Distributed Water Balance Model in Watershed Coupling with Dynamic and Diffusive River Flow Routing

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

長良川河口堰が汽水域生息場の特性に与えた影響に関する研究

1)河口堰の建設、扉門を全閉するという運用により汽水域が消滅した。河口堰建設前には淡水域、汽水域、海水域と連続的に変化していたものが、河口堰を境に上流側は淡水域、下流側はほぼ海水域と考えてよい状態となった事がわかった。5年間のモニタリング結果を精査することにより、堰下流側の塩分分布の変化、堰上下流における汽水性魚種の消失により実証されたといえる。2)長良川下流域に生息する魚類の種数や個体数には大きな変化はなかったが、94〜97年と98〜99年の種組成を比較すると、記録された全94種のうち16種が消失し19種が新たに出現しており、全体の37%が入れ代わったことがわかった。特に、淡水域と汽水域の境界に分布域の中心をもつグループが河口堰の影響を強く受けたことがわかった。3)河口域に共通な溶存酸素の変化様式は、大潮、小潮のサイクルに支配されて貧酸素化になったり、また回復したりという現象を繰り返している。それに重畳して、河川の洪水が時々攪乱的に溶存酸素を変化させる要因になっている。大規模な河川の出水は河道をフラッシュするので溶存酸素が回復するが、これは一時的であり、すぐその後で大規模な循環流を引き起こして貧酸素水塊が海から河川域に侵入し、溶存酸素が急に低下するような現象が見られる。長良川と伊勢湾とはこうした関係にあることが分かった。4)浮遊藻類相とその密度の変動から、湛水の滞留日数が長期化し、滞流水域に特徴的な河川棲浮遊藻類の増殖が生じたものと判断された。河口堰の建設後、低流量の時期、特に晩春から秋にかけて頻繁な浮遊藻類の発生が認められた。優占的な種類は、中心珪藻類である。河川軸に沿う藻類の分布は、流量によって変化する増殖と沈降の速度により決定されるので、空間的な分布に注意すべきである。Major results obtained by this research group are summarized as follows.1) Exhaustive study both on five-year monitoring data and other existing field data clarified a present situation that the upstream of the Barrage is fresh water zone and the downstream of the Barrage is sea water zone with no blackish zone. Salinity distribution downstream of the Barrage changed from mixed type to fully mixed type almost all days through a year.2) Recorded total number of fish species is 94 within which 16 species disappeared and 19 species appeared newly during 1994 through 1999. Altered ratio of fish species amounted to 37% and especially blackish species were affected greatly to disappear.3) A major component that governs the dissolved oxygen concentration in an estuary is a tidal cycle with disturbance of floods. Large floods recover DO concentration but bring about low DO conditions after floods by the intrusion of anoxic water body from Ise Bay.4) Complete mixing including the bottom water did not occur every day, maintaing temporary thermal stratification for a few days in summer. Judging from the rapid oxygen consumption rate by the water column, such temporary thermal stratifications could cause frequent oxygen deficits in the impoundment of the Barrage in summer.研究課題/領域番号:13305035, 研究期間(年度):2001-2002出典：「長良川河口堰が汽水域生息場の特性に与えた影響に関する研究」研究成果報告書　課題番号13305035 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）)　　　本文データは著者版報告書より作

Regulation of hepatitis C virus secretion by the Hrs-dependent exosomal pathway

AbstractThe molecular mechanisms of assembly and budding of hepatitis C virus (HCV) remain poorly understood. The budding of several enveloped viruses requires an endosomal sorting complex required for transport (ESCRT), which is part of the cellular machinery used to form multivesicular bodies (MVBs). Here, we demonstrated that Hrs, an ESCRT-0 component, is critical for the budding of HCV through the exosomal secretion pathway. Hrs depletion caused reduced exosome production, which paralleled with the decrease of HCV replication in the host cell, and that in the culture supernatant. Sucrose-density gradient separation of the culture supernatant of HCV-infected cells revealed the co-existence of HCV core proteins and the exosome marker. Furthermore, both the core protein and an envelope protein of HCV were detected in the intraluminal vesicles of MVBs. These results suggested that HCV secretion from host cells requires Hrs-dependent exosomal pathway in which the viral assembly is also involved

The AAA-ATPase VPS4 Regulates Extracellular Secretion and Lysosomal Targeting of α-Synuclein

Many neurodegenerative diseases share a common pathological feature: the deposition of amyloid-like fibrils composed of misfolded proteins. Emerging evidence suggests that these proteins may spread from cell-to-cell and encourage the propagation of neurodegeneration in a prion-like manner. Here, we demonstrated that α-synuclein (αSYN), a principal culprit for Lewy pathology in Parkinson's disease (PD), was present in endosomal compartments and detectably secreted into the extracellular milieu. Unlike prion protein, extracellular αSYN was mainly recovered in the supernatant fraction rather than in exosome-containing pellets from the neuronal culture medium and cerebrospinal fluid. Surprisingly, impaired biogenesis of multivesicular body (MVB), an organelle from which exosomes are derived, by dominant-negative mutant vacuolar protein sorting 4 (VPS4) not only interfered with lysosomal targeting of αSYN but facilitated αSYN secretion. The hypersecretion of αSYN in VPS4-defective cells was efficiently restored by the functional disruption of recycling endosome regulator Rab11a. Furthermore, both brainstem and cortical Lewy bodies in PD were found to be immunoreactive for VPS4. Thus, VPS4, a master regulator of MVB sorting, may serve as a determinant of lysosomal targeting or extracellular secretion of αSYN and thereby contribute to the intercellular propagation of Lewy pathology in PD

Modelling of the moisture and heat flux at the vegetated landsurface

The moisture and heat transfer in the SPAC' are studied by establishing a coupled full-interacting physical SPAC model. A vegetation model which preserves the essential mechanisms is employed to describe the vegetation as simply as possible. The required input data in atmosphere are limited to only four, being net radiation, wind speed, vapor pressure, and air temperature, so that the present method can be easily applied in practical problems. Finally, the present model is verified by a field observation

Diffusion of suspended load in unsteady open-channel flows

After a brief survey of the major theories on suspended-load diffusion under different flow conditions, we present here an analytical study on the diffusion of suspended load in unsteady open-channel flows. The histograms of suspended load and of flow discharge in rivers are examined, and the concept of sediment-wave celerity is introduced. It is noted that discussed here is but a small and humble step toward understanding the much complex phenomenon of suspended-load diffusion in unsteady flows