Accelerated Evolution of the Prdm9 Speciation Gene across Diverse Metazoan Taxa

The onset of prezygotic and postzygotic barriers to gene flow between populations is a hallmark of speciation. One of the earliest postzygotic isolating barriers to arise between incipient species is the sterility of the heterogametic sex in interspecies' hybrids. Four genes that underlie hybrid sterility have been identified in animals: Odysseus, JYalpha, and Overdrive in Drosophila and Prdm9 (Meisetz) in mice. Mouse Prdm9 encodes a protein with a KRAB motif, a histone methyltransferase domain and several zinc fingers. The difference of a single zinc finger distinguishes Prdm9 alleles that cause hybrid sterility from those that do not. We find that concerted evolution and positive selection have rapidly altered the number and sequence of Prdm9 zinc fingers across 13 rodent genomes. The patterns of positive selection in Prdm9 zinc fingers imply that rapid evolution has acted on the interface between the Prdm9 protein and the DNA sequences to which it binds. Similar patterns are apparent for Prdm9 zinc fingers for diverse metazoans, including primates. Indeed, allelic variation at the DNA–binding positions of human PRDM9 zinc fingers show significant association with decreased risk of infertility. Prdm9 thus plays a role in determining male sterility both between species (mouse) and within species (human). The recurrent episodes of positive selection acting on Prdm9 suggest that the DNA sequences to which it binds must also be evolving rapidly. Our findings do not identify the nature of the underlying DNA sequences, but argue against the proposed role of Prdm9 as an essential transcription factor in mouse meiosis. We propose a hypothetical model in which incompatibilities between Prdm9-binding specificity and satellite DNAs provide the molecular basis for Prdm9-mediated hybrid sterility. We suggest that Prdm9 should be investigated as a candidate gene in other instances of hybrid sterility in metazoans

Christianity, Englishness and the southern English countryside: a study of the work of H.J. Massingham

This paper explores the relationships between Christianity, Englishness, and ideas about the southern English landscape in the writings of the 1930s and 1940s rural commentator, H.J. Massingham. The paper begins by looking in general terms at the conjunction of religious and national identities in the context of national landscapes before moving on to consider in more detail one particular instance of this in the writing of H.J. Massingham. Massingham's understanding of a divine natural order, his construction of a kind of 'divine Englishness' and the way in which he relates this to particular English landscapes is explored. In particular, the paper investigates the natural, social and political power relationships which are embedded in Massingham's work, and suggests that his writing provides an interesting example of one way in which theological reasoning can reflect and reinforce concepts of a naturally ordered national identity

The Effect of Host Country Nationals’ Social Support on Expatriates’ Adjustment—A Multiple Stakeholder Approach

The social support provided by host country nationals (HCNs) has been identified as an important source of successful expatriation. However, the roles of different HCN actors have not yet been sufficiently differentiated in this process. Drawing on social support theory and conservation of resources theory, this chapter aims to fill this void by investigating the impact of social support provided by five groups of HCN actors on expatriates’ cross-cultural adjustment: HCN top management team members, supervisors, colleagues, and subordinates in the work domain, as well as friends in the non-work domain. The resulting model suggests that all these HCN actors can increase expatriates’ adjustment; however, colleagues in the work domain and friends in the non-work domain have the highest influence on all types of adjustments