Influence of forest structure on density and nest success of mature forest birds in managed landscapes

Managing for forest wildlife requires attention not only to quantity but quality of forests within the landscape. We examined the extent to which local structural attributes and landscape context of forest stands explained variation in density and reproductive success of mature forest birds across 12 sites in southeast Ohio, USA, 2004–2006. Results suggest that several structural characteristics influenced bird–habitat relationships in our study. Densities of 3 songbird species (i.e., ovenbird [Seiurus aurocapilla], cerulean warbler [Setophaga cerulea], and scarlet tanager [Piranga olivacea]) were positively related to canopy openness, which is usually a function of canopy gaps. Habitat attributes described by ground litter, understory density, and canopy height were positively associated with densities of ground (i.e., worm-eating warbler [Helmitheros vermivorum]), or shrub nesting species (i.e., Kentucky and hooded warblers [Geothlypis formosa and Setophaga citrina], respectively). Furthermore, the number of small trees likely drove the positive relationship between density of wood thrush (Hylocichla mustelina), a subcanopy nester. After accounting for temporal variability in daily nest survival rates, the odds of nest survival for all species increased 10.5% for every 1% increase in canopy openness and decreased 1.4% for each 5% increase in understory vegetation density. Habitat–nest survival relationships were not apparent at the level of the individual species. Our results suggest that structural attributes produced by increasing habitat heterogeneity may be necessary for conservation of forest bird communities. © 2012 The Wildlife Society.     

Learning to live with black bears: A psychological model of acceptance

The reappearance and recovery of large carnivores in human-dominated landscapes creates a need to understand how people will respond to the presence of these animals. We tested a psychological model of acceptance to determine what variables most influence people's acceptance for black bears (Ursus americanus) in an area with an emerging black bear population (Ohio, USA). We hypothesized that people's perceptions of risk and benefit related to bears would mediate the effect of trust (in wildlife management agencies) and personal control (over interactions with and management of wildlife) on acceptance for black bears. We used a mail-back survey of Ohio residents (n = 9,400; adjusted response rate = 35%) to assess the variables of interest and test the hypothesized model. Based on multiple criteria of model fit, the hypothesized model fit the data acceptably well. The model explained approximately 62% of the variance in acceptance, and perception of risk associated with black bears had the largest impact on the level of acceptance. As large carnivore populations expand and interactions with humans increase, our results will aid managers in designing outreach materials and communications aimed at promoting acceptance for large carnivores. Our model suggests that interventions raising an individual's social trust in the managing agency, or personal control can indirectly raise stakeholders' acceptance by reducing risk perception and increasing perception of benefit from carnivores. © 2012 The Wildlife Society.     

Prostaglandins, not cyclic GMP, inhibit oxytocinase isoenzymes from human amniotic fluid in vitro

Two isoenzymes of oxytocinase (EC 3.4.11.3) activity were fractionated from human amniotic fluid samples between the 14th and 22nd weeks of gestation by Ultrogel acrylamide-agarose gel filtration and partially characterized. The isoenzymes were competitively inhibited by PGE₁, PGE₂ and PGF_2α more at pH 6.2 than at pH 6.8, whereas cyclic GMP (cGMP) and its 8-bromo derivative had no effect at either pH. The implications of these findings are discussed and it is suggested that since the activity of amniotic fluid oxytocinases is very low or minimal at or near term, inhibition of these by prostaglandins may not have physiological significance in the initiation of human parturition.     

Isolation and properties of four alpha-amylase isozymes from human submandibular saliva

Four isoamylases have been isolated from human submandibular secretions by gel filtration and isoelectric focusing. The isozymes (1A, 1B, 2A, 2B) were each purified about 8-fold and each yielded one major band on disc gel electrophoresis. In all cases the major protein band contained more than 95% of the protein and amylase activity recovered. The isoenzymes, in order of their relative positions on the polyacrylamide gels (from the anodal end), their isoelectric points, and percentage distribution in the submandibular secretion are as follows: isozyme 2A, pH 5.9, 9%; isozyme 1A, pH 5.9, 18%; isozyme 2B, pH 6.4, 63%; isozyme 1B, pH 6.4, 10%. Amino acid analyses showed that the protein compositions of the four isoamylases were essentially the same. Possible differences were noted in aspartic acid, serine, glutamic acid, and proline contents. Molecular weights, determined by SDS disc gel electrophoresis, were 57,000 for 1A and 1B, and 54,000 for 2A and 2B. This molecular weight difference is attributed mainly to the presence of bound carbohydrate on isozymes 1A and 1B. Gas Chromatographic analysis was used for determining the carbohydrate compositions. Molar ratios of sugars were similar for both glycoprotein amylases (moles sugar/mole enzyme): glucosamine, 3; mannose, 3; galactose, 2; fucose, 3. Isoamylase 1A, which had more carbohydrate than 1B, also contained about 2 moles of N-acetylneuraminic acid. Sialic acid was not detected in isozyme 1B.     

Changing Global Climate: Historical Carbon and Nitrogen Budgets and Projected Responses of Ohio’s Cropland Ecosystems

As the evidence of global climate change continues to mount, its consequences for cropland productivity assume particular significance. Against the backdrop of past agricultural practices, simulation models offer a glimpse into the future, showing the effect of temperature changes on crop production. In this study, we first quantified the carbon (C) and nitrogen (N) budgets of Ohios cropland ecosystems using inventory yield data of corn for grain, oat, and all wheat for the period 1866–1996 and soybean for the period 1924–96. Then we explored the responses of Ohios continuous soybean croplands to changes in temperature, carbon dioxide (CO₂) concentration, initial soil organic C and N (SOC-N) pools, soil texture, and management practices by developing a simple cropland ecosystem model (CEM) and performing a long-term sensitivity analysis. Finally, CEM simulations were evaluated against independent observations of SOC values (0–19 cm) averaged over 470 northwest Ohio sites between 1954 and 1987 under conventional tillage and rotations of corn–soybean–winter wheat by using the historical yield data (r ² = 0.8). The C contents per hectare of crop harvests increased by 178% for oats, 300% for corn for grain, and 652% for all wheat between 1866 and 1996 and by 305% for soybean between 1924 and 1996. Ohio croplands acted as C–N sources, releasing average net ecosystem emissions (NEE), including the removal of harvested C–N, of 4,598 kg CO₂ ha^–1 and 141 kg N ha^–1 in 1886 and 205 kg CO₂ ha^–1 (except for the corn-for-grain cropland) and 39 kg N ha^–1 in 1996. The continuous corn croplands continued to become a C sink, sequestering 255 kg C ha^–1 in 1996. Results of the sensitivity analysis for Ohios continuous soybean croplands revealed that the SOC pool increased by 6.9% and decreased by 7.5% in response to a doubled CO₂ concentration and a temperature increase of 2.8°C over 100 years, respectively. The sequestration potential of the SOC pool increased by 6.5% at a rate of 24.6 kg C ha^–1 y^–1 for the same period with finer soil texture (loam to silty clay loam). The shift from conventional to conservation residue practice led to an 11% increase in the steady-state SOC storage at a rate of 42 kg C ha^–1 y^–1 for 100 years.     

On the lack of formation of l-(+)-3-hydroxybutyrate by liver

The terminal carbon of palmitic acid, traced with ¹⁴C, is preferentially incorporated into carbon 4 of hydroxybutyrate formed by hepatocytes and perfused livers from 18- to 19-day-old rats and perfused livers from fasted adult rats. However, ¹⁴C from [13-¹⁴C]palmitic acid is incorporated into carbon 1 of the hydroxybutyrate to the same extent as any one of the first 12 carbons of palmitic acid as assessed with [1-¹⁴C]palmitic acid and [6-¹⁴C]palmitic acid. Therefore, the hydroxybutyrate is formed via hydroxymethylglutaryl-CoA, i.e., it is in the d configuration, and hydrolysis of l-hydroxybutyryl-CoA, the intermediate in the β oxidation of the palmitate, does not occur. Further, a negligible amount of ¹⁴C remains in hydroxybutyrate formed from ¹⁴C-labeled palmitic acid by isolated hepatocytes and perfused livers from the young rats, when the hydroxybutyrate is treated with d-(?)-3-hydroxybutyrate dehydrogenase to convert the d isomer to acetoacetate. Thus, l-(+)-3-hydroxybutyrate is not produced by rat liver as assessed using these preparations.     

Beclobrinic acid--a new hypolipidemic agent--inhibits in vitro human platelet activation by blocking prostaglandin synthesis

Effects and the mechanism of the antiplatelet actions of beclobrinic acid, free acid form of a new hypolipidemic agent beclobrate [(+)-2-[d-(P-chlorophenyl)p-tolyl)oxy)-2-methyl-butyrate), were examined using human platelets. Platelet-rich plasma (PRP) which has been prelabeled with (14C)-serotonin was incubated with beclobrinic acid (BBA) for one minute before the addition of various agonists. BBA (0.1-1.5 mM) inhibited platelet aggregation and serotonin secretion induced by ADP, epinephrine, arachidonic acid and collagen in a concentration dependent manner. BBA also inhibited arachidonic acid-induced production of malondialdehyde (MDA), a byproduct of prostaglandins, in a concentration dependent manner. However, up to 1.0 mM BBA did not inhibit platelet aggregation induced by U46619, a stable analog of prostaglandin H2. In other experiments BBA also blocked thrombin-induced release of (3H)-arachidonic acid from platelet phospholipids. These findings suggest that: (a) BBA inhibits platelet aggregation and serotonin secretion by inhibiting prostaglandin synthesis at two steps. First by interfering in the release of arachidonic acid from platelet phospholipids and second by inhibiting its conversion into prostaglandins; and (b) BBA does not inhibit the action of prostaglandins on human platelets.