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Joris Mergaert Caroline Anderson Ann Wouters Jean Swings 《Journal of Polymers and the Environment》1994,2(3):177-183
The microbial degradation of tensile test pieces made of poly(3-hydroxybutyrate) [P(3HB)] or copolymers with 10% [P(3HB-co-10%3HV)] and 20% [P(3HB-co-20%3HV)] 3-hydroxyvaleric acid was studied in small household compost heaps. Degradation was measured through loss of weight (surface erosion) and changes in molecular weight and mechanical strength. It was concluded, on the basis of weight loss and loss of mechanical properties, that P(3HB) and P(3HB-co-3HV) plastics were degraded in compost by the action of microorganisms. No decrease inM
w could be detected during the degradation process. The P(3HB-co-20%3HV) copolymer was degraded much faster than the homopolymer and P(3HB-co-10%3HV). One hundred nine microbial strains capable of degrading the polymersin vitro were isolated from the samples used in the biodegradation studies, as well as from two other composts, and identified. They consisted of 61 Gram-negative bacteria (e.g.,Acidovorax facilis), 10 Gram-positive bacteria (mainlyBacillus megaterium), 35Streptomyces strains, and 3 molds. 相似文献
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Tengteng Liu Joris M. Koene Xiaoxiao Dong Rongshu Fu 《Environmental monitoring and assessment》2013,185(5):4183-4190
The concentration of heavy metals in the environment is normally low. We here address whether using the development of isolated pond snail Radix auricularia eggs would provide a more sensitive endpoint and whether the gelatinous matrix of the egg mass surrounding the eggs indeed protects the snail embryos. In the present study, artificial removal of the gelatinous matrix of egg masses greatly increased the sensitivity of developing eggs to a heavy metal (cadmium). The sensitivity of isolated eggs to cadmium was determined using several convenient endpoints, including mortality, hatching rate, and heart rate, with an acute toxicity test and a subchronic test. In the acute toxicity test, a 96-h LC50 value of 58.26 μg/L cadmium was determined. In the subchronic toxicity test, sublethal effects in terms of a significant reduction in hatching rate could be found in the 25-μg/L treatment, and a significant decrease of heart rate was observed in both treatments (5 and 25 μg/L). The high sensitivity of isolated eggs indicates that such tests can be efficient for toxicity assays and risk assessment, although one needs to keep in mind that the ecologically relevant measure of toxicity will be how eggs are affected when they are still inside the egg mass. 相似文献
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Joris M. Koene Kora Montagne-Wajer Andries Ter Maat 《Behavioral ecology and sociobiology》2006,60(3):332-338
Simultaneous hermaphrodites have the opportunity to control the allocation of resources to the male and female function depending on the circumstances. Such flexibility also provides the possibility to influence sex allocation in the mating partner. To investigate this idea, we measured egg production (female investment) and sperm production as well as prostate gland size (both are part of male investment) under different mating regimes in the great pond snail Lymnaea stagnalis. We find no evidence for the prediction from sex allocation theory that sperm production increases with mating frequency. However, we do find that animals with more mating opporunities develop smaller prostate glands, in which seminal fluid is produced. Moreover, repeated mating increases egg production, thus shifting allocation towards the female function, and probably decreases growth. So, our data hint at a three-way trade-off between part of the male function (prostate gland), female function, and growth. Interestingly, sex allocation seems to be shifted in the opposite direction from the one predicted by theory. We discuss how this feminization is suggestive of a direct manipulation by the sperm donor, probably to stimulate immediate sperm use. 相似文献
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Joris M. Koene Tina Pförtner Nico K. Michiels 《Behavioral ecology and sociobiology》2005,59(2):243-249
Sexual conflict between mating partners can give rise to strategies that are advantageous for one sex but harmful to the opposite sex. Usually, sperm donors develop (offensive) traits to enhance their chances in sperm competition, while sperm recipients evolve (defensive) traits that allow them to stay in control of who fathers their offspring. Here, we demonstrate that these processes are also at work in simultaneous hermaphrodites. The hermaphroditic earthworm Lumbricus terrestris uses 40 to 44 copulatory setae to pierce into its partner's skin, causing damage and injecting a substance from its setal glands. Experimental injection of the gland substance indicates that a refractory period may be induced. More importantly, removal of the copulatory setae shows that they influence the partner's sperm uptake. When the setae are present, more sperm are taken up and sperm are distributed more equally over the four spermathecae. We interpret this as a strategy that stacks the odds for the donor's sperm in fertilizing cocoons. 相似文献
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Joke Muys Bettina Blaumeiser Yves Jacquemyn Claude Bandelier Nathalie Brison Saskia Bulk Patrizia Chiarappa Winnie Courtens Anne De Leener Marjan De Rademaeker Julie Désir Anne Destrée Koenraad Devriendt Annelies Dheedene Annelies Fieuw Erik Fransen Jean-Stéphane Gatot Philip Holmgren Mauricette Jamar Sandra Janssens Kathelijn Keymolen Damien Lederer Björn Menten Marije Meuwissen Benoit Parmentier Bruno Pichon Sonia Rombout Yves Sznajer Ann Van Den Bogaert Kris Van Den Bogaert Olivier Vanakker Joris Vermeesch Katrien Janssens 《黑龙江环境通报》2018,38(13):1120-1128
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Joke Muys Yves Jacquemyn Bettina Blaumeiser Laura Bourlard Nathalie Brison Saskia Bulk Patrizia Chiarappa Anne De Leener Marjan De Rademaeker Julie Désir Anne Destrée Koenraad Devriendt Annelies Dheedene Armelle Duquenne Annelies Fieuw Erik Fransen Jean-Stéphane Gatot Mauricette Jamar Sandra Janssens Jorien Kerstjens Kathelijn Keymolen Damien Lederer Björn Menten Bruno Pichon Sonia Rombout Yves Sznajer Ann Van Den Bogaert Kris Van Den Bogaert Joris Vermeesch Katrien Janssens 《黑龙江环境通报》2020,40(10):1272-1283
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Degassing of H/He, CFCs and SF6 by denitrification: Measurements and two-phase transport simulations
Ate Visser Joris D. Schaap Hans Peter Broers Marc F.P. Bierkens 《Journal of contaminant hydrology》2009,103(3-4):206-218
The production of N2 gas by denitrification may lead to the appearance of a gas phase below the water table prohibiting the conservative transport of tracer gases required for groundwater dating. We used a two-phase flow and transport model (STOMP) to study the reliability of 3H/3He, CFCs and SF6 as groundwater age tracers under agricultural land where denitrification causes degassing. We were able to reproduce the amount of degassing (R2 = 69%), as well as the 3H (R2 = 79%) and 3He (R2 = 76%) concentrations observed in a 3H/3He data set using simple 2D models. We found that the TDG correction of the 3H/3He age overestimated the control 3He/3He age by 2.1 years, due to the accumulation of 3He in the gas phase. The total uncertainty of degassed 3H/3He ages of 6 years (± 2 σ) is due to the correction of degassed 3He using the TDG method, but also due to the travel time in the unsaturated zone and the diffusion of bomb peak 3He. CFCs appear to be subject to significant degradation in anoxic groundwater and SF6 is highly susceptible to degassing. We conclude that 3H/3He is the most reliable method to date degassed groundwater and that two-phase flow models such as STOMP are useful tools to assist in the interpretation of degassed groundwater age tracer data. 相似文献