Inhibition of gut digestive proteases by cyanobacterial diets decreases infection in a Daphnia host-parasite system

Secondary metabolites produced by primary producers have a wide range of functions as well as indirect effects outside the scope of their direct target. Research suggests that protease inhibitors produced by cyanobacteria influence grazing by herbivores and may also protect against parasites of cyanobacteria. In this study we asked whether those same protease inhibitors produced by cyanobacteria also can influence interactions of herbivores with their parasites. 
We used the Daphnia-Metschnikowia zooplankton host-fungal parasite system to address this question because it is well-documented that cyanobacteria protease inhibitors suppress trypsin and chymotrypsin in the gut of Daphnia, and because it is known that Metschnikowia infects via the gut. We tested the hypothesis that Daphnia gut proteases are necessary for Metschnikowia spores to be released from their asci. We then also tested whether diets that decrease trypsin and chymotrypsin activity in the guts of Daphnia lead to lower le..., Host-parasite system
Our study used 11 clones of Daphnia magna, which is a common species in ponds and lakes, especially in Europe. These clones come from different populations and have been used in studies focusing on the impact of cyanobacterial diets on Daphnia gut digestive enzymes (e.g., Schwarzenberger et al., 2021; see supplementary material and Table S1 for additional information about these clones). We used the common fungal parasite Metschnikowia bicuspidata (“Standard” isolate, originally isolated from Baker Lake in Barry County, Michigan). Daphnia become infected after consuming transmission spores they encounter in the water column when feeding. Infection takes place when the needle-shaped spore crosses the gut barrier and is not fought off by a host hemocyte response (Metschnikoff, 1884; Stewart Merrill and Cáceres, 2018). Once infection has taken hold, the fungus replicates within the hemolymph of the host (Stewart Merrill and Cáceres, 2018). The parasite reduces the fecu..., , # Inhibition of gut digestive proteases by cyanobacterial diets decreases infection in a Daphnia host-parasite system

[https://doi.org/10.5061/dryad.nzs7h44xq](https://doi.org/10.5061/dryad.nzs7h44xq)

There are three datasets for this project.

* The first dataset focuses on Experiment 1. Dehiscence assay: isolating the impact of gut extracts and chymotrypsin on spore dehiscence.
* The second dataset is for Experiment 2. Quantification of effects of diet treatments on gut digestive enzymes and infection levels, and focuses on *Daphnia's* life parameters such as offspring produced, infection status and infection load.
* The third dataset is the rest of the data for Experiment 2. Quantification of effects of diet treatments on gut digestive enzymes and infection levels, which contains data on *Daphnia* clone enzyme activity.

## Description of the data and file structure

The following explains all of the variables in the dataset dehisence_Jan2023.csv which are part of
Sanchez KF,...