France is particularly important in the field of civilian use of nuclear energy, as 78% of its energy is of nuclear origin (Bosch et al., 2009). Studies conducted at the individual level show that uranium reduces the growth and survival of larvae (Bourrachot et al., 2008) and the reproductive output of adults (Bourrachot, 2009).
Project outline
I was interested in the function of the digestive tract in nutrient assimilation, cellular defense and communication with the microbiota. The aim of this study is to provide such a quantifier for the level of development of an individual.
DEB model
EH - J Cumulative energy invested in adulthood up to puberty and reproduction after puberty Primary energy parameters. EG] 4652 J cm−3 Cost of synthesis of a structural unit EHb 0.54 J Cumulative energy invested in maturity on.
Materials and methods
Caloric restriction experiment
Data and parameter estimation
Maturity (accumulated energy invested in maturity) as well as maturity and somatic maintenance are dissipated in the environment as minerals (e.g. CO2). Although we were able to assume constant food density and temperature for most of the data (Appendix A.1), a dynamic formulation of the model was required to predict growth and reproduction in the calorie restriction experiment (Appendix A.2).
Results
The predicted length at birth (4 mm in the abundant food table 2.2) is not very sensitive to the nutritional status of the mother, which is consistent with both Parichy. The DEB theory predicts that age at birth also depends on the level of maternal ingestion (maternal effect).
Discussion
Pecquerie et al.(2009) believe that starved female Anchovies pay for somatic maintenance ([˙pM]) by reabsorbing energy from the reproductive buffer. The impact of food history accumulates over time (see table 2.4) and can become irreversible (Kooijman et al.,2011).
Model and methods
Formulation of starvation rules
Part κ of the current ˙pC(J d−1), which is mobilized from the reserve, is invested in somatic maintenance ˙pM = [ ˙pM]V and growth ˙pG=κp˙C−p˙M. The fraction κG (conversion efficiency) of the flow allocated to growth is fixed in the new structure.
Linking state variables to measurements
Stochastic feeding module
Results and Discussion
Constant food
Links between egg size and the mother's condition can be more complex and depending on the applications deviations from the mother effect rule must be considered. E0 = 1.7: feeding is never initiated (negative growth until death by shrinkage) and feeding is delayed at 0, 4 and 8 days after birth.
Stochastic searching
Monte Carlo simulation results for each of the 500 individuals at day 30 since birth are shown in Figure 3.5. Nearly all individuals in both populations in low food density environments (x = 0.3) are at risk due to rejuvenation.
Concluding remarks
CV increases two-fold between high and low food density environments for all predicted observations, regardless of the initial energy content of the egg. Thus, the present simulations hint at a negligible contribution of maternal effects to measurable endpoints after one month of development, regardless of food density.
Methods
- Egg collection and incubation
- Mass and energy density
- O 2 consumption
- DEB Model
When the forelegs emerged, small stones were placed in the containers so that the juveniles could climb out of the water. The energy density of the pellets was measured with a 1107 semi-microbomb of a 1261 bomb calorimeter (Parr, Moline, USA) after calibration with dry benzoic acid.
Results
Empirical results
We used a constant price of an egg, E0, to equate the initial amount of reserve energy to the observed value of each species. However, young O2 costs of development, from EH27 to EH46, were over three and a half times higher inC.
However, developmental costs for O2 in young children, from EH27 to EH46, were more than three and a half times higher in C. georgiana, due to a combination of less O2 consumed and reduced mass production. The total mass-specific O2 development costs were 1.5 times higher in C. Figure 4.2: Developmental stage as a function of age in Crinia georgiana and Pseudophryne bibronii. The dotted lines indicate first hatching and then birth inC. Georgiana and the solid line represents both hatching and birth inP. bibronii, which occur at the same age and stage. niles) (fig. 4.3c, d, e, f).
The contribution to maturation increased between EH22 and EH27 while the contribution to growth declined and continued to do so throughout juvenile development (fig. 4.1e).
Discussion
The developmental stages of zebrafish (Danio rerio), a species that also practices metabolic acceleration, are also linked to maturity levels as specified by deb theory (Augustine et al., 2011a). If we use either the gut-free mass or the dry biomass, it is very clear that there is a discrepancy between the difference in mass of the two species at metamorphosis and the difference in the total O2 consumed. The theory provides a standard deb model that is applicable to all animals (Kooijman, 2010, chapter 2); the model is mechanistic, so each parameter quantifies a single metabolic process.
The identification of the first process affected by the presence of uranium is thus the main concern of this analysis (Kooijman and Bedaux, 1996; Kooijman, 2010; Jager et al., 2010).
DEB model
- Temperature affects metabolic rates
- Buffer handling rules
- Starvation
- Toxico-kinetics
- Toxic effects
Allocation for reproduction, ˙pR is a continuous process where energy/mass accumulates in the reproductive buffer ER. Spawning buffer handling rules specify spawning dynamics and play an important role in the dynamics of total dry massWd. When there is no energy left in the reproduction buffer, then ˙r < 0 and energy is degraded by the structure to cover ˙pM with efficiency κG (table 5.1; Eq.
Partitioning of U in the organism is assumed to be instantaneous between reserve material (E+ER) and structureV.
Materials and Methods
- Animal maintenance
- Experimental conditions
- Water sample analysis
- Biometry
- Other data and parameter estimation
The water in the daily water renewal reservoirs for each condition was maintained at nominal cd. For simplicity, the water U concentration cd(t) is constant and equal to the nominal exposure concentration for each experiment. We also adjusted the predicted Wd0 to that observed for each individual female in the 37d trial using the maternal effect rule.
Assuming ER1(0) = 0, then there are three free parameters for each condition in Barillet et al.
Results
- Control Reproduction trials
- Fitting the control model to exposed females
- Mode of action of uranium on females in reproduction
- Adult whole body residues
- Embryo and early juvenile
As a result, women in the 37d trial have on average a higher V than in the 15d trial. Model fits to each individual in the 15d trial can be found in Appendix I. C) Mean cumulated N generated during the 37d trial. As noted earlier, growth is negligible in females in the 37d trial and most likely negligible in many females in the 15d trial.
Mode of action (M) most satisfactorily captured final mass and observed cumulated nitrogen for females in the 37d-U84 condition (Figure 5.6).
Discussion
- Insights on reproductive physiology
- Reproductive toxicology
- Effects on growth
- Elimination and uptake
- On the origin of variability in bioaccumulation measure-
- Deviations from the extended one compartment toxico-
- Perspectives
An additional study also shows uranium-induced damage to the intestinal wall in zebrafish (Augustine et al., 2012b). Dual mechanisms of action have also been observed in Folsomia candida exposed to chlorpyrifos (Jager et al., 2006a). However, U was efficiently eliminated in the annular Eisenia fetida (Labrot et al.,1999) and the arthropod Hyalella azteca (Alves et al.,2009).
This model applies to actinide uptake in general for the mussel Mytilus edulis (Lobel et al., 1991).
Concluding remarks
Uranium is a naturally occurring element, but activities related to the nuclear fuel cycle can increase background levels in the surrounding waters. Sublethal effects of waterborne uranium (U) on cumulative energy investment in growth and reproduction of zebrafish, Danio rerio have already been demonstrated. TEM coupled to energy-dispersive X-ray spectroscopy microanalysis of intestinal wall tissue shows that some uranium is internalized in the nucleus of epithelial cells in the 420 nM treatment.
Fluorescent in situ hybridization using specific probes to detect all eubacteria was performed on frozen sections of 6 individual fish in the 87 nM and 420 nM treatments.
Introduction
Host-microbe interactions are important players in terms of energy (food assimilation) and innate immunity (Bates et al., 2006; Kanther and Rawls, 2010). Furthermore, the effects of U on the growth and reproduction of Daphnia magna were also characterized using the deb theory (Massarin et al.). It was shown that a decrease in assimilation can explain the observed decrease in growth and reproduction (Massarin et al.,2011).
In contrast, effects of U on the metabolism of zebrafish are shown to occur around exposure media concentrations of 0-2 nM U (Augustine et al., 2012a).
Material and Methods
Experimental conditions and tissue sampling
Light and transmission electron microscopy
Results are presented as total observed MMG/mitochondria for each section of all replicates (Fig. 6.1B).
Fluorescent in situ hybridization
Results
- Uranium induces damage to gut wall
- Subcellular effects of uranium
- Effects of U on bacterial colonization of intestinal lumen 114
- Histopathology of gut wall
- Alterations of mitochondrial metabolism
- Bacterial colonization of intestinal lumen
High-energy dispersive X-ray spectrometry analysis of intestinal wall tissue revealed U precipitates in the nucleus of an enterocyte cell (fig. 6.3C) in the U420 state. Lumen of DT in the 420 nM condition was much less colonized by eubacteria than controls or 84 nM conditions. Histopathology of zebrafish tissue in response to similar exposure conditions reveals ultra-structural damage to gills, muscles and gonadal tissue after 20 d of exposure to 420 nM U in the water (Barillet et al., 2010).
This is in fact the first study where U was localized to the nucleus of zebrafish cells.
Conclusion
Harmful effects on the organism are detected by comparing the performance of individuals who are exposed to the stressor (uranium) with the performance of individuals who are not (blank). Therefore, in order to understand uranium-induced deviations in zebrafish physiological performance, I first needed to understand (and quantify) the physiological performance of a blank. The involvement of the V1-morph juvenile stage I to explain the accelerated growth and differences in parameter values between fry and adults (Kooijman et al., 2011) still remains an open point of debate.
The morphology of the O2 consumption vs. volume (or mass) curve varies with surface-to-volume ratios (for a specific example, see White et al., 2011), so inclusion of the V1-morph juvenile stage I may account for the observed biphasic allometric relationships between O2 consumption and body mass for some teleost species (Post and Lee, 1996; Killen et al., 2007).
Organism stress responses
Effects of uranium ingestion on transcriptional responses, histological structures and survival rate of the crayfish Procambarus clarkii. A quantitative estimate of the energetic costs of brown ring disease in the Manila clam using Dynamic Energy Budget theory. The 'covariation method' for estimating the parameters of the standard Dynamic Energy Budget model I: philosophy and approach.
Modeling fish growth and reproduction in the context of dynamic energy budget theory to predict environmental influence on anchovy spawning duration. Effects of dietary uranium on reproductive endpoints - fecundity, survival, reproductive success - of Danio rerio fish. Uranium was shown to alter the histology of the gut wall (key player in nutrient assimilation) and may even modify the homeostasis of the host-microbe interaction (key players in assimilation and innate immunity).
From individuals to molecules
From individuals to populations
Applications of this work to environmental risk assessment
An acceleration of growth in zebrafish and development in the croaking frog was detected due to deviations in the observations from the predictions of the standard DEB model. Valve closure response to uranium exposure for a freshwater bivalve bird (Corbicula fluminea): Quantifying the influence of pH. The 'covariation method' for estimating the parameters of the standard Dynamic Energy Budget model II: properties and preliminary patterns.
Effects of temperature on the energy costs and timing of embryonic and larval development of the terrestrially breeding moss frog, Bryobatrachus nimbus.
Dynamic formulation of the model
Survival probability
A hollow cylinder (5 cm ø) occupies the center of the aquarium and provides support for the removable partitions. Hose couplings (Eheim) are used to connect the hoses to the pumps and to each of the water distributors. The screen is held approximately 5 cm from the bottom of the aquarium by a support system.
Based on the assumption that all frogs have similar shapes and a specific wet mass density of 1 g cm−3, we derived estimates for the final dry mass of both species. The wet weight of the actual number of eggs hatched is subtracted from the total predicted wet weight on each spawning day. The amount of total reserve material (reserve + reproduction buffer) determines the severity of the toxic effect and contributes significantly to the dispersion of the data.