The relationship between consumption of tyrosine and phenylalanine as precursors of catecholamine at breakfast and the circadian typology and mental health in Japanese infants aged 2 to 5 years

Background

This study aims to examine the relationship between tyrosine and phenylalanine intake at breakfast as precursors of dopamine, and scores on the Torsvall-Åkerstedt Diurnal Type Scale and of mental health in Japanese infants aged 2 to 5 years.

Results

An integrated questionnaire was administered to parents of 1,367 infants attending one of ten nursery schools governed by Kochi City or a kindergarten affiliated with the Faculty of Education at Kochi University (775 answers for analysis: 56.7%) in May and June 2008. Questionnaires included the Torsvall-Åkerstedt Diurnal Type Scale and questions on sleep habits (onset, offset, quality, quantity, and so on), meal habits (content and regularity of timing), and mental health (depressive states). Amount of tyrosine and phenylalanine intake was calculated based on a breakfast content questionnaire and data on the components of amino acids in foods. Infants who ingested more than 800 mg of tyrosine or phenylalanine at breakfast per meal were more morning-type than those who ingested less than 800 mg (ANOVA: P= 0.005). However, this relationship disappeared in the ANCOVA analysis (with the covariance of tryptophan intake, P= 0.894). Infants who ingested more than 800 mg of the two amino acids at breakfast showed significantly higher mental health scores (lower frequency of depressive states) than those who ingested less than 800 mg (ANOVA: P = 0.004). This relationship remained significant when ANCOVA analysis was performed with the covariance of tryptophan (ANCOVA: P= 0.017).

Conclusions

These results suggest that tyrosine and phenylalanine ingested at breakfast are not related with circadian phase, but are relate with mental health in infants.     

Single-Molecule Analysis of the Rotation of F1-ATPase under High Hydrostatic Pressure

F₁-ATPase is the water-soluble part of ATP synthase and is an ATP-driven rotary molecular motor that rotates the rotary shaft against the surrounding stator ring, hydrolyzing ATP. Although the mechanochemical coupling mechanism of F₁-ATPase has been well studied, the molecular details of individual reaction steps remain unclear. In this study, we conducted a single-molecule rotation assay of F₁ from thermophilic bacteria under various pressures from 0.1 to 140 MPa. Even at 140 MPa, F₁ actively rotated with regular 120° steps in a counterclockwise direction, showing high conformational stability and retention of native properties. Rotational torque was also not affected. However, high hydrostatic pressure induced a distinct intervening pause at the ATP-binding angles during continuous rotation. The pause was observed under both ATP-limiting and ATP-saturating conditions, suggesting that F₁ has two pressure-sensitive reactions, one of which is evidently ATP binding. The rotation assay using a mutant F₁(βE190D) suggested that the other pressure-sensitive reaction occurs at the same angle at which ATP binding occurs. The activation volumes were determined from the pressure dependence of the rate constants to be +100 Å³ and +88 Å³ for ATP binding and the other pressure-sensitive reaction, respectively. These results are discussed in relation to recent single-molecule studies of F₁ and pressure-induced protein unfolding.     

Expression patterns of hedgehog, wingless, and decapentaplegic during gut formation of Gryllus bimaculatus (cricket).

We observed expression patterns of hedgehog (hh), wingless (wg), and decapentaplegic (dpp) during gut development of Gryllus bimaculatus (the cricket), a typical hemimetabolous insect, and compared with those observed in Drosophila, a typical holometabolous insect. Gryllus hh(Gbhh) and Gbwg are expressed in both foregut and hindgut, while Gbdpp is expressed only in the hindgut: at the boundaries between the small and large intestine, and between the large intestine and rectum. Although the expression patterns of Gbhh and Gbwg are essentially comparable to those observed in Drosophila, the expression pattern of Gbdpp differs from those of the Drosophila dpp.     

Cysteine synthase overexpression in tobacco confers tolerance to sulfur-containing environmental pollutants.

Cysteine (Cys) synthase [O-acetyl-L-Ser(thiol)-lyase, EC 4.2.99.8; CSase] is responsible for the final step in biosynthesis of Cys. Transgenic tobacco (Nicotiana tabacum; F(1)) plants with enhanced CSase activities in the cytosol and in the chloroplasts were generated by cross-fertilization of two transformants expressing cytosolic CSase or chloroplastic CSase. The F(1) transgenic plants were highly tolerant to toxic sulfur dioxide and sulfite. Upon fumigation with 0.1 microL L(-1) sulfur dioxide, the Cys and glutathione contents in leaves of F(1) plants were increased significantly, but not in leaves of non-transformed control plants. Furthermore, the leaves of F(1) plants exhibited the increased resistance to paraquat, a herbicide generating active oxygen species.     

Single-molecule Imaging Analysis of Elementary Reaction Steps of Trichoderma reesei Cellobiohydrolase I (Cel7A) Hydrolyzing Crystalline Cellulose Iα and IIII

Trichoderma reesei cellobiohydrolase I (TrCel7A) is a molecular motor that directly hydrolyzes crystalline celluloses into water-soluble cellobioses. It has recently drawn attention as a tool that could be used to convert cellulosic materials into biofuel. However, detailed mechanisms of action, including elementary reaction steps such as binding, processive hydrolysis, and dissociation, have not been thoroughly explored because of the inherent challenges associated with monitoring reactions occurring at the solid/liquid interface. The crystalline cellulose I_α and III_I were previously reported as substrates with different crystalline forms and different susceptibilities to hydrolysis by TrCel7A. In this study, we observed that different susceptibilities of cellulose I_α and III_I are highly dependent on enzyme concentration, and at nanomolar enzyme concentration, TrCel7A shows similar rates of hydrolysis against cellulose I_α and III_I. Using single-molecule fluorescence microscopy and high speed atomic force microscopy, we also determined kinetic constants of the elementary reaction steps for TrCel7A against cellulose I_α and III_I. These measurements were performed at picomolar enzyme concentration in which density of TrCel7A on crystalline cellulose was very low. Under this condition, TrCel7A displayed similar binding and dissociation rate constants for cellulose I_α and III_I and similar fractions of productive binding on cellulose I_α and III_I. Furthermore, once productively bound, TrCel7A processively hydrolyzes and moves along cellulose I_α and III_I with similar translational rates. With structural models of cellulose I_α and III_I, we propose that different susceptibilities at high TrCel7A concentration arise from surface properties of substrate, including ratio of hydrophobic surface and number of available lanes.     

Torque Generation of Enterococcus hirae V-ATPase

V-ATPase (V_oV₁) converts the chemical free energy of ATP into an ion-motive force across the cell membrane via mechanical rotation. This energy conversion requires proper interactions between the rotor and stator in V_oV₁ for tight coupling among chemical reaction, torque generation, and ion transport. We developed an Escherichia coli expression system for Enterococcus hirae V_oV₁ (EhV_oV₁) and established a single-molecule rotation assay to measure the torque generated. Recombinant and native EhV_oV₁ exhibited almost identical dependence of ATP hydrolysis activity on sodium ion and ATP concentrations, indicating their functional equivalence. In a single-molecule rotation assay with a low load probe at high ATP concentration, EhV_oV₁ only showed the “clear” state without apparent backward steps, whereas EhV₁ showed two states, “clear” and “unclear.” Furthermore, EhV_oV₁ showed slower rotation than EhV₁ without the three distinct pauses separated by 120° that were observed in EhV₁. When using a large probe, EhV_oV₁ showed faster rotation than EhV₁, and the torque of EhV_oV₁ estimated from the continuous rotation was nearly double that of EhV₁. On the other hand, stepping torque of EhV₁ in the clear state was comparable with that of EhV_oV₁. These results indicate that rotor-stator interactions of the V_o moiety and/or sodium ion transport limit the rotation driven by the V₁ moiety, and the rotor-stator interactions in EhV_oV₁ are stabilized by two peripheral stalks to generate a larger torque than that of isolated EhV₁. However, the torque value was substantially lower than that of other rotary ATPases, implying the low energy conversion efficiency of EhV_oV₁.     

A Transient Rise in Free Mg2+ Ions Released from ATP-Mg Hydrolysis Contributes to Mitotic Chromosome Condensation

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