Inhibition of tumorigenesis in ApcMin/+ mice by a combination of (-)-epigallocatechin-3-gallate and fish oil

The effect of a combination of (-)-epigallocatechin-3-gallate (EGCG) with fish oil on intestinal tumorigenesis in Apc (Min/+) mice fed a high-fat diet was investigated in the present study. The combined treatment of EGCG and fish oil for 9 weeks reduced the tumor number by 53% as compared to controls while neither agent alone had a significant effect. Apoptosis was significantly increased in all treatment groups. beta-Catenin nuclear positivity in adenomas from the combination group was lower than control mice, implicating the modulation of Wnt signaling by the combination. Fish oil and the combination significantly reduced prostaglandin E 2 (PGE 2) levels in small intestinal tumors as compared to controls, suggesting modulation of aberrant arachidonic acid metabolism by fish oil. Akt phosphorylation in adenomas was significantly reduced in all treatment groups, which may have contributed to the observed increase in apoptosis. The results indicate that a combination of low doses of EGCG and fish oil can inhibit tumor multiplicity in Apc (Min/+) mice.     

A spatial risk assessment of bighorn sheep extirpation by grazing domestic sheep on public lands

Bighorn sheep currently occupy just 30% of their historic distribution, and persist in populations less than 5% as abundant overall as their early 19th century counterparts. Present-day recovery of bighorn sheep populations is in large part limited by periodic outbreaks of respiratory disease, which can be transmitted to bighorn sheep via contact with domestic sheep grazing in their vicinity. In order to assess the viability of bighorn sheep populations on the Payette National Forest (PNF) under several alternative proposals for domestic sheep grazing, we developed a series of interlinked models. Using telemetry and habitat data, we characterized herd home ranges and foray movements of bighorn sheep from their home ranges. Combining foray model movement estimates with known domestic sheep grazing areas (allotments), a Risk of Contact Model estimated bighorn sheep contact rates with domestic sheep allotments. Finally, we used demographic and epidemiologic data to construct population and disease transmission models (Disease Model), which we used to estimate bighorn sheep persistence under each alternative grazing scenario. Depending on the probability of disease transmission following interspecies contact, extirpation probabilities for the seven bighorn sheep herds examined here ranged from 20% to 100%. The Disease Model allowed us to assess the probabilities that varied domestic sheep management scenarios would support persistent populations of free-ranging bighorn sheep.     

Nitrogen fertilization of black walnut (Juglans nigra L.) during plantation establishment. Physiology of production

Physiological mechanisms by which nitrogen (N) fertilization affects growth and development in temperate deciduous forest trees are not clearly understood, especially under intensive silvicultural systems. Grafted, Tippecanoe 1 cultivar black walnut (Juglans nigra L.) trees were grown in an intensively managed plantation in west-central Spain and subjected to six, fixed-nutrient-ratio complete fertilizer treatments (defined as 0, 25, 50, 75, 150, and 300 g N tree^?1) delivered via daily fertigation. Leaf chemistry and morphology were evaluated from June to September, and gas exchange was measured in July. Specific leaf mass, leaflet nitrogen (N), and chlorophyll concentrations varied over the course of the growing season, yet consistently increased with increasing fertilization. Net photosynthesis at ambient (A _net) and light-saturated (A _max) conditions increased from the unfertilized control to lowest treatment (25 g N) but did not increase at higher fertilizer rates. Photosynthetic N and chlorophyll use efficiencies decreased with increasing fertilization, but photosynthetic phosphorus and water use efficiencies increased. Transpiration rates and dark respiration were not significantly affected by treatment. Overall, the lowest fertilizer treatment (25 g N) had the greatest photosynthetic efficiency. Interactions between N and other nutrients with increasing fertilizer application suggested potential for nutrient imbalances at high fertilization rates. Our results provide a physiological justification for the use of low-to-moderate fertilization as an efficient strategy to promote black walnut plantation establishment under intensive cultural systems.     

Mapping sources,sinks, and connectivity using a simulation model of northern spotted owls

Source-sink dynamics are an emergent property of complex species–landscape interactions. A better understanding of how human activities affect source-sink dynamics has the potential to inform and improve the management of species of conservation concern. Here we use a study of the northern spotted owl (Strix occidentalis caurina) to introduce new methods for quantifying source-sink dynamics that simultaneously describe the population-wide consequences of changes to landscape connectivity. Our spotted owl model is mechanistic, spatially-explicit, individual-based, and incorporates competition with barred owls (Strix varia). Our observations of spotted owl source-sink dynamics could not have been inferred solely from habitat quality, and were sensitive to landscape connectivity and the spatial sampling schemes employed by the model. We conclude that a clear understanding of source-sink dynamics can best be obtained from sampling simultaneously at multiple spatial scales. Our methodology is general, can be readily adapted to other systems, and will work with population models ranging from simple and low-parameter to complex and data-intensive.     

Establishment and early productivity of perennial biomass alley cropping systems in Minnesota,USA

In May 2010, alley cropping systems consisting of switchgrass (Panicum virgatum L.), prairie cordgrass (Spartina pectinata Bosc ex Link), an alfalfa (Medicago sativa L.) and intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth and Dewey) mixture, and a native tallgrass-forb-legume polyculture, planted between multi-row strips of poplar hybrid ‘NM6’ (Populus maximowiczii x P. nigra) and willow cultivar ‘Fish Creek’ (Salix purpurea) were established at Empire and Granada, Minnesota, USA. Crop establishment and productivity were characterized for each species over two growing seasons and at two distances from the tree-crop interface. Prairie cordgrass and the native polyculture were among the most productive herbaceous crops at both sites, averaging between 7.1 and 11.9 Mg DM ha^?1, and have shown no evidence of competition for resources along the tree-crop interface thus far. Basal area (BA) was similar at Empire for NM6 (1,744 mm² tree^?1) and Fish Creek (1,609 mm² tree^?1), but was greater for NM6 (1,045 mm² tree^?1) than Fish Creek (770 mm² tree^?1) at Granada. Despite this, stand basal area (SBA) was greater for Fish Creek at both sites due to greater planting density. Across species, BA and SBA were greater for trees along the alley than those in center rows at Empire, whereas no difference was observed at Granada. Results suggest that alley cropping provides suitable conditions for establishment of short-rotation woody and certain herbaceous biomass crops, and that some of these crops may be well suited to the alley cropping environment. However, continued research is needed to evaluate crop persistence and productivity as crops and trees mature and the potential for interspecies competition increases.     

Influence of wetland networks on bat activity in mixed-use landscapes

Parks and other protected lands can provide important source habitat and act as valuable dispersal corridors in urbanizing environments. However, most wetlands within protected areas are managed in isolation without consideration of the broader landscape connections. We studied the importance of wetland habitat connectivity and landscape context to bat activity in five National Parks along a gradient of increasing urbanization within the Mid-Atlantic United States. Ninety-six Anabat stations were set up throughout the parks, from which we derived the characteristic spatial scales at which bat activity was associated with wetlands. This information was used in a graph theoretic framework to construct network models of potential landscape connectivity for those species that had positive associations with wetland land cover. We found that the importance of wetlands as a predictor of bat activity varied on a species-by-species basis and increased when network measures were used that accounted for connected area in a broad spatial context. The results demonstrate that both area and connectivity of wetland foraging habitat may act as orthogonal variables to availability of roosting habitat in explaining the distribution of highly mobile species. We use the results to illustrate the value of network analysis to guide the coordinated management of two of the parks’ most valued natural resources - wetlands and bats.     

Industrial Structure and the Sources of Agglomeration Economies: Evidence from Manufacturing Plant Production

The impacts of agglomeration and local industrial structure are examined through an analysis of establishment‐level productivity. Using micro‐level data, measures of regional industrial specialization, economic diversity, and industrial competitive structure are incorporated together into a production function system estimated cross‐sectionally for three years and three manufacturing industries in the U.S. The findings demonstrate the importance of the influences of regional industrial competitive structure and diversity on performance.     

Large-sample hypothesis tests for stratified group-testing data

Insect-vectored plant diseases impact the agricultural community each year by affecting the economic value, the quantity, and the quality of crops. Controlling the spread of disease is an important area in risk assessment, and understanding the dynamics of vector populations helps researchers to develop effective treatments. In this article, we consider an experimental design commonly used by researchers who study plant disease and examine large-sample, likelihood-based hypothesis tests that can be used to characterize disease-transmission behavior in a stratified population. Small-sample size and power results along with design considerations are provided. We illustrate our testing procedures using two real data examples and provide recommendations for plant-disease researchers in the field.     

Effects of fertilization and irrigation on American sycamore and black locust planted on a reclaimed surface mine in Appalachia

Short rotation woody biofuel plantations on reclaimed surface mines in Appalachia can diversify domestic energy supplies and facilitate the reforestation of these disturbed lands. This study examined growth, survival, biomass accumulation and allocation, and nitrogen concentrations following two growing seasons in American sycamore (Platanus occidentalis L.) and black locust (Robinia pseudoacacia L.) seedlings receiving irrigation, granular fertilization, and irrigation + fertilization compared with untreated controls. Fertilization increased basal diameter, height, and stem mass of American sycamore following two growing seasons. Increased stem production was attributed to accelerated development and not shifts in biomass allocation due to treatment. Irrigation and irrigation + fertilization treatments did not enhance growth or biomass accumulation of American sycamore. Similarly, black locust basal diameter, height, and stem mass did not differ among the treatments. Browse surveys showed that more than 76% of black locust seedlings experienced arrested or retrogressed growth due to browse; less than 3% of American sycamores were browsed. This intensive browse by ungulates, likely including reintroduced elk, may have affected growth differences among species and confounded the effects of treatments on black locust. Survival was unaffected by treatment in both species, but mean survival was greatest in American sycamore (80%) compared to black locust (58%). Per tree total nitrogen uptake was highest in fertilized American sycamore (7.9 g) and lowest in irrigated American sycamore (0.9 g). The results of our study suggest that granular fertilizer applications can accelerate seedling growth on reclaimed surface mines in the Appalachian region.