Models in stress research Bas.Kooijman@vu.nl http://www.bio.vu.nl/thb Brest, 2016/08/29/14:00 MEMS Summer school

Contents Stress Research - in biology - in energetics - in stress Meta-models

Stress stress factor too little enough too much too little enough too much No stress for a range of factor values Stress = difference from no-stress Consequence: We need to know the no-stress situation to recognize stress, including `variability’

Arrhenius relationship stress ln pop growth rate, h-1     103/T, K-1 103/TH 103/TL

Space-time scales system earth space ecosystem population individual Each process has its characteristic domain of space-time scales molecule cell individual population ecosystem system earth time space When changing the space-time scale, new processes will become important other will become less important This can be used to simplify models, by coupling space-time scales Complex models are required for small time and big space scales and vv Models with many variables & parameters hardly contribute to insight

Biochemical ↔ Pools many compounds few pools need for selection conservation laws cannot be used wide range in scales complex dynamics easy connection with molecular level with literature few pools use of homeostasis conservation laws can be used narrow range in scales simple dynamics complex connection with molecular level with literature Bridge calls for intermediary levels of organisation

Homeostasis strong homeostasis weak homeostasis structural homeostasis constant composition of pools (reserves/structures) generalized compounds, stoichiometric constraints on synthesis weak homeostasis constant composition of biomass during growth in constant environments determines reserve dynamics (in combination with strong homeostasis) structural homeostasis constant relative proportions during growth in constant environments isomorphy .work load allocation thermal homeostasis ectothermy  homeothermy  endothermy acquisition homeostasis supply  demand systems development of sensors, behavioural adaptations Homeostasis is the ability to run metabolism independent from environmental conditions. This can obviously not be perfect, all organisms require food and/or nutrients. We need 5 difference homeostasis concepts to capture the extent organisms sport homeostasis.

Static vs Dynamic Budgets Net production models time-dependent static models no damping by reserve Assimilation models dynamics by nature reserve damps food fluctuations

Criteria for general energetic models Quantitative Based on explicit assumptions that together specify all quantitative aspects to allow for mass and energy balancing Consistency Assumptions should be consistent in terms of internal logic, with physics and chemistry, as well as with empirical patterns Simplicity Implied model(s) should be simple (numbers of variables and parameters) enough to allow testing against data Generality The conditions species should fulfill to be captured by the model(s) must be explicit and make evolutionary sense Explanatory The more empirical patterns are explained, the better the model

Stress by chemical compounds Par values depend on internal concentration: transport 1 compartment 1-1 compartment   internal conc external conc partition coef = vol environ vol organism dim(partition coef) = vol organism time × vol environ 1 time dim(accum rate) = dim(elim rate) =

n,n-compartment models 6.3a 1,1-comparment model film model Compound can cross, interface between media with different rates vice versa sub-layers with equal rates for all sublayers

Meta models models for parameter values Null model: group pars in either intensive or extensive find a simple function of pars that contains 1 extensitive par x example: max struct length for standard DEB model, example: bioconc factor for 1 compartment model find ratios of extensive pars that are intensive and contains x this links all extensive parameters to x write property of interest as function of pars and study how is scales with x

Primary parameters standard DEB model The are all standard DEB model parameters for an individual with a max structural length of 1 cm at 20°C Simple rules apply for individuals of different max length and/or temperature. Kooijman 1986 J. Theor. Biol. 121: 269-282

Primary parameters 1-1 compartment, film model time to reach x-level saturation film model   Kooijman et al 2007 SAR & QSAR Environ. Res. 18: 315-330

DEB tele course 2017 Audience: thank you for your attention http://deb.akvaplan.com/debschool.html Free of financial costs; Some 108 or 216 h effort investment Program for 2017: Feb/Mar general theory (5w) May symposium in Tromso (N) (8d +3 d) Target audience: PhD students We encourage participation in groups who organize local meetings weekly Software package DEBtool for Octave/ Matlab freely downloadable Slides of this presentation are downloadable from http://www.bio.vu.nl/thb/users/bas/lectures/ Cambridge Univ Press 2009 Audience: thank you for your attention