Modifications of glucocorticoid receptors mRNA expression in the hypothalamic‐pituitary‐adrenal axis in response to early-life stress in female Japanese quail

The present study was funded by a BBSRC David Phillips Research Fellowship to KAS.Stress exposure during early‐life development can programme individual brain and physiology. The hypothalamic‐pituitary‐adrenal (HPA) axis is one of the primary targets of this programming, which is generally associated with a hyperactive HPA axis, indicative of a reduced negative‐feedback. This reduced feedback efficiency usually results from a reduced level of the glucocorticoid receptor (GR) and/or the mineralocorticoid receptor (MR) within the HPA axis. However, a few studies have shown that early‐life stress exposure results in an attenuated physiological stress response, suggesting an enhance feedback efficiency. In the present study, we aimed to determine whether early‐life stress had long‐term consequences on GR and MR levels in quail and whether the effects on the physiological response to acute stress observed in prenatally stressed individuals were underpinned by changes in GR and/or MR levels in one or more HPA axis components. We determined GR and MR mRNA expression in the hippocampus, hypothalamus and pituitary gland in quail exposed to elevated corticosterone during prenatal development, postnatal development, or both, and in control individuals exposed to none of the stressors. We showed that prenatal stress increased the GR:MR ratio in the hippocampus, GR and MR expression in the hypothalamus and GR expression in the pituitary gland. Postnatal stress resulted in a reduced MR expression in the hippocampus. Both early‐life treatments permanently affected the expression of both receptor types in HPA axis regions. The effects of prenatal stress are in accordance with a more efficient negative‐feedback within the HPA axis and thus can explain the attenuated stress response observed in these birds. Therefore, these changes in receptor density or number as a consequence of early‐life stress exposure might be the mechanism that allows an adaptive response to later‐life stressful conditions.Publisher PDFPeer reviewe

Kin recognition and incest avoidance in a group-living insect

International audienceMate choice theories predict that animals evolved strategies to mate with optimally genetically dissimilar partners, providing fitness benefits. In group-living species, when adults do not disperse, assessment of relatedness between conspecifics can be a key factor for choosing mates. Here, we report for the first time, kin recognition abilities and their implication in mate choice in the gregarious cockroach, Blattella germanica (L.). Binary choice tests showed that females mated preferentially with nonsibling rather than with sibling males, thus avoiding incest. In addition, inbreeding induced an important decrease of their reproductive success. Contrary to what could be expected when females had the choice between a nonsibling strain member and a nonstrain member, they did not avoid mating with distantly related nonstrain members, and extreme outbreeding induced an increase of their reproductive success. Furthermore, our mate choice experiments disentangled the influences of familiarity from those of relatedness and evidenced that kin discrimination was based on genetic cues independently of familiarity. Phenotype matching was a plausible mechanism for kin recognition. Contrary to many insect species, body size was not a salient criterion for mate choice and had no consequences on reproductive success

Transgenerational transmission of a stress-coping phenotype programmed by early-life stress in the Japanese quail

This study was funded by a BBSRC David Phillips Research Fellowship to K.A. Spencer (BB/L002264/1).An interesting aspect of developmental programming is the existence of transgenerational effects that influence offspring characteristics and performance later in life. These transgenerational effects have been hypothesized to allow individuals to cope better with predictable environmental fluctuations and thus facilitate adaptation to changing environments. Here, we test for the first time how early-life stress drives developmental programming and transgenerational effects of maternal exposure to early-life stress on several phenotypic traits in their offspring in a functionally relevant context using a fully factorial design. We manipulated pre- and/or post-natal stress in both Japanese quail mothers and offspring and examined the consequences for several stress-related traits in the offspring generation. We show that pre-natal stress experienced by the mother did not simply affect offspring phenotype but resulted in the inheritance of the same stress-coping traits in the offspring across all phenotypic levels that we investigated, shaping neuroendocrine, physiological and behavioural traits. This may serve mothers to better prepare their offspring to cope with later environments where the same stressors are experienced.Publisher PDFPeer reviewe

Behavioural Adjustment in Response to Increased Predation Risk: A Study in Three Duck Species

Predation directly triggers behavioural decisions designed to increase immediate survival. However, these behavioural modifications can have long term costs. There is therefore a trade-off between antipredator behaviours and other activities. This trade-off is generally considered between vigilance and only one other behaviour, thus neglecting potential compensations. In this study, we considered the effect of an increase in predation risk on the diurnal time-budget of three captive duck species during the wintering period. We artificially increased predation risk by disturbing two groups of 14 mallard and teals at different frequencies, and one group of 14 tufted ducks with a radio-controlled stressor. We recorded foraging, vigilance, preening and sleeping durations the week before, during and after disturbance sessions. Disturbed groups were compared to an undisturbed control group. We showed that in all three species, the increase in predation risk resulted in a decrease in foraging and preening and led to an increase in sleeping. It is worth noting that contrary to common observations, vigilance did not increase. However, ducks are known to be vigilant while sleeping. This complex behavioural adjustment therefore seems to be optimal as it may allow ducks to reduce their predation risk. Our results highlight the fact that it is necessary to encompass the whole individual time-budget when studying behavioural modifications under predation risk. Finally, we propose that studies of behavioural time-budget changes under predation risk should be included in the more general framework of the starvation-predation risk trade-off

Early-life adversity programs long-term cytokine and microglia expression within the HPA axis in female Japanese quail

This work was funded by the Biotechnology and Biological Sciences Research Council (BBSRC grant no. BB/L002264/1 to K.A.S., C.Z. and S.D.H.), a David Phillips Research Fellowship (K.A.S.) and an EASTBIO BBSRC Doctoral Training Programme studentship (grant no. BB/J01446X/1 to D.J.W., supervisors K.A.S., S.D.H.). Data are available from Mendeley (Walker, 2019): http://dx.doi.org/10.17632/ 6r7d2pg2zk.1Stress exposure during prenatal and postnatal development can have persistent and often dysfunctional effects on several physiological systems, including immune function, affecting the ability to combat infection. The neuroimmune response is inextricably linked to the action of the hypothalamic–pituitary–adrenal (HPA) axis. Cytokines released from neuroimmune cells, including microglia, activate the HPA axis, while glucocorticoids in turn regulate cytokine release from microglia. Because of the close links between these two physiological systems, coupled with potential for persistent changes to HPA axis activity following developmental stress, components of the neuroimmune system could be targets for developmental programming. However, little is known of any programming effects of developmental stress on neuroimmune function. We investigated whether developmental stress exposure via elevated prenatal corticosterone (CORT) or postnatal unpredictable food availability had long-term effects on pro- (IL-1β) and anti-inflammatory (IL-10) cytokine and microglia-dependent gene (CSF1R) expression within HPA axis tissues in a precocial bird, the Japanese quail (Coturnix japonica). Following postnatal stress, we observed increased IL-1β expression in the pituitary gland, reduced IL-10 expression in the amygdala and hypothalamus, and reduced CSF1R expression within the hypothalamus and pituitary gland. Postnatal stress disrupted the ratio of IL-1β:IL-10 expression within the hippocampus and hypothalamus. Prenatal stress only increased IL-1β expression in the pituitary gland. We found no evidence for interactive or cumulative effects across life stages on basal cytokine and glia expression in adulthood. We show that postnatal stress may have a larger impact than elevated prenatal CORT on basal immunity in HPA-axis-specific brain regions, with changes in cytokine homeostasis and microglia abundance. These results provide evidence for postnatal programming of a pro-inflammatory neuroimmune phenotype at the expense of reduced microglia, which could have implications for central nervous system health and subsequent neuroimmune responses.Publisher PDFPeer reviewe

Post-hatching parental care behaviour and hormonal status in a precocial bird

In birds, the link between parental care behaviour and prolactin release during incubation persists after hatching in altricial birds, but has never been precisely studied during the whole rearing period in precocial species, such as ducks. The present study aims to understand how changes in parental care after hatching are related to circulating prolactin levels in mallard hens rearing ducklings. Blood was sampled in hens over at least 13 post-hatching weeks and the behaviour of the hens and the ducklings was recorded daily until fledging. Contacts between hens and the ducklings, leadership of the ducklings and gathering of them steadily decreased over post-hatching time. Conversely, resting, preening and agonistic behaviour of hens towards ducklings increased. Plasma prolactin concentrations remained at high levels after hatching and then fell after week 6 when body mass and structural size of the young were close to those of the hen. Parental care behaviour declined linearly with brood age, showed a disruption of the hen-brood bond at week 6 post-hatching and was related to prolactin concentration according to a sigmoid function. Our results suggest that a definite threshold in circulating prolactin is necessary to promote and/or to maintain post-hatching parental care in ducks

Individual Preferences and Social Interactions Determine the Aggregation of Woodlice

n°e17389.info:eu-repo/semantics/publishe

Evidence of the Trade-Off between Starvation and Predation Risks in Ducks

The theory of trade-off between starvation and predation risks predicts a decrease in body mass in order to improve flight performance when facing high predation risk. To date, this trade-off has mainly been validated in passerines, birds that store limited body reserves for short-term use. In the largest avian species in which the trade-off has been investigated (the mallard, Anas platyrhynchos), the slope of the relationship between mass and flight performance was steeper in proportion to lean body mass than in passerines. In order to verify whether the same case can be applied to other birds with large body reserves, we analyzed the response to this trade-off in two other duck species, the common teal (Anas crecca) and the tufted duck (Aythya fuligula). Predation risk was simulated by disturbing birds. Ducks within disturbed groups were compared to non-disturbed control birds. In disturbed groups, both species showed a much greater decrease in food intake and body mass during the period of simulated high risk than those observed in the control group. This loss of body mass allows reaching a more favourable wing loading and increases power for flight, hence enhancing flight performances and reducing predation risk. Moreover, body mass loss and power margin gain in both species were higher than in passerines, as observed in mallards. Our results suggest that the starvation-predation risk trade-off is one of the major life history traits underlying body mass adjustments, and these findings can be generalized to all birds facing predation. Additionally, the response magnitude seems to be influenced by the strategy of body reserve management

Mutual Mate Choice: When it Pays Both Sexes to Avoid Inbreeding

Theoretical models of sexual selection predict that both males and females of many species should benefit by selecting their mating partners. However, empirical evidence testing and validating this prediction is scarce. In particular, whereas inbreeding avoidance is expected to induce sexual conflicts, in some cases both partners could benefit by acting in concert and exerting mutual mate choice for non-assortative pairings. We tested this prediction with the gregarious cockroach Blattella germanica (L.). We demonstrated that males and females base their mate choice on different criteria and that choice occurs at different steps during the mating sequence. Males assess their relatedness to females through antennal contacts before deciding to court preferentially non-siblings. Conversely, females biased their choice towards the most vigorously courting males that happened to be non-siblings. This study is the first to demonstrate mutual mate choice leading to close inbreeding avoidance. The fact that outbred pairs were more fertile than inbred pairs strongly supports the adaptive value of this mating system, which includes no “best phenotype” as the quality of two mating partners is primarily linked to their relatedness. We discuss the implications of our results in the light of inbreeding conflict models

Impact of disturbance on energy balance, behaviour and reproduction of Anatidae,generalisation of the starvation-predation risk trade-off

Le compromis entre le risque de jeûne et de prédation est un compromis majeur chez les oiseaux. Il prédit que les oiseaux devraient maintenir une masse corporelle plus faible lorsque le risque de prédation est élevé afin de le limiter. Cependant, les principaux résultats qui soutiennent ce compromis proviennent d'études sur des passereaux de petite taille ayant peu de réserves énergétiques. De plus, l'étude de ce compromis se limite généralement à une approche énergétique. Ainsi, l'objectif principal de cette étude expérimentale était de généraliser cette théorie en vérifiant si elle peut s'appliquer à des espèces de grande taille (anatidés) ayant une régulation des réserves énergétiques différente des passereaux. D autre part, l'impact d'un risque de prédation élevé a été pris en compte sur un plus grand nombre de facteurs et à différents niveaux d'intégration pour mieux comprendre les ajustements mis en jeu. Ainsi, les variations de masse corporelle, des réserves énergétiques, de la consommation alimentaire, d'hormones liées au stress et sexuelles, de facteurs immunitaires et du budget temps ont été mesurées. Les effets à long terme sur le succès reproducteur ont également été déterminés. Nous avons montré que le compromis entre les risques de jeûne et de prédation s'applique chez les 3 espèces de canards considérées. Il apparaît que, dans nos conditions un risque de prédation élevé durant l'hivernage n a pas d'effet à long terme sur le succès reproducteur. Enfin, nous avons mis en évidence que des ajustements physiologiques et comportementaux complexes, et pas seulement énergétiques, sont mis en place pour répondre efficacement à l'augmentation du risque de prédation.A major trade-off birds have to deal with is the one related to the starvation-predation risk. This trade-off predicts that, to limit effects of risk, birds should maintain their body mass as low as possible when predation risk is high. However, the main results on that trade-off only come from studies on small passerines birds having a low level of body reserves. Moreover, such studies are generally limited to an energetic approach. Thus, the main aim of this study was to generalize this theory by checking whether it may apply to large species that developed different body reserves management strategies than passerines. In addition, this work takes into account the effect of a high predation risk on a greater number of factors and at different integrative levels to have a better understanding of the underlying adjustments. To do so, predation risk was experimentally increased in three ducks species which body mass and body reserves are at least three times higher than in the largest passerines. Body mass, body reserves, food intake, stress and sexual hormones, immune factors and time-budget variations were measured. Long-term effects on reproductive success were also assessed. We showed that the starvation-predation risk trade-off applies to ducks and may probably be extended to all bird species. Moreover, it appears that, in our conditions, an elevated predation risk during the wintering period did not have long-term negative effect on ducks reproductive success. Finally, we highlighted that advantageous complex physiological and behavioural adjustments (not only directly based on energetics) occurred in order to respond efficiently to the increase in predation risk