.A.)

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We have constructed two types of THz spectrometers using the frequency-tunable THz wave generators based on difference-frequency generation (DFG) in GaP crystal. The OPO-source system is for high accuracy measurement to detect fine structures in THz absorption spectra. The Cr:F-source system has merit in simple structure, easy maintenance and low-cost, but still has sufficient resolution for room temperature observation of solids or liquids. Comparing the absorption spectra of saccharides measured with these spectrometers and those measured with FT-IR or TDS, our spectrometers have superiority in frequency range and resolution, enough to record sub peaks, which can be analyzed as structural defects in organic compounds.


(Contributed by Jun-ichi NISHIZAWA, M.J.A.)

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Effects of types of amino acids on assembling of a feast/famine regulatory protein (FFRP), pot1216151 (DM1) from the hyperthermophilic archaeon Pyrococcus sp. OT3, was studied using its two fractions; more assembled (A) and more disassembled (D). The amino acid isoleucine was found to shift the equilibrium of both A and D to more assembling states. Valine showed weaker effects of assembling DM1. While seven other amino acids showed effects of disassembling DM1 in both A and D with different degrees, thereby creating an order, I/V/(L, T, F, A)/R/M/C, from the most assembling amino acid isoleucine to the most disassembling one cysteine. When one of the top three amino acids in this sequence, isoleucine, valine and leucine, was added to mother solutions yielding crystals of DM octamers, the crystals lost polarization, suggesting disordering inside. Some other metabolic intermediates, oxaloacetic acid, 2-oxoglutaric acid, and L-malic acid, also showed disassembling effects. On the basis of these findings, molecular interactions of DM1 and ligands, and their possible roles for metabolic regulation are discussed.


(Communicated by Masanori OTSUKA, M.J.A.)

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