The Male Warrior Hypothesis: Testosterone-related Cooperation and Aggression in the Context of Intergroup Conflict

The Male Warrior Hypothesis (MWH) establishes that men's psychology has been shaped by inter-group competition to acquire and protect reproductive resources. In this context, sex-specific selective pressures would have favored cooperation with the members of one's group in combination with hostility towards outsiders. We investigate the role of developmental testosterone, as measured indirectly through static markers of prenatal testosterone (2D:4D digit ratio) and pubertal testosterone (body musculature and facial masculinity), on both cooperation and aggressive behavior in the context of intergroup conflict among men. Supporting the MWH, our results show that the intergroup conflict scenario promotes cooperation within group members and aggression toward outgroup members. Regarding the hormonal underpinnings of this phenomenon, we find that body musculature is positively associated with aggression and cooperation, but only for cooperation when context (inter-group competition) is taken into account. Finally, we did not find evidence that the formidability of the group affected individual rates of aggression or cooperation, controlling for individual characteristics.

Sex-biased expression of sex-differentiating genes FOXL2 and FGF9 in American alligators, alligator Mississippiensis

Across amniotes, sex-determining mechanisms exhibit great variation, yet the genes that govern sexual differentiation are largely conserved. Studies of evolution of sex-determining and sex-differentiating genes require an exhaustive characterization of functions of those genes such as FOXL2 and FGF9. FOXL2 is associated with ovarian development, and FGF9 is known to play a role in testicular organogenesis in mammals and other amniotes. As a step toward characterization of the evolutionary history of sexual development, we measured expression of FOXL2 and FGF9 across 3 developmental stages and 8 juvenile tissue types in male and female American alligators, Alligator mississippiensis. We report surprisingly high expression of FOXL2 before the stage of embryonic development when sex is determined in response to temperature, and sustained and variable expression of FGF9 in juvenile male, but not female tissue types. Novel characterization of gene expression in reptiles with temperature-dependent sex determination such as American alligators may inform the evolution of sex-determining and sex-differentiating gene networks, as they suggest alternative functions from which the genes may have been exapted. Future functional profiling of sex-differentiating genes should similarly follow other genes and other species to enable a broad comparison across sex-determining mechanisms.

Co-evolution of genomic structure and selective forces underlying sexual development and reproduction

Genomic structure affects the expression and evolution of phenotypes via its effect on genomic function. One example is the presence of sex chromosomes and the development of the sexual phenotype. Multiple forces account for the evolution of genomic structure and function, some acting synergistically and some in an antagonistic manner, in a co-evolutionary process between genomic architecture and environmental effects at different time scales. Here I review the evolution of sex chromosomes and how they affect sex determination, sex ratios, sexual selection, and sexual conflict, at the same time that these phenomena influence the evolution of genome organization. Because of this reciprocal interaction, the need to correctly identify sex chromosome systems in order to understand the causes and consequences of their evolution is emphasized. Importantly, it is argued that the existence of taxa lacking sex chromosomes poses a challenge to current evolutionary models and a unique opportunity to test them empirically using reptiles as a model system.

Sexual development and the evolution of sex determination

The evolution of sex had profound consequences for life on earth as it brought about the origin of males and females. Yet understanding the amazing variety of mechanisms employed by organisms to produce males and females has evaded scientific explanation. Developmental biology provides essential insight to understand how the sexes are formed, and how the regulatory network underlying sexual development changes over evolutionary time. This is a critical step in revealing why the diversity of mechanisms arose in the first place. Here I present significant reciprocal contributions made by evolutionary genetics and developmental biology that bear on this question. In particular, I explore how changes in the timing of events during development can be viewed as heterochronic changes that alleviate the strong selection on the master trigger of male and female sexual development, enabling the evolutionary transitions between genotypic and environmental sex determination.

Topical tacrolimus 0.1% ointment (protopic) reverses nickel contact dermatitis elicited by allergen challenge to a similar degree to mometasone furoate 0.1% with greater suppression of late erythema

The aim of this study was to evaluate the ability of topical tacrolimus 0.1% under occlusion for 48 h to suppress nickel-elicited allergic contact dermatitis in a randomized, petrolatum- and mometasone furoate 0.1% ointment-controlled double-blind, intra-individual study which included 28 women volunteers. 3 closed patch tests (Finn Chambers on Scanpor, Epitest Ltd Oy, Tuusula, Finland) containing 0.1 ml of 5% nickel sulfate in petrolatum were applied on day 0. After removal on day 2, the study compounds were applied under occlusion for 48 h. The eczema reaction and the degree of erythema were evaluated clinically and by reflectance spectrophotometry at days 4 and 7, respectively. Mean visual scores corresponding to petrolatum-treated sites were significantly higher than those corresponding to both mometasone furoate and tacrolimus at days 4 (P < 0.001) and 7 (P < 0.001). In both tacrolimus- and mometasone furoate-treated sites, there was a significant decrease in visual scores with time (P < 0.001) from day 2 to day 7, and the corresponding mean decreases in scores were 0.73 and 1.04, respectively. The difference between both was 0.30 in favour of tacrolimus (95% confidence intervals, -0.04 and 0.65), although this did not reach statistical significance (P = 0.084). Mean erythema index values were similar at day 2. Significant differences among treatment sites were seen at days 4 (P < 0.001) and 7 (P < 0.001). The decrease was significantly more pronounced on day 7 in patches where tacrolimus had been supplied (P < 0.5). This method might provide useful means to compare different concentrations and/or presentations of tacrolimus or other calcineurin inhibitors and topical anti-inflammatory agents.

[Calcifications from cardiac etiology in chest radiography]

OBJECTIVE: Children s chest X-ray calcification images can be related to pulmonary, mediastinal and rarely cardiac parenchymatous pathology. This report describes cases of cardio thoracic calcifications. We emphasize the importance of chest X-ray to track thoracic calcifications. In spite of the fact that it is rare, the cardiac etiology must be considered due to the possibility of surgical treatment.METHODS: Regarding the period from 1988 to 1997 the authors reviewed the chest X-rays of 2108 patients. In 3 of them thoracic calcifications of cardiac etiology were observed.RESULTS: Of these three patients, two were 7 years old and the third was 3 years old. Case 1 presented a calcification in the right atrium topography caused by a heart tumor of Fibroma type. In case 2 the calcification was in the pulmonary trunk, presenting as a calcified aneurysm of the ductus arteriosus. In case 3 the child had pulmonary stenosis and the chest X-ray showed a calcified image on the left cardiac boards caused by a thrombo in the right ventricle wall.CONCLUSION: The authors emphasize the importance of chest X-ray in the diagnosis of thoracic calcifications, and comment that in spite of the being rare, the cardiac causes should be considered due to the possibility of surgical treatment.

Multiple paternity in side-neck turtles Podocnemis expansa: evidence from microsatellite DNA data

Multiple paternity was found in two clutches of Podocnemis expansa using eight microsatellite loci. When loci were analysed separately a minimum of two males was estimated for nest N23, and three for nest C17. When all loci were combined, three patrilines were detected in N23, and six in C17. The distribution of full-sib cluster sizes indicated a disproportionate contribution of one male to clutch C17, consistent with possible sperm competition, or the mixing of leftover and newly acquired sperm. High mutation rates were detected at several loci. Multiple paternity has positive implications for this endangered species as it may slow the loss of genetic variability caused by drift. This is the first report of multiple paternity in the suborder Pleurodira.