Bruni, L. | Search bioRxiv

bioRxiv2021

Behavior in mice subjected to a Token Slot-machine: effect of Unpredictable Chronic Mild Stress

Several studies have succeeded in teaching animals (primates, pigeons, rats, but not mice) the value of tokens by having them executing a task using a vending-machine apparatus, where in order to receive the primary reinforcement (food), the animals had to perform a specific action that allowed them to obtain the secondary reinforcement (tokens: metal balls). We tried to assess this kind of behavior in mice that had previously been trained to use some tokens, with the aim of rewarding them not with food, but with other tokens, as a result of a token economy task. We found that mice exhibit economic behavior. Further on, our research tried to investigate the effect of stress on their operant decision-making. Therefore, the mice were divided into two groups: a Control group (n=10) and a group subjected to an Unpredictable Chronic Mild Stress (UCMS) treatment (n=8). We found that chronic stress increases some aspects of sub-optimal economic activity. Summary statementWe designed an original model enabling to assess behavior in mice that had previously been trained to use some tokens, with the aim of rewarding them not with food, but with other tokens. Further on, our research investigated the effect of stress on their operant decision-making.

animal behavior and cognition↗

bioRxiv2020

Differential Response of Digesta- and Mucosa-Associated Intestinal Microbiota to Dietary Black Soldier Fly (Hermetia illucens) Larvae Meal in Seawater Phase Atlantic Salmon (Salmo salar)

Intestinal digesta is commonly used for studying responses of microbiota to dietary shifts, yet evidence is accumulating that it represents an incomplete view of the intestinal microbiota. In a 16-week seawater feeding trial, Atlantic salmon (Salmo salar) were fed either a commercially-relevant reference diet or an insect meal diet containing 15% black soldier fly (Hermetia illucens) larvae meal. The digesta- and mucosa-associated distal intestinal microbiota were profiled by 16S rRNA gene sequencing. Regardless of diet, we observed substantial differences between digesta- and mucosa-associated intestinal microbiota. Microbial richness and diversity were much higher in the digesta than the mucosa. The insect meal diet altered the distal intestinal microbiota resulting in higher microbial richness and diversity. The diet effect, however, depended on the sample origin. Digesta-associated intestinal microbiota showed more pronounced changes than the mucosa-associated microbiota. Lastly, multivariate association analyses identified two mucosa-enriched taxa, Brevinema andersonii and unclassified Spirochaetaceae, associated with the expression of genes related to immune responses and barrier function in the distal intestine, respectively. Overall, our data clearly indicate that responses in digesta- and mucosa-associated microbiota to dietary inclusion of insect meal differ, with the latter being more resilient to dietary changes.

microbiology↗