Bijma Jelle

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Bijma
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Jelle
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  • Article
    Thermal stress reduces pocilloporid coral resilience to ocean acidification by impairing control over calcifying fluid chemistry
    (American Association for the Advancement of Science, 2021-01-22) Guillermic, Maxence ; Cameron, Louise P. ; De Corte, Ilian ; Misra, Sambuddha ; Bijma, Jelle ; de Beer, Dirk ; Reymond, Claire E. ; Westphal, Hildegard ; Ries, Justin B. ; Eagle, Robert A.
    The combination of thermal stress and ocean acidification (OA) can more negatively affect coral calcification than an individual stressors, but the mechanism behind this interaction is unknown. We used two independent methods (microelectrode and boron geochemistry) to measure calcifying fluid pH (pHcf) and carbonate chemistry of the corals Pocillopora damicornis and Stylophora pistillata grown under various temperature and pCO2 conditions. Although these approaches demonstrate that they record pHcf over different time scales, they reveal that both species can cope with OA under optimal temperatures (28°C) by elevating pHcf and aragonite saturation state (Ωcf) in support of calcification. At 31°C, neither species elevated these parameters as they did at 28°C and, likewise, could not maintain substantially positive calcification rates under any pH treatment. These results reveal a previously uncharacterized influence of temperature on coral pHcf regulation—the apparent mechanism behind the negative interaction between thermal stress and OA on coral calcification.
  • Article
    Foraminiferal ultrastructure: A perspective from fluorescent and fluorogenic probes
    (American Geophysical Union, 2019-08-22) Frontalini, Fabrizio ; Losada, Maria Teresa ; Toyofuku, Takashi ; Tyszka, Jarosław ; Goleń, Jan ; de Nooijer, Lennart ; Canonico, Barbara ; Cesarini, Erica ; Nagai, Yukiko ; Bickmeyer, Ulf ; Ikuta, Tetsuro ; Tsubaki, Remi ; Rodriguez, Celia Besteiro ; Al-Enezi, Eqbal ; Papa, Stefano ; Coccioni, Rodolfo ; Bijma, Jelle ; Bernhard, Joan M.
    Microscopy techniques have been widely applied to observe cellular ultrastructure. Most of these techniques, such as transmission electron microscopy, produce high‐resolution images, but they may require extensive preparation, hampering their application for in vivo examination. Other approaches, such as fluorescent and fluorogenic probes, can be applied not only to fixed specimens but also to living cells when the probes are nontoxic. Fluorescence‐based methods, which are generally relatively easy to use, allow visual and (semi)quantitative studies of the ultrastructural organization and processes of the cell under natural as well as manipulated conditions. To date, there are relatively few published studies on the nearly ubiquitous marine protistan group Foraminifera that have used fluorescent and fluorogenic probes, despite their huge potential. The aim of the present contribution is to document the feasible application of a wide array of these probes to foraminiferal biology. More specifically, we applied fluorescence‐based probes to study esterase activity, cell viability, calcium signaling, pH variation, reactive oxygen species, neutral and polar lipids, lipid droplets, cytoskeleton structures, Golgi complex, acidic vesicles, nuclei, and mitochondria in selected foraminiferal species.