Changes in Water network Management since the Meiji Era and Issues Regarding Disaster Prevention at the Foot of Mt. Hira in Shiga Prefecture, Japan

In considering Eco-DRR, it is important to use resources and disaster prevention techniques that make the most of the unique ecosystems of each region. The purpose of this study was to analyze the changes in the water network and its management methods since the Meiji period in Minamikomatsu, Otsu City, located at the foot of Mt. Hira. Based on a literature survey of maps and documents stored in Minamikomatsu, interviews, and field surveys, a water network map was created for each period, and the changes in the management of the water network and issues related to disaster prevention were analyzed. As a result, we were able to confirm the traditional wisdom and techniques of water use and drainage by controlling water intake. On the other hand, the system of water network management has changed with the development of government, agriculture, tourism, and residential areas, and integrated management has become difficult. In addition, changes in the shape and flow of waterways and their disappearance have impeded and fragmented the flow in downstream areas, creating problems for disaster prevention. In the future, it will be important to secure and regenerate the continuity of water networks for watershed basin water control, and to establish a comprehensive water network management system

Postnatal lethality and chondrodysplasia in mice lacking both chondroitin sulfate N-acetylgalactosaminyltransferase-1 and -2

Chondroitin sulfate (CS) is a sulfated glycosaminoglycan (GAG) chain. In cartilage, CS plays important roles as the main component of the extracellular matrix (ECM), existing as side chains of the major cartilage proteoglycan, aggrecan. Six glycosyltransferases are known to coordinately synthesize the backbone structure of CS; however, their in vivo synthetic mechanism remains unknown. Previous studies have suggested that two glycosyltransferases, Csgalnact1 (t1) and Csgalnact2 (t2), are critical for initiation of CS synthesis in vitro. Indeed, t1 single knockout mice (t1 KO) exhibit slight dwarfism and a reduction in CS content in cartilage compared with wild-type (WT) mice. To reveal the synergetic roles of t1 and t2 in CS synthesis in vivo, we generated systemic single and double knockout (DKO) mice and cartilage-specific t1 and t2 double knockout (Col2-DKO) mice. DKO mice exhibited postnatal lethality, whereas t2 KO mice showed normal size and skeletal development. Col2-DKO mice survived to adulthood and showed severe dwarfism compared with t1 KO mice. Histological analysis of epiphyseal cartilage from Col2-DKO mice revealed disrupted endochondral ossification, characterized by drastic GAG reduction in the ECM. Moreover, DKO cartilage had reduced chondrocyte proliferation and an increased number of apoptotic chondrocytes compared with WT cartilage. Conversely, primary chondrocyte cultures from Col2-DKO knee cartilage had the same proliferation rate as WT chondrocytes and low GAG expression levels, indicating that the chondrocytes themselves had an intact proliferative ability. Quantitative RT-PCR analysis of E18.5 cartilage showed that the expression levels of Col2a1 and Ptch1 transcripts tended to decrease in DKO compared with those in WT mice. The CS content in DKO cartilage was decreased compared with that in t1 KO cartilage but was not completely absent. These results suggest that aberrant ECM caused by CS reduction disrupted endochondral ossification. Overall, we propose that both t1 and t2 are necessary for CS synthesis and normal chondrocyte differentiation but are not sufficient for all CS synthesis in cartilage