Baseline and post-stress seasonal changes in immunocompetence and redox state maintenance in the fishing bat Myotis vivesi.

Little is known of how the stress response varies when animals confront seasonal life-history processes. Antioxidant defenses and damage caused by oxidative stress and their link with immunocompetence are powerful biomarkers to assess animal´s physiological stress response. The aim of this study was A) to determine redox state and variation in basal (pre-acute stress) immune function during summer, autumn and winter (spring was not assessed due to restrictions in collecting permit) in the fish-eating Myotis (Myotis vivesi; Chiroptera), and B) to determine the effect of acute stress on immunocompetence and redox state during each season. Acute stress was stimulated by restricting animal movement for 6 and 12 h. The magnitude of the cellular immune response was higher during winter whilst that of the humoral response was at its highest during summer. Humoral response increased after 6 h of movement restriction stress and returned to baseline levels after 12 h. Basal redox state was maintained throughout the year, with no significant changes in protein damage, and antioxidant activity was modulated mainly in relation to variation to environment cues, increasing during high temperatures and decreasing during windy nights. Antioxidant activity increased after the 6 h of stressful stimuli especially during summer and autumn, and to a lesser extent in early winter, but redox state did not vary. However, protein damage increased after 12 h of stress during summer. Prolonged stress when the bat is engaged in activities of high energy demand overcame its capacity to maintain homeostasis resulting in oxidative damage

Le Miroir des sports : publication hebdomadaire illustrée

21 octobre 19301930/10/21 (N565)-1930/10/21

Seasonal swelling response after 12 hours of PHA injection.

<p>A) Data separated by sex from P1. B) Combined data from P1 (estimated marginal mean ± SE). C) Data separated by sex from P2. Pink arrows represent seasonal variation in the swelling response in females; black arrows represent seasonal changes in swelling response in males. D) Combined data from P2 (estimated marginal mean ± SE); different letters indicate significant differences among seasons.</p

Acute stress stimuli impact on physiological markers.

<p>Change in SOD, CAT and GPx activity (mean ± SD). Asterisks indicate significant differences in the response between basal and post-stress levels based on Student’s t-tests. Bold numbers inside bars indicate sample sizes.</p

Bactericidal activity of plasma.

<p>Samples correspond to seasons within periods 1 (mean ± SD), and 2 (median ± interquartile range), as revealed by ANOVA analysis with Welch correction and Kruskal-wallis analysis, respectively. Different letters indicate significant differences between seasons within a period, asteisks indicate significant differences between the same season of different periods, as revealed by Kruskal-Wallis post-hoc analysis. Numbers in parenthesis indicate sample sizes.</p

Seasonal swelling response after 6 hours of PHA post injection.

<p>A) P1, pink arrows represent seasonal variation in the swelling response in females; black arrows represent seasonal changes in the swelling response in males; different letters indicate significant differences among seasons within a period; asterisks indicate differences between periods for a given season. B) P2, pink arrows represent females and black arrows represent males; no significant differences were found. C) Combined data from P2 (estimated mean ± SE).</p

Seasonal swelling response after 24 hours of PHA injection.

<p>A) Data separated by sex from P1. B) Combined data from P1 (estimated marginal mean ± SE). C) Data separated by sex from P2. Pink arrows represent seasonal variation in the swelling response in females; black arrows represent seasonal changes in swelling response in males; D) Combined data from P2 (estimated marginal mean ± SE); different letters indicate significant differences among seasons.</p

Graphic representation of principal component analysis plotting PC1 against PC2.

<p>A) Period 1 basal disregard-PCA, B) Period 1 basal between groups-PCA, C) Period 1 six hours Post-stress disregard-PCA, D) Period 1 six hours Post-stress between groups-PCA, E) Period 2 basal disregard-PCA, F) Period 2 basal between groups-PCA, G) Period 2 six hours Post-stress disregard-PCA, H) Period 2 six hours Post-stress between groups-PCA.</p

Oxidative stress on bats by season for both periods (period 1 and period 2) of sample collection.

<p>A) P1 antioxidant enzymatic activity in erythrocytes (mean ± SD). B) P2 antioxidant enzymatic activity in erythrocytes (mean ± SD). C) Protein damage measured by carbonyl quantification in erythrocytes (mean ± SD) on P1. D) Protein damage measured by carbonyl quantification in erythrocytes (mean ± SD) on P2. Different letters indicate significant differences among seasons of a period as revealed by ANOVA with Welch correction. Numbers in parenthesis indicate sample sizes.</p

Bats body condition by season on both periods (period 1 and period 2) of sample collection.

<p>A) Hematocrit percentage (mean ± SD); B) Scaled mass index (mean ± SD). Different letters indicate significant differences between seasons within a period and asterisks indicate significant differences between the same seasons of different periods as determined by ANOVA. Numbers in bold indicate sample sizes.</p