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Advances in medical technology have assisted with the provision of care for children with severe physical and mental disabilities, helping to improve and maintain their living standards, and enabling a high level of care to be given at home. But there remains a burden on the families delivering care, particularly when communication is difficult. Researchers in the Society 5.0 Study Group, Interdisciplinary Research Institute, Shikoku University, Japan, are exploring the potential of information and communication technology (ICT) to be used to improve the quality of care for children with severe physical and mental disabilities. The researchers are developing a conceptual model for understanding the subtle reactions of children, including the sensing of biological reactions such as facial muscle movement. The goal is to better understand the reactions of children with severe disabilities, leading to improved levels of care and benefiting the families of patients. Dr Emiko Yokozeki leads the team. She has three decades of nursing experience and is a member of the Society 5.0 Research Society, which is chaired by Professor Kohji Yamamoto and promotes research with the aim of creating a society where everyone can live safely and comfortably by utilising innovation.

Background: Glutamate cysteine ligase (GCL) is a crucial enzyme involved in the synthesis of glutathione (GSH). Despite various studies on glutathione transferase and its essential role in detoxification and resistance to oxidative stress, GSH synthesis has not been described in silkworms to date. Silkworms form part of the lepidopterans that are considered as a model of agricultural pests. This study aimed to understand the GSH synthesis through the GCL in silkworms so that insecticides can be formulated to tackle agricultural pests. Methods and Results: Based on the amino acid sequence and phylogenetic tree, this GCL belonged to group 2 and designated bmGCL. Recombinant bmGCL was overproduced and purified to ensure homogeneity. Biochemical studies revealed that bmGCL uses ATP and Mg2+ to ligate glutamate and cysteine, respectively. High expression levels of bmgcl mRNA and GSH were observed in the silkworm fat body after exposure to insecticides and UV-B. Moreover, we found an increase in bmgcl mRNA and GSH content during pupation in the silkworm fat body. Conclusion: In this study, we found GCL in the silkworm Bombyx mori and its biochemical properties were investigated. These observations indicate that bmGCL might play an important role in the resistance to oxidative stress in B. mori.

We studied the effects of green leaf volatiles (including reactive aldehydes) emitted by plants on insects that feed on these plants. The silkworm (Bombyx mori) is a model lepidopteran that eats mulberry leaves. Defense-related enzymes in silkworms can be targeted for developing new pest control methods. The aldo-keto reductase (AKR) superfamily catalyzes aldehyde reduction by converting a carbonyl group into an alcohol group. Here, we characterized a novel silkworm AKR, designated as AKR2E9. Recombinant AKR2E9 was overexpressed in Escherichia coli. The recombinant protein was used, along with nicotinamide adenine dinucleotide phosphate as a coenzyme, to reduce aldehydes present in mulberry (Morus alba) leaves. The catalytic efficiency of AKR2E9 toward various aldehyde substrates and its inhibitor sensitivity was lower than those of AKR2E8. High expression levels of akr2e9 messenger RNA (mRNA) were detected in the midgut and antennae of silkworms. In the antennae of adult silkworms, akr2e9 mRNA was more abundant than akr2e8 mRNA. The catalytic efficiency of AKR2E9 was low because of steric hindrance, due to which its active site is blocked. High expression levels of AKR2E9 in the midgut and antennae suggest that it may regulate the detoxification of toxic aldehydes in silkworms.

Prostaglandin E synthase (PGES) catalyzes the conversion of prostaglandin H2 to prostaglandin E2 in the presence of glutathione (GSH) in mammals. Amid the limited knowledge on prostaglandin and its related enzymes in insects, we recently identified PGES from the silkworm Bombyx mori (bmPGES) and determined its crystal structure complexed with GSH. In the current study, we investigated the substrate-binding site of bmPGES by site-directed mutagenesis and X-ray crystallography. We found that the residues Tyr107, Val155, Met159, and Glu203 are located in the catalytic pockets of bmPGES, and mutagenesis of each residue reduced the bmPGES activity. Our results suggest that these four residues contribute to the catalytic activity of bmPGES. Overall, this structure-function study holds implications in controlling pests by designing rational and efficient pesticides.

The brown planthopper (Nilaparvata lugens) is a major agricultural pest of rice crops. Analysis of the enzymes produced by N. lugens is important to develop pest-control methods. Superoxide dismutase (SOD) is a detoxification enzyme that catalyzes the conversion of superoxide anions (reactive oxygen species) into oxygen and hydrogen peroxide. As there have been no reports on SOD in N. lugens, in this study, we characterized a new SOD in the brown planthopper, nlSOD1. Amino acid sequence and phylogenetic analyses revealed that nlSOD1 is a member of the Cu/Zn-SOD family. Recombinant nlSOD1, when overexpressed in Escherichia coli, catalyzes the dismutation of superoxide radicals into molecular O

Glutathione transferase (GST) is an important class of detoxification enzymes that are vital for defense against various xenobiotics and cellular oxidative stress. Previously, we had reported an unclassified glutathione transferase 2 in Bombyx mori (bmGSTu2) to be responsible for detoxifying diazinon. In this study, we aimed to identify the amino acid residues that constitute a hydrogen-bonding network important for GST activity. Site-directed mutagenesis of bmGSTu2 suggested that residues Asn102, Pro162, and Ser166 contribute to its catalytic activity.

We had previously reported a prostaglandin E synthase (bmPGES) in the silkworm Bombyx mori that catalyzes the isomerization of PGH2 to PGE2. The present study aimed to provide a genome-editing characterization of bmPGES in B. mori. Results showed bmPGES gene disruption to result in a reduced content of PGE2. The change affected the expression of chorion genes and egg formation in silkworms. Collectively, the results indicated that bmPGES could be involved in reproduction of B. mori. Therefore, this study provides insights into the physiological role of bmPGES and PGE2 in silkworms.

Mid-infrared free-electron laser (MIR-FEL) is potentially applicable for tissue ablation and dissociation of pathological peptide aggregates in medicine. However, it is still poorly understood how the MIR-FEL irradiation influences on functional proteins such as enzymes. In the current study, the effect of MIR-FEL on both aggregate and non-aggregate (= native) states of hen egg-white lysozyme (HEWL) as a representative enzyme has been investigated. Absorption intensity at terahertz region (0.3–1.2 THz, 10–40 cm−1) of the aggregate of HEWL was lower than that of the native HEWL, but the former was increased nearly to the same level with the latter after the MIR-FEL irradiation tuned to 6 μm that corresponds to carbonyl stretching vibrational mode of amide bonds (amide I). This indicates that the aggregate of HEWL was converted to the native state by the irradiation. On the other hand, synchrotron-radiation vacuum-ultraviolet circular-dichroism spectroscopy showed that protein conformation of the native HEWL, which was rich in α-helix, was little changed after the MIR-FEL irradiation under the same condition with the case of the aggregate of HEWL. Furthermore, the enzymatic hydrolysis activity of the native HEWL against bacterial glycan was not remarkably decreased by the irradiation. Therefore, it can be estimated that the native structure of HEWL is little damaged although the aggregate state can be easily dissociated by the resonant excitation at amide bonds.

The enzyme 5,10-methylenetetrahydrofolate dehydrogenase (MTHFD) is essential for the production of certain amino acids (glycine, serine, and methionine) and nucleic acids (thymidylate and purine). Here, we identified a cDNA encoding this enzyme from the silkworm Bombyx mori. The recombinant B. mori MTHFD (bmMTHFD) expressed in Escherichia coli recognized 5,10-methylenetetrahydrofolate and 5,10-methenyltetrahydrofolate as substrate in the presence of NADP + as well as NAD +. The bmMTHFD structure was determined at a resolution of 1.75 A by X-ray crystallography. Site-directed mutagenesis indicated that the amino acid residue Tyr49 contributed to its catalytic activity. Our findings provide insight into the mechanism underlying the activity of MTHFD from B. mori and potentially other insects and may therefore facilitate the development of inhibitors specific to MTHFD as insecticides.

Lepidopterans are agricultural pests. Since the silkworm is a model for lepidopterans, analysis of the enzymes produced by silkworms is of great interest for developing methods of pest control. The aldo-keto reductase (AKR) superfamily catalyzes the reduction of aldehydes by converting a carbonyl group to an alcohol group. Here, we characterized a new AKR present in the silkworm Bombyx mori, which has been designated as AKR2E8. Amino acid sequence and phylogenetic analyses showed that AKR2E8 is similar to human AKR1B1 and AKR1B10. Three amino acid residues in the active site were identical among AKR2E8, AKR1B1, and AKR1B10. Recombinant AKR2E8 overexpressed in Escherichia coli used nicotinamide adenine dinucleotide phosphate as a coenzyme to reduce the aldehydes present in mulberry (Morus alba) leaves. AKR2E8 was found to reduce benzaldehyde, hexanal, heptanal, nonanal, trans-2-nonenal, and citral. No nicotinamide adenine dinucleotide-dependent activity was detected. Akr2e8 mRNA was detected in the testes, ovaries, and fat body; the highest expression was found in the midgut. The substrate specificity and highest observed expression of AKR2E8 in the midgut suggests that AKR2E8 may play a major role in aldehyde detoxification in silkworms. The findings of this study may assist in the development of pest control methods for controlling the population of lepidopterans, such as silkworms, that damage crops.

Low cost and stable THz waves generation and detection are achieved using laser chaos. This system applied to THz spectroscopy to distinguish water and oil.

Two types of back scattering systems are utilized for high temperature fusion plasma turbulence study. W-band backscattering system is used for measuring the electron Larmor radius scale turbulence and around Q-band frequency comb Doppler backscattering system have been designed for measuring the ion Larmor radius scale turbulence.

We demonstrate experimentally highly sensitive electro-optic sampling of THz pulses by $1.55-\mu\mathrm{m}$ -wavelength femtosecond laser pulses in a 0.1-mm thick and 10-mm long GaAs crystal inserted into a tapered parallel plate waveguide. High sensitivity is achieved due to THz field focusing by the waveguide and noncollinear velocity matching of the optical and THz pulses in the crystal. More than 20 times more efficient detection than in a 1-mm thick ZnTe crystal at $1.55\ \mu\mathrm{m}$ has been obtained.

D-3-phosphoglycerate dehydrogenase (PHGDH) is a key enzyme involved in the synthesis of l-serine. Despite the high serine content in silk proteins and the crucial role of PHGDH in serine biosynthesis, PHGDH has not been described in silkworms to date. Here, we identified PHGDH in the silkworm Bombyx mori and evaluated its biochemical properties. On the basis of the amino acid sequence and phylogenetic tree, this PHGDH has been categorized as a new type and designated as bmPHGDH. The recombinant bmPHGDH was overexpressed and purified to homogeneity. Kinetic studies revealed that PHGDH uses NADH as a coenzyme to reduce phosphohydroxypyruvate. High expression levels of bmphgdh messenger RNA (mRNA) were observed in the middle part of the silk gland and midgut in a standard strain of silkworm. Moreover, a sericin-deficient silkworm strain displayed reduced expression of bmphgdh mRNA. These findings indicate that bmPHGDH might play a crucial role in the provision of l-serine in the larva of B. mori.

Stable THz waves are obtained from the multimode-laser diode excited photoconductive antennas using a laser chaos. Because the many longitudinal modes oscillate simultaneously. This THz wave is suitable for the spectroscopy. Stable THz waves are obtained from the multimode-laser diode excited photoconductive antennas using a laser chaos. Because the many longitudinal modes oscillate simultaneously. This THz wave is suitable for the spectroscopy.

We describe a new member of the aldo-keto reductase (AKR) superfamily in the silkworm Bombyx mori. On the basis of its amino acid sequence and phylogenetic tree, this AKR belongs to the AKR1B family and has been designated as bmALD1. In the current study, recombinant bmALD1 was overexpressed, purified to homogeneity and kinetically characterized. We discovered that bmALD1 uses NADPH as a coenzyme to reduce carbonyl compounds such as DL-glyceraldehyde, glucose and 2-nonenal. No NADH-dependent activity was detected. To the best of our knowledge, bmALD1 is only the third AKR characterized in silkworm which, given its substrate specificity, could play a major role in glucose metabolism and antioxidant reactions. Our data provide an increased understanding of insect AKR function.

The influence of crystal thickness of metal-coated -cut GaAs (M-G-M) on Cherenkov-phase-matched terahertz (THz) pulse detection was studied. The M-G-M detectors were utilized in conjunction with a metallic tapered parallel-plate waveguide (TPPWG). Polarization-sensitive measurements were carried out to exemplify the efficacy of GaAs in detecting transverse magnetic (TM)- and transverse electric (TE)-polarized THz waves. The reduction of GaAs’ thickness increased the THz amplitude spectra of the detected TM-polarized THz electro-optic (EO) signal due to enhanced electric field associated with a more tightly-focused and well-concentrated THz radiation on the thinner M-G-M. The higher-fluence THz beam coupled to the thinner M-G-M improved the integrated intensity of the detected THz amplitude spectrum. This trend was not observed for TE-polarized THz waves, wherein the integrated intensities were almost comparable. Nevertheless, good agreement of spectral line shapes of the superposed TM- and TE-polarized THz-EO signals with that of elliptically polarized THz-EO signal demonstrates excellent polarization-resolved detection capabilities of M-G-M via Cherenkov-phase-matched EO sampling technique.

Following a previous detailed investigation of the β subunit of α2β2 human adult hemoglobin (Hb A), this study focuses on the α subunit by using three natural valency hybrid α(Fe2+-deoxy/O2)β(Fe3+) hemoglobin M (Hb M) in which O2 cannot bind to the β subunit: Hb M Hyde Park (β92His → Tyr), Hb M Saskatoon (β63His → Tyr), and Hb M Milwaukee (β67Val → Glu). In contrast with the β subunit that exhibited a clear correlation between O2 affinity and Fe2+–His stretching frequencies, the Fe2+–His stretching mode of the α subunit gave two Raman bands only in the T quaternary structure. This means the presence of two tertiary structures in α subunits of the α2β2 tetramer with T structure, and the two structures seemed to be nondynamical as judged from terahertz absorption spectra in the 5–30 cm–1 region of Hb M Milwaukee, α(Fe2+-deoxy)β(Fe3+). This kind of heterogeneity of α subunits was noticed in the reported spectra of a metal hybrid Hb A like α(Fe2+-deoxy)β(Co2+) and, therefore, seems to be universal among α sub...

Prostaglandins are involved in many physiological processes, and prostaglandin synthases facilitate the detoxification of xenobiotics as well as endogenous compounds, such as through glutathione conjugation. Specifically, prostaglandin D synthase (PGDS) catalyzes the isomerization of PGH2 to PGD2. Here we report the identification and structural analysis of PGDS from the brown planthopper rice pest Nilaparvata lugens (nlPGDS), which belongs to the sigma-class glutathione transferases. The structure of nlPGDS in complex with glutathione was determined at a resolution of 2.0 A by X-ray crystallography. Bound glutathione was localized to the glutathione-binding site (G-site). Enzyme activity measurements following site-directed mutagenesis of nlPGDS indicated that amino acid residues Tyr8, Leu14, Trp39, Lys43, Gln50, Val51, Gln63, and Ser64 in the G-site contribute to its catalytic activity. To our knowledge, this represents the first report of a PGDS in insects. Our findings provide insights into the mechanism of nlPGDS activity and potentially that of other insects and therefore may facilitate the development of more effective and safe insecticides.

We investigate the effects of an externally applied magnetic field on the terahertz (THz) emission of Gallium Manganese Arsenide (GaMnAs) films grown via molecular beam epitaxy (MBE). Results show that low Mn-doping in GaMnAs resulted to increased THz emission as compared with a SI-GaAs substrate. Further increase in Mn-doping content resulted to a comparably less THz emission, which is attributed to reduced crystallinity and higher free-carrier absorption. Under an external magnetic field, the contributions of the B u p and B d o w n -related THz emission were observed to be asymmetric: possibly due to intrinsic magnetic properties of GaMnAs.

Sulfoconjugation plays a vital role in the detoxification of xenobiotics and in the metabolism of endogenous compounds. In this study, we aimed to identify new members of the sulfotransferase (SULT) superfamily in the silkworm Bombyx mori. Based on amino acid sequence and phylogenetic analyses, two new enzymes, swSULT ST1 and swSULT ST2, were identified that appear to belong to a distinct group of SULTs including several other insect SULTs. We expressed, purified, and characterized recombinant SULTs. While swSULT ST1 sulfated xanthurenic acid and pentachlorophenol, swSULT ST2 exclusively utilized xanthurenic acid as a substrate. Based on these results, and those concerning the tissue distribution and substrate specificity toward pentachlorophenol analyses, we hypothesize that swSULT ST1 plays a role in the detoxification of xenobiotics, including insecticides, in the silkworm midgut and in the induction of gametogenesis in silkworm ovary and testis. Collectively, the data obtained herein contribute to a better understanding of SULT enzymatic functions in insects.

Glutathione conjugation is a crucial step in xenobiotic detoxification. In the current study, we have functionally characterized an epsilon-class glutathione S-transferase (GST) from a brown planthopper Nilaparvata lugens (nlGSTE). The amino acid sequence of nlGSTE revealed approximately 36–44% identity with epsilon-class GSTs of other species. The recombinant nlGSTE was prepared in soluble form by bacterial expression and was purified to homogeneity. Mutation experiments revealed that the putative substrate-binding sites, including Phe107, Arg112, Phe118, and Phe119, were important for glutathione transferase activity. Furthermore, inhibition study displayed that nlGSTE activity was affected by insecticides, proposing that, in brown planthopper, nlGSTE could recognize insecticides as substrates.

Stable and wide range THz waves are obtained from the chaotically oscillated multimode-laser diode excited photoconductive antennas. This system is chap system And. this THz wave is suitable for the spectroscopy. In this paper, it is applied to distinguish water and oil.

A detection module for the heterodyne electro-optic sampling of terahertz pulses composed of a GaAs plate inserted into a tapered parallel plate waveguide has been designed and fabricated. The detector was installed into a standard terahertz time-domain spectrometer with a 1.5-$\mu \text{m}$ femtosecond laser as a light source. The spectral bandwidth of 3.5 THz and dynamic range of 5 orders of magnitude were experimentally demonstrated, even with a photo-conductive antenna designed for 800-nm as an emitter.

A complementary DNA that encodes an omega-class glutathione S-transferase (GST) of the brown planthopper, Nilaparvata lugens (nlGSTO), was isolated by reverse transcriptase polymerase chain reaction. A recombinant protein (nlGSTO) was obtained via overexpression in the Escherichia coli cells and purified. nlGSTO catalyzes the biotransformation of glutathione with 1-chloro-2,4-dinitrobenzene, a general substrate for GST, as well as with dehydroascorbate to synthesize ascorbate. Mutation experiments revealed that putative substrate-binding sites, including Phe28, Cys29, Phe30, Arg176, and Lue225, were important for glutathione transferase and dehydroascorbate reductase activities. As ascorbate is a reducing agent, nlGSTO may participate in antioxidant resistance.

Serine hydroxymethyltransferase (SHMT) catalyzes the interconversion of serine and tetrahydrofolate (THF) to glycine and methylenetetrahydrofolate. cDNA encoding Bombyx mori SHMT (bmSHMT) was cloned and sequenced. The deduced amino acid sequence consisted of 465 amino acids and was found to share homology with other SHMTs. Recombinant bmSHMT was overexpressed in Escherichia coli and purified to homogeneity. The enzyme showed optimum activity at pH 3.0 and 30°C and was stable under acidic conditions. The Km and kcat /Km values for THF in the presence of Nicotinamide adenine dinucleotide phosphate (NADP+ ) were 0.055 mM and 0.081 mM-1 s-1 , respectively, whereas those toward NADP+ were 0.16 mM and 0.018 mM-1 s-1 and toward l-serine were 1.8 mM and 0.0022 mM-1 s-1 , respectively. Mutagenesis experiments revealed that His119, His132, and His135 are important for enzymatic activity. Our results provide insight into the roles and regulation mechanism of one-carbon metabolism in the silkworm B. mori.

In this paper, we demonstrate significant enhancement of electro-optic (EO) sampling signal in the detection of pulsed terahertz (THz) waves by using a technique we call “polarization filtering”. In the EO sampling of pulsed THz waves, a linearly polarized probe optical pulse is phase-modulated by THz electric field through the linear EO effect and, as the result, it becomes slightly elliptically polarized after passing through the EO crystal. The phase-retardation of the probe optical pulse is then detected as an optical intensity modulation (EO signal), dI/I (the ratio of the intensity change, dI, and the original intensity, I) with an appropriate optical detection system. In “polarization filtering,” the EO sampling signal, dI/I, is enhanced by suppressing the main polarization component of the probe beam, resulting in a reduced probe beam intensity I’ = b^2*I, after the interaction with THz field in the EO crystal. Since the intensity modulation, dI, also reduces to dI’= b*dI, as the result of the polarization filtering, the THz EO sampling signal is enhanced by a factor of 1/b: dI’/I’ =(1/b)*dI/I. This “polarization filtering” is applicable not only to the conventional ellipsometric EO sampling but also to the heterodyne EO sampling. Firstly, we explain the principle of the polarization filtering, and then show the results of the proof-of-principle experiment for the standard and the heterodyne EO sampling, respectively.

Phosphoserine phosphatase (PSP) catalyses the synthesis of l-serine via the phosphorylated pathway by facilitating the dephosphorylation of phosphoserine. A cDNA encoding PSP from the silkworm Bombyx mori (bmPSP) was isolated using reverse transcription-PCR and then sequenced. The resulting clone encoded 236 amino acids with a molecular weight of 26 150, exhibiting 14-60% sequence identity with other PSPs. The recombinant PSP was overexpressed in Escherichia coli and purified. Kinetic studies showed that bmPSP possessed activity toward l-phosphoserine, and Asp20, Asp22 and Asp204 in bmPSP were found to be critical for modulating bmPSP activity. Real-time PCR analysis provided evidence that the amount of bmpsp transcript was reduced in middle silk glands of a sericin-deficient silkworm strain. These findings revealed that bmPSP may play important roles in synthesizing one-carbon donors of l-serine, which is abundant in silk, as well as other cell metabolites in B. mori.

The generation of a wide-range THz wave is investigated from a photoconductive antenna excited using a chaotic oscillation multimode semiconductor laser with optical delayed feedback by an external mirror. The stable THz wave is obtained from the multimode-laser diode excited photoconductive antenna by using a laser chaos. For a high sensitive detection, a metal V-grooved waveguide (MVG) is also used. About 10 times high amplitude signal is obtained using laser chaos. The signal is also increased about 1.6 time using MVG compared to Si lens. As the MVG gap is narrower from 200 to 20[μｍ], the detected signal is increased about twice.

In this study, we identified and characterized a phosphoserine aminotransferase (bmPSAT) from Bombyx mori (B. mori) that is responsible for l-serine biosynthesis. A complementary DNA that encodes bmPSAT was cloned by reverse transcriptase polymerase reaction and sequenced. The presumed amino acid sequence revealed 47-87% identity with known PSATs from insects, humans, plants, and bacteria. Through phylogenetic analysis, we found that bmPSAT is evolutionary related to insect PSATs. Recombinant bmPSAT was produced in Escherichia coli by using a cold-shock promotor and purified to homogeneity. This enzyme utilizes phosphohydroxypyruvate and glutamate for transamination. bmPSAT messenger RNA (mRNA) was expressed at higher levels in several tissues of standard strain silkworm including the silk gland, whereas a sericin-deficient silkworm strain exhibited a diminished expression of bmPSAT mRNA in the silk gland. These findings indicate that bmPSAT may play an important role in synthesizing and supplying l-serine in the larva of B. mori.

A low-cost type terahertz time-domain spectroscopic system can be constituted using a multimode laser diode instead of a pulse laser. To suppress noise, a window function is usually used in the Fourier transformation. When this system is used to measure an optically thick sample, the obtained refractive index shows sinusoidal structures. This is caused by ingress of a signal fragment into the measured range and egress of another signal fragment out of the measured range. In addition, a broad positive background component appears in the imaginary part of the refractive index. This is because of the decreased amplitude of the central structure of the signal, which results from the time shift under the window function caused by sample insertion. These false structures can be eliminated by using a modified window function that is shifted with the signal when the sample is inserted.

We report a new member of the aldo-keto reductase (AKR) superfamily in the silkworm Bombyx mori. Based on its amino acid sequence, the new enzyme belongs to the AKR2 family and was previously assigned the systematic name AKR2E5. In the present study, recombinant AKR2E5 was expressed, purified to homogeneity, and characterized. The X-ray crystal structures were determined at 2.2 A for the apoenzyme and at 2.3 A resolution for the NADPH-AKR2E5 complex. Our results demonstrate that AKR2E5 is a 40-kDa monomer and includes the TIM- or (β/α)8-barrel typical for other AKRs. We found that AKR2E5 uses NADPH as a cosubstrate to reduce carbonyl compounds such as DL-glyceraldehyde, xylose, 3-hydroxy benzaldehyde, 17α-hydroxy progesterone, 11-hexadecenal, and bombykal. No NADH-dependent activity was detected. Site-directed mutagenesis of AKR2E5 indicates that amino acid residues Asp70, Tyr75, Lys104, and His137 contribute to catalytic activity, which is consistent with the data on other AKRs. To the best of our knowledge, AKR2E5 is only the second AKR characterized in silkworm. Our data should contribute to further understanding of the functional activity of insect AKRs.

We designed and fabricated a second harmonic generation device in THz frequency region with an array of split-ring resonators (SRR) on GaAs substrate. The properties of the structure were simulated by finite element method (Ansys HFSS) calculations and evaluated experimentally by THz time-domain spectroscopy (THz-TDS).

We propose and experimentally demonstrate a technique for improving the sensitivity of electro-optic sampling (EOS) detection of terahertz waves. The technique is based on polarization filtering of the probe optical beam after the nonlinear detector crystal. By applying the technique to heterodyne EOS scheme, the sensitivity was increased by 8 times.

Plasmonic theory is applied to the E-plane sectoral horn antennas discussed in microwave technology where metals is treated as perfect conductors approximately. The theory enables us to reconsider the sectoral horn antennas with a finite metallic permittivity for more realistic estimation of an enhancement factor of electric field that enters at the mouth of the sectoral horn antennas through the throat to the parallel- plate waveguide as a limit case of the rectangular waveguide.

To improve the detection efficiency of electro-optic (EO) sampling of terahertz waves, we propose “polarization filtering,” where the main polarization component of the probe optical beam is suppressed after the interaction in the EO crystal. Experimentally, we achieved a factor of 2.4 increase in the EO sampling signal by the polarization filtering.

We performed polarization-dependent terahertz (THz) time-domain coherent Raman spectroscopy on varying concentrations of aqueous NaCI solutions. Using this technique, the bending and stretching vibrational modes of water molecules under the influence of electrolytic ions were observed.

cDNA encoding an unclassified glutathione S-transferase (GST) of the diamondback moth, Plutella xylostella, was cloned by reverse transcriptase-polymerase chain reaction. The resulting clone was sequenced and the amino acid sequence deduced, revealing 67%-73% identities with unclassified GSTs from other organisms. A recombinant protein was functionally overexpressed in Escherichia coli cells in a soluble form and purified to homogeneity. The enzyme was capable to catalyze the transformation of 1-chloro-2,4-dinitrobenzene and ethacrynic acid with glutathione. A competition assay revealed that GST activity was inhibited by insecticides, suggesting that the enzyme could contribute to insecticide metabolism in the diamondback moth.

Two cDNAs encoding glutathione S-transferase (GST) of the tobacco cutworm, Spodoptera litura, were cloned by reverse transcriptase-polymerase chain reaction. The deduced amino acid sequences of the resulting clones revealed 32-51% identities to the epsilon-class GSTs from other organisms. The recombinant proteins were functionally overexpressed in Escherichia coli cells in soluble form and were purified to homogeneity. The enzymes were capable of catalyzing the bioconjugation of glutathione with 1-chloro-2,4-dinitrobenzene, 1,2-epoxy-3-(4-nitrophenoxy)-propane, and ethacrynic acid. A competition assay revealed that the GST activity was inhibited by insecticides, suggesting that it could be conducive to insecticide tolerance in the tobacco cutworm.

Following a previous detailed investigation of the β subunit of α

Influence of THz waves resonant to molecular vibrations to coherent Raman signal is studied by using THz time-domain coherent Raman spectroscopy. Enhancement of coherent Raman signal in THz region is observed depending on the intensity and polarization of irradiated THz waves.

We used a 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST) crystal coupled with a Si prism to detect THz pulsed radiation in heterodyne electro-optic sampling scheme. The detection efficiency is higher than that for a DAST crystal without a prism, as well as for a LiNbO 3 crystal with a Si prism.

The generation of a wide-range THz wave is investigated from a photoconductive antenna excited using a chaotic oscillation multimode semiconductor laser with optical delayed feedback by an external mirror. The stable THz wave is obtained from the multimode-laser diode excited photoconductive antenna by using a laser chaos. For a high sensitive detection, a metal V-grooved waveguide (MVG) is also used. As the MVG gap is narrower from 200 to 20[μm], the detected signal is increased about twice.

Principle and analysis for ellipsometers usable in the vacuum ultraviolet (VUV) region up to about 25 eV, which are consisting of a sample mirror and an inclined photodiode, are described. Our ellipsometer has two degrees of freedom in rotation; the main chamber can rotate around the axis of incidence and, the analyzer unit can also rotate around the axis of reflection. All the unknown parameters (Stokes parameters of the source, ellipsometric parameters of the sample and the polarization sensitivity of the inclined detector) are obtained by rotating the main chamber and analyzer independently and solving the simultaneous equations with the measurands. Measurement results on polarization characteristics of photodiodes, Stokes parameters of the beam emerging from a synchrotron radiation beamline, and optical constants of AlN film are given. It is concluded that the ellipsometer is advantageous in the simplicity and worked as intended.

SnO2-Ag composite nanomaterials of mass ratio 1:4, 2:3, 3:2 and 4:1 were fabricated and tested for toxicity to E. coli using the pour-plate technique. The said nanomaterials were mixed with laminating fluid and then coated on glass slides. The intensity of UVA transmitted through the coated glass slides was measured. Results revealed that the 1:4 ratios of SnO2-Ag composite nanomaterials have the optimum toxicity to E. coli. Furthermore, the glass slides coated with SnO2 nanomaterial showed the lowest intensity of transmitted UVA.