Acyl specificity in glyceride synthesis by lactating rat mammary gland

We have investigated the possibility that the nonrandom association of fatty acids in rat milk triglycerides results from specificity of the acyl transferases in the glycerolphosphate pathway. Subcellular fractionation of lactating rat mammary gland revealed that the microsomal fraction was the most active in acylation of 3-sn-[U-¹⁴C] glycerolphosphate with various acyl-CoA's. The major products were diacylglycerolphosphate and diglyceride; no monoacylglycerolphosphate was detected. Maximum rate of acylation occurred at or below the critical micelle concentration for each acyl-CoA, indicating that only the monomeric substrate molecules were acceptable by the enzyme system. The observed acyl specificity, 16∶0>18∶0≏14∶0>12∶0>10∶0>8∶0 is consistent with the concept that, in general, milk triglycerides are synthesized by insertion of a short or medium chain fatty acid into a long chain diglyceride.     

Isolation and characterization of peroxisomal protein import (Pim−) mutants of Hansenula polymorpha

In the course of our studies on the molecular mechanisms involved in peroxisome biogenesis, we have isolated several mutants of the methylotrophic yeast Hansenula polymorpha impaired in the import of peroximal matrix proteins. These mutants are characterized by the presence of small intact peroxisomes, while the bulk of the peroxisomal matrix protein is not imported and resides in the cytosol (Pim^? phenotype). Genetic analysis of back-crossed mutants revealed five different complementation groups, which were designated PERI–PER5. Mapping studies to determine the linkage relationships indicated that the observed Pim^? phenotypes were determined by single recessive nuclear mutations. The different mutants had comparable phenotypes: (i) they were impaired to utilize methanol as the sole source of carbon and energy but grew well on various other compounds, including nitrogen sources, the metabolism of which is known to be mediated by peroxisome-borne enzymes in wild-type cells; (ii) all peroxisomal enzymes tested were induced, assembled and activated as in wild-type cells although their activities varied between the different representative mutants; (iii) all peroxisomal proteins, whether constitutive or inducible, were found both in the cytosol and in the small peroxisomes. These results suggest that a general, major import mechanism is affected in all mutants.     

Reaction Sintering of Polycarbosilane-Impregnated Compact of Silicon Carbide Hollow Particles and the Resultant Thermoelectric Properties

Porous SiC ceramics fabricated from hollow particles and polycarbosilane (PSC) are promising materials for high-temperature thermoelectric energy conversion. Reaction sintering of PCS-impregnated compacts of SiC hollow particles gave rise to porous microstructures with the hollow shape remaining. The repetition of the PCS-impregnation and sintering process resulted in only a slight increase in density but in a great improvement in thermoelectric properties.     

Effects of lipase,lipoxygenase, peroxidase and free fatty acids on volatile compound found in boiled buckwheat noodles

BACKGROUND: Relationships between buckwheat (Fagopyrum esculentum Moench) flour lipase, lipoxygenase and peroxidase activity, along with levels of individual free fatty acids (FFAs) and levels of headspace volatile compounds of boiled buckwheat noodles, were investigated for 12 different buckwheat varieties. Enzyme activities and FFA levels in flour were correlated with their respective varietal arrays of boiled noodle headspace volatile compounds, measured by gas chromatography–mass spectrometry. RESULTS: The volatiles hexanal, tentative butanal, tentative 3‐methylbutanal and tentative 2‐methylbutanal showed significant positive correlation with one another, indicating that they may be generated through similar mechanisms. These important volatile components of buckwheat flavor were also positively correlated with lipase and/or peroxidase activity, indicating that enzymatic reactions are important in flavor generation in boiled buckwheat noodles. On the other hand, pentanal, which showed no significant correlation with any enzyme activity, showed a significant positive correlation to the levels of C18:2 and C18:3 FFAs, suggesting the existence of a ‘non‐enzymatic’ and/or ‘uncertain enzymatic pathway’ for flavor generation in boiled buckwheat noodles. CONCLUSION: Lipase and peroxidase in buckwheat flour are important for flavor generation of boiled buckwheat noodles. This information is important for increasing desirable flavor of buckwheat products as well as for selecting varieties with improved flavor. Copyright © 2010 Society of Chemical Industry     

Fast ion charge exchange spectroscopy adapted for tangential viewing geometry in LHD

A tangential Fast Ion Charge eXchange Spectroscopy is newly applied on a Large Helical Device (LHD) for co/countercirculating fast ions, which are produced by high energy tangential negative-ion based neutral beam injection. With this new observation geometry, both the tangential-neutral beam (NB) and a low-energy radial-NB based on positive ions can be utilized as probe beams of the measurement. We have successfully observed Doppler-shifted H-alpha lights due to the charge exchange process between the probing NB and circulating hydrogen ions of around 100 keV in LHD plasmas.     

Note: Unshielded bilateral magnetoencephalography system using two-dimensional gradiometers

Magnetoencephalography (MEG) noninvasively measures neuronal activity with high temporal resolution. The aim of this study was to develop a new type of MEG system that can measure bilateral MEG waveforms without a magnetically shielded room, which is an obstacle to reducing both the cost and size of an MEG system. An unshielded bilateral MEG system was developed using four two-dimensional (2D) gradiometers and two symmetric cryostats. The 2D gradiometer, which is based on a low-T(c) superconducting quantum interference device and wire-wound pickup coil detects a magnetic-field gradient in two orthogonal directions, or ?/?x(?(2)B(z)/?z(2)), and reduces environmental magnetic-field noise by more than 50 dB. The cryostats can be symmetrically positioned in three directions: vertical, horizontal, and rotational. This makes it possible to detect bilateral neuronal activity in the cerebral cortex simultaneously. Bilateral auditory-evoked fields (AEF) of 18 elderly subjects were measured in an unshielded hospital environment using the MEG system. As a result, both the ipsilateral and the contralateral AEF component N100m, which is the magnetic counterpart of electric N100 in electroencephalography and appears about 100 ms after the onset of an auditory stimulus, were successfully detected for all the subjects. Moreover, the ipsilateral P50m and the contralateral P50m were also detected for 12 (67%) and 16 (89%) subjects, respectively. Experimental results demonstrate that the unshielded bilateral MEG system can detect MEG waveforms, which are associated with brain dysfunction such as epilepsy, Alzheimer's disease, and Down syndrome.     

Electrical Properties of Isotropic Conductive Adhesives Composed of Silicone-Based Elastomer Binders Containing Ag Particles

The electrical properties of isotropic conductive adhesives (ICAs) with two different types of silicone-based binder containing Ag particles were examined. The ICAs were printed on glass substrates in order to prepare specimens for evaluating the electrical properties. In the case of adhesives containing a denatured silicone binder, both the curing and cooling steps in the isothermal curing process generated electrical conductivity. Adhesives that were cured at 120°C to 200°C exhibited similar values of electrical resistivity regardless of the different curing temperatures. By contrast, electrical conductivity was generated only during the cooling step when adhesives containing a dimethyl methylvinyl siloxane were isothermally cured. In this case, adhesives cured above 160°C exhibited high electrical resistivity. In evaluating the temperature dependence of the electrical resistivity, we found physical annealing to have significantly different effects on these specimens. In addition, we were able to make small sensitive variations in the properties of silicone-based ICAs by controlling the isothermal annealing and thermal cycling processes.     

Monitoring biofilm development in a microfluidic device using modified confocal reflection microscopy

The feasibility of a method to monitor biofilm development non-destructively in a microfluidic device was addressed. Here, we report that biofilm growth could be non-destructively monitored by an image analysis technique based on modification of confocal reflection microscopy.