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Dekker A Dercksen D Snoep J van Wuyjckhuise L 《Tijdschrift voor diergeneeskunde》2007,132(18):695-701
On 26th of july 2007 a new case of bluetongue was notified in the Netherlands and on 2nd of august 2007 foot-and-mouth disease was diagnosed in Surrey, England, which raised the threat of having both infections simultaniously in one area. Bluetongue and foot-and-mouth disease have a different pathogenesis, but symptoms may resemble each other at a later stage of infection. The pathogenesis and possible clinical symptoms of both infections are discussed and illustrated with pictures. 相似文献
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Circadian oscillations in rodents: a systematic increase of their frequency with age 总被引:2,自引:0,他引:2
The circadian activity rhythms of golden hamsters and two species of deermouse, when released from a light-dark cycle of 12 hours light and 12 hours of darkness into constant darkness, had progressively shorter periods as the animals became older. A possible bearing of this fact on the aging process is briefly outlined. 相似文献
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Borgsteede F Verkaik J Moll L Dercksen D Vellema P Bavinck G 《Tijdschrift voor diergeneeskunde》2010,135(21):782-785
In Autumn 2009, a faecal egg count reduction test (FERCT) was carried out on three sheep farms. Groups of 8-11 lambs were treated with ivermectin or moxidectin, with a 14-day interval between treatment and sampling. Ivermectin resistance was present on all three farms. Treatment with ivermectin resulted in a reduction in faecal egg numbers of 94.6%, 63%, and 59%. On two farms, 14 days after treatment pooled faecal samples yielded predominantly larvae of Hamonchus contortus (100% and 98%, respectively). On the third farm, H. contortus and (probably) Teladorsagia circumcincta were resistant to ivermectin (64% and 36% of the larvae, respectively). Treatment with moxidectin resulted in a 100% reduction in egg output in sheep on all three farms. More sensitive culture techniques failed to detect any larvae in samples taken from two farms, but a few Ostertagia-type larvae, probably of T. circumcincta, were detected in samples from the third farm. It can be concluded that gastrointestinal nematodes in sheep from these three farms were resistant to ivermectin, whereas resistance to moxidectin was not detected. 相似文献
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Long-term effects of fertilisation regime on earthworm abundance in a semi-natural grassland area 总被引:1,自引:0,他引:1
Environmental protection organisations involved in farmland-bird conservation promote the use of organic fertilisers, especially farmyard manure, to enhance the availability of earthworms, which are an important prey for farmland-birds. We studied changes in earthworm numbers in a field experiment on a semi-natural grassland with three different types of fertilisation; no fertilisation (NF), and application of slurry manure (SM) or farmyard manure (FM). Samples were taken in April, yearly from 1982 to 1990 and in 2005. On average, the SM treatment had a lower (29%) earthworm abundance and a higher mean individual body weight than the FM and NF treatments. No statistically significant differences were observed between the FM and NF treatment. In 2005, earthworm abundance did not differ between the SM and NF treatment. The yearly variation in earthworm numbers and biomass was high, and significantly related to winter coldness. Colder winters resulted in lower earthworm abundances in the next spring. Especially the number of endogeic earthworms varied with winter coldness. The large variation between years stresses the need to be careful with the interpretation of short-term field experiments, or comparisons between areas based on single sampling events. 相似文献
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Stefania Dooms Spiros Papakostas Stefan Hoffman Daan Delbare Alexander Triantafyllidis Olav Vadstein Patrick Sorgeloos 《Aquaculture (Amsterdam, Netherlands)》2007,262(1):29-40
Many zooplanktonic organisms, like the cyclic parthenogenetic rotifer Brachionus plicatilis (Rotifera: Monogononta), are actually a complex of species and biotypes with a high degree of morphological similarity (i.e. cryptic species). Various phylogenetic studies with molecular markers (e.g. ITS1 and COI) on wild Brachionus populations described the presence of at least nine genetically divergent Brachionus species and biotypes. Because different studies found evidence that these cryptic species and biotypes differ significantly in ecological preferences and thus probably behave differently in response to rearing conditions in the hatchery, questions rise on the actual identity of the rotifer strains used in aquaculture, where Brachionus discrimination is still based on morphology. This study is a part of an investigation of the genetic make-up of strains used in hatcheries, aquaculture research institutes and laboratories, and describes the rapid and sensitive PCR-DGGE method for the detection of Brachionus species and biotypes based on nucleotide sequence variation within the mitochondrial 16S rRNA gene. Considerable genetic diversity was found, albeit smaller within hatcheries than within laboratories and aquaculture research institutes. All 16S haplotypes produced an unambiguous DGGE fingerprint out of which a database was constructed. 相似文献
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Daan Kuiper Simon Ribot Helen S. van Reenen Nollie Marissen 《Scientia Horticulturae》1995,60(3-4):325-336
Complete flower bud opening is characterised by an increase in the petal area, and by enhanced dry and fresh weights of the petals. The import of dry matter into the petals is used for osmotic, biosynthetic and respiratory demands. However, flowers of ‘Madelon’ cut roses frequently fail to open completely under postharvest conditions. An aqueous solution containing 45 mM sucrose induces proper flower bud opening, even when the cut roses have been exposed initially to a sucrose-free solution for 48 h. This points to a requirement for a supply of organic matter from source tissue to the flower as main sink. This conclusion is confirmed by the observation that complete flower bud opening can also be achieved without any addition of sucrose by a reduction in the number of participating petals. Replacing two-thirds part of the 45 mM sucrose by an isomolalic amount of KNO3 does not affect the flower opening process, implying that a considerable amount of the added sucrose is claimed for osmoregulation. The role of added sucrose and the contribution of the endogenous storage pool in the process of flower bud opening is discussed. 相似文献
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Inge Mestdagh Steven Sleutel Peter Lootens Oswald Van Cleemput Daan Beheydt Pascal Boeckx Stefaan De Neve George Hofman Nancy Van Camp Inge Vande Walle Roeland Samson Kris Verheyen Raoul Lemeur Lucien Carlier 《植物养料与土壤学杂志》2009,172(1):24-31
Total soil organic‐carbon (SOC) stocks for grassland soils in Flanders (N Belgium) were determined for the Kyoto Protocol reference year 1990 and 2000 in order to investigate whether these soils have been CO2 sinks or sources during that period. The stocks were calculated by means of detailed SOC datasets, which were available at the community scale for the whole of Flanders. The total SOC stocks for Flemish grassland soils (1 m depth) were estimated at 38 Mt SOC in 1990 and 34 Mt SOC in 2000. The loss of SOC resulted from a decrease in the SOC content of grassland soils (71%) and could also partly (29%) be explained by a decline in grassland area. Significant decreases in %SOC for the 0–6 cm depth layer were found for the 1990s for the coarser‐textured soils with SOC losses ranging between –0.3% and –0.5% over the 10 y period. Specific management practices that disturb the SOC balance such as conversion to temporary grassland and a reduction of animal‐manure application are hypothesized to have contributed to the observed loss of SOC stocks. We furthermore conducted an analysis of uncertainty of the 1990 and 2000 grassland SOC–stocks calculation using Monte Carlo analysis. Probability‐distribution functions were determined for each of the inputs of the SOC‐stock calculation, enabling us to assess the uncertainty on the 1990 and 2000 SOC stocks. The frequency distributions of these simulated stocks both closely approached lognormal distributions, and their 95%‐confidence intervals ranged between 150% and 50% of the calculated mean SOC stock. The standard error on the measured decrease in SOC stocks in Flemish grassland soils during the 1990s was calculated to be 7–8 Tg SOC, which is equivalent to twice this decrease. This clearly shows that large‐scale changes in SOC stocks are uncertainty‐ridden, even when they are based on detailed datasets. 相似文献