Nutrient sensing controlling gut motility in the stomachless fish ballan wrasse (Labrus berggylta)

Ex vivo intestines from 15-20 g ballan wrass (Labrus bergylta) were administered a bolus (lipid, protein, inert matter or empty control) before being mounted in oxygenated physiological buffer inside a glass vial. The intestinal motility patterns were documented with time lapse imaging for 14 hours. The images were used to construct spatio-temporal maps for gut motility analysis; i.e. to determine the speed, amplitude, frequency, travelled distance, direction, and initiation site of waves of muscle contractions. The experiments were repeated for RNA sampling and deep seq analysis. Gene expression analysis showed that intestines administered intact lipids clustered closer to the empty intestines compared to those given hydrolyzed lipids. Four different treatments were included in this study; Lipid (Hydrolyzed lipids), Protein (hydrolyzed casein), cellulose and Empty (n = 6). The diets were prepared to explore the effects of nutrient sensing on intestinal motility of ballan wrasse in vitro. Eviscerated ballan wrasse intestines containing the different “diets” were put in to a ringer’s solution for 60 min incubation before tissue sampling and downstream RNA extraction.