Naoki Harikai

Differences in hypothalamic Fos expressions between two heat stress conditions in conscious mice.

Hyperthermia and dehydration were important physiological phenomena in heat stress. But, the degrees of these phenomena were changed by heat stress conditions, and the distinction between both phenomena is necessary for investigation of response for individual phenomenon. Heat stress at 34 degrees C for 60 min increased rectal temperature, and heat stress at 38.5 degrees C for 60 min further increased rectal temperature and increased osmolality in mice. We investigated the activated region in hypothalamus, which played a role in thermoregulation, fluid regulation and so on, using immunostaining for Fos protein under these conditions in conscious mice. At 34 degrees C, Fos-positive neurons increased in the median preoptic nucleus, lateral preoptic area and anterior hypothalamic area, which were known to be the thermoregulatory center, and the dorsomedial hypothalamic nucleus, which was known to control eating. At 38.5 degrees C, Fos-positive neurons further increased in the regions mentioned above and appeared in the lateral septal nucleus, medial preoptic area, lateral hypothalamic area and zona incerta, which were thought to be involved in thermoregulation and/or fluid regulation, and the paraventricular hypothalamic nucleus, supraoptic nucleus and supraoptic nucleus in the retrochiasmatic part, which were known to be involved in neuroendocrine effector systems. These results support that the activated regions in hypothalamus differed with heat stress conditions, which induced only hyperthermia and both hyperthermia and dehydration.

Effect of chondroitin sulfate on murine splenocytes sensitized with ovalbumin

Chondroitin sulfate (CS) is a glycosaminoglycan that is widely present in animals organisms, and it has anti-inflammatory and chondroprotective properties. To examine the effects of CS on the immune system, splenocytes obtained from ovalbumin (OVA)-sensitized BALB/c mice were challenged with OVA in the presence of CS, and cytokine levels in the medium of the cultured cells were measured. CS induced secretion of Th1-type cytokines (IFN-gamma, IL-2, and IL-12) by OVA-sensitized splenocytes but suppressed secretion of Th2-type cytokines (IL-5 and IL-10). Flow cytometric assay showed a significantly higher percentage of helper T cells (CD4(+)CD8(-) cells) among the splenocytes cultured with OVA and CS than with OVA alone. Analysis of the IFN-gamma mRNA level of the splenocytes by the real-time quantitative RT-PCR technique revealed higher levels in the splenocytes cultured with OVA and CS than in the splenocytes cultured with OVA alone. This is the first demonstration that CS inhibits antigen-induced IgE production through induction of cytokine secretion by Th1 cells, and this finding suggests a potential use of CS in preventing IgE-mediated allergy.

特定原材料(卵)測定の厚生労働省通知ELISA法の複数機関による評価研究

Inter-laboratory evaluation studies were conducted for the notified ELISA methods for allergic substances (Egg). Standard extracts of egg spiked in extracts of sausage, sauce, cookie, bread and cereal at a level of 5-20 ng/mL as the sample solution were analyzed in replicate in 10 laboratories. Coefficients of variation (CVs) of all three ELISA methods using an Egg Protein ovalbumin ELISA Kit (ovalbumin kit), an Egg Protein ovomucoid ELISA Kit (ovomucoid kit) and a FASTKIT Egg ELISA kit (Egg ELISA kit) were mostly less than 10%. Mean recoveries of the standard extract of egg were over 40% in the three ELISA methods. Repeatability relative standard deviations of egg standard solution in five food extracts were in the ranges of 18.7-25.5%, 18.6-41.8%, 21.3-43.3% for the ovalbumin kit, the ovomucoid kit and the Egg ELISA kit, respectively. Reproducibility relative standard deviations of egg standard solution in five food extracts were 16.8-35.1%, 19.6-35.8%, 24.7-51.1% for the ovalbumin kit, the ovomucoid kit and the Egg ELISA kit, respectively. The detection limits of all the ELISA methods were 4-5 ng/mL in sample solutions. These results suggested that the notified ELISA methods are reliable and reproducible for the inspection of egg protein levels in extracts of sausage, sauce, cookie, bread and cereal.

Acute heat stress induces jumping escape behavior in mice

A new heat escape behavior was revealed in mice (ddY mice) under acute heat stress conditions. Mice in a fully covered cage were exposed to 24, 34, 37 and 38.5 degrees C for 60 min. Rectal temperature increased in conditions above 34 degrees C. Furthermore, serum osmolality and body weight loss also increased in conditions above 37 degrees C. At above 37 degrees C, a large number of mice attempted to escape from the partially covered cage, and so exhibited jumping behavior during a period of 60 min. However, mice exposed to 24 and 34 degrees C did not exhibit such behavior. These results indicated that acute heat stress above 37 degrees C induced evaporative water loss and jumping escape behavior in mice.

Kinetic Study of the Equilibration between Carminic Acid and Its Two Isomers Isolated from Cochineal Dye

Carminic acid (CA) is a major component of cochineal dye used in food additives, cosmetics, and pharmaceuticals. CA and its isomers, 2-C-α-glucofuranoside and 2-C-β-glucofuranoside of kermesic acid (DCIV and DCVII, respectively), were isolated from cochineal dye and the equilibrium constants (K) between CA, DCIV and DCVII were investigated. DCIV was partially converted to CA and DCVII, and DCVII was converted to CA and DCIV, whereas CA was very stable and only very slightly converted to DCIV and DCVII. Most of the DCIV and DCVII was converted to CA under aqueous conditions. The kinetic rate constants (k) for the degradation of DCIV within the first day of incubation at 24°C was determined to be 0.901 d-1 and for the degradation of DCVII it was determined to be 1.102 d-1. The k value for the formation of CA from the remaining DCIV was calculated to be 0.146 d-1 and for the formation of CA from the produced DCVII it was found to be 0.148 d-1. The K values were calculated as 1.22×10-7, 2.61×10-3 and 2.36×10-3 mol/L for CA, DCIV and DCVII, respectively. These findings will be helpful for ensuring the safety and for aiding the quality assurance of cochineal dye products.

Characteristic induction of steroidogenic factor 1 (SF-1) and DAX-1 and enhanced expression of glucocorticoid synthesis-related genes in adrenals from spontaneously hypertensive rats.

To gain insight into the molecular mechanism of hyper-glucocorticoidism in spontaneously hypertensive rats (SHR), this study investigated the expression of genes related to glucocorticoid synthesis, melanocortin 2 receptor (MC2R), steroidogenic acute regulatory protein (StAR), cytochrome P450 side chain cleavage enzyme (P450scc) and 11β-hydroxylase (P450c11), and the transcription factors of steroidogenic factor 1 (SF-1), which stimulates expression of the above gene, and DAX-1 (dosage-sensitive sex reversal-adrenal hypoplasia congenita critical region on the X chromosome gene 1), which negatively regulates the transcriptional activity of SF-1, in adrenals from SHR. On quantitative real time RT-PCR analysis, gene expression levels of MC2R, StAR, P450scc and P450c11 in SHR were high compared with those in normotensive Wistar Kyoto rats (WKY). The gene expression level of SF-1 was not different between the two rats. However, the expression level of DAX-1 in SHR was markedly lower than that in WKY. Furthermore, the protein levels of StAR, SF-1 and DAX-1 determined by Western blot analysis coincided well with the gene expressions in both rats. These results suggest that the low level of DAX-1 may enhance the transcriptional activity of SF-1 and expression of genes related to glucocorticoid synthesis, which are targeted by SF-1, in adrenals from SHR.

Design of a coil satellite centrifuge and its performance on counter-current chromatographic separation of 4-methylumbelliferyl sugar derivatives with polar organic–aqueous two-phase solvent systems☆

A new high-speed counter-current chromatograph, named coil satellite centrifuge (CSC), was designed and fabricated in our laboratory. The CSC apparatus produces the satellite motion such that the coiled column simultaneously rotates around the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (the central axis of the column) (ω3). In order to achieve this triplicate rotary motion without twisting of the flow tube, the rotation of each axis was determined by the following formula: ω1=ω2+ω3. This relation enabled to lay out the flow tube without twisting by the simultaneous rotation of three axes. The flow tube was introduced from the bottom side of the apparatus into the sun axis of the first rotary frame reaching the upper side of the planet axis and connected to the column in the satellite axis. The performance of the apparatus was examined on separation of 4-methylumbelliferyl (MU) sugar derivatives as test samples with organic-aqueous two-phase solvent systems composed of ethyl acetate/1-butanol/water (3:2:5, v/v) for lower phase mobile and (1:4:5, v/v) for upper phase mobile. With lower phase mobile, five 4-MU sugar derivatives including β-D-cellobioside (Cel), β-D-glucopyranoside, α-D-mannopyranoside, β-D-fucopyranoside and α-L-fucopyranoside (α-L-Fuc) were separated with the combined rotation around each axis at counterclockwise (CCW) (ω1) - CCW (ω2) - CCW (ω3) by the flow tube distribution. With upper phase mobile, three 4-MU sugar derivatives including α-L-Fuc, β-D-galactopyranoside and Cel were separated with the combined rotation around each axis at clockwise (CW) (ω1) - CW (ω2) - CW (ω3) by the flow tube distribution. A series of experiments on peak resolution and stationary phase retention revealed that better partition efficiencies were obtained at the flow rate of 0.5 mL/min (column 1) and 0.8 mL/min (column 2) for lower phase mobile and 0.2 mL/min (column 1) and 0.4 mL/min (column 2) for upper phase mobile when using the left-handed multilayer coil (total capacity: 57.0 mL for column 1 and 75.0 mL for column 2) under the rotation speeds of approximately ω1=300 rpm, ω2=150 rpm and ω3=150 rpm.

Optical detection of specific genes for genetically modified soybean and maize using multiplex PCR coupled with primer extension on a plastic plate.

A novel DNA microarray method to detect one line of genetically modified (GM) soybean and five lines of GM maize was developed using multiplex PCR coupled with primer extension on a plastic plate. Multiplex PCR products were applied on an extension primer-immobilized plate and the spots corresponding to the DNA sequences were visualized. This method is a rapid and simple way to detect GM soybean and GM maize optically.

Application of an Alkaline and Silica Membrane DNA Extraction Method to Detect Mitochondrial DNA in Foods

To improve the efficiency of mitochondrial DNA (mtDNA) extraction from food, a simple method, PrepM, was developed by effectively combining alkaline sodium dodecyl sulfate lysis and DNA binding to a silica membrane. PrepM was evaluated using fresh, cold, and autoclaved rat liver samples and compared with commercial total DNA extraction kits. When PrepM was applied to fresh and cold samples, the DNA yield was low, but the OD260/280 ratio was close to 1.8. The cytochrome C oxidase subunit I (COI) copy number, which is the number of mtDNA copies, per DNA weight and the ratio of COI to β-actin, which is the ratio of mitochondrial to genomic DNA, were higher with PrepM than with total DNA extraction kits. When PrepM was applied to autoclaved samples, the DNA purity and yield and the COI copy number per DNA weight were relatively high, but the COI to β-actin ratio was low. PrepM was then applied to shrimp samples, a known allergenic food. Data obtained from cold and autoclaved shrimp samples were similar to data obtained from rat liver samples. When PrepM was applied to food samples spiked with shrimp, the DNA purity was high, but the DNA yield and the mtDNA levels were almost same as those obtained with total DNA extraction kits. We concluded that PrepM has a comparative advantage for sensitive polymerase chain reaction detection of mtDNA sequences in relatively fresh samples, and it has almost the same performance as general total DNA extraction kits with autoclaved and/or complex mixture samples.

Real-time PCR method using capturing oligo-immobilized PCR tubes to determine the specific gene for soybean and genetically modified soybean in food matrices.

A new real-time PCR method using capturing oligo-immobilized PCR tubes is described. This method was used to detect specific genes for soybean and genetically modified (GM) soybean in food matrices. In a standard reaction using soybean genomic DNA and a capturing oligo for the lectin gene (Le1) immobilized on the tube, we examined the effects of such hybridization conditions as the location, length, and amount of the capturing oligo, and the incubation time and temperature. Under optimized conditions, the copy number of Le1 was determined in a concentration-dependent manner from soybean genomic DNA and soybean lysate (DNA 10–1000 ng, r=0.99; lysate 1–100%, r=0.99). The copy number of a Roundup Ready soybean (RRS) gene was also successfully detected in a concentration-dependent manner (1–100%, r=0.99) from GM soybean lysate, using PCR tubes with an immobilized capturing oligo for the transgene. Our data indicate that this is a rapid and simple method to determine specific genes for soybean and GM soybean in food matrices.