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Stem cells of the Drosophilamidgut (ISCs) are the only mitotically dividing cells of the epithelium and, therefore, presumably the only epithelial cells that require functional kinetochores for microtubule spindle attachment during mitosis. The histone variant CENP-A marks centromeric chromatin as the site of kinetochore formation and spindle attachment during mitotic chromosome segregation. Here, we show that centromeric proteins distribute asymmetrically during ISC division. Whereas newly synthesized CENP-A is enriched in differentiating progeny, CENP-C is undetectable in these cells. Remarkably, CENP-A persists in ISCs for weeks without being replaced, consistent with it being an epigenetic mark responsible for maintaining stem cell properties. Furthermore, CENP-A and its loading factor CAL1 were found to be essential for post-mitotic, differentiating cells; removal of any of these factors interferes with endoreduplication. Taken together, we propose two additional roles of CENP-A: to maintain stem cell-unique properties and to regulate post-mitotic cells.

Intensive agriculture is the leading perturbation on freshwater ecosystems due to the agrochemical inputs that compromise biodiversity and ecosystem services. The importance of agriculture cannot be neglected nor the fact that freshwater biodiversity is being depleted worldwide owing to anthropogenic pressures. Therefore, a balance between economic and environmental values must be achieved. The present experiment explores the EEC legal limits on the concentration of agrochemicals (nitrate used as fertilizer) and investigates if even when assuming safe limits there are impacts in freshwater ecosystems. The objective is to assess direct and indirect effects of legal toxicant concentrations on the ecological integrity of plankton communities. This information seeks to assist policy makers with more ecological relevant results to establish legal thresholds that neither overestimates nor underestimates environmental risks. Microcosm experiments were set up outdoors with local assemblages of plankton for 8 weeks. Two nitrate treatments were established: (1) a low treatment (L) of 25 mg l–1 of nitrate, and (2) a high treatment (H) of 50 mg l–1 of nitrate. In conclusion, firstly, we detected that zooplankton taxa shifted from a cladocera-dominated to a copepod-dominated community as an indirect response to phytoplankton decrease. Secondly, both L and H treatments had a negative effect on the plankton community in spite of being within assumed safe legal limits.