Effects of soy sauce <Emphasis Type="Italic">koji</Emphasis> and lactic acid bacteria on the fermentation of fish sauce from freshwater silver carp <Emphasis Type="Italic">Hypophthalmichthys molitrix</Emphasis>

The effects of soy sauce koji and the lactic acid bacterium, Tetragenococcus halophilus, were studied on the fermentation of fish sauce prepared from Chinese silver carp. The fish sauce prepared without koji and the lactic acid bacterium contained low levels of organic materials, total nitrogen, and organic acids. The use of koji was effective in increasing these qualitative parameters and further improved the amino acid score of the fish sauce. Addition of T. halophilus had an effect on lowering the pH value during the initial period of fermentation when the soy sauce koji was also supplemented. In contrast, T. halophilus-like bacteria were found to be predominant for all tanks fermented under the different starting conditions. Although it was not examined whether the T. halophilus-like bacteria observed after fermentation were the same as the starter-bacterium or not, it was suggested that T. halophilus plays an important role in the successful fermentation of silver carp fish sauce. Sensory evaluation conducted with Japanese and Chinese panelists also suggested the superiority of the use of koji for fermentation of silver carp fish sauce.     

Purification and properties of a histidine decarboxylase from Staphylococcus epidermidis TYH1 isolated from Japanese fish-miso

Histidine decarboxylase (HDC) from Staphylococcus epidermidis TYH1, a halotolerant histamine-producing bacterium isolated from Japanese fermented fish-miso, was purified to homogeneity for the first time. The enzyme was purified 182-fold from cell-free extracts by ammonium sulfate precipitation, anion exchange chromatography and gel filtration chromatography. The N-terminal amino acid sequences of two polypeptide chains of 27–30 and 7–9 kDa were highly homologous with those of α- and β-chains of other staphylococcal HDCs. The optimum pH and temperature for the enzyme were 6.0 and 60 °C, respectively. This enzyme did not decarboxylate lysine, arginine, tyrosine, tryptophan or ornithine. The enzyme activity decreased with the addition of NaCl. At pH 4.8, the V _max and K _m values were 45.5 μmol histamine min^?1 mg^?1 and 1.10 mmol/L, respectively. Moreover, this enzyme was resistant to heat treatment (80 °C for 15 min) and was stable upon freezing at ?30 °C for 7 days. The very similar physiological properties of this enzyme and the almost identical N-terminal amino acid sequence to that of the HDC from S. capitis indicated that this enzyme may be evolutionally highly conserved in the genus Staphylococcus. The biophysical properties of staphylococcal HDC were elucidated using native purified enzyme.     

Accumulation of paralytic shellfish poisoning toxin by the swimming crab <Emphasis Type="Italic">Charybdis japonica</Emphasis> in Kure Bay,Hiroshima Prefecture

The accumulation of paralytic shellfish poisoning (PSP) toxin in the crab Charybdis japonica was investigated in Kure Bay, when a bivalve Mytilus galloprovincialis, in the same water, showed toxicity caused by PSP toxin. In 2005, 17 specimens of the crab had PSP toxin over 4 MU/g in the hepatopancreas, and the highest toxicity was at 37.4 MU/g. Since the regulation limit of PSP for crab hepatopancreas was set in 2004, this is the first observation of regulatory level of PSP toxin in C. japonica. Unlike in the hepatopancreas of the crab, the hazardous level of the toxin was not detected in the muscle of the cephalothorax and the appendage. The toxin accumulation in the crab was also investigated by feeding toxic mussels to the crab. The crab retained the toxin mainly in the hepatopancreas, and the ratio of retention in the crab was from 12.9 to 24.6%. The toxin profiles, shown in the feeding experiments, suggest that the transformation of PSP toxin occurs in the crab because dcGTX2 and dcGTX3 was detected in all crab specimens despite the lack of these analogs in the mussels used as feed.     

Near-infrared spectroscopic sensing system for on-line milk quality assessment in a milking robot

A near-infrared (NIR) spectroscopic sensing system was constructed on an experimental basis. This system enabled NIR spectra of raw milk to be obtained in an automatic milking system (milking robot system) over a wavelength range of 600–1050 nm. Calibration models for determining three major milk constituents (fat, protein and lactose), somatic cell count (SCC) and milk urea nitrogen (MUN) of unhomogenized milk were developed, and the precision and accuracy of the models were validated. The coefficient of determination (r²) and standard error of prediction (SEP) of the validation set for fat were 0.95 and 0.25%, respectively. The values of r² and SEP for lactose were 0.83 and 0.26%, those for protein were 0.72 and 0.15%, those for SCC were 0.68 and 0.28 log SCC/mL, and those for MUN were 0.53 and 1.50 mg/dL, respectively. These results indicate that the NIR spectroscopic system can be used to assess milk quality in real-time in an automatic milking system. The system can provide dairy farmers with information on milk quality and physiological condition of an individual cow and, therefore, give them feedback control for optimizing dairy farm management. By using the system, dairy farmers will be able to produce high-quality milk and precision dairy farming will be realized.     

Short-term uptake of <Superscript>15</Superscript>NH<Subscript>4</Subscript><Superscript>+</Superscript> into soil microbes and seedlings of pine,spruce and birch in potted soils

Short-term competition between soil microbes and seedlings of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth) for N was assessed in a pot study using (¹⁵NH₄)₂SO₄ as a tracer. Seedlings were grown in organic and mineral soil, collected from a podsol soil; 3.18 mg (¹⁵NH₄)₂SO₄ per pot were injected into the soil, corresponding to 4 µg ¹⁵N g^-1 d.m. (dry matter) mineral soil and 17 µg ¹⁵N g^-1 d.m. organic soil. The amounts of N and ¹⁵N in the seedlings and in microbial biomass derived from fumigation-extraction were measured 48 h after addition of ¹⁵N. In the mineral soil, 19–30% of the added ¹⁵N was found in the plants and 14–20% in the microbial biomass. There were no statistically significant differences between the tree species. In the organic soil, 74% of the added ¹⁵N was recovered in the microbial biomass in birch soil, compared to 26% and 17% in pine and spruce soils, respectively. Correspondingly, about 70% of the ¹⁵N was recovered in pine and spruce seedlings, and only 23% in birch seedlings. In conclusion, plants generally competed more successfully for added ¹⁵NH₄ ⁺ than soil microbes did. An exception was birch growing in organic soil, where the greater amount of available C from birch root exudates perhaps enabled micro-organisms to utilise more N.     

Effects of melophlins on colony formation of Chinese hamster V79 cells and IL-8 production in PMA-stimulated HL-60 cells

We have recently isolated four new melophlins P (1), Q (2), R (3), and S (4) together with seven known melophlins A (5), D (6), E (7), G (8), H (9), I (10), and O (11) from two marine sponges of the genus Melophlus collected in Palau. In this study, the influence of these compounds on the colony formation of Chinese hamster V79 cells and the production of IL-8 in PMA-stimulated HL-60 cells were examined. These 11 compounds did not show any effect on IL-8 production. The EC₅₀ values of compounds 2, 3, 4, 5, 7, 9, 10, and 11 against V79 cells were 44.0, 13.3, 16.7, 27.2, 19.8, 8.5, 23.1, and 9.6 μM, respectively. The linear-chain-type compounds (1, 6, and 8) were not active against V79 cells at 50 μM. Although the growth inhibitory activity of these melophlins was not remarkable, some structure-activity relationships of these compounds against V79 and murine leukemia L1210 cells were observed.     

Flow cytometric analysis of bronchoalveolar lavage fluid immune dynamics in calves

Understanding the immune dynamics in the respiratory mucosa of calves is necessary for a good management of bovine respiratory disease. Immune dynamics in the respiratory mucosa in humans and experimental animals has been assessed by flow cytometric analysis of bronchoalveolar lavage fluid (BALF); however, few reports have addressed this subject in calves. The aim of this study was to establish a universal method to analyze bronchoalveolar lavage fluid (BALF) by flow cytometry and to obtain basic knowledge of bovine respiratory mucosal immune dynamics. We investigated the immune cell populations in BALF and evaluated the surface antigen expression of alveolar macrophages in calves using flow cytometer. To further analyze the surface antigen variation observed in alveolar macrophages in detail, stimulation assays were performed in vitro. BALF cells were separated into three distinct populations based on their light scatter plot, which were considered to be macrophages, lymphocytes, and neutrophils. In most individuals, most of the BALF immune cells were alveolar macrophages, but an increased proportion of lymphocytes and neutrophils was observed in some individuals. Analysis of each surface antigen expression in alveolar macrophages showed that CD21 and MHC class II expression changed in response to changes in the leukocyte population. Moreover, when alveolar macrophages were stimulated with interferon-γ in vitro, the expression of CD21 was drastically reduced and MHC class II was increased, suggesting that functional changes in alveolar macrophages themselves are involved in the immune dynamics.     

Race distribution of Phytophthora sojae on soybean in Hyogo, Japan

Since 1987, Phytophthora root and stem rot of soybean [Glycine max (L.) Merr. cv. Tanbakuro], caused by Phytophthora sojae Kaufman and Gerdemann, has been increasing in the Sasayama, Nishiwaki, and Kasai regions in Hyogo, the most famous soybean (cv. Tanbakuro)-producing areas in Japan. In 2002 to 2004, 51 isolates (one from each field) of P. sojae were recovered from 51 fields in Hyogo. These isolates were tested for virulence on six Japanese differential soybean cultivars used for race determination in Japan, and three additional ones containing four Rps genes used in Indiana, USA. Race E was the most prevalent from 2002 to 2004, followed by races A, C, D, and four new races (proposed as races K, L, M, and N). Interestingly, none of the new races had high virulence on the Japanese differential cultivars, compared with other races in each area. One (race N) was avirulent on all six soybean differentials. There was a difference in race distribution on each of three individual areas; race E seemed to be a major component of the P. sojae population in Sasayama, whereas race A and the new race M were the most prevalent in Nishiwaki and Kasai, respectively. Rps6 (cv. Altona) and Rps1a + Rps7 (cv. Harosoy 63) were infected by 90.2% and 33.3% of all isolates, respectively. However, Rps1d (cv. PI103091) was not susceptible to any of the 51 isolates, nor was cv. Gedenshirazu-1. These two soybean cultivars were considered to be potential sources of resistance to breed new resistant cultivars with the desirable characteristics of cv. Tanbakuro for this region.     

Mediator-type biosensor for real-time wireless monitoring of blood glucose concentrations in fish

We developed a wireless mediator-type biosensor system to rapidly monitor blood glucose concentrations in free-swimming fish. Glucose oxidase was used to determine the glucose concentration, but fluctuations in the oxygen concentrations in the samples affected the measurements. In this work, we used a mediator, a synthetic electron acceptor, as a substitute in the oxidation–reduction reaction, thus ensuring that changes in the concentration of oxygen do not affect the measurements of glucose concentration performed by the sensor. We especially focused on the use of ferrocene as a mediator. The resulting enzyme sensor utilized a Pt–Ir wire (diameter 0.178 mm) as the working electrode and Ag/AgCl paste as the reference electrode. Chitosan was used to fix ferrocene and glucose oxidase to the working electrode. The characteristics of the sensor were tested, and it was found to be capable of measuring glucose independent of the oxygen concentration of the sample. Its reproducibility was also tested, and the results showed that the sensor was suitable for performing measurements in vivo. The sensor was then inserted into to eyeball interstitial sclera fluid in order to wirelessly monitor the glucose concentration in free-swimming fish. Measurements were taken for a total of 48 h. During these measurements, artificial stress was applied to the fish. The glucose concentrations of fish rise with their stress levels. The output current from the sensor gradually increased during the application of stress, which hinted that the stress was monitored by this system.     

A new arylnaphthalene lignan from Knema furfuracea

A new arylnaphthalene lignan, named furfuracin (1), was isolated from the leaves of Knema furfuracea (Myristicaceae), whereas 7 known compounds including (+)-trans-1,2-dihydrodehydroguaiaretic acid, fragransin A₂, biochanin A, gingkolic acid, anarcardic acid, 2-hydroxy-6-(12-phenyldodecyl)-benzoic acid and 2-hydroxy-6-(12-phenyldodecen-8′Z-yl)-benzoic acid were obtained from its stems. The structure of the new lignan was established by analysis of spectroscopic data (UV, IR, MS and NMR).