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

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

Research Strategy Understanding the physiology of the blank Estimation of a single set of parameters for zebrafish, Danio rerio ( see Lika et al 2011) based on observations of: - Embryonic development - Growth - Reproduction - Survival Augustine et al. J Biochem Physiol A 2011 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 Monte Carlo simulations to understand the contribution of uncertainty on the food input on measurable enpoints such as growth and respiration Augustine et al. Subm J Sea Res Synthesis of data collected in the laboratory -Data collection : reproduction at different levels of uranium in the water -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) -IBM modelling using NetLogo (Ben Martin et al 2011) -Euler-Lotka equation (Kooijman 2010)

DEB Symposium, Lisbon, Pt April DEB model applied to the whole lifecycle of Danio rerio Food Reserve Structure Somatic Maintenance Maturity Maturity Maintenance қXқX қ G (0.67) қ R (0.95) Eggs Reproduction Buffer Қ (0.44) 1 – қ BIRTHMETAMORPHOSISPUBERTY EMBRYOJUV IJ IIADULT AGE

DEB Symposium, Lisbon, Pt April age size Developmental milestone quantified as cumulated energy invested in maturity (J) 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 High variability in reproduction buffer handling rules combines with low variability of cumulated reproductive output Surface area-specific assimilation and reserve mobilization rates are higher for adults than for embryos

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

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

Monte Carlo simulation studies with stochastic food input over the first month of development DEB Symposium, Lisbon, Pt April Initial egg energetic content Environmental food density LENGTH (mm)MASS (mg)O 2 (µmole d -1 )

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

DEB Symposium, Lisbon, Pt April Broad patterns of effects of uranium on the metabolism SurvivalGrowthreproducti on Egg size EMBRO ++ JUVENILE ++ ADULT +- Bourrachot 2009 Barillet 2008 Augustine unpublished Adam-Guillermin unpublished ACCUMULATESDEPURATES EMBRO +- JUVENILE +- ADULT + Through reproduction

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

DEB Symposium, Lisbon, Pt April Conclusions/ Perspectives 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. 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 We can now calculate cumulative joules invested to reach each described developmental milestone in the zebrafish staging atlas The next step consists in fitting the model to the toxicity data and extrapolating to population level effects

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