Toxicity of aqueous aluminium to the ectoparasitic monogenean Gyrodactylus salaris     

Arnulf Soleng  Antonio B.S. Polo  Tor A. Bakke 《Aquaculture (Amsterdam, Netherlands)》2005,250(3-4):616-620

Both laboratory and field experiments have demonstrated that aqueous aluminium can act as a paraciticide to the monogenean Gyrodactylus salaris Malmberg, 1957 infecting freshwater salmonids. However, the reproductive conditions of gyrodactylids surviving to cessation of an aluminium exposure is unknown. Therefore, Atlantic salmon (Salmo salar L.) parr infected with G. salaris was experimentally exposed to elevated concentrations of aqueous aluminium for more than 1 month. During this period, the infection increased the first week before it peaked and started to steadily decline approaching elimination. When almost all parasite specimens were eliminated, the water quality was adjusted to normal aluminium-poor freshwater. During the next 3 weeks, the surviving G. salaris were shown to clearly resume their reproduction. The experiment demonstrates the potential of the gyrodactylids to reproduce after cessation of an aluminium exposure. Thus, the as-yet unknown mechanism behind the toxic effects of aluminium on G. salaris survival and reproduction might to some extent be reversible. The present study gives further support for this metal as a parasiticide to G. salaris but demonstrates at the same time that in order to eliminate the parasites totally, the aluminium treatment must eradicate all G. salaris from the skin of the infected hosts. Furthermore, the potential development of resistance to aluminium should also be studied.  相似文献   

Medicine management in 12 Norwegian fish farms     

Anne-Grethe T Berg  Kari Grave  & Tor E Horsberg 《Aquaculture Research》2008,39(8):861-868

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Diagnosis of Taxus (yew) poisoning in a horse.     

Asheesh K Tiwary  Birgit Puschner  Hailu Kinde  Elizabeth R Tor 《Journal of veterinary diagnostic investigation》2005,17(3):252-255

A 2-year-old bay Thoroughbred colt was found dead overnight in its stall without a known history of any illness, existing disease, or toxicant exposure. No information on the clinical signs before this animal's death was reported. A full necropsy was performed the next morning and revealed a mild to moderate degree of endocardial hemorrhages in both ventricles. Microscopic examination of the heart showed an acute mild multifocal necrosis of papillary muscles and ventricles. The stomach content contained approximately 2% Taxus alkaloids as determined by gas chromatography/mass spectrometry. In the past, diagnosis of Taxus poisoning has been mainly based on history of exposure and the presence of plant parts in the gastrointestinal tract. Pathological lesions associated with Taxus poisoning have not been published for horses. Therefore, this is the first report of cardiac lesions in a horse after lethal exposure to Taxus. On the basis of these findings, it is suggested that Taxus exposure needs to be considered in the differential diagnosis of horses that die suddenly or have cardiac lesions suggestive of Taxus exposure, even if intact plant parts are not identified in the stomach by the naked eye.  相似文献   

Molecular biology. Mothers setting boundaries     

Thorvaldsen JL  Bartolomei MS 《Science (New York, N.Y.)》2000,288(5474):2145-2146

Certain genes are only expressed at one allele, a phenomenon called imprinting. Although it is well established that one allele of certain imprinted genes is silenced through methylation, this does not appear to be the case for all imprinted genes. In a thoughtful Perspective, Thorvaldsen and Bartolomei discuss new findings showing that insertion of insulator elements (boundary regions) between the promoter of a gene and its enhancer (a sequence that boosts gene expression) may be another way in which genes are silenced during imprinting.  相似文献   

History, manufacture and properties of lime bast cordage in northern Europe     

Myking  Tor; Hertzberg  Anja; Skroppa  Tore 《Forestry》2005,78(1):65-71

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Patterns of Tetracapsuloides bryosalmonae infection of three salmonid species in large,deep Norwegian lakes     

Tone Jran Oredalen  Mona Sb  Tor Atle Mo 《Journal of fish diseases》2022,45(1):185-202

Proliferative kidney disease (PKD), caused by the myxozoan endoparasite Tetracapsuloides bryosalmonae, is of serious ecological and economical concern to wild and farmed salmonids. Wild salmonid populations have declined due to PKD, primarily in rivers, in Europe and North America. Deep lakes are also important habitats for salmonids, and this work aimed to investigate parasite presence in five deep Norwegian lakes. Kidney samples from three salmonid species from deep lakes were collected and tested using real-time PCR to detect PKD parasite presence. We present the first detection of T. bryosalmonae in European whitefish in Norway for the first time, as well as the first published documentation of the parasite in kidneys of Arctic charr, brown trout and whitefish in four lakes. The observed prevalence of the parasite was higher in populations of brown trout than of Arctic charr and whitefish. The parasite was detected in farmed, but not in wild, charr in one lake. This suggests a possible link with a depth of fish habitat and fewer T. bryosalmonae-infected and PKD-affected fish. Towards a warmer climate, cold hypolimnion in deep lakes may act as a refuge for wild salmonids, while cold deep water may be used to control PKD in farmed salmonids.  相似文献   

Effects of ground fires on understorey bird assemblages in Amazonian forests     

Jos Barlow  Tor HaugaasenCarlos A Peres 《Biological conservation》2002,105(2):157-169

Avifaunal responses to understorey fire disturbance and subsequent changes in habitat structure were examined within 20 burnt and unburnt forest plots of 0.25 ha (10×250 m), 10-15 months after an unprecedented understorey fire swept through the Tapajós-Arapiuns Extractive Reserve of central Brazilian Amazonia following the severe 1997-1998 El-Niño dry season. Although these surface fires in the previously undisturbed primary forest were relatively mild, they resulted in dramatic changes in forest structure consistent with those found elsewhere in Amazonia. Bird species negatively affected by these changes tended to be the least common, the most disturbance-sensitive, and habitat specialists. Considering different guilds, ant followers, dead-leaf gleaners, terrestrial gleaners, and arboreal sallying insectivores were the most negatively affected, whereas nectivores and arboreal granivores became more abundant in the burnt forest. The results highlight the severe consequences of even relatively mild surface fires in neotropical forests, and the importance of controlling haphazard frontier expansion for the conservation of susceptible species that are endemic to fire-prone regions.  相似文献   

Radar soundings of the subsurface of Mars   总被引：2，自引：0，他引：2  

Picardi G  Plaut JJ  Biccari D  Bombaci O  Calabrese D  Cartacci M  Cicchetti A  Clifford SM  Edenhofer P  Farrell WM  Federico C  Frigeri A  Gurnett DA  Hagfors T  Heggy E  Herique A  Huff RL  Ivanov AB  Johnson WT  Jordan RL  Kirchner DL  Kofman W  Leuschen CJ  Nielsen E  Orosei R  Pettinelli E  Phillips RJ  Plettemeier D  Safaeinili A  Seu R  Stofan ER  Vannaroni G  Watters TR  Zampolini E 《Science (New York, N.Y.)》2005,310(5756):1925-1928

The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.  相似文献   

Determination of oleandrin in tissues and biological fluids by liquid chromatography-electrospray tandem mass spectrometry     

Tor ER  Filigenzi MS  Puschner B 《Journal of agricultural and food chemistry》2005,53(11):4322-4325

A rapid LC-MS/MS method, using a triple-quadrupole/linear ion trap mass spectrometer, was developed for the quantitative determination of oleandrin in serum, urine, and tissue samples. Oleandrin, the major cardiac glycoside of oleander (Nerium oleander L.), was extracted from serum and urine samples with methylene chloride and from tissues with acetonitrile. The tissue extracts were cleaned up using Florisil solid-phase extraction columns. Six replicate fortifications of serum and urine at 0.001 microg/g (1 ppb) oleandrin gave average recoveries of 97% with 5% CV (relative standard deviation) and 107% with 7% CV, respectively. Six replicate fortifications of liver at 0.005 microg/g (5 ppb) oleandrin gave average recoveries of 98% with 6% CV. This is the first report of a positive mass spectrometric identification and quantitation of oleandrin in tissue samples from oleander intoxication cases. The sensitivity and specificity of the LC-MS/MS analysis enables it to be the method of choice for toxicological investigations of oleander poisoning.  相似文献   

Effects of cold and warm years on the water chemistry at the Birkenes catchment,Norway     

Espen Lydersen 《Water, air, and soil pollution》1995,84(3-4):217-232

During the last years, several scientists have been concerned with the consequences of global warming. In the Birkenes catchment, situated in southernmost Norway, several warm years have occurred during the last decade. In this climatic region, warm years primarily mean warmer winters with mean air temperatures close to or higher than 0 °C. Small temperature changes are therefore decisive for the quality of precipitation, i.e. whether the precipitation enters the catchments as snow or rain, which accordingly has large consequences for the residence time of water and its pathways through the catchment. Another important effect of higher winter-temperatures at Birkenes, is that stronger and more frequent seasalt episodes seem to occur. This may enhance the negative effects to aquatic organisms, because the most extreme concentrations of acute toxic Al-forms in streamwater are related to seasalt episodes during warm winters, when the precipitation comes as rain and thus leaves the catchment relatively fast through the uppermost soil layers. When seasalt-enriched water enters into the uppermost soil horizons, a large amount of sodium will be temporarily retained due to cation exchange processes, where sodium may substitute for H⁺ and cationic Al. At Birkenes, but also in similar acidified areas with high seasalt input, seasalt episodes are probably of greater importance for the periodic variations in streamwater H⁺ and Alⁿ⁺ than commonly recognized. Higher winter-temperatures may also change the timing of the highest streamwater fluxes of nitrate. This may have local consequences for the primary-production in the fjords, both quantitatively and qualitatively. Thus, global warming may have negative consequences for the surface water chemistry in near-coastal areas that also receive high amounts of acidifying atmospheric compounds, and may change the eutrophication status of many fjords.  相似文献