Induced maternal behavior in the domestic hen. Influence of partial or total separation on the maintenance of maternal responsiveness

The influence of direct physical contact on maintaining maternal responsiveness in induced adult hens was investigated using a separation procedure. Partial separation from chicks causes a significant decline of the clucking rate in hens, this response however does not disappear as in the case of total separation. The possibility for physical contact between hen and chicks contributes largely, but not uniquely, to maintain maternal responsiveness in the domestic hen.     

Induction and Maintenance of Maternal Behaviour in the Domestic Hen: Influence of Testosterone and Oestradiol Treatments

Confining an adult hen with two newly-hatched chicks induced a gradual emergence of maternal behaviour in the hen. The aim of the experiments presented here was to analyse the effects of testosterone or oestradiol treatments on the induction and maintenance of maternal behaviour in hens with no previous maternal experience. The ability of a hen to positively respond towards chicks was not altered by either testosterone or oestradiol injections. However, testosterone therapy prevented both the appearance and the maintenance of the most typical call, clucking. Testosterone injected hens responded to chicks with a contact-type call, but oestradiol treated ones did not. These results indicate that some aspects of maternal behaviour can be modulated by peripheral levels of hormones.     

Foster rather than biological parental telomere length predicts offspring survival and telomere length in king penguins

Because telomere length and dynamics relate to individual growth, reproductive investment and survival, telomeres have emerged as possible markers of individual quality. Here, we tested the hypothesis that, in species with parental care, parental telomere length can be a marker of parental quality that predicts offspring phenotype and survival. In king penguins (Aptenodytes patagonicus), we experimentally swapped the single egg of 66 breeding pairs just after egg laying to disentangle the contribution of prelaying parental quality (e.g., genetics, investment in the egg) and/or postlaying parental quality (e.g., incubation, postnatal feeding rate) on offspring growth, telomere length and survival. Parental quality was estimated through the joint effects of biological and foster parent telomere length on offspring traits, both soon after hatching (day 10) and at the end of the prewinter growth period (day 105). We expected that offspring traits would be mostly related to the telomere lengths (i.e., quality) of biological parents at day 10 and to the telomere lengths of foster parents at day 105. Results show that chick survival up to 10 days was negatively related to biological fathers’ telomere length, whereas survival up to 105 days was positively related to foster fathers’ telomere lengths. Chick growth was not related to either biological or foster parents’ telomere length. Chick telomere length was positively related to foster mothers’ telomere length at both 10 and 105 days. Overall, our study shows that, in a species with biparental care, parents’ telomere length is foremost a proxy of postlaying parental care quality, supporting the “telomere – parental quality hypothesis.”     

Epigenetic Maternal Effects on Endogenous Rhythms in Precocial Birds

Development involves interactions between genetic and environmental influences. Vertebrate mothers are generally the first individuals to encounter and interact with young animals. Thus, their role is primordial during ontogeny. The present study evaluated non‐genomic effects of mothers on the development of rhythms of precocial Japanese quail (Coturnix c. japonica). First, we investigated the influence of mothering on the ontogeny of endogenous rhythms of young. We compared circadian and ultradian rhythms of feeding activity of quail reared with or without adoptive mothers. More brooded than non‐brooded quail presented a circadian and/or an ultradian rhythm. Thus, the presence of the mother during the normal brooding period favors, in the long term, expression of rhythms in the young. Second, we investigated the influence of rhythmic phenotype of the mother on the development of endogenous rhythms of young by comparing quail brooded by circadian‐rhythmic adoptive mothers (R) to quail brooded by circadian‐arrhythmic adoptive mothers (A). More R‐brooded than A‐brooded quail expressed circadian rhythmicity, and circadian rhythm clarities were greater in R‐brooded than A‐brooded quail. Ultradian rhythmicity did not differ between R‐ and A‐brooded quail, nor between R and A adoptive mothers. Thus, the rhythmic phenotypes of quail mothers influence the rhythmic phenotypes of their young. Our results demonstrate that mothers of precocial birds influence epigenetically the ontogeny of endogenous rhythms of the young they raise.     

Morphology and physiology of the serotonin-immunoreactive putative antennal lobe feedback neuron in the male silkmoth Bombyx mori

In the male silkmoth Bombyx mori, olfactory information is relayed from olfactory receptor neurons in the antennae to the antennal lobe, and then to a variety of protocerebral neuropils. Currently, very little is known about neuromodulators that may affect the dynamics of this olfactory neural network. Immunocytochemical studies have revealed the presence of a serotonin-immunoreactive (SI) neuron that, in several insect species, is thought to provide feedback to the antennal lobe. To date, no studies have revealed details of this neuron's physiology. Using intracellular recording and staining, the silkmoth SI neuron (in two individuals) was first characterized physiologically and then stained with Lucifer Yellow to reveal morphological details. Immunocytochemical methods were also used to confirm the presence of serotonin. The silkmoth SI neuron branched in many important brain neuropils such as the mushroom body, central body, lateral accessory lobe and antennal lobe. The SI neuron in both individuals fired spontaneous, long duration action potentials, and responded to mechanosensory stimuli to the antennae.     

Mothering influences the distribution of activity in young domestic chicks

The aim of this study was to determine whether the presence of a maternal hen influences the quality, quantity, and distribution of activity in young chicks. Brooded and nonbrooded chicks were observed during the entire light phase when they were 4 d of age. Our results revealed that although both brooded and nonbrooded chicks expressed the same behavioral items and in quite the same quantity, activity bouts were much longer in brooded chicks. However, only brooded chicks presented a high level of ultradian rhythmicity. Moreover, the brooded chicks made greater use of the space. The presence and the behavior of maternal hens appeared to provide structuring factors for the expression of the chicks' behavior.     

Maternal food calling in domestic hens: influence of feeding context

The aim of this study was to understand the relationship between production of food calls by maternal hens and food context. In a series of experiments with broody hens, we manipulated quality of items, quantity of food, food experience and dispersion of food items. We measured the frequency of food calling during standardized tests. Our results show that all the variables tested had significant effects on food calling. These results present some similarities and some discrepancies with previous reports on food calling by cockerels.     

Experience modulates emission of food calls in broody hens.

The aim of these experiments was to determine if previous experience of chicks' response to food calling influences subsequent propension of maternal hens to utter food calls. Seventeen broody hens were tested three times a day without their 3- or 4-day-old chicks. Hens were tested in two situations: chicks were returned either after each test or at the end of all the day's tests. As palatability influences food calling in maternal hens, experiments were conducted first with a highly preferred food item and then with the hens' usual feed. The chicks' capacity to respond regularly to their mother influences the hens' capacity to emit food calls. In fact, although the hens did not lose their maternal state, they uttered fewer food calls when their chicks were removed all day. These results suggest that the chicks' behaviour following food calling could be a social reinforcement for broody hens.     

Cooperative Anti-Invasive Effect of Cdc42/Rac1 Activation and ROCK Inhibition in SW620 Colorectal Cancer Cells with Elevated Blebbing Activity

Rho GTPases are key regulators of tumour cell invasion and therefore constitute attractive targets for the design of anticancer agents. Several strategies have been developed to modulate their increased activities during cancer progression. Interestingly, none of these approaches took into account the existence of the well-known antagonistic relationship between RhoA and Rac1. In this study, we first compared the invasiveness of a collection of colorectal cancer cell lines with their RhoA, Rac1 and Cdc42 activities. A marked decrease of active Cdc42 and Rac1 correlated with the high invasive potential of the cell lines established from metastatic sites of colorectal adenocarcinoma (LoVo, SKCo1, SW620 and CoLo205). Conversely, no correlation between RhoA activity and invasiveness was detected, whereas the activity of its kinase effector ROCK was higher in cancer cell lines with a more invasive phenotype. In addition, invasiveness in these colon cancer cell lines was correlated with a typical round and blebbing morphology. We then tested whether treatment with PDGF to restore Cdc42 and Rac1 activities and/or with Y27632, a chemical inhibitor of ROCK, could decrease the invasiveness of SW620 cells. The association of both treatments substantially decreased the invasive potential of SW620 cells and this effect was accompanied by loss of membrane blebbing, restoration of a more elongated cell morphology and re-establishment of E-cadherin-dependent adherens junctions. This study paves the road to the development of therapeutic strategies in which different Rho GTPase modulators are combined to modulate the cross-talk between Rho GTPases and their specific input in metastatic progression.     

Local weather and body condition influence habitat use and movements on land of molting female southern elephant seals (Mirounga leonina)

Southern elephant seals (Mirounga leonina) are known to move and aggregate while molting, but little is known about their behavior on land during this time. In this study, 60 adult females were monitored (23 with GPS tags) during four molting seasons, between 2012 and 2016 at Kerguelen Archipelago, Indian Ocean. Population surveys were recorded each year (N = 230 daily counts), and habitat use was analyzed in relation to the stage of the molt and local weather. Based on stage of molt, habitat use, and movements on land, we classified the molt of elephant seals into three phases: (1) a “search phase” at the initial stage of molt when grass and wallow habitats were used and characterized by greater mean distances travelled on land per day compared with the two other phases; (2) a “resident phase”: during initial and mid‐stage of molt when animals were found in grass and wallow habitats but with less distance moved on land; and (3) a “termination phase” at the final stage of molt where grass and beach habitats were occupied with no change in distances. Windchill and solar radiation influenced individual distances moved per day (mean 590 ± 237.0 m) at the mid‐ and final stage of molt such that animals travelled greater distances on days of low windchill or high solar radiation. Individual variation in distance moved and relative habitat use were also linked to body mass index (BMI) at arrival on the colony, as females with higher BMI moved less and preferred beach habitat. Moreover, the individual rate of molt increased with the use of wallows. Aggregation rate tended to be negatively correlated with distances moved. We therefore suggest that individuals face an energetic trade‐off while molting, balancing energy expenditure between movement and thermoregulation.