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161.
Suzanne L. Hansen Ane H. Nielsen Katrine E. Knudsen Andreas Artmann Gitte Petersen Uffe Kristiansen Steen H. Hansen Harald S. Hansen 《Neurochemistry international》2009,54(3-4):199-204
The ketogenic diet (KD) is used for the treatment of refractory epilepsy in children, however, the mechanism(s) remains largely unknown. Also, the antiepileptogenic potential in animal models of epilepsy has been poorly addressed. Activation of cannabinoid type-1 receptor (CB1-R) upon seizure activity may mediate neuroprotection as may several N-acylethanolamines. It is unknown how the KD interfere with the endocannabinoid system.We investigated the antiepileptogenic potential of the KD in the pentylenetetrazole kindling model in young mice and measured the hippocampal levels of CB1-R by Western blot and of endocannabinoids and N-acylethanolamines by mass spectrometry.The KD significantly decreased incidence and severity of seizures, and significantly increased the latency to clonic convulsions. There were no changes in levels of endocannabinoids or CB1-R expression by either seizure activity or type of diet. The level of oleoylethanolamide as well as the sum of N-acylethanolamines were significantly decreased by the KD, but were unaffected by seizure activity.The study shows that the KD had clear antiepileptogenic properties in the pentylenetetrazole kindling model and does not support a role of endocannabinoids in this model. The significance of the decreased hippocampal level of oleoylethanolamide awaits further studies. 相似文献
162.
Floral volatiles controlling ant behaviour 总被引:1,自引:1,他引:0
Pat G. Willmer Clive V. Nuttman Nigel E. Raine Graham N. Stone Jonathan G. Pattrick Kate Henson Philip Stillman Lynn McIlroy Simon G. Potts Jeffe T. Knudsen 《Functional ecology》2009,23(5):888-900
1 . Ants show complex interactions with plants, both facultative and mutualistic, ranging from grazers through seed predators and dispersers to herders of some herbivores and guards against others. But ants are rarely pollinators, and their visits to flowers may be detrimental to plant fitness.
2 . Plants therefore have various strategies to control ant distributions, and restrict them to foliage rather than flowers. These 'filters' may involve physical barriers on or around flowers, or 'decoys and bribes' sited on the foliage (usually extrafloral nectaries - EFNs). Alternatively, volatile organic compounds (VOCs) are used as signals to control ant behaviour, attracting ants to leaves and/or deterring them from functional flowers. Some of the past evidence that flowers repel ants by VOCs has been equivocal and we describe the shortcomings of some experimental approaches, which involve behavioural tests in artificial conditions.
3 . We review our previous study of myrmecophytic acacias, which used in situ experiments to show that volatiles derived from pollen can specifically and transiently deter ants during dehiscence, the effects being stronger in ant-guarded species and more effective on resident ants, both in African and Neotropical species. In these plants, repellence involves at least some volatiles that are known components of ant alarm pheromones, but are not repellent to beneficial bee visitors.
4 . We also present new evidence of ant repellence by VOCs in temperate flowers, which is usually pollen-based and active on common European ants. We use these data to indicate that across a wide range of plants there is an apparent trade-off in ant-controlling filter strategies between the use of defensive floral volatiles and the alternatives of decoying EFNs or physical barriers. 相似文献
2 . Plants therefore have various strategies to control ant distributions, and restrict them to foliage rather than flowers. These 'filters' may involve physical barriers on or around flowers, or 'decoys and bribes' sited on the foliage (usually extrafloral nectaries - EFNs). Alternatively, volatile organic compounds (VOCs) are used as signals to control ant behaviour, attracting ants to leaves and/or deterring them from functional flowers. Some of the past evidence that flowers repel ants by VOCs has been equivocal and we describe the shortcomings of some experimental approaches, which involve behavioural tests in artificial conditions.
3 . We review our previous study of myrmecophytic acacias, which used in situ experiments to show that volatiles derived from pollen can specifically and transiently deter ants during dehiscence, the effects being stronger in ant-guarded species and more effective on resident ants, both in African and Neotropical species. In these plants, repellence involves at least some volatiles that are known components of ant alarm pheromones, but are not repellent to beneficial bee visitors.
4 . We also present new evidence of ant repellence by VOCs in temperate flowers, which is usually pollen-based and active on common European ants. We use these data to indicate that across a wide range of plants there is an apparent trade-off in ant-controlling filter strategies between the use of defensive floral volatiles and the alternatives of decoying EFNs or physical barriers. 相似文献
163.
164.
A. C. Winger † R. Kristoffersen S. I. Siikavuopio ‡ R. Knudsen 《Journal of fish biology》2009,74(7):1476-1486
There has been an increased focus on Salvelinus alpinus as a potential long-term host to Gyrodactylus salaris and, here, both susceptibility to G. salaris and ability to sustain a parasite population seasonally, was tested using fry and parr of S. alpinus from the River Skibotnelva, northern Norway. Fry were highly susceptible. Gyrodactylus salaris survived on allopatric S. alpinus parr during the 5 month-long winter when water temperatures were c. 1° C. Salvelinus alpinus fry also maintained a pulse of G. salaris infection for over 155 days from early May until autumn. Gyrodactylus salaris are thus able to reproduce and survive on S. alpinus for long periods and at low water temperatures. In spring, newly hatched fry of S. alpinus may serve as an important host to maintain a G. salaris metapopulation within a river system. The results suggest that S. alpinus are adequate long-term hosts of G. salaris independent of the presence of the co-occurring highly susceptible S. salar . 相似文献
165.
Selection may reduce the deleterious consequences of inbreeding. This may be due to purging of recessive deleterious alleles
or balancing selection favouring heterozygote offspring. Such selection is expected to be more efficient at slower compared
to at faster rates of inbreeding. In this study we tested the impact of inbreeding and the rate of inbreeding on fitness related
traits (egg productivity, egg-to-adult viability, developmental time and behaviour) under cold and benign semi-natural thermal
conditions using Drosophila melanogaster as a model organism. We used non-inbred control and slow and fast inbred lines (both with an expected inbreeding level of
0.25). The results show that contrary to expectations the slow inbred lines do not maintain higher average fitness than the
fast inbred lines. Furthermore, we found that stressful environmental conditions increased the level of inbreeding depression
but the impact of inbreeding rate on the level of inbreeding depression was not affected by the environmental conditions.
The results do not support the hypothesis that inbreeding depression is less severe with slow compared to fast rates of inbreeding
and illustrate that although selection may be more efficient with slower rates of inbreeding this does not necessary lead
to less inbreeding depression. 相似文献
166.
Gerhart J Scheinfeld VL Milito T Pfautz J Neely C Fisher-Vance D Sutter K Crawford M Knudsen K George-Weinstein M 《Developmental biology》2011,(1):12-25
Cells that express MyoD mRNA, the G8 antigen and the bone morphogenetic protein (BMP) inhibitor noggin (Nog) are present in the epiblast before gastrulation. Ablation of “Myo/Nog” cells in the blastocyst results in an expansion of canonical BMP signaling and prevents the expression of noggin and follistatin before and after the onset of gastrulation. Once eliminated in the epiblast, they are neither replaced nor compensated for as development progresses. Older embryos lacking Myo/Nog cells exhibit severe axial malformations. Although Wnts and Sonic hedgehog are expressed in ablated embryos, skeletal muscle progenitors expressing Pax3 are missing in the somites. Pax3+ cells do emerge adjacent to Wnt3a+ cells in vitro; however, few undergo skeletal myogenesis. Ablation of Myo/Nog cells also results in ectopically placed cardiac progenitors and cardiomyocytes in the somites. Reintroduction of Myo/Nog cells into the epiblast of ablated embryos restores normal patterns of BMP signaling, morphogenesis and skeletal myogenesis, and inhibits the expression of cardiac markers in the somites. This study demonstrates that Myo/Nog cells are essential regulators of BMP signaling in the early epiblast and are indispensable for normal morphogenesis and striated muscle lineage specification. 相似文献
167.
168.
It has been argued that agonist ligands for dopamine D(2/3) receptors recognize a privileged subset of the receptors in living striatum, those which are functionally coupled to intracellular G-proteins. In support of this claim, the D(2/3) agonist [(3)H]-N-propylnorapomorphine ([(3)H]NPA) proved to be more vulnerable to competition from endogenous dopamine than was the antagonist ligand [(11)C]raclopride, measured ex vivo in mouse striatum, and subsequently in multi-tracer PET studies of analogous design. Based on these results, we predicted that prolonged dopamine depletion would result in a preferential increase in agonist binding, and a lesser competition from residual dopamine to the agonist binding. To test this hypothesis we used autoradiography to measure [(3)H]NPA and [(3)H]raclopride binding sites in hemi-parkinsonian rats with unilateral 6-OHDA lesions, with and without amphetamine challenge. Unilateral lesions were associated with a more distinct increase in [(3)H]NPA binding ex vivo than was seen for [(3)H]raclopride binding in vitro. Furthermore, this preferential asymmetry in [(3)H]NPA binding was more pronounced in amphetamine treated rats. We consequently predict that agonist ligands should likewise be fitter than antagonists for detecting responses to denervation in positron emission tomography studies of idiopathic Parkinson's disease. Agonist binding increases in vivo are likely to reflect the composite of a sensitization-like phenomenon, and relatively less competition from endogenous dopamine, as seen in the lesioned side of 6-OHDA induced hemi-parkinsonism. 相似文献
169.
Nadja Schultz-Jensen Berith E. Knudsen Zuzana Frkova Jens Aamand Tina Johansen Jette Thykaer Sebastian R. Sørensen 《Applied microbiology and biotechnology》2014,98(5):2335-2344
The Aminobacter sp. strain MSH1 has potential for pesticide bioremediation because it degrades the herbicide metabolite 2,6-dichlorobenzamide (BAM). Production of the BAM-degrading bacterium using aerobic bioreactor fermentation was investigated. A mineral salt medium limited for carbon and with an element composition similar to the strain was generated. The optimal pH and temperature for strain growth were determined using shaker flasks and verified in bioreactors. Glucose, fructose, and glycerol were suitable carbon sources for MSH1 (μ?=?0.1 h?1); slower growth was observed on succinate and acetic acid (μ?=?0.01 h?1). Standard conditions for growth of the MSH1 strain were defined at pH 7 and 25 °C, with glucose as the carbon source. In bioreactors (1 and 5 L), the specific growth rate of MSH1 increased from μ?=?0.1 h?1 on traditional mineral salt medium to μ?=?0.18 h?1 on the optimized mineral salt medium. The biomass yield under standard conditions was 0.47 g dry weight biomass/g glucose consumed. An investigation of the catabolic capacity of MSH1 cells harvested in exponential and stationary growth phases showed a degradation activity per cell of about 3?×?10?9 μg BAM h?1. Thus, fast, efficient, large-scale production of herbicide-degrading Aminobacter was possible, bringing the use of this bacterium in bioaugmentation field remediation closer to reality. 相似文献
170.
Yew Kok Lee Shengnan Jin Shiwei Duan Yen Ching Lim Desmond PY Ng Xueqin Michelle Lin George SH Yeo Chunming Ding 《Biological procedures online》2014,16(1):1-9