@article{WeithoffTaubeBolius2017,
  author    = {Weithoff, Guntram and Taube, Anne and Bolius, Sarah},
  title     = {The invasion success of the cyanobacterium Cylindrospermopsis raciborskii in experimental mesocosms},
  series = {Aquatic Invasions},
  volume    = {12},
  journal   = {Aquatic Invasions},
  publisher = {Regional Euro-Asian Biological Invasions centre-reabic},
  address   = {Helsinki},
  issn      = {1798-6540},
  doi       = {10.3391/ai.2017.12.3.07},
  pages     = {333 -- 341},
  year      = {2017},
  abstract  = {The potentially toxic, invasive cyanobacterium Cylindrospermopsis raciborskii, originating from sub-tropical regions, has spread into temperate climate zones in almost all continents. Potential factors in its success are temperature, light and nutrient levels. Grazing losses through zooplankton have been measured in the laboratory but are typically not regarded as a factor in (failed) invasion success. In some potentially suitable lakes, C. raciborskii has never been found, although it is present in water bodies close by. Therefore, we tested the invasive potential of three different isolates introduced into natural plankton communities using laboratory mesocosm experiments under three grazing levels: ambient zooplankton densities, removal of large species using 100 mu m mesh and a ca. doubling of large species. Three C. raciborskii isolates originating from the same geographic region (North-East Germany) were added separately to the four replicates of each treatment and kept in semi-continuous cultures for 21 days. Two isolates disappeared from the mesocosms and were also not viable in filtered lake water indicating that the lake water itself or the switch from culture medium to lake water led to the decay of the inoculated C. raciborskii. Only one out of the three isolates persisted in the plankton communities at a rather low level and only in the treatment without larger zooplankton. This result demonstrates that under potentially suitable environmental conditions, top-down control from zooplankton might hamper the establishment of C. raciborskii. Non-metric multidimensional scaling showed distinct variation in resident phytoplankton communities between the different grazing levels, thus differential grazing impact shaped the resident community in different ways allowing C. raciborskii only to invade under competitive (= low grazing pressure) conditions. Furthermore, even after invasion failure, the temporary presence of C. raciborskii influenced the phytoplankton community.},
  language  = {en}
}
@article{KoussoroplisSchwarzenbergerWacker2017,
  author    = {Koussoroplis, Apostolos-Manuel and Schwarzenberger, Anke and Wacker, Alexander},
  title     = {Diet quality determines lipase gene expression and lipase/esterase activity in Daphnia pulex},
  series = {Biology open : BiO},
  volume    = {6},
  journal   = {Biology open : BiO},
  publisher = {The company of Biologists},
  address   = {Cambridge},
  doi       = {10.1242/bio.022046},
  pages     = {210 -- 216},
  year      = {2017},
  abstract  = {We studied the short- (12 h) and long-term (144 h) response of Daphnia pulex lipases to quality shifts in diets consisting of different mixtures of the green alga Scenedesmus with the cyanobacterium Synechococcus, two species with contrasting lipid compositions. The lipase/esterase activity in both the gut and the body tissues had fast responses to the diet shift and increased with higher dietary contributions of Synechococcus. When screening the Daphnia genome for TAG lipases, we discovered a large gene-family expansion of these enzymes. We used a subset of eight genes for mRNA expression analyses and distinguished between influences of time and diet on the observed gene expression patterns. We identified five diet-responsive lipases of which three showed a sophisticated short- and long-term pattern of expression in response to small changes in food-quality. Furthermore, the gene expression of one of the lipases was strongly correlated to lipase/esterase activity in the gut suggesting its potentially major role in digestion. These findings demonstrate that the lipid-related enzymatic machinery of D. pulex is finely tuned to diet and might constitute an important mechanism of physiological adaptation in nutritionally complex environments.},
  language  = {en}
}