Dietary supply with polyunsaturated fatty acids and resulting maternal effects influence host – parasite interactions

Abstract

BackgroundInteractions between hosts and parasites can be substantially modulated by host nutrition. Polyunsaturated fatty acids (PUFAs) are essential dietary nutrients; they are indispensable as structural components of cell membranes and as precursors for eicosanoids, signalling molecules which act on reproduction and immunity. Here, we explored the potential of dietary PUFAs to affect the course of parasitic infections using a well-established invertebrate host – parasite system, the freshwater herbivore Daphnia magna and its bacterial parasite Pasteuria ramosa.ResultsUsing natural food sources differing in their PUFA composition and by experimentally modifying the availability of dietary arachidonic acid (ARA) and eicosapentaenoic acid (EPA) we examined PUFA-mediated effects resulting from direct consumption as well as maternal effects on offspring of treated mothers. We found that both host and parasite were affected by food quality. Feeding on C20 PUFA-containing food sources resulted in higher offspring production of hosts and these effects were conveyed to a great extent to the next generation. While feeding on a diet containing high PUFA concentrations significantly reduced the likelihood of becoming infected, the infection success in the next generation increased whenever the maternal diet contained PUFAs. We suggest that this opposing effect was caused by a trade-off between reproduction and immunity in the second generation.ConclusionsConsidering the direct and maternal effects of dietary PUFAs on host and parasite we propose that host – parasite interactions and thus disease dynamics under natural conditions are subject to the availability of dietary PUFAs.

Does infection tilt the scales? Disease effects on the mass balance of an invertebrate nutrient recycler

“…Parasitism may also alter ecosystem nutrient availability via many pathways that we did not explore (e.g., via the production of transmission stages that serve as dietary supplements for other organisms, Grami et al 2011, and behavioral modifications that increase predation rates on infected individuals, Johnson et al 2010). In addition to diet, many factors (e.g., temperature, maternal nutrition and exposure to the parasite) may alter the physiological responses of D. magna to infection by P. ramosa (Vale and Little 2009;Frost et al 2010;Schlotz et al (upper) and P (lower) excretion rates as a function of Daphnia diet C:P ratio. We calculated these effects by subtracting the nutrient excretion rates that were predicted from parameters measured on uninfected individuals from the nutrient excretion rates that were predicted from parameters measured on infected individuals and then dividing this predicted difference in excretion by the predicted excretion rates of uninfected individuals.…”

The development of pathogen resistance in Daphnia magna: implications for disease spread in age-structured populations

“…Thus, the most intense period of reproduction is approximately when susceptibility is highest. Other lines of evidence support a connection (or, perhaps, a trade-off) between reproduction and resistance in this system (Schlotz et al, 2013;Stjernman and Little, 2011), though a study explicitly designed to correlate reproduction and immunity across time and age is still required. Given that the main effect of infection in this system is fecundity reduction, this would essentially be a study of age-specific virulence, and an important contribution to our understanding of the interplay between immunity and reproduction.…”

The contribution of individual and maternal experience in shaping Daphnia life history

“…In Daphnia, the role of maternal effect in the expression of phenotypic reactions to environmental factors by offspring has been extensively discussed (Rossiter, 1996;Mousseau & Fox, 1998). Maternal effects have also been investigated in the context of predator-induced shifts in morphology (Agrawal et al, 1999), resting egg production induced by deteriorating environmental conditions (Boersma et al, 2000;Alekseev & Lampert, 2001;LaMontagne & McCauley, 2001;Mikulski & Pijanowska, 2009), and enhancing Daphnia tolerance to toxic Cyanobacteria (Gustafsson et al, 2005;Jiang et al, 2013) and parasitic disease (Little, 2003;Mitchell & Read, 2005;Schlotz et al, 2013;Garbutt et al, 2014). Maternal contributions to predator-induced changes in Daphnia life history were also revealed by Mikulski & Pijanowska (2009, but the relative contribution of individual's and mother's experience in shaping the eventual phenotype of the descendants has not been approached so far.…”