Dataset Sabbagh 2023

Studies of host physiology in response to parasite infection tend to focus on impacts at the whole-organism level such as aerobic metabolic rates, body condition, behavior, etc. Very few of these studies investigate cellular mechanisms that may very well explain alterations to metabolic rates and body condition often observed in infected organisms, and even fewer compare these cellular mechanisms across populations. Mitochondria are the organelles responsible for energy production and are linked to whole-animal metabolic rates as well as body condition. Mitochondria are also implicated in the production and regulation of reactive oxygen species, molecules that play an important role in cellular immune responses. In this manuscript, we studied the activity of some key metabolic and antioxidant enzymes in three populations of wild pumpkinseed sunfish (Lepomis gibbosus (Linnaeus, 1758)) naturally infected by the bass tapeworm (Proteocephallus ambloplitis (Leidy, 1887)). Enzymatic activity was measured in the liver tissue, the most infected organ by the cestodes, and linked to infection intensity and fish body condition. We found that cestode infection was associated with reduced lipid metabolism and increased lactic fermentation, suggesting that infection may alter oxygen availability in host tissues. Additionally, population body condition varied differently with cestode density; positive as well as negative correlations where found, depending the population. Some enzymatic activity also varied among populations, such as the activity of the electron transport system and the antioxidant glutathione peroxidase, suggesting the adoption of different immunological responses. The differences could be attributed to ecological and demographic differences, factors that may influence the physiological effects and resistance of populations to parasite infections. These results highlight the importance of accounting for infection when studying animal physiology and we hope that the publication of this work will help guide future research on this topic.