The effects of operations to increase nitrogen discharge from sewage treatment plants to prevent oligotrophication at Harima-nada in the Seto Inland Sea on concentrations of organic matter, nitrogen, and phosphorus in surface water were evaluated. First, the sea waters around the Futami treatment center, which has been conducting the operation, were analyzed. The results show that no significant changes in water quality were observed during the operation. Next, the effects of the operations of 20 sewage treatment plants at Harima-nada on the water quality were simulated using a numerical simulation model. As a result, it was estimated that dissolved inorganic nitrogen and phosphorus were taken up by phytoplankton, and organic matter and nitrogen concentrations in the entire area of Harima-nada were increased by phytoplankton advection and diffusion. The observed values could not confirm the effect of the operation to increase nitrogen discharge at the Futami treatment center owing to dilution by seawater and the drainages of other nitrogen emission sources. However, it was shown that when the number of operations to increase nitrogen discharge from sewage treatment plants increased, the water quality in a wide area of Harima-nada may be affected.

Increased permeability of vascular endothelial cells in the brain is an underlying cause of stroke, which is associated with high mortality rates worldwide. Vascular permeability is regulated by tight junctions (TJs) formed by claudin family and occludin proteins. In particular, increased vascular permeability is associated with decreased claudin domain-containing 1 (CLDND1) expression, which belongs to the TJs family. We previously reported that myeloid zinc finger 1 (MZF1) acts as an activator of CLDND1 expression by binding to its first intron. Several transcription factors regulate transcription by acting on the promoter regions of target genes. However, transcription factors acting on the promoter of CLDND1 are not completely elucidated. Thus, we focused on the promoter region of human CLDND1 to identify factors that could regulate its transcription. Reporter analysis of CLDND1 promoter region revealed an enhancer in the-742/-734 region with MZF1 and specificity protein 1 (SP1) binding sites. Chromatin immunoprecipitation assays confirmed that both MZF1 and SP1 could bind to CLDND1 enhancer region. MZF1 overexpression significantly increased CLDND1 expression, whereas overexpression of SP1 had no effect. Moreover, the identified enhancer region exhibited stronger transcriptional and binding capacity than the first intron. Thus, CLDND1 expression is more strongly regulated by competitive action of MZF1 and SP1 binding to the promoter-enhancer region than the first intron silencer region. These results provide novel insights for the development of potential therapies and preventive strategies for stroke in the future.

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Harima-Nada region, located in the east of Seto Inland Sea, is a semi-enclosed sea-area next to Osaka Bay that has been suffering a sustained oligotrophication process during the past 25 years. A hydrogeological model, coupled with a water quality model, was applied to assess the numerical discharge of freshwater and total nitrogen (TN) load from rivers into the sea. The model was validated for the main rivers from the northern and southern regions (the Kako River and the Yoshino River, respectively). The obtained results showed that the main contribution of freshwater and TN load to the sea comes from Hyogo Prefecture Rivers. The type of activities developed on each watershed showed to be substantially more relevant on TN load contribution than the size itself of the considered watershed. For the eight years considered in this study (2009 - 2016), the annual average of TN discharged into Harima-Nada was almost constant, while the volume of discharged freshwater showed more variations. Additionally, the sustained decrement in nitrogen concentration in Harima-Nada seemed not to be directly bonded with riverine TN load, suggesting that nitrogen availability is closely related to sea nutrients mechanisms more than to TN inland contribution.