Rick J.A.,University of Minnesota |
Rick J.A.,University of Wyoming |
Moen R.A.,University of Minnesota |
Moen R.A.,Natural Resources Research Institute |
And 2 more authors.
Conservation Genetics | Year: 2017
The genetic effects of harvest may be especially important in species that form social groups, such as gray wolves (Canis lupus). Though much research exists on the ecology and population dynamics of gray wolves, little research has focused on how anthropogenic harvest relates to the genetics of wolf populations. To analyze the short-term genetic consequences of the first two years of public wolf harvest in Minnesota following delisting under the Endangered Species Act, we genotyped harvested individuals at 18 microsatellite loci and quantified changes in population genetic structure and diversity in the first post-harvest year. If the harvest rate was high enough to create detectable genetic changes, population structure and differentiation between clusters could both increase because of decreased natal dispersal and increased disperser mortality, or they could decrease because of increased immigration from outside the population. In the Minnesota population, heterozygosity and allelic richness were not significantly different between years. However, population genetic structure increased and effective migration decreased among the sampled wolves. While the role of anthropogenic harvest in these changes cannot be distinguished from other confounding factors, this analysis suggests that harvest has a non-negligible effect and indicates the need for continued study to determine whether harvest-induced changes in genetic structure affect the evolutionary trajectory of harvested populations. © 2017 Springer Science+Business Media Dordrecht
Hwang Y.P.,Chungnam National University |
Oh K.N.,Natural Resources Research Institute |
Yun H.J.,Chungnam National University |
Yun H.J.,Chosun University |
Jeong H.G.,Chungnam National University
Journal of Dermatological Science | Year: 2011
Background: Ultraviolet (UV) irradiation causes major changes in skin connective tissues as a result of the degradation of collagen, a major structural component of the extracellular matrix. This process is likely mediated by matrix metalloproteinases (MMPs). Such changes in collagenous skin tissues have been suggested to be causes of cutaneous aging and skin cancer. Objective: We investigated the protective effects of apigenin and luteolin on immortalized human keratinocytes (HaCaT) against UVA damage. We then explored the inhibitory effects of apigenin and luteolin on UVA-induced MMP-1 and investigated the molecular mechanism underlying those effects. Methods: HaCaT cells were treated with apigenin and luteolin for the indicated times followed by irradiation with UVA. Those effects were assessed by semi-quantitative PCR, Western blotting and enzymic activity assays. Results: These two compounds, at concentrations of 1-5μM, increased the viability of, and inhibited ROS production in HaCaT cells exposed to UVA irradiation. Pre-treatment of HaCaT cells with apigenin and luteolin also inhibited UVA-induced production of the collagenases MMP-1. They also suppressed UVA-induced expression of c-Jun and c-Fos and the phosphorylation of three MAP kinases, upstream modulators of AP-1. Furthermore, the same two flavonoids decreased the UVA-induced influx of Ca2+ into HaCaT cells and the phosphorylation of Ca2+/calmodulin-dependent kinases (CaMKs). Conclusion: The results indicate that apigenin and luteolin inhibited UVA-induced collagenolytic MMP-1 production by interfering with Ca2+-dependent MAPKs and AP-1 signaling. They may thus be potentially useful in the prevention and treatment of skin photoaging. © 2010 Japanese Society for Investigative Dermatology.
Dumke J.D.,University of Minnesota |
Hrabik T.R.,University of Minnesota |
Brady V.J.,Natural Resources Research Institute |
Gran K.B.,University of Minnesota |
And 2 more authors.
North American Journal of Fisheries Management | Year: 2010
Large sand bed loads in trout stream headwaters can limit salmonid spawning habitat and reproductive success. This phenomenon has been observed in many northern Wisconsin watersheds, where historic logging practices are the likely source of the sediment loading. Presently, sediment transport is limited by abundant woody debris, causing channels to aggrade and bury gravels. We evaluated the impacts of a wood debris and beaver dam removal remediation strategy on fine sediment transport and exposure of the underlying gravel and cobble substrates in a second-order Lake Superior tributary. A 300-m treatment reach received selective wood removals and was compared with both an upstream 300-m reference reach receiving no alteration and a downstream reach to monitor the effects of transferred fine sediment. Physical channel measurements were taken before the wood removal process, with repeat sampling at 10 and 12 months posttreatment. The wood removal treatment resulted in a significant 25% narrowing of mean stream widths, a 32% increase in mean flow velocities, a 58% reduction in the sand bed load, and a 400% increase in the available coarse substrate across the channel. Grain size distributions coarsened noticeably from pre- to posttreatment. Water depth and temperature were not altered by the treatment, and the reference station physical measures were relatively unchanged over the 12-month study period. Immediately after the wood removal there was an observable pulse of sediment traveling through the downstream reach that increased the sand bed load, increased stream widths, and filled pools. However, these impacts diminished with time, and near-preremoval conditions had returned after 12 months. The wood removal treatment caused a significant reduction in sand content and enhanced the availability of salmonid spawning substrates. © American Fisheries Society 2010.
Choi J.H.,Chungnam National University |
Hwang Y.P.,Chungnam National University |
Park B.H.,Chungnam National University |
Choi C.Y.,Natural Resources Research Institute |
And 2 more authors.
Environmental Toxicology and Pharmacology | Year: 2011
During the process of liver fibrosis, hepatic stellate cells (HSCs) play a critical role in the increased formation and reduced degradation of extracellular matrix in the liver. We investigated the anti-proliferative effects of an anthocyanin fraction (AF), isolated from the purple-fleshed sweet potato, on platelet-derived growth factor (PDGF)-BB-dependent signaling pathways in HSC-T6 cells. HSC proliferation plays a pivotal role in liver fibrogenesis. The AF suppressed HSC activation, including PDGF-induced proliferation and α-smooth muscle actin (α-SMA) expression. Additionally, AF inhibited PDGF-BB-induced Akt and ERK1/2 phosphorylation. AF inhibited the phosphorylation level of PDGF receptor-β (PDGFR-β) following PDGF-BB stimulation, providing a mechanism for the inhibition of AF-mediated kinase. These results suggest that AF suppresses HSC proliferation by blocking PDGFR-β signaling, inhibiting Akt and ERK1/2 activation and α-SMA expression. © 2010 Elsevier B.V.
Merten E.,University of Minnesota |
Finlay J.,University of Minnesota |
Johnson L.,Natural Resources Research Institute |
Newman R.,University of Minnesota |
And 2 more authors.
Water Resources Research | Year: 2010
Natural pieces of wood provide a variety of ecosystem functions in streams including habitat, organic matter retention, increased hyporheic exchange and transient storage, and enhanced hydraulic and geomorphic heterogeneity. Wood mobilization is a critical process in determining the residence time of wood. We documented the characteristics and locations of 865 natural wood pieces (>0.05 m in diameter for a portion >1 m in length) in nine streams along the north shore of Lake Superior in Minnesota. We determined the locations of the pieces again after an overbank stormflow event to determine the factors that influenced mobilization of stationary wood pieces in natural streams. Seven of 11 potential predictor variables were identified with multiple logistic regression as significant to mobilization: burial, effective depth, ratio of piece length to effective stream width (length ratio), bracing, rootwad presence, downstream force ratio, and draft ratio. The final model (P < 0.001, r2 = 0.39) indicated that wood mobilization under natural conditions is a complex function of both mechanical factors (burial, length ratio, bracing, rootwad presence, draft ratio) and hydraulic factors (effective depth, downstream force ratio). If stable pieces are a goal for stream management then features such as partial burial, low effective depth, high length relative to channel width, bracing against other objects (e.g., stream banks, trees, rocks, or larger wood pieces), and rootwads are desirable. Using the model equation from this study, stewards of natural resources can better manage in-stream wood for the benefit of stream ecosystems. Copyright 2010 by the American Geophysical Union.
Kwon H.-J.,Korea Research Institute of Bioscience and Biotechnology |
Kwon H.-J.,Seoul National University |
Won Y.-S.,Korea Research Institute of Bioscience and Biotechnology |
Yoon Y.-D.,Natural Resources Research Institute |
And 5 more authors.
Journal of Hepatology | Year: 2011
Background & Aims: Liver regeneration is a complicated process involving a variety of interacting factors. Vitamin D3 up-regulated protein 1 (VDUP1) is a potent growth suppressor that, upon over-expression, inhibits tumor cell proliferation and cell-cycle progression. Here, we investigated the function of VDUP1 in liver regeneration following hepatectomy in mice. Methods: Liver regeneration after 70% partial hepatectomy (PH) was compared in VDUP1 knockout (KO) and wild-type (WT) mice, and the activities of proliferative- and cell-cycle-related signaling pathways were measured. Results: Compared with WT mice, liver recovery was significantly accelerated in VDUP1 KO mice during the first day after PH, in association with increased DNA synthesis. Consistent with this observation, the expression levels of key cell-cycle regulatory proteins, including cyclin D, cyclin E, cyclin-dependent kinase 4 (CDK4), p21, and p27, were markedly altered in the livers of VDUP1 KO mice. Induction of growth factors and activation of proliferative signaling pathway components including extracellular signal-regulated kinase 1/2 (ERK1/2), Akt, glycogen synthase kinase 3β (GSK3β), mammalian target of rapamycin (mTOR), and p70S6 kinase (p70S6K), occurred much earlier and to a greater extent in VDUP1 KO mouse livers. In addition, primary hepatocytes isolated from VDUP1 KO mice displayed increased activation of ERK1/2 and Akt in response to HGF and TGF-α. Conclusions: Our results reveal an important role for VDUP1 in the regulation of proliferative signaling during liver regeneration. Altered activation of genes involved in ERK1/2 and Akt signaling pathways may explain the accelerated growth responses seen in VDUP1 KO mice. © 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.
Aro M.D.,Natural Resources Research Institute |
Wang X.,U.S. Department of Agriculture |
McDonald D.E.,U.S. Department of Agriculture |
Begel M.,U.S. Department of Agriculture
Wood Material Science and Engineering | Year: 2016
Laminated strand lumber (LSL) and laminated veneer lumber (LVL) were thermally modified as a post-treatment at 140°C, 150°C, 160°C, 170°C, and 180°C. The tension modulus of elasticity (MOE) of LSL was not significantly impacted by the treatments, with the 180°C treatment group exhibiting the highest tension MOE (11.8 GPa). The LVL also experienced minimal impacts, with the 150°C treatment group having the highest tension MOE (19.4 GPa) and the 160°C treatment group exhibiting the lowest (17.1 GPa). The maximum tensile strength (MTS) of the LSL and LVL significantly decreased with increasing temperatures, with the control and 180°C treatment groups experiencing the highest and lowest MTS, respectively. The lowest MTS for LSL was 10.8 MPa (180°C treatment), which was 70% lower than the controls. The lowest MTS of the LVL was 24.4 MPa (also at the 180°C treatment), which was a 49% decrease compared to the controls. These results suggest that thermal-modification post-treatments minimally impact tension MOE, but can significantly reduce MTS at higher treatment temperatures. Combined with previous work improving the moisture properties and equilibrium moisture content of thermally modified LSL and LVL, it may be possible to optimize the treatment technique(s) to yield products with desirable properties. © 2016 Informa UK Limited, trading as Taylor & Francis Group
Chizinski C.J.,University of Minnesota |
Chizinski C.J.,University of Nebraska - Lincoln |
Peterson A.,Natural Resources Research Institute |
Hanowski J.,Natural Resources Research Institute |
And 3 more authors.
Forest Ecology and Management | Year: 2011
We compared avian communities among three timber harvesting treatments in 45-m wide even-age riparian management zones (RMZs) placed between upland clearcuts and along one side of first- or second-order streams in northern Minnesota, USA. The RMZs had three treatments: (1) unharvested, (2) intermediate residual basal area (RBA) (targeted goal 11.5m2/ha, realized 16.0m2/ha), and (3) low RBA (targeted goal 5.7m2/ha, realized 8.7m2/ha). Surveys were conducted one year pre-harvest and three consecutive years post-harvest. There was no change in species richness, diversity, or total abundance associated with harvest but there were shifts in the types of birds within the community. In particular, White-throated Sparrows (Zonotrichia albicollis) and Chestnut-sided Warblers (Dendroica pensylvanica) increased while Ovenbirds (Seiurus aurocapilla) and Red-eyed Vireos (Vireo olivaceus) decreased. The decline of avian species associated with mature forest in the partially harvested treatments relative to controls indicates that maintaining an unharvested RMZ adjacent to an upland harvest may aid in maintaining avian species associated mature forest in Minnesota for at least three years post-harvest. However, our observations do not reflect reproductive success, which is an area for future research. © 2011 Elsevier B.V.
News Article | March 9, 2016
At a minimum, potholes create rough roads and poor driving conditions. Too often they degenerate into vehicle-damaging safety hazards that incur the wrath of drivers, attract negative attention from the news media and adversely affect commerce by disrupting or slowing traffic. Our nation's deteriorating roads – of which potholes are an obvious manifestation – are adrag on our economy. That's why transportation department maintenance crews and pavement engineers continue to stress the need for more effective and efficient pavement repair and maintenance. From their perspective, the ideal repair would last at least a year, could be performed in all seasons, and could be installed easily and relatively quickly – all while keeping traffic delays to a minimum and repair costs down. Recurring "zombie" potholes are too often a reflection of the type of method that's used to patch or "fix" them – many of which are short-lived and only marginally effective. Researchers around the world, including my colleagues and me, are working to develop better and longer lasting repair alternatives. At the same time, researchers and pavement engineers in academia and in the private and public sectors are developing improved construction techniques and innovative pavement formulations – such as "self healing" materials – that will help prevent potholes from forming in the first place. But we still have to deal with the millions of miles of roads – and their potholes – we already have. They form when water penetrates a crack. In cold climates, that water freezes and expands, pushing up on the overlying pavement. Repeated freezing and thawing is a great way to create a pothole. Water also softens and weakens the base material below a pavement, making it susceptible to deformation by passing traffic loads. As the base material deforms, the pavement loses structural support and breaks up. And another pothole is born! Bottom line: a roadway marred by multiple potholes means the pavement is probably failing and should be replaced. But before that can happen, potholes still need to be repaired. Traditional repair techniques are, at best, temporary fixes. Take "throw-and-go" cold patching methods, for example. These use repair mixtures that are worked when cold. Some cold patch repairs don't bond well to the edges of the hole, a shortcoming made worse when attempting a repair under challenging wintertime conditions. The same pothole repaired with cold mix patches may have to be redone several times a winter. Without a good interface bond, the freezing and thawing cycles of late winter and early spring can further weaken the repair and enlarge the crack between the patch and the surrounding pavement. Another way a repair gets weakened is analogous to hydraulic fracturing, or "fracking." The tires of vehicles passing over the repair forcefully push liquid water and fine aggregate particles down into the crack, progressively widening any cracks. Road salt further enhances the latter effect by keeping water in liquid form in subfreezing conditions. Together, it's all a prescription for a repair's early demise – hello again, zombie pothole. Search for better repairs heats up In an effort to address the ongoing need for better repair mechanisms, my colleagues at the Natural Resources Research Institute - University of Minnesota Duluth, outside project collaborators, and I recently completed a study to evaluate promising innovative pothole repair tactics. Our emphasis is on all-season approaches that use the iron oxide mineral magnetite (Fe3O4). More than 10 years ago, we showed that magnetite and magnetite-containing rock were excellent microwave energy absorbers. The mineral is contained in iron ore rock mined and processed on Minnesota's Mesabi Iron Range, and has the ability to readily absorb microwaves and heat very quickly. We started thinking: when combined with portable microwave technology, could magnetite-containing materials be an effective solution to cold-weather pothole repair? We mixed small amounts (1 to 2 percent) of magnetite into patching compound, typically made of recycled asphalt pavement (RAP) augmented with ground-up recycled asphalt shingles (RAS); the RAS adds a little more asphaltic binder to the overall mix. Then we pack the mixture into a pothole and microwave until the binder softens and is compactible, thanks to the magnetite. Here's our cookbook recipe (emphasis on cook) for the microwave repairs we performed. First, find a pothole (easy).Clean loose debris and/or blow water from pothole.In subfreezing temperatures, preheat pothole and pavement adjacent to hole with microwave unit to melt or debond any ice or snow in the hole, and to soften the surrounding pavement. This warming contributes to a good bond since the edges of the pothole are able to plasticly intermix – that is, smush together – and meld with the patch material.Remove or blow out loosened/melted ice/snow.Place mixture of RAP, microwave-absorbing taconite materials, and RAS into the pothole. Overfill the hole by about two inches to allow for final compaction.Heat mixture until temperature reaches at least 100°C (212°F) at base of mixture in the hole. Sufficient heating takes place in about 8 to 12 minutes at a 40kW power level.Tamp down heated mixture with portable gasoline-powered compactor. The existing pavement essentially becomes part of the repair itself – a unique and key benefit of this technique. And our repairs showed excellent longevity, with some performing well more than two years after their installation. Obviously, we're not just opening the door of a kitchen microwave oven and pointing it down at the road. In the pilot test, we worked with a small company which had previously developed a truck-mounted microwave system to thaw frozen ground to access buried utilities. They adapted their high-power (50kW), vehicle-based microwave system for the project. And it wouldn't be much of a stretch for Minnesota's taconite industry to supply the relatively small quantities of magnetite a repair compound would consume. The industry typically produces about 40 million tons of magnetite concentrate annually, and generates tens of millions of tons of additional byproduct rock that also contains magnetite. The byproduct taconite rock actually represents a potential source of hard and durable high quality aggregate for our nation's roads and highways. One welcome side effect of the in-place heating mechanism is that it drives off moisture, letting the patch more readily adhere to the surrounding pavement. Patch material can be premixed and stockpiled or mixed on site. And you don't need to keep material hot during transport, making this patching system well-suited for cold weather situations. Importantly, our project also demonstrated that an effective microwave pothole repair compound can be made almost entirely from inexpensive and abundant recycled materials (such as RAP and RAS) that many maintenance departments have on hand, as opposed to repair compounds that rely on specialized asphalt formulations, virgin asphalt and/or specialty binders. Microwave technology is not yet a routine method of repair, and it's best-suited for potholes in asphalt rather than concrete. But this approach merits further consideration, and we are working to advance the technology. After all, given our nation's aging network of roads, zombie potholes will continue to flourish. Microwave repair could be an effective method for keeping them at bay. Explore further: Researcher using nanoclays to build better asphalt
Najafi B.,Islamic Azad University at Marvdasht |
Torabi Dastgerduei S.,Natural Resources Research Institute
Journal of Agricultural Science and Technology | Year: 2015
This study was conducted to determine timeliness costs in using machinery and their effects on farmers’ revenues. In addition, optimum cropping pattern was compared with the existing one assuming removal of timeliness cost. For the purpose of the study, mixed integer and linear programming methods were used. The study was conduced in Marvdasht region in southern Iran. The data were collected through interviews with a sample of 80 farm managers. Selected farmers were divided into six groups in terms of farm size and farm machinery use, and in each group a representative farm was selected. Findings of the study showed that 19 percent of farmers owned and 81 percent rented tractor and, as a result, timeliness cost was considerable for the latter group. The results also showed that for the farmers whose farm size was more than 10 hectares, it was justified to buy tractor and rent a combine. The results revealed that there was a gap between the optimum and existing cropping patterns with respect to timeliness cost and gross margin increased mostly in the groups that owned tractor and more than five hectares of land. Finally, in order to minimize timeliness cost, joint ownership of machinery by neighboring farms was recommended. © 2015, Tarbiat Modares University. All rights reserved.