PhD ceremony: Mr. D. de Corte, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen
Dissertation: Norms of constitutionalism in the international constitutionalisation debate
Promotor(s): prof. M.M.T.A. Brus
Faculty: Mathematics and Natural Sciences
The results presented in the PhD thesis of Daniele de Corte suggest that the dark ocean is more dynamic than commonly assumed and that the viral-host interactions change in response to changes in the biotic and abiotic variables.
Three cruises were conducted by him to assess the diversity of prokaryotes and the links between viruses and prokaryotes in the Atlantic and the Mediterranean Sea throughout the water column down to abyssopelagic (below 4000 m depth) waters. A high variability in the prokaryotic and viral abundance and production was found in the bathy- and abyssopelagic zones, indicating that the heterogeneity of the microbiota in the bathy- and abyssopelagic waters is as pronounced as in the epipelagic layer (0-150 m depth). Additionally, the community composition of the different microbial components, assessed by fingerprinting techniques, showed that the bacterial, archaeal and viral community were stratified with depth. The contribution of lysogenic and/or pseudolysogenic to total viral production increases towards the deep waters and towards more oligotrophic regions. Also, the low temperature in the abyssopelagic realm might provoke a longer persistence of infective viruses (lower decay rates) than in epipelagic waters exposed to high temperature and ultraviolet radiation.
Furthermore, the results from a study of De Corte in the coastal Arctic showed clear differences between the bulk bacterial community and its active fraction. Moreover, the discrepancies found between viral and prokaryotic communities in this coastal Arctic environment might be explained by the differential effect of the UV, and/or the high particle load of terrestrial origin on the prokaryotic and viral production.
Two top professors appointed at the Stratingh Institute for Chemistry
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