Is Promiscuity Associated with Enhanced Selection on MHC-DQα in Mice (genus Peromyscus)?

Reproductive behavior may play an important role in shaping selection on Major Histocompatibility Complex (MHC) genes. For example, the number of sexual partners that an individual has may affect exposure to sexually transmitted pathogens, with more partners leading to greater exposure and, hence, potentially greater selection for variation at MHC loci. To explore this hypothesis, we examined the strength of selection on exon 2 of the MHC-DQα locus in two species of Peromyscus. While the California mouse (P. californicus) is characterized by lifetime social and genetic monogamy, the deer mouse (P. maniculatus) is socially and genetically promiscuous; consistent with these differences in mating behavior, the diversity of bacteria present within the reproductive tracts of females is significantly greater for P. maniculatus. To test the prediction that more reproductive partners and exposure to a greater range of sexually transmitted pathogens are associated with enhanced diversifying selection on genes responsible for immune function, we compared patterns and levels of diversity at the Class II MHC-DQα locus in sympatric populations of P. maniculatus and P. californicus. Using likelihood based analyses, we show that selection is enhanced in the promiscuous P. maniculatus. This study is the first to compare the strength of selection in wild sympatric rodents with known differences in pathogen milieu

SBML Level 3: an extensible format for the exchange and reuse of biological models

Systems biology has experienced dramatic growth in the number, size, and complexity of computational models. To reproduce simulation results and reuse models, researchers must exchange unambiguous model descriptions. We review the latest edition of the Systems Biology Markup Language (SBML), a format designed for this purpose. A community of modelers and software authors developed SBML Level 3 over the past decade. Its modular form consists of a core suited to representing reaction-based models and packages that extend the core with features suited to other model types including constraint-based models, reaction-diffusion models, logical network models, and rule-based models. The format leverages two decades of SBML and a rich software ecosystem that transformed how systems biologists build and interact with models. More recently, the rise of multiscale models of whole cells and organs, and new data sources such as single-cell measurements and live imaging, has precipitated new ways of integrating data with models. We provide our perspectives on the challenges presented by these developments and how SBML Level 3 provides the foundation needed to support this evolution

A method to establish the relationship between chronological age and stage of union from radiographic assessment of epiphyseal fusion at the knee: an Irish population study

Characteristic changes during epiphyseal union provide a skeletal age, which when compared with age-based standards provides an estimation of chronological age. Currently there are no data on epiphyseal union for the purposes of age estimation specific to an Irish population. This cross-sectional study aims to investigate the relationship between stage of epiphyseal union at the knee joint and chronological age in a modern Irish population. A novel radiographic method that sub-divides the continuum of development into five specific stages of union is presented. Anteroposterior and lateral knee radiographs of 148 males and 86 females, aged 9–19 years, were examined. Fusion was scored as Stage 0, non-union; Stage 1, beginning union; Stage 2, active union; Stage 3, recent union; or Stage 4, complete union. Stage of epiphyseal union is correlated with chronological age in both males and females. Mean age gradually increases with each stage of union and also varies between male and female subjects. A statistically significant difference in mean age was recorded between stages when compared to the previous stage, for the three epiphyses. Irish children are comparable to those from previously published studies with epiphyseal union in females occurring earlier than males. A significant difference was noted between the mean age of union for males and females for each of Stages 1 and 2 for the femur and Stages 0, 1, 2 and 3 for the tibia and the fibula. The results also suggest that the stages of union occur at earlier ages in this Irish population. Implementation of standardized methodology is necessary to investigate if this is due to a secular or population variation in maturation or to a methodology which clearly identifies five stages of union