Water stress is one of the major stresses experienced by cellular systems and can take a number of distinct forms. In response to turgor-related osmotic stress, cells produce compatible solutes that are macromolecule protectants and also counteract the outflow of water from stressed cells. In this report we show that the germination of conidia of Aspergillus nidulans, a sensitive indicator of water stress, in the presence of ethanol is correlated with the intracellular concentration of the compatible solutes glycerol and erythritol, which protect against both osmotic and nonturgor forms of water stress.Cellular systems consist of up to 97% water, so thermodynamic changes in water availability cause fundamental biological stress that can severely impact vital metabolic processes (3). Water stress can be induced by a net loss of water from cells, e.g., due to high levels of extracellular solutes such as NaCl that reduce cell turgor and induce osmotic stress. Cells exposed to such agents are subjected to both reduced turgor and stabilizing effects on macromolecules, which can lead to membrane rigidity and impairment of protein structure (3,16,19,25). Intracellular water activity also may be reduced by chaotropic compounds, such as ethanol, that decrease the strength of hydrogen bonding and other electrostatic interactions and thereby perturb the structure and function of hydrated macromolecules, including nucleic acids, proteins, and lipids.Cells generally respond to osmotic stress by acquiring and/or producing compatible solutes that protect macromolecule structure and at the same time increase the osmotic pressure of the cytoplasm and thereby counteract water loss from cells (1, 3). Our working hypothesis is that these compatible solutes also protect against intracellular water stress due to alterations in the hydration of cellular macromolecules caused by ethanol, a chaotropic solute that does not cause osmotic stress.The ascomycete Aspergillus (Emericella) nidulans is a model microorganism whose genetics and metabolism, including those related to stress and toxicology, have been widely studied. A. nidulans, like most yeast and fungal cells, synthesizes low-molecular-weight polyols, such as glycerol, in response to osmotic stress (3, 21). Our objective in this study was to determine whether increased intracellular levels of glycerol and erythritol affect conidial germination in A. nidulans when the organism is cultured under conditions that reduce cell turgor and induce osmotic stress (e.g., in a high-NaCl environment), as well as those that increase intracellular water stress by reducing the strength of water-macromolecule interactions (e.g., at high ethanol concentrations). MATERIALS AND METHODSOrganism, media, and production of conidia. A culture of A. nidulans (IFO 4342) was obtained from the Institute for Fermentation Osaka (Osaka, Japan) and maintained on potato dextrose agar (PDA; Nissui, Tokyo, Japan) at 25°C. All media were buffered with 21.3 g of 2-(N-morpholino)ethanesulfonic acid (MES) liter Ϫ1 , and...

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In lactic acid fermentation by Lactobacillus delbrueckii, the produced lactic acid affected the lactic acid productivity. Therefore, for the purpose of alleviating this inhibitory effect, an electrodialysis fermentation method which can continuously remove produced lactic acid from the fermentation broth was applied to this fermentation process. As a result, the continuation of fermentation activity was obtained, and the productivity was three times higher than in non-pH-controlled fermentation. In electrodialysis fermentation, the amount of produced lactic acid was 82.2 g/liter, which was about 5.5 times greater than that produced in non-pHcontrolled fermentation. It was concluded that these good results were obtained on account of alleviating the lactic acid inhibitory effect by electrodialysis fermentation. However, the fouling of anion-exchange membranes by cells was observed in electrodialysis fermentation.

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This paper describes a new application of a spin-valve-type giant magnetoresistance sensor in the biomedical field. The hyperthermia treatment, based on the hysteresis loss of magnetite under external ac fields, requires determination of the content density of magnetite injected inside the body to control the heat capacity. We propose a low-invasive methodology to estimate the density of magnetite by measuring magnetic fields inside the cavity. For this purpose, we investigated the relationship between the density of magnetite and the magnetic fields, and developed a needle-type magnetic probe with a giant magnetoresistance sensor for low-invasive measurement. The experimental results demonstrate the possibility of estimating the density of magnetite injected into the body.

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Two types of magnetic bearing systems employing permanent magnets to be used for vertical-shaft and horizontal-shaft machines, respectively, have been designed and fabricated in our laboratory. In this article we report a comparative evaluation of (i) the permanent magnet configuration and its effect on radial disturbance attenuation, (ii) magnetic losses and their effect on energy storage, and (iii) the off-state position of the rotor magnet in two types of bearing systems. Experimental results are presented.