DOI: 10.5061/dryad.s4mw6m9hc
title: Effects of endurance flight on mitochondrial physiology, lean mass dynamics and flight muscle morphology in blackpoll warblers

description: Migratory birds are physiologically challenged by intense exercise while
 fasting during flights that may last hours to days. Exercise-induced
 oxidative stress could compromise flight performance by inducing
 mitochondrial dysfunction in the flight muscle. Endurance flight is
 partially fuelled by the catabolism of lean tissues, but how this
 catabolism is partitioned between different organs and muscles has not
 been previously studied under controlled conditions. We hypothesized that
 simulated migratory flight would result in dysfunction of flight muscle
 mitochondria, and selective catabolism of lean tissues. We predicted that
 simulated migratory flight would cause reduced mitochondrial oxidative
 phosphorylation capacity while increasing emission of reactive oxygen
 species (ROS) and that lean tissue mass catabolism would preferentially
 occur in digestive organs not needed in flight. We measured mitochondrial
 function, muscle morphology and the wet masses of organs and muscles
 following 8-hour wind tunnel flights in blackpoll warblers (Setophaga
 striata), which use multi-day nonstop flights as part of their migration
 strategy. In contrast to our predictions, we found that simulated
 migratory flight did not alter mitochondrial fatty acid oxidation capacity
 or ROS emission. However, flight and fasting increased whole-animal lean
 mass catabolism and was associated with reductions in the masses of liver,
 gizzard and proventriculus, but masses of tissues in the flight apparatus
 (pectoralis, heart, lungs) were unaffected. Pectoralis muscle fiber
 morphology was also unchanged over the tested flight duration. Our
 findings indicate that mitochondrial function in blackpoll warblers is
 robust against damage induced by simulated migratory flight, and energy
 deprivation is sufficient for organ catabolism.
description: # Effects of endurance flight on mitochondrial physiology, lean mass
 dynamics and flight muscle morphology in blackpoll warblers
 [https://doi.org/10.5061/dryad.s4mw6m9hc](https://doi.org/10.5061/dryad.s4mw6m9hc) ## Description of the data and file structure Blackpoll warblers (*Setophaga striata*) were split into three experimental groups and each was fasted for one hour prior to each group's intervention: 1. Flown: birds were sampled after being flown 7.5-8 hours in a wind tunnel 2. Fasted: birds were sampled after being fasted from food and water for 7.5-8 hours in the wind tunnel antechamber 3. Pre-flight: birds were sampled following the 1 hour fast Body composition for flown and fasted birds was measured before and after flight/fasting using quantitive magnetic resonance imaging. After euthanasia, multiple tissues were harvested and weighed. Some flight muscle was embedded for histological analyses, while remaining muscle was used to isolate mitochondria. High-resolution respirometry was conducted on isolated mitochondria to measure mitochondrial respiration and ROS emission while oxidizing fatty acids. ### Files and variables #### File: blpw\_data.xlsx **Description:** All data used in the manuscript ##### Variables | Table 1 | | | :---------------------- | :------------------------------------------------- | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | inmass | initial body mass (g) | | infat\_avg | initial fat mass (g) | | inlean\_avg | initial lean mass (g) | | sex | sex: unknown (U); male (M) | | age | age class: hatch-year (HY); after hatch-year (AHY) | | wing\_cord | wing chord (mm) | | | | | Figure 1 | | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | fat\_energy | whole-animal fat energy use (kJ) | | lean\_energy | whole-animal lean energy use (kJ) | | fat\_energy\_pct | relative whole-animal fat energy use (%) | | power | average power (W) | | | | | Figure 2 | | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | wing\_cord | wing chord (mm) | | s3\_jo2 | state 3 respiration (nmol O2/min/mg) | | s4\_jo2 | state 4 respiration (nmol O2/min/mg) | | net\_oxphos | net OXPHOS capacity (nmol O2/min/mg) | | fat\_energy | whole-animal fat energy use (kJ) | | | | | Figure 3 | | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | wing\_cord | wing chord (mm) | | coupling | OXPHOS coupling efficiency (unitless) | | fat\_energy | whole-animal fat energy use (kJ) | | | | | Figure 4 | | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | wing\_cord | wing chord (mm) | | CI | complex I-IV flux (nmol O2/min/mg) | | CII+III | complex II-IV flux (nmol O2/min/mg) | | CIV | complex IV capacity (nmol O2/min/mg) | | fat\_energy | whole-animal fat energy use (kJ) | | | | | Figure 5 | | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | wing\_cord | wing chord (mm) | | s3\_jh2o2 | state 3 ROS emission (nmol H2O2/min/mg) | | s3\_frl | state 3 free radical leak (% respiration) | | s3\_o2 | state 3 O2 concentration (μmol/L) | | s4\_jh2o2 | state 4 ROS emission (nmol H2O2/min/mg) | | s4\_frl | state 4 free radical leak (% respiration) | | s4\_o2 | state 4 O2 concentration (μmol/L) | | fat\_energy | whole-animal fat energy use (kJ) | | | | | Figure 6 | | | ID | bird identification number | | year\_samp | sampling year | | flight\_group | experimental group | | wing\_cord | wing chord (mm) | | body | final body mass (g) | | pec | pectoralis wet mass (mg) | | liver | liver wet mass (mg) | | heart | heart wet mass (mg) | | lungs | lungs wet mass (mg) | | dig\_tract | digestive tract wet mass (mg) | | gizz\_prov | gizzard and proventriculus wet mass (mg) | | fat\_energy | whole-animal fat energy use (kJ) | | | | | Figure 7 | | | ID | bird identification number | | flight\_group | experimental group | | wing\_cord | wing chord (mm) | | fiber\_density | pectoralis fiber density (mm^-2) | | fiber\_transverse\_area | pectoralis fiber transverse area (μm^2) | | fat\_energy | whole-animal fat energy use (kJ) | Missing data code: NA ## Code/software All analyses conducted using R (v 4.3.1).