| 1. |
- Andersson, Anders G., et al.
(författare)
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A numerical study of the location and function of the entrance of a fishway in a regulated river
- 2010
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Ingår i: 8th International Symposium on ECOHYDRAULICS. ; , s. 277-284
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Konferensbidrag (refereegranskat)abstract
- Simulation driven design with Computational Fluid Dynamics has been used to evaluate the flow downstream a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations and the tailrace jet from the turbines is stronger in the simulations. The simulations are however considered to capture the important features of the flow in a way that makes them viable for attraction water simulations. A fishway entrance was included in the simulations and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.
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| 2. |
- Andersson, Anders G., et al.
(författare)
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A study of the location of the entrance of a fishway in a regulated river with CFD and ADCP
- 2012
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Ingår i: Modelling and Simulation in Engineering. - : Hindawi Limited. - 1687-5591 .- 1687-5605. ; 2012
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Tidskriftsartikel (refereegranskat)abstract
- Simulation-driven design with computational fluid dynamics has been used to evaluate the flow downstream of a hydropower plant with regards to upstream migrating fish. Field measurements with an Acoustic Doppler Current Profiler were performed, and the measurements were used to validate the simulations. The measurements indicate a more unstable flow than the simulations, and the tailrace jet from the turbines is stronger in the simulations. A fishway entrance was included in the simulations, and the subsequent attraction water was evaluated for two positions and two angles of the entrance at different turbine discharges. Results show that both positions are viable and that a position where the flow from the fishway does not have to compete with the flow from the power plant will generate superior attraction water. Simulations were also performed for further downstream where the flow from the turbines meets the old river bed which is the current fish passage for upstream migrating fish. A modification of the old river bed was made in the model as one scenario to generate better attraction water. This considerably increases the attraction water although it cannot compete with the flow from the tailrace tunnel.
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| 3. |
- Bin Asad, S M Sayeed, 1985-, et al.
(författare)
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Wall shear stress measurement on curve objects with PIV in connection to benthic fauna in regulated rivers
- 2019
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Ingår i: Water. - : MDPI. - 2073-4441. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- The flow characteristics in the vicinity of a set of half-cylinders of different sizes simulating benthic objects were studied experimentally using particle image velocimetry (PIV). The cylinders were mounted on the bottom of an open channel, and the influence of the flow speed on the distribution of the shear stress along the bottom geometry was investigated. Of special interest was how the shear stress changes close to the wall as a function of the flow speed and cylinder arrangement. It was found that the shear stress varies significantly as a function of position. This implies habitat heterogeneity allowing benthic invertebrates with different shear stress tolerance exists when the bottom consists of differently sized stones. It was also shown that direct measurements of near wall velocity gradients are necessary to accurately calculate the wall shear stress for more complex geometries.
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| 4. |
- Ferguson, J.W., et al.
(författare)
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Combining turbine blade-strike and life cycle models to assess mitigation strategies for fish passing dams
- 2008
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - 0706-652X .- 1205-7533. ; 65:8, s. 1568-1585
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Tidskriftsartikel (refereegranskat)abstract
- The combined model produced a tool for evaluating effects on fish populations from passage through hydro-power turbines at dams. Mean blade-strike mortality was higher for adult Atlantic salmon (Salmo salar) and sea-run brown trout (Salmo trutta) (25.2%-45.3%) than for juveniles (5.3%-9.7%). Based on life cycle modeling, salmon populations in two Swedish rivers responded differently to strategies for mitigating mortality caused by fish striking turbine blades. Although population growth rates increased up to 3% and were relatively similar for both rivers. the relative increase in the number of female salmon escaping above a dam annually after 20 years when both juveniles and adults were protected was greater in the River Pitealven (68%) than in the River Vindelalven (46%) and was approximately four times greater in the River Pitealven (38% vs. 10%) when only adults were protected. These population responses were not predicted by estimates of mortality through turbines. They showed the model could be used to evaluate strategies to conserve fish populations affected by dams located in fish migratory corridors and how postspawn adults contributed to population productivity.
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| 5. |
- Holmberg, M, et al.
(författare)
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The species-specific differences in the cAMP regulation of the tissue-type plasminogen activator gene between rat, mouse and human is caused by a one-nucleotide substitution in the cAMP-responsive element of the promoters.
- 1995
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Ingår i: European Journal of Biochemistry. - 0014-2956 .- 1432-1033. ; 231:2, s. 466-74
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Tidskriftsartikel (refereegranskat)abstract
- In rat ovarian cells tissue-type plasminogen activator (tPA) is induced by gonadotropins, by a cAMP-dependent pathway and the induction correlates with the time of follicle rupture in vivo. However, in mice, gonadotropins induce the related but distinct protease urokinase-type plasminogen activator (uPA). Comparison of rat, mouse and human tPA genes reveal that there is a species-specific difference in the promoter that could explain the difference in regulation of the tPA gene between these species. At the position where the rat promoter contains a consensus cAMP-responsive element (CRE), the mouse and human counterparts contains a CRE variant with a one-nucleotide substitution. Transient transfection experiments of rat glial and granulosa cells demonstrated that reporter constructs driven by rat but not mouse or human tPA promoters were efficiently induced by the cAMP-inducing agents forskolin or follicle-stimulating hormone. Following the conversion of the mouse and human CRE-like sequences to rat consensus CRE these promoters became cAMP responsive. In contrast the rat promoter, following conversion of the consensus CRE to the corresponding mouse and human CRE-like sequence, lost the ability to efficiently respond to cAMP. Deoxyribonuclease I footprinting analysis and electrophoretic mobility shift assays were used to examine interactions of nuclear factors with the consensus and variant CRE. Compared to rat CRE, the mouse and human CRE-like sequences had a drastically reduced binding affinity for a nuclear factor identified as the cAMP-responsive element binding protein. Thus the inability of the mouse and human tPA promoters to respond efficiently to forskolin and follicle-stimulation hormone seem to be due to the inability of these CRE-like sequences to efficiently bind transcription factor CRE binding protein.
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| 6. |
- Hägglund, A C, et al.
(författare)
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Regulation and localization of matrix metalloproteinases and tissue inhibitors of metalloproteinases in the mouse ovary during gonadotropin-induced ovulation.
- 1999
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Ingår i: Endocrinology. - 0013-7227 .- 1945-7170. ; 140:9, s. 4351-8
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Tidskriftsartikel (refereegranskat)abstract
- At the time of ovulation, proteolytic degradation of the follicular wall is required to release the mature oocyte. Extracellular proteases, such as serine proteases and matrix metalloproteinases (MMPs), are thought to play important roles in this process. In this study we have examined the regulation of 11 MMPs and 3 tissue inhibitors of metalloproteinases (TIMPs) during gonadotropin-induced ovulation in the mouse. Northern blot hybridization showed that messenger RNA for several MMPs and TIMPs, including gelatinase A, MT1-MMP, stromelysin-3, MMP-19, TIMP-1, TIMP-2, and TIMP-3, were present at detectable levels in the mouse ovary. In addition, ovarian extracts contained gelatinolytic activities corresponding to the inactive proforms of gelatinase A and gelatinase B. Most of the MMPs and TIMPs were expressed at a constitutive level throughout the periovulatory period. However, MMP-19 and TIMP-1 revealed a different expression pattern; they were both induced 5-10 times by hCG and reached their maximum levels at 12 h after hCG treatment, corresponding to the time of ovulation. At this time point, MMP-19 and TIMP-1 messenger RNA were localized to the granulosa and thecal-interstitial cells of large preovulatory and ovulating follicles. This temporal and spatial regulation pattern suggests that MMP-19 might be involved in the tissue degradation that occurs during follicular rupture and that TIMP-1 could have a role in terminating MMP activity after ovulation.
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| 7. |
- Leonardsson, G, et al.
(författare)
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Characterisation of the rat tissue-type plasminogen activator gene promoter -- identification of a TAAT-containing promoter element.
- 1997
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Ingår i: European Journal of Biochemistry. - 0014-2956 .- 1432-1033. ; 248:3, s. 676-83
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Tidskriftsartikel (refereegranskat)abstract
- Tissue-type plasminogen activator (tPA) activates plasminogen to the active protease plasmin and is implicated in many biological processes that require extracellular proteolysis. In rat ovarian cells, gonadotropins induce the tPA gene by a cAMP-dependent pathway and this induction correlates with the time of follicular rupture. We have previously identified several promoter elements within the first 621 bp of the rat tPA promoter that are important for constitutive and cAMP-induced expression of the gene, including a cAMP responsive element (CRE), a nuclear factor 1 (NF1) element, a SP1-binding site and a G+C-rich box. In this report we have extended our study by analysing promoter constructs, ranging in size from 7.7 kb to 135 bp fused to the luciferase reporter gene. Transient transfection analysis of rat granulosa cells and human 293 cells, reveal that the proximal 268 bp of the promoter is enough to confer high basal and cAMP-induced expression of the gene. At position -162 to -172, between the previously identified CRE and NF1 sites, a novel TAAT-containing promoter element was identified. Mutational inactivation of the TAAT motif indicates that this element is important for both constitutive and cAMP-induced expression of the gene, and for the binding of a presumably novel nuclear factor that we have termed tPA promoter factor-1 (tPF-1).
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| 8. |
- Leonardsson, G, et al.
(författare)
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Ovulation efficiency is reduced in mice that lack plasminogen activator gene function : functional redundancy among physiological plasminogen activators.
- 1995
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 92:26, s. 12446-50
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Tidskriftsartikel (refereegranskat)abstract
- Several lines of indirect evidence suggest that plasminogen activation plays a crucial role in degradation of the follicular wall during ovulation. However, single-deficient mice lacking tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), or PA inhibitor type 1(PAI-1) gene function were recently found to have normal reproduction, although mice with a combined deficiency of tPA and uPA were significantly less fertile. To investigate whether the reduced fertility of mice lacking PA gene function is due to a reduced ovulation mechanism, we have determined the ovulation efficiency in 25-day-old mice during gonadotropin-induced ovulation. Our results reveal that ovulation efficiency is normal in mice with a single deficiency of tPA or uPA but reduced by 26% in mice lacking both physiological PAs. This result suggests that plasminogen activation plays a role in ovulatory response, although neither tPA nor uPA individually or in combination is obligatory for ovulation. The loss of an individual PA seems to be functionally complemented by the remaining PA but this compensation does not appear to involve any compensatory up-regulation. Our data imply that a functionally redundant mechanism for plasmin formation operates during gonadotropin-induced ovulation and that PAs together with other proteases generate the proteolytic activity required for follicular wall degradation.
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| 9. |
- Lindberg, Dan-Erik, et al.
(författare)
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Methods for locating the proper position of a planned fishway entrance near a hydropower tailrace
- 2013
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Ingår i: Limnologica. - : Elsevier BV. - 0075-9511 .- 1873-5851. ; 43:5, s. 339-347
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distribution of upstream migrating Atlantic salmon (Salmo salar) spawners was studied in 2008 and 2009 in the surroundings of the tailrace from a hydropower station in the River Umeälven. This area is problematic because the fish have difficulties finding their way into the original riverbed, which prompted an investigation on the feasibility of adding a fishway in the area. Echo sounding was used in 2008 to investigate the spatial use of fish in the tailrace channel during the time of salmon migration. Presence of other fish species was so low that all echo sounding detections were assumed to be salmon. In 2009, data on wild radio-tagged salmon (n = 94) was collected in the same tailrace by an array of underwater antennas with a detection radius of approximately 10 m, to validate the results from the echo sounding. Both types of surveys showed aggregations of fish in one part of the tailrace. As a final step, Computational Fluid Dynamics (CFD) modeling was performed to analyze hydrodynamics. This CFD modeling showed a coincidence of fish detections in areas with turbulence intensities between 0.6 and 0.8, which may be an indication that the fish are holding in these areas to reduce energy expenditure during migration. A high proportion of the radio-tagged salmon were observed in the tailrace area (a median of 21 days between their first and last detection), indicating that the salmon are delayed in their upstream migration by the attraction to the tailrace in this area. The overall data on fish behavior in the tailrace led us to suggest a location for a new fishway where the fish aggregation was most pronounced. The number of detections from either technology had similar distributions over the tailrace, suggesting that the results are comparable. Thus, the split beam echo sounder can preferably be used to investigate which location is most appropriate for locations of entrances to new fishways since many more individual fishes are covered by this method compared to telemetry. Furthermore, there is no need to handle the fish in the echo sounding studies as is required in telemetry studies
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| 10. |
- Ny, A, et al.
(författare)
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Ovulation in plasminogen-deficient mice.
- 1999
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Ingår i: Endocrinology. - 0013-7227 .- 1945-7170. ; 140:11, s. 5030-5
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Tidskriftsartikel (refereegranskat)abstract
- Many different studies suggest that plasmin generated from plasminogen plays a crucial role in the degradation of the follicular wall at the time of ovulation. We have assessed the physiological relevance of plasmin on ovulation by studying plasminogen-deficient mice. Ovulation efficiency (mean number of ova released per mouse) was determined both in a standardized ovulation model in which 25-day-old immature mice were injected with finite amounts of gonadotropins to induce ovulation and during physiological ovulation using adult normally cycling mice. Our results revealed that the temporal onset of follicular wall rupture (first ova observed in bursa or oviduct) was not delayed in plasminogen-deficient mice during gonadotropin-induced ovulation. However, there was a trend toward slightly reduced ovulation efficiency in the plasminogen-deficient mice. This reduction was only 13% and not statistically significant (P = 0.084) and may be connected to a delayed maturation of these mice manifested in reduced body and ovary weights. During physiological ovulation adult plasminogen-deficient mice had normal ovulation efficiency compared with plasminogen wild-type mice. Taken together our results indicate that under the conditions used in this study plasmin is not required for efficient follicular rupture or for activation of other proteases involved in this process. Alternatively, the role of plasmin may be effectively compensated for by other mechanisms in the absence of plasmin.
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