Gestational Exposure to Low Dose Bisphenol A Alters Social Behavior in Juvenile Mice

Bisphenol A (BPA) is a man-made compound used to make polycarbonate plastics and epoxy resins; public health concerns have been fueled by findings that BPA exposure can reduce sex differences in brain and some behaviors. We asked if a low BPA dose, within the range measured in humans, ingested during pregnancy, would affect social behaviors in prepubertal mice. We noted sex differences in social interactions whereby females spent more time sitting side-by-side, while males engaged in more exploring and sitting alone. In addition BPA increased display of nose-to-nose contacts, play solicitations and approaches in both sexes. Interactions between sex and diet were found for self grooming, social interactions while sitting side-by-side and following the other mouse. In all these cases interactions were produced by differences between control and BPA females. We examined brains from embryos during late gestation to determine if gene expression differences might be correlated with some of the sexually dimorphic or BPA affected behaviors we observed. Because BPA treatments ended at birth we took the brains during embryogenesis to increase the probability of discovering BPA mediated effects. We also selected this embryonic age (E18.5) because it coincides with the onset of sexual differentiation of the brain. Interestingly, mRNA for the glutamate transporter, Slc1a1, was enhanced by exposure to BPA in female brains. Also we noted that BPA changed the expression of two of the three DNA methyltransferase genes, Dnmt1 and Dnmt3a. We propose that BPA affects DNA methylation of Sc1a1 during neural development. Sex differences in juvenile social interactions are affected by BPA and in particular this compound modifies behavior in females

WATTLE SIZE IS CORRELATED WITH MALE TERRITORIAL RANK IN JUVENILE RING-NECKED PHEASANTS

We used morphological measurements and behavioral observations to investigate the relationship between male ornaments and male social rank during the breeding season in a free-ranging population of one-year-old Ring-necked Pheasants (Phasianus colchicus). The sample was of birds of the same age class to avoid the confounding effect of age differences. Tail length, used by females in mate choice, and tarsal spur length, used by males as a weapon in fights, were not correlated with male rank, whereas the size of the wattle was the most important trait. This combined with recent studies showing that wattle size reliably indicates male testosterone levels at the beginning of the breeding season suggest that, among males, wattle size may be used as a signal of aggression level, and body condition. Utilizamos medidas morfológicas y observaciones de comportamiento para investigar la relación entre los ornamentos de los machos y el rango social de éstos durante la época reproductiva en una población silvestre de faisanes Phasianus colchicus de un año de edad. La muestra consistió´ de aves de la misma clase de edad para evitar el efecto de diferencias entre edades. La longitud de la cola (utilizada por las hembras en la selección de pareja) y la longitud de la espuela tarsal (utilizada por los machos como un arma en enfrentamientos) no se correlacionaron con el rango de los machos, mientras que el tamaño de la carúncula fue el caracter más importante. En combinación con estudios recientes que muestran que el tamaño de la carúncula indica confiablemente los niveles de testosterona en los machos al inicio de la época reproductiva, esto sugiere que el tamaño de la carúncula podría ser usado como una señal de niveles de agresión y condición corporal entre los machos

Conflicts induce affiliative interactions among bystanders in a tolerant species of macaque (Macaca tonkeana)

International audienceAggression is potentially disruptive for social groups. Although individuals witnessing a conflict are not directly threatened by aggressive interactions, the aftermath of aggression appears to be a period of social instability.We expected bystanders to respond to conflicts by affiliating with other group members and so reducing social tension. To test this hypothesis we collected data on two captive groups of Tonkean macaques, Macaca tonkeana. After an agonistic interaction, the behaviours of focal individuals uninvolved in the conflict were recorded over 5 min postconflict periods, for comparison with baseline periods. The results showed that bystanders were more likely to show affiliation during postconflict periods than in baselines. We found that affiliation occurred more frequently between individuals linked by friendship, whereas no significant effect of kinship appeared, which may be related to the open social relationships reported in Tonkean macaques. Females initiated affiliation sooner than males and conflicts involving physical contact were more quickly followed by affiliation between bystanders. Rates of scratching tended to decrease after the first affiliative interaction. None the less, few signs of anxiety were observed in bystanders. Our results reflect the high propensity of Tonkean macaques to appease others and stop aggression. This study demonstrates that postconflict affiliation occurs between bystanders in a species characterized by tolerant social relationships. It could be a pervasive means of social cohesion among primates

Are large wattles related to particular MHC genotypes in the male pheasant?

In sexually dimorphic species, partners can assess heritable mate quality by analyzing costly sexual ornaments in terms of their dimension and possibly of their symmetry. In vertebrates an important aspect of genetic quality is the efficiency of the immune system, and in particular the Major Histocompatibility Complex (MHC). If ornaments are honest advertisements of pathogen resistance (good genes), in line with the Hamilton-Zuk hypothesis, a correlation between ornament expression and MHC profiles should exist. We tested this hypothesis in the common pheasant Phasianus colchicus by comparing male ornament characteristics (wattle and spur size, and wattle fluctuating asymmetry) with a portion of exon 2 of the class IIB MHC genes containing 19 putative antigen recognition sites. A total of 8 new alleles was observed in the MHCPhco exon IIB. We found significant differences in the occurrence of MHC genotypes between males carrying large or small wattles. Homozygous genotypes predicted large wattle males more correctly than small wattle males. The association between the dimension of the spur and the occurrence of MHC genotypes was marginally significant, however, we did not find any significant association between MHC genotypes and asymmetry. Our results suggest that female pheasants may use the ornament size as a cue to evaluate male quality and thus choose males carrying particular MHC profiles