Oxygen isotopic compositions of asteroidal materials returned from Itokawa by the Hayabusa mission

Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.     

Network thinking in riverscape conservation – A graph-based approach

Graph theoretic approaches have received increased interest recently in landscape planning and conservation in the terrestrial realm, because these approaches facilitate the effective modelling of connectivity among habitats. We examined whether basic principles of graph theory can be extended to other ecosystems. Specifically, we demonstrate how a network-based context can be used for enhancing the more effective conservation of riverine systems. We first show how to use graph theoretic techniques to model riverscapes at the segment level. Then we use a real stream network (Zagyva river basin, Hungary) to examine the topological importance of segments in maintaining riverscape connectivity, using betweenness centrality, a commonly used network measure. Using the undirected graph model of this riverscape, we then prioritize segments for conservation purpose. We examine the value of each of the 93 segments present in the Zagyva river basin by considering the conservation value of local fish assemblages, connectivity and the size of the habitat patches. For this purpose we use the ‘integral index of connectivity’, a recently advocated habitat availability index. Based on the results the selection of the most valuable habitat segments can be optimized depending on conservation resources. Because of their inherent advantage in the consideration of connectivity relationships, we suggest that network analyses offer a simple, yet effective tool for searching for key segments (or junctions) in riverscapes for conservation and environmental management. Further, although the joint consideration of aquatic and terrestrial networks is challenging, the extension of network analyses to freshwater systems may facilitate the more effective selection of priority areas for conservation in continental areas.     

Antinociceptive efficacy and plasma concentrations of transdermal buprenorphine in dogs

To assess the antinociceptive efficacy of transdermal (TD) buprenorphine (B) in dogs, a prospective, positive-controlled experimental study was performed in 10 healthy Beagles. In an open label crossover design, the dogs initially received intravenous B (IVB, 0.02 mg kg^?1) as a positive control, followed by TDB (52.5 μg h^?1) 4 months later. Blood was collected at regular intervals for determination of the plasma concentrations of B ([B]) and its metabolite norbuprenorphine. The antinociceptive efficacy was assessed using thermal and mechanical models of nociception. The peak concentration [B] was 1.54 ng mL^?1 (±1.98) 60 h after TDB application, although three dogs had no measurable [B] after TDB. Maximum thermal threshold (TT) was 52.6 °C (±0.48) at 1 h after IVB administration and 51.63 °C (±1.01) 72 h after TDB application. The significant increase in TT indicated that effective antinociception was achieved beyond 36 h after the application of TDB, lasting until patch removal. There was hysteresis between [B] and the antinociceptive effect.     

Characteristics of soil microbiostasis

No increase in numbers of fungi, actinomycetes and bacteria in 3 days, as measured by selective media, was used as an indication of the presence of fungistasis, actinostasis and bacteriostasis in soil, respectively. The population of fungi, actinomycetes and bacteria did not increase in 9 of 10 soils tested indicating concurrent existence of fungistasis, actinostasis and bacteriostasis in a wide range of soils. When Penicillium funiculosum, Streptomyces scabies and Agrobacterium radiobacter were used as test organisms, these three types of microbiostasis were detected simultaneously in all 8 soils tested. All three groups of microorganisms flourished in autoclaved soil, and microbiostasis was restored to sterilized soil by reinoculation with 1% natural soil or microorganisms including antibiotic and non-antibiotic producers. Soil microbiostasis was annulled completely or partially by addition of different nutrie0nts. Bacteriostasis appeared to be the easiest to overcome with nutrients among these three types of microbiostasis.     

Propagule size: Its relation to population density of microorganisms in soil

Analysis of published data on occurrence of bacteria and fungi in soil revealed an inverse linear relationship between the logarithm of propagule size and the logarithm of population density among these microorganisms. The regression equation Y= 8.841? 0.540.X (in which Y is log numbers of propagules kg^?1 of soil and X is log volumes per 100 propagules), describing the relationship between propagule size and maximum population density of microorganisms in soil, afforded the predicted values of the population density very close to the reported values. The regression equation may also be used for predicting the possible propagule type of a microorganism in soil, if its population density is known.     

Physiological changes and defense mechanisms induced by cadmium stress in maize

Heavy metals such as cadmium (Cd) enter the ecosystem chiefly as the result of human activities. Nowadays the heavy‐metal pollution of the soil is causing ever greater problems, exacerbated by the fact that the heavy metals accumulated in plants may, either directly or indirectly, find their way into animals and human beings. Maize is one of the world's most important crops, ranking third after wheat and rice, so the changes induced by one of the most toxic heavy metals, Cd, in maize plants is a cause of some concern. This review discusses not only the toxic symptoms caused by Cd stress, but also the tolerance mechanisms activated in the plants. Cadmium induces a number of physiological changes, such as growth inhibition, changes in the water and ion metabolism, the inhibition of photosynthesis, changes in enzyme activities, and the formation of free radicals. The synthesis and compartmentalization of phytochelatins is induced shortly after the initiation of Cd stress, while other defense mechanisms also play an important role.     

Hypolipidemic effect of glycosaminoglycans from the sea cucumber Metriatyla scabra in rats fed a cholesterol-supplemented diet

The purpose of this study was to determine the hypolipidemic effects of the glycosaminoglycans (GAGs) extracted from a sea cucumber, Metriatyla scabra. Using DEAE column chromatography, two major peaks containing GAGs were obtained: peak 1 (P-1) contained mainly GAGs (as hexuronic acid and hexosamine), whereas P-2 contained mostly free glycan (as fucose) with little hexuronic acid or hexosamine. Therefore, we used only the P-1 fraction (with molecular weights in the range 200-500 kDa) for evaluation of hypolipidemic effects. The lyophilized GAGs were administered orally to male Wistar rats at 5, 10, 20, and 50 mg/kg body weight for six consecutive weeks, during which the rats were fed ad libitum a basal laboratory diet with or without 1% cholesterol. The results show that the 1% cholesterol diet significantly increased plasma total cholesterol, LDL-cholesterol, and atherogenic index. Cholesterol supplementation also significantly increased hepatic TG, cholesterol, phospholipid, and liver weight. When rats fed the 1% cholesterol diet were supplemented orally with the sea cucumber GAGs, plasma levels of total cholesterol, LDL-cholesterol, and atherogenic index were significantly decreased, while HDL-cholesterol was significantly increased, although these effects of the GAGs were only dose-dependent at doses lower than 20 mg/kg b.w. Similarly, the GAGs significantly prevented the increase (p < 0.05) in hepatic contents of triglyceride, cholesterol, and phospholipid. Thus, the present study demonstrates that the sea cucumber GAGs have the potential of being used for reducing the risk of atherosclerosis and hyperlipoproteinemia.     

ISCOM of BHV-1 envelope glycoproteins protected calves against both disease and infection.

A subunit vaccine in the form of immunostimulating complex (iscom) was prepared to contain the envelope glycoproteins of bovine herpesvirus type 1 (BHV-1). This iscom preparation was tested in a vaccination experiment on 4-month-old calves seronegative to BHV-1. In this experiment, four groups with three animals per group were used. Two groups were vaccinated with the iscom preparation twice, four weeks apart, one group with 50 micrograms and the other with 100 micrograms per calf. The third group received a commercial inactivated whole-virus vaccine applying the same vaccination program. The fourth group served as control. Two weeks after the second vaccination, all the animals were challenge-infected intranasally with a virulent BHV-1 strain and four days later with a virulent Pasteurella multocida--this in order to mimic hard field conditions. When exposed to challenge infection, all the animals vaccinated with the iscom were fully protected, i.e., no virus could be recovered from their nasal secretions and no clinical symptoms were recorded. In contrast, the animals vaccinated with the commercial vaccine, responded to challenge with moderate fever and loss of appetite, and virus was isolated from the nasal secretions. The animals in the control group developed severe clinical symptoms. In the sera of iscom-vaccinated animals, the virus neutralization titers reached levels of 1/3500 or higher.