Intermediate disturbance on rangelands : Management applicability of the intermediate disturbance hypothesis across Mongolian rangeland ecosystems

The current growing body of evidence for diversity-disturbance relationships suggests that the peaked pattern predicted by the intermediate disturbance hypothesis (IDH) may not be the rule. Even if ecologists could quantify the diversity-disturbance relationship consistent with the IDH, the applicability of the IDH to land management has rarely been addressed. We examined two hypotheses related to the generality and management applicability of the IDH to Mongolian rangeland ecosystems: that the diversity-disturbance relationship varies as a function of landscape condition and that some intermediate scales of grazing can play an important role in terms of sustainable rangeland management through a grazing gradient approach. We quantified the landscape condition of each ecological site using an ordination technique and determined two types of landscape conditions, relatively benign and harsh environmental conditions. At the ecological sites characterized by relatively benign environmental conditions, diversity-disturbance relationships were generally consistent with the IDH and maximum diversity was observed at some intermediate distance from the source of the grazing gradient. In contrast, the IDH was not supported at most but not all sites characterized by relatively harsh environmental conditions. The intermediate levels of grazing were generally located below the ecological threshold representing the points or zones at which disturbance should be limited to prevent drastic changes in ecological conditions, suggesting that there is little “conundrum” with regard to intermediate disturbance in the studied systems in terms of land management. We suggest that the landscape condition is one of the primary factors that cause inconsistencies in diversity-disturbance relationships. The ecological threshold can extend its utility in rangeland management because it also has the compatibility with the maintenance of species diversity. This study thus suggests that some intermediate scales of grazing and ecological thresholds are mutually supportive tools for sustainable management of Mongolian rangelands

The Linkage Between Pastoralists\u27 Perspectives and Vegetation Threshold Changes in Mongolian Rangelands (Advanced Studies on Sustainable Animal Production: Interrelationships among Human, Animal and Environment, 8th International Symposium of Integrated Field Science)

Poster Sessio

Resource Variations across the Landscape Mediate the Impact of Grazing on Vegetation in Mongolian Rangeland under High Climatic Variability

Assessment of grazing-induced degradation of arid and semi-arid rangelands with stochastic rainfall regimes is challenging. For the last two decades, rangeland ecologists have been discussing the relative importance of biotic and abiotic factors in controlling vegetation dynamics. According to the non-equilibrium concept, which emerged as a new paradigm to describe ecosystems in highly variable and poorly predictable environments, vegetation dynamics are driven primarily by abiotic factors such as rainfall, rather than by internal biotic regulation (e.g. grazing impact). Although a number of studies have emphasized the non-equilibrium nature of most rangelands, they have produced inconsistent results and there is still no consensus on the relative importance of grazing impact. Alternatively, recent studies have suggested that a continuum of systems exists, rather than a stark dichotomy between equilibrium and non-equilibrium rangelands. Moreover, theoretical studies have predicted that, in addition to climatic variability, resource variations occurring in space and time as a result of landscape heterogeneity should be taken into account in assessments of grazing impact. However, there have been few empirical studies of the role of resource variations in either mitigating or enhancing the impacts of grazing on vegetation. This study explores the impact of grazing strategies on vegetation in Mongolian rangelands under high climatic variability. Specifically, it is focused on key resource areas, defined in terms of the key factor determining livestock population, and thus the ability to forage during drought. Based on the prediction proposed by Illius and O’Connor (1999) that animal numbers are regulated in a density-dependent manner by the limited forage availability in key resource areas, we established and examined the hypothesis that grazing impacts would be greater in key resource areas than in other areas even in Mongolian rangelands

Induction of apoptosis during the early phase of reperfusion after rat liver ischemia

This study was designed to investigate the induction of apoptosis during the reperfusion phase following warm liver ischemia in vivo. We evaluated apoptotic bodies (ABs) in sections stained with hematoxylin and eosin (H. E.) and positive hepatocytes in sections stained by the in situ nick end labeling method (TUNEL method) during the reperfusion phase up to 48 h after a 70% liver ischemia for 30 or 60min in duration (30 or 60 min group). The peak number of ABs in H. E.-stained sections was observed at 1 to 3 h in the 30 min group and 3 to 6 h in the 60 min group. The number of ABs gradually fell as the length of the perfusion period increased, and few ABs were observed at 24 and 48 h after reperfusion. A peak number of TUNEL-positive hepatocytes was recognized at 3 h after reperfusion in both groups, after which the numbers decreased gradually. DNA extracted from both groups was electrophoresed on a 1.5% agarose gel. In both groups, a ladder-like pattern over smear pattern was recognized at 3 h after reperfusion. These results show that hepatocyte apoptosis was induced during the early phase of reperfusion after rat liver ischemia morphologically and biochemically, which suggests that hepatocyte apoptosis may be associated with ischemia and reperfusion injury.</p

Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica

<p>Abstract</p> <p>Background</p> <p><it>Pasteurella pneumotropica </it>is a ubiquitous bacterium that is frequently isolated from laboratory rodents and causes various clinical symptoms in immunodeficient animals. Currently two RTX toxins, PnxIA and PnxIIA, which are similar to hemolysin-like high-molecular-weight exoproteins are known in this species. In this study, we identified and analyzed a further RTX toxin named PnxIIIA and the corresponding type I secretion system.</p> <p>Results</p> <p>The RTX exoprotein, PnxIIIA, contains only a few copies of the RTX repeat-like sequence and 3 large repeat sequences that are partially similar to the outer membrane protein found in several prokaryotes. Recombinant PnxIIIA protein (rPnxIIIA) was cytotoxic toward J774A.1 mouse macrophage cells, whereas cytotoxicity was attenuated by the addition of anti-CD11a monoclonal antibody. rPnxIIIA could bind to extracellular matrices (ECMs) and cause hemagglutination of sheep erythrocytes. Binding was dependent on the 3 large repeat sequences in PnxIIIA. Protein interaction analyses indicated that PnxIIIA is mainly localized in the outer membrane of <it>P. pneumotropica </it>ATCC 35149 in a self-assembled oligomeric form. PnxIIIA is less cytotoxic to J774A.1 cells than PnxIA and PnxIIA.</p> <p>Conclusions</p> <p>The results implicate that PnxIIIA is located on the cell surface and participates in adhesion to ECMs and enhanced hemagglutination in the rodent pathogen <it>P. pneumotropica</it>.</p

Direct Supply Chain from Forest to House Builder: A Japanese Business Model

AbstractWe developed a direct supply chain from a forest to a house builder for environment-friendly wooden long-life housing based on the “progressive market-in” method. This business model successfully incorporates the external environmental value of the house into its market price.In this paper, we discuss the direct supply chain business model and its environmental effect in Japan, using a micro approach (for individual economic bodies) and a macro approach for the country

Comparative analysis of photosynthetic properties in ice algae and phytoplankton inhabiting Franklin Bay, the Canadian Arctic, with those in mesophilic diatoms during CASES 03-04

Psychrophilic phytoplankton and ice algae were collected in Franklin Bay, the Canadian Arctic, in late May 2004, and the photosynthetic properties were measured at 4°C using a pulse amplitude modulation fluorometer (Phyto-PAM). Rapid light curve measurements allowed for the assessment of the photosynthetic efficiency (α), maximal electron transport rate (rETRmax), and minimum saturating irradiance (Ek) in the samples. The values of α in phytoplankton (0.63-0.68) were much larger than those in ice algae (0.10-0.51), and the values of rETRmax in phytoplankton (4.6-6.7) were relatively larger than those in ice algae (1.8-4.3). However, Ek showed similar values in both samples and were around 10μmol photonsm^・s^. These values were systematically compared with those obtained from mesophilic marine diatoms (a centric diatom, Chaetoceros gracilis, and a pennate diatom, Phaeodactylum tricornutum) grown under various irradiances in the laboratory. The highly shade-adapted features of ice algae and phytoplankton were disclosed through this comparative analysis. It was also found that the non-photochemical quenching was much higher in psychrophilic samples than in mesophilic diatoms grown under moderate irradiance. Furthermore, in ice algae and phytoplankton, the decrease in rETR at high irradiances was prominent, showing that they were highly susceptible to photoinhibition. Our comparative analysis using psychrophilic phytoplankton, ice algae and two strains of mesophilic diatoms also revealed that the dependency on the xanthophyll cycle for the protection mechanisms of photosystems were remarkably different between the groups, indicating that the acclimation strategies to growth irradiances were variable between species. Such variable acclimation strategies could be one of the forces that results in a diverse algal flora that enables this region around Franklin Bay to be a productive area, even though the psychrophilic phytoplankton and ice algae are highly shade-adapted

The AMPK β2 subunit is required for energy homeostasis during metabolic stress

AMP activated protein kinase (AMPK) plays a key role in the regulatory network responsible for maintaining systemic energy homeostasis during exercise or nutrient deprivation. To understand the function of the regulatory β2 subunit of AMPK in systemic energy metabolism, we characterized β2 subunit-deficient mice. Using these mutant mice, we demonstrated that the β2 subunit plays an important role in regulating glucose, glycogen, and lipid metabolism during metabolic stress. The β2 mutant animals failed to maintain euglycemia and muscle ATP levels during fasting. In addition, β2-deficient animals showed classic symptoms of metabolic syndrome, including hyperglycemia, glucose intolerance, and insulin resistance when maintained on a high-fat diet (HFD), and were unable to maintain muscle ATP levels during exercise. Cell surface-associated glucose transporter levels were reduced in skeletal muscle from β2 mutant animals on an HFD. In addition, they displayed poor exercise performance and impaired muscle glycogen metabolism. These mutant mice had decreased activation of AMPK and deficits in PGC1α-mediated transcription in skeletal muscle. Our results highlight specific roles of AMPK complexes containing the β2 subunit and suggest the potential utility of AMPK isoform-specific pharmacological modulators for treatment of metabolic, cardiac, and neurological disorders