Hiroko Isoda

Effect of nitrate and phosphate concentration on production of microcystins by Microcystis viridis NIES 102

The effects of nitrate and phosphate concentrations on the production of three microcystins, namely, types LR, RR and YR by Microcystis viridis NIES 102, were determined in batch culture experiments at in situ level concentrations. The yield of microcystin-RR during the exponential growth phase increased favorably in nitrate concentrations ranging from 0.2 to 0.8 mg l -1 of NO 3 -N. The effect plateaued at 1.0 mg l -1 . This tendency was similar to the effect of nitrate on the specific growth rate. There was no significant correlation between the amounts of intracellular microcystins at exponential growth phase and nitrate concentrations. On the other hand, the specific growth rate was constant regardless of the phosphate concentrations. However, the yield of the three types of microcystins in the culture broth and the amounts of intracellular microcystins decreased with increasing the phosphate concentration. Furthermore, it was found that the correlation between total yield of microcystins (LR, RR and YR) and the ratio of microcystins during the exponential growth phase showed almost constant values, as follows: microcystin LR (0.24), RR (0.66) and YR (0.10).

Analysis of the mechanism of the tight-junctional permeability increase by capsaicin treatment on the intestinal Caco-2 cells.

In a previous experiment (Isoda et al., 2001), we showed that the tight-junctional (TJ) permeability increase in Caco-2 cells during capsaicin exposure was through binding of the capsaicin molecule to a capsaicin receptor-like protein. In the present study, we examined how actin, which modulates TJ permeability, is influenced by capsaicin. We showed that after treatment of the Caco-2 cells with capsaicin, the volume of F-actin decreased. Moreover, we also examined protein kinase C (PKC) and heat shock protein 47 (HSP47), which act as probable second messengers in causing TJ permeability increase. We showed that after capsaicin treatment, HSP47 was activated. However, PKC activity was the same in both control and treatment setups. These results suggest that, while PKC is not involved, it is highly possible that HSP47plays a role in TJ permeability increase in intestinal Caco-2 cells exposed to capsaicin.

Proteomic analysis of changes in excitable and non-excitable cells exposed to DC electric fields of physiological strength

In life sciences, many studies show that electric fields mediate very important roles in cellular functions and it is becoming clearer that such fields might play a much deeper and more complex role in the functioning of higher organisms as a whole. One way to help understand this role is to study the protein expression changes caused by electric fields. In this study, we use the excitable SH-SY5Y cell line and the non-excitable CaCo-2 cell line to examine the changes in their protein state after exposure to electric fields of physiological strength. Both cells lines were stimulated for 20 min with different voltages ranging from l00mV/cm to lV/cm. Their protein state was studied using the two-dimensional electrophoresis technique. In the experimental set-up, two Controls were used. One control being the in-incubator cell protein state, which is the optimal for cell growth and metabolism, and the other control being same as the stimulation (treatment) set-up, just without voltage applied. The preliminary results show that with both cell lines, in some areas there was a change in the protein state in the second control sample. This is possible since the cells were stimulated at room temperature and the media was not culture medium, but an ionic solution (Tyrode’s). Interestingly, the treatment seems to restore the protein state of the first control in most of these areas. In other areas, some changes in protein pI occur, and in only few areas, there are newly expressed proteins after stimulation. These areas and the corresponding spots will further be analyzed using a broader range IPG strips, and the proteins identified using mass spectrometry.

Development of Functional Foodstaffs Operated by a Liquid Bioreactor of an Edible Fungus

In this study, the evaluation as functional foodstuffs of mycelium and used culture solution obtained from liquid culture of mycelium of Agaricus blazei Murill mushroom was examined. The liquid culture of mycelium was operated using a bioreactor having effective volume of 1L. The maximum duration of culture was about 48 hours after the inoculation. Both harvested mycelium and used liquid culture possessed significant˜-D-glucan content, and the ethanol-extracted product from the harvested mycelium was proved to be highly effective on anti- allergic activity of suppressing the physiological activities of hyaluronidase and ˜-hexosaminidase releasing from rat basophilic leukemia (RBL-2H3) cells stimulated by antigen stimulation. Neurite outgrowth and acetylcholinesterase of rat pheochromocytoma cell line PC12 were also activated by the mycelial extract with hot water and ethanol.