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From developmental energetics to effects of toxicants: a story born of zebrafish and uranium

From developmental energetics to effects of toxicants: a story born of zebrafish and uranium. S. Augustine B.Gagnaire C. Adam-Guillermin S. A. L. M. Kooijman. Processes at different levels of biological organisation. Time. ecosystems. populations. Individuals. cells. molecules.

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From developmental energetics to effects of toxicants: a story born of zebrafish and uranium

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  1. From developmental energetics to effects of toxicants: a story born of zebrafish and uranium S. Augustine B.Gagnaire C. Adam-Guillermin S. A. L. M. Kooijman

  2. Processes at different levels of biological organisation Time ecosystems populations Individuals cells molecules Role of behavior on food intake and mate preference Differences between individuals = differences in parameter values Space Role of differences in individuals + selection in evolution Energy + Mass Balances Kooijman 2010 DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  3. Research Strategy Understanding the physiology of the blank Physiological deviations from the blank: toxic mode of action of uranium Extrapolate to effects at the population level Metabolic handling of starvation of the early juvenile Estimation of a single set of parameters for zebrafish, Danio rerio ( see Lika et al 2011) based on observations of: -Synthesis of data collected in the laboratory -Data collection : reproduction at different levels of uranium in the water • IBM modelling using NetLogo (Ben Martin et al 2011) • Euler-Lotka equation (Kooijman 2010) Monte Carlo simulations to understand the contribution of uncertainty on the food input on measurable enpoints such as growth and respiration - Embryonic development - Growth - Reproduction - Survival • Fit the model to the totality of observed effects: elucidate the toxic mode of action of uranium on the metabolism • - simple model for uranium uptake and elimination (T. Jager and E. Zimmer this morning) Augustine et al. J Biochem Physiol A 2011 Augustine et al. Subm J Sea Res 2011

  4. Structure Somatic Maintenance Maturity Maintenance Maturity DEB model applied to the whole lifecycle of Danio rerio EMBRYO JUV I J II ADULT AGE BIRTH METAMORPHOSIS PUBERTY қG (0.67) Қ(0.44) Food Reserve қX Reproduction Buffer 1 – қ қR (0.95) DEB Symposium, Lisbon, Pt 13 - 15 April 2011 Eggs

  5. Effects of feeding history accumulate over time Maturity is a good quantifier for developmental stage The value of қ is close to the one that maximises reproduction size High variability in reproduction buffer handling rules combines with low variability of cumulated reproductive output age Surface area-specific assimilation and reserve mobilization rates are higher for adults than for embryos Developmental milestone quantified as cumulated energy invested in maturity (J) DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  6. Possible origins of inter-individual biological variability Role of behavior on food intake and mate preference Stochastic buffer handling rules Stochastic food input Deterministic system with conserved biochemical machinery Monte Carlo simulation studies DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  7. Relationships between egg size, and cumulated energy invested in the different metabolic processes at birth 1 J 1.67 J Relationship between egg size and resistance to starvation? DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  8. Monte Carlo simulation studies with stochastic food input over the first month of development Initial egg energetic content Environmental food density LENGTH (mm) MASS (mg) O2 (µmole d-1) DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  9. Effects of compounds: URANIUM Uranium is toxic for organisms (Canadian law on environmental protection 1999) Effects Internalised U Internalised U No Internal Effect Concentration Exposure to contaminants induces physiological deviations from the blank • Modified growth • Modified reproductive output DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  10. Broad patterns of effects of uranium on the metabolism Bourrachot 2009 Barillet 2008 Augustine unpublished Adam-Guillermin unpublished DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  11. Scenario Analysis: the observed effects can be translated into the modification of a parameter value Scenario 3 : Bring up maturity maintenance costs Scenario 2 : Bring up the volume linked somatic maintenance costs Scenario 1 : Bring up the cost for a unit of structure BLANK Length (mm) Maturation (kJ) Cumulated # eggs 40 8.104 3 0 0 0 5 200 200 200 5 5 Age, day Age, day Age, day DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  12. Conclusions/ Perspectives We can now calculate cumulative joules invested to reach each described developmental milestone in the zebrafish staging atlas Monte Carlo simulations where the uncertainty resides in food intake are useful tools for understanding empirical patterns in observed scatter of length, mass and respiration data For effects of compounds the predictive power of the model is linked to the level of knowledge of the physiology of the blank which translates in terms of DEB theory in model parameter values. The next step consists in fitting the model to the toxicity data and extrapolating to population level effects DEB Symposium, Lisbon, Pt 13 - 15 April 2011

  13. Thank you for your attention … DEB Symposium, Lisbon, Pt 13 - 15 April 2011

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