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51.
Diurnal vertical migration is a well-known phenomenon in the circadian activity rhythms of zooplankton. Our goal was to test
whether negative phototaxis in Daphnia magna clone BEAK (provoked by artificially induced light stress, alternating light and dark phases in 2 h intervals), and its interference
with the endogenous rhythm of diurnal vertical migration, can be automatically registered with a biomonitor. For the first
time the vertical swimming behaviour of D. magna was recorded quantitatively based on non-optical data recording in a fully automated biotest system, the Multispecies Freshwater
Biomonitor in a new experimental setup consisting of a column of three recording units (3-level chambers). Circadian vertical
migration was clearly recorded in the 3-level chambers and the rhythm was more clear with 5 than with 1 organism per chamber.
The organisms clearly responded to induced light stress with negative phototaxis, however best in larger chambers. The artificially
induced rhythm was influenced by the endogenous rhythm. This approach may facilitate long-term observations of vertical swimming
activity of zooplankton in the future. 相似文献
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Michelle Janssens Jeroen van Smeden Gert S. Gooris Wim Bras Guiseppe Portale Peter J. Caspers Rob J. Vreeken Thomas Hankemeier Sanja Kezic Ron Wolterbeek Adriana P. Lavrijsen Joke A. Bouwstra 《Journal of lipid research》2012,53(12):2755-2766
A hallmark of atopic eczema (AE) is skin barrier dysfunction. Lipids in the stratum corneum (SC), primarily ceramides, fatty acids, and cholesterol, are crucial for the barrier function, but their role in relation to AE is indistinct. Filaggrin is an epithelial barrier protein with a central role in the pathogenesis of AE. Nevertheless, the precise causes of AE-associated barrier dysfunction are largely unknown. In this study, a comprehensive analysis of ceramide composition and lipid organization in nonlesional SC of AE patients and control subjects was performed by means of mass spectrometry, infrared spectroscopy, and X-ray diffraction. In addition, the skin barrier and clinical state of the disease were examined. The level of ceramides with an extreme short chain length is drastically increased in SC of AE patients, which leads to an aberrant lipid organization and a decreased skin barrier function. Changes in SC lipid properties correlate with disease severity but are independent of filaggrin mutations. We demonstrate for the first time that changes in ceramide chain length and lipid organization are directly correlated with the skin barrier defects in nonlesional skin of AE patients. We envisage that these insights will provide a new therapeutic entry in therapy and prevention of AE. 相似文献
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Vanhauteghem D Janssens GP Lauwaerts A Sys S Boyen F Kalmar ID Meyer E 《Amino acids》2012,43(1):245-253
The current study first investigates the emulsifying potential of glycine and its N-methylated derivatives N-methylglycine (sarcosine), N,N-dimethylglycine (DMG) and N,N,N-trimethylglycine (betaine) under varying pH conditions. Subsequently, the effect of these test compounds on the membrane integrity of enterotoxigenic Escherichia coli (ETEC) was evaluated. Oil in water emulsions containing each compound show that DMG is a more potent enhancer of emulsification than glycine, sarcosine and betaine under the conditions tested. Flow cytometry was used to investigate whether the emulsifying potential is associated with an effect on ETEC membrane integrity. The bacteria were exposed to each of the test compounds under varying pH conditions and membrane integrity was assessed using the LIVE/DEAD BacLight kit. Results show a membrane deteriorating effect caused by glycine, sarcosine and DMG, but not by betaine. This effect is pH- and time-dependent and has an apparent threshold at pH 9.0. Conventional plate counts confirmed concomitant changes in culturability of the membrane comprised bacteria. 相似文献
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An Caris Cathy Macharis Gerrit K. Janssens 《Flexible Services and Manufacturing Journal》2012,24(3):294-319
In this paper the design of the service network in intermodal barge transport is studied. The network of inland barge terminals is modelled to demonstrate potential cooperations in a corridor network. Cooperation between inland terminals leads to bundling of freight flows in the hinterland of major ports. A service network design model for intermodal barge transport is developed and applied to the hinterland network of the port of Antwerp in Belgium. Selected cooperation schemes are simulated by means of a discrete event simulation model for intermodal barge transport and compared with simulation results of bundling in the port area. Cooperation between inland terminals offers an opportunity to attain economies of scale, but may not be perceived as a sole solution for reducing waiting times of inland barges at sea terminals. A combination of bundling measures in the port area and in the hinterland may be necessary to improve the intermodal transport chain. 相似文献
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Josep Peñuelas Jordi Sardans Albert Rivas‐ubach Ivan A. Janssens 《Global Change Biology》2012,18(1):3-6
Human‐induced carbon and nitrogen fertilization are generating a strong imbalance with P. This imbalance confers an increasingly important role to P availability and N : P ratio in the Earth's life system, affecting carbon sequestration potential and the structure, function and evolution of the Earth's ecosystems. 相似文献
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