Circadian rhythms mediate infection risk inDaphnia dentifera

Abstract

Biological rhythms mediate important within‐host processes such as metabolism, immunity, and behavior which are often linked to combating disease exposure. For many hosts, exposure to pathogens occurs while feeding. However, the link between feeding rhythms and infection risk is unclear because feeding behavior is tightly coupled with immune and metabolic processes which may decrease susceptibility to infection. Here, we use the Daphnia dentifera–Metschnikowia bicuspidata host–pathogen system to determine how rhythms in feeding rate and immune function mediate infection risk. The host is known to have a nocturnal circadian rhythm in feeding rate, yet we found that they do not exhibit a circadian rhythm in phenoloxidase activity. We found that the time of day when individuals are exposed to pathogens affects the probability of infection with higher infection prevalence at night, indicating that infection risk is driven by a host's circadian rhythm in feeding behavior. These results suggest that the natural circadian rhythm of the host should be considered when addressing epidemiological dynamics.

Differential gene expression in response to fungal pathogen exposure in the aquatic invertebrate, Daphnia dentifera

“…In the future, similar studies extending beyond the first 24 h of exposure will provide a more holistic perspective of the genetic interplay of host and pathogen. It is also important to note that circadian rhythm has been shown to drive infection risk in the D. dentifera-M. bicuspidata system, and our results could be shaped by this relationship (Pfenning-Butterworth et al, 2022). Decaestecker et al (2011) failed to find differential gene expression in response to infection when specifically targeting genes coding for prophenoloxidase, two nitric oxide synthases, alpha-2macroglobulin, and arginase, all of which have been established as core components of invertebrate immune systems (McTaggart et al, 2009).…”

“…It is also important to note that circadian rhythm has been shown to drive infection risk in the D. dentifera‐M. bicuspidata system, and our results could be shaped by this relationship (Pfenning‐Butterworth et al, 2022 ).…”