The Inhibition of Polo Kinase by Matrimony Maintains G2 Arrest in the Meiotic Cell Cycle

Many meiotic systems in female animals include a lengthy arrest in G2 that separates the end of pachytene from nuclear envelope breakdown (NEB). However, the mechanisms by which a meiotic cell can arrest for long periods of time (decades in human females) have remained a mystery. The Drosophila Matrimony (Mtrm) protein is expressed from the end of pachytene until the completion of meiosis I. Loss-of-function mtrm mutants result in precocious NEB. Coimmunoprecipitation experiments reveal that Mtrm physically interacts with Polo kinase (Polo) in vivo, and multidimensional protein identification technology mass spectrometry analysis reveals that Mtrm binds to Polo with an approximate stoichiometry of 1:1. Mutation of a Polo-Box Domain (PBD) binding site in Mtrm ablates the function of Mtrm and the physical interaction of Mtrm with Polo. The meiotic defects observed in mtrm/+ heterozygotes are fully suppressed by reducing the dose of polo+, demonstrating that Mtrm acts as an inhibitor of Polo. Mtrm acts as a negative regulator of Polo during the later stages of G2 arrest. Indeed, both the repression of Polo expression until stage 11 and the inactivation of newly synthesized Polo by Mtrm until stage 13 play critical roles in maintaining and properly terminating G2 arrest. Our data suggest a model in which the eventual activation of Cdc25 by an excess of Polo at stage 13 triggers NEB and entry into prometaphase

How to make a sex chromosome

Sex chromosomes can evolve once recombination is halted between a homologous pair of chromosomes. Owing to detailed studies using key model systems, we have a nuanced understanding and a rich review literature of what happens to sex chromosomes once recombination is arrested. However, three broad questions remain unanswered. First, why do sex chromosomes stop recombining in the first place? Second, how is recombination halted? Finally, why does the spread of recombination suppression, and therefore the rate of sex chromosome divergence, vary so substantially across clades? In this review, we consider each of these three questions in turn to address fundamental questions in the field, summarize our current understanding, and highlight important areas for future work

Visible organisational boundaries and the invisible boundaries of the scholarly profession

The role of universities in knowledge production has changed. Although most higher learning still takes place in universities, knowledge is increasingly produced in collaborative networks comprising partners from different sectors (Välimaa, J., V. Papatsiba, and D. M. Hoffman. 2016. “Higher Education in Networked Knowledge Societies.” In Re-becoming Universities, The Changing Academy – The Changing Academic Profession in International Comparative Perspective. Vol. 15, edited by D. M. Hoffman and J. Välimaa, 13–39. Dordrecht: Springer). In addition, the focus of universities’ personnel policies has shifted from supporting professional inclusion and exclusion towards supporting the national development of talent and human capital. New kinds of networks and collaborative arrangements have emerged to facilitate the mobility of academics between universities and other sectors. This paper draws upon survey data collected in 2017 from PhD graduates working in universities and the private and public sector in Finland, in order to explore their perceptions related to the relevance of their work, and their commitment to the organisation and the scientific community. We found some differences between the private sector, and the public sector and universities, and between disciplines. Between public sector and universities only small differences occurred. The results indicate that the research work between sectors is rather similar according to the indicators that were used, in some cases the differences might be more significant between disciplines.peerReviewe