Uniquely stable 40 kDa subfragment-2 in carp myosin

Digestion of carp myofibrils at 30 degrees C in 0.5 M KCl medium with calcium ion generated unique 135 kDa heavy meromyosin (HMM). The HMM was not produced when digested at 10 degrees C. A further digestion of the 135 kD HMM isolated in the absence of calcium ion generated uniquely short subfragment-2 (S-2) with a size of 40 kDa (40 kDa S-2) together with subfragment-1 (S-1). The 40 kDa S-2 was identified by N- and C-end sequencing, and demonstrated to locate the amino end of the rod portion. The unfolding temperature for the 40 kDa S-2 was around 52 degrees C as studied by circular dichroism measurement. The same unfolding peak was also detected with the intact rod together with a large unfolding peak at around 36 degrees C coming from the rest of the rod portion, light meromyosin. The unfolding peak for the 40 kDa S-2 in myosin was a little lower (48 degrees C) than that in free form, suggesting the involvement of the head portion in the stability of the 40 kDa S-2 in the structure.     

Study of the Water Solubility and Sorption on Particulate Matters of Phthalate in the Presence of Humic Acid Using 14C Labelled Di-(2-Ethylhexyl)Phthalate

Phthalate esters have become widespread contaminants in the aquatic environment, because of their extensive use as non-reactive plasticizers. There is, however, little accurate data on their solubility, transportation, and distribution in the aquatic environment. In this work, we have investigated the influence of humic acid on the water solubility of di-(2-ethylhexyl)phthalate (DEHP), one of the most frequently used phthalate esters in the laboratory studies for DEHP. We have also studied the solid–water distribution of DEHP in the presence of humic acid and particulate matter (activated carbon, ferrihydrite, and kaolinite) to simulate their distribution in a natural aquifer (ternary system). The results show that the water solubility of DEHP can be significantly increased by humic acid. The shape K _eq value, the binding constant of DEHP between water and humic acid at equilibrium, was obtained by fitting experimental data for each humic acid. The shape K _eq values in the ternary system apparently decreased in the order of ferrihydrite ≤ kaolinite ≈ octanol/water partition activated carbon systems. This result shows that the increase in the hydrophobicity of HA remaining in the solution will lead to the apparent increase of shape K _eq in the system since more hydrophilic solid sorbs relatively more hydrophilic HA molecule. The solid–water partition coefficient (shape K _W-P ) for DEHP in the environment estimated from this study is consistent with those reported based on the experiments for natural samples. Quantitative values obtained in this study, such as K'_ow, shape K _eq, and shape K _W-P , can be useful for estimating the behavior of DEHP.     

Separation of sardine oil without heating from surimi waste and its effect on lipid metabolism in rats

Sardine oil was obtained by centrifugation of surimi wastewater without heating or chemical refining. This oil (CE) showed light yellow color and the peroxide value was less than 1.0 meq/kg. The main lipid class of CE was triacylglycerol (TG) (>99%). These features indicate that CE can be directly used as food materials without further purification. Commercial sardine oil (CO) is usually prepared via some kind of refining process with high temperature (250 degrees C) and chemical treatment. The comparative study on the physiological effects of these sardine oils (CE and CO) revealed that the dietary sardine oils were more effective in reducing abdominal fat pads, plasma total cholesterol, and TG levels of rats than was a soybean oil diet (control). Furthermore, these effects were greater in CE than CO, although there was little difference in the fatty acid composition of both oils. Although the main lipid class of CE was TG (>99%), CE was prepared by centrifugation from surimi waste and directly used as dietary fat without further purification. Therefore, CE may contain some kinds of minor components, which could be attributed to the higher physiological activity of CE. To reveal the involvement of the minor compounds in CE, we prepared TG from CE by column chromatography and measured its effect on lipid metabolism of rats. TG from CE also showed the reducing effects on abdominal fad pads and plasma lipid levels. The effect of TG from CE was almost the same as that of original CE, suggesting that the higher nutritional activity of CE than CO may not be due to the minor compounds in CE.     

Effects of management, environment and landscape conditions on establishment of hardwood seedlings and saplings in central Japanese coniferous plantations

There is an increasing need to restore natural hardwood forests in landscapes dominated by monocultural conifer plantations. A convenient restoration approach is to exploit natural regeneration processes. Natural regeneration, however, is affected by diverse interacting factors, for which better understanding is required, in order to optimize restoration programs. To identify optimal management practices for improving natural regeneration of hardwood trees in coniferous plantations, we examined the effects of multiple factors on the abundance of seedlings, small saplings and large saplings (height <0.3, 0.3-1.3 and ?1.3 m, respectively) of hardwood tree and shrub species in both line thinned (LT) and unthinned (UT) plantations of sugi (Cryptomeria japonica) and hardwood forests (HF) in central Japan. The effects of management practices (number of the times of weeding and cleaning, thinning method, years after thinning and forest age), environment (slope position, slope angle and canopy openness), and landscape conditions (distance from nearest hardwood forest, altitude and landuse before planting) on the number of hardwood individuals were examined by using the data obtained from the LT plantations. We also compared hardwood density between LT and UT plantations to examine the effect of line thinning. Finally, we examined species composition of LT plantations and HF to identify hardwood forest components in the thinned plantations. The effects on hardwood regeneration of environmental conditions, landscape factors and management practices applied in the plantations varied, depending on the size class and life form of the regenerating species. The abundance of large saplings of tall tree species was affected by several management factors, especially number of the times of weeding. Landscape conditions (distance from the nearest hardwood forest and altitude) affected the abundance of small saplings and seedlings of tall tree species, but not the other classes. Seedlings and small saplings of many tall tree species that contribute to hardwood forest canopies were less abundant in the LT plantations. The results show that numerous factors affect the establishment and abundance of naturally regenerating hardwood tree species, and suggest that successful establishment during early plantation stages can have long-lasting effects on natural regeneration of tall tree species.     

Nitrogen-fixing activity in decomposing litter of three tree species at a watershed in eastern Japan

Nitrogen fixation during litter decomposition was studied for 34 months using litterbags containing newly fallen litter of coniferous species Cryptomeria japonica and Pinus densiflora and that of deciduous species Quercus serrata. Litterbags were set in contact with the forest floor in a deciduous broad-leaved forest near the top of a slope and in a C. japonica stand at the middle of the slope at a watershed in eastern Japan. Nitrogen-fixing activity, estimated by acetylene reduction after 16 and 19 months of incubation, was 62.65–3.86 nmoles C₂H₄ h⁻¹ g⁻¹ DW in Cryptomeria litter, but only 1.07–0.09 in Pinus and 0.72–0.04 in Quercus. The rate of N increase in decomposing litter was highest in Cryptomeria. Fungal biomass in decomposing litter, estimated by ergosterol content, increased during the initial 16 months of incubation in Cryptomeria and Quercus, and during the initial 19 months of incubation in Pinus. The litter decomposition rate was highest in Cryptomeria among the three species, due to increased N content and fungal biomass in Cryptomeria litter. Thus, N increase in decomposing Cryptomeria litter affects the subsequent N dynamics and decomposition pattern.     

Structure-physicochemical function relationships of soybean beta-conglycinin heterotrimers

We purified four single molecular species of beta-conglycinin heterotrimers consisting of the alpha and beta subunits or the alpha' and beta subunits from mutant soybean cultivars lacking the alpha or alpha' subunit, respectively, and examined their structural features and physicochemical functions. The extent of the hydrophobicities of the heterotrimers was related to the number of the alpha or alpha' subunit. The thermal stabilities of the heterotrimers were mainly conferred by the subunit which had lower thermal stability. Solubilities at low ionic strength (mu = 0.08) of the heterotrimers containing the alpha or alpha' subunit were very similar to those of the alpha and alpha' homotrimers, respectively. Emulsifying abilities and heat-induced associations of the heterotrimers containing one beta subunit were similar to those of the alpha or alpha' homotrimer, whereas those of the heterotrimers containing two beta subunits were similar to those of the beta homotrimer.     

Rearing technique for proturans (Hexapoda: Protura)

A chamber for rearing proturans is described. The chamber is double-walled, and was used successfully to rear proturans for one generation.     

Radiocarbon Content in Urban Atmospheric Aerosols

We attempted to elucidate seasonal variations in fossil-fuel-derived carbon (FC) and biomass-derived carbon (BC) in urban atmospheric aerosols. We undertook continuous measurements of the composition of fine particle (PM_2.1) in central Tokyo, including the ¹⁴C/¹²C ratio. The percent modern carbon (pMC) contained in all samples averaged 43, and the highest was 54 in late December and the lowest was 31 in early August. From the observed carbonaceous component concentrations and the pMC we could calculate the content ratio of FC and BC in PM_2.1 and investigate their seasonal variations. Although there was almost no seasonal variation in the ratio of FC, the ratio of BC was observed to rise in early winter. This indicates that FC is influenced by the emission sources without seasonal variations (such as automobiles driven in urban areas). Furthermore, there is significant correlation between BC and organic carbon (OC), and even for urban areas, it is considered that the contribution of biomass carbon to OC in PM_2.1 is high.     

Functional changes in beta-lactoglobulin by conjugation with cationic saccharides

Bovine beta-lactoglobulin (beta-LG) was conjugated to each of three cationic saccharides [glucosamine (GlcN), chitopentaose (CPO), and chitosan (CHS)] by means of a water-soluble carbodiimide or by the Maillard reaction in an effort to improve the functional properties of beta-LG. The molar ratios of beta-LG to the cationic saccharide in the beta-LG-GlcN, beta-LG-CPO, and beta-LG-CHS conjugates were 2:1, 2:5, and 2:1, respectively. Fluorescence studies indicated that the conformation around Trp had changed in each conjugate and that the surface of each of the conjugates was covered with a saccharide chain. Structural analysis using monoclonal antibodies indicated that the conformation around (15)Val-(29)Ile (beta-sheet region) in beta-LG-GlcN and beta-LG-CPO had changed but that in beta-LG-CHS was maintained, whereas the conformation around (125)Thr-(135)Lys (alpha-helix region) in the conjugates had changed. The emulsifying activity of beta-LG was improved by conjugation with CPO or CHS, and aggregation of beta-LG was suppressed by conjugation with CHS. Reduction of the antigenicity and immunogenicity of beta-LG was achieved by conjugation with CHS.