Study of water quality distribution in Lake Biwa in consideration of runoff pollutant loads from its catchment basin.

Many strategies for water quality conservation in Lake Biwa are being carried out mainly by reducing runoff pollutant loads into the lake. But influence of the runoff load reduction on the water quality in Lake Biwa has not been clarified enough so far. This study is aimed at discussing methodology to estimate water quality distribution in Lake Biwa using runoff pollutant loads from its basin. The runoff loads from the basin are calculated by Macro Model with GIS database of the Lake Biwa basin, and the water quality distribution in the lake is estimated by the spline technique with the calculated runoff loads. As a result, it has been proved that the methodology has enough reproducibility to estimate the water quality distribution in Lake Biwa and is available to examine the water quality in the lake.

The presence of giant granules in the juxtaglomerular cells of beige rats may affect plasma renin activity and blood pressure.

Chediak-Higashi syndrome (CHS) is an autosomal recessive disorder, characterized histopathologically by giant granules in various cells. Since little is known about the juxtaglomerular (JG) cells of CHS, the present study was undertaken as a morphological investigation of the JG cell of Beige rats, which were found to be a new animal model of CHS. In addition, we measured the blood pressure and plasma renin activity. The blood pressure of Beige rats is similar to that of DA rats, the mother strain of Beige rats. However, the plasma renin activity of Beige rats increases with age, whereas that of DA rats decreases. Morphologically, JG cells of Beige rats gave no evidence of hyperplasia and hypertrophy. The most conspicuous change was a small number of giant JG granules. Ultrastructurally, JG granules of Beige rats were large, irregular, and varied in size at 2 months of age, but no age-dependent changes were detected. These results suggested that giant JG granule formation slightly increases renin release with age, but does not affect blood pressure.