The genome, transcriptome, and proteome of the nematode Steinernema carpocapsae: Evolutionary signatures of a pathogenic lifestyle

The entomopathogenic nematode Steinernema carpocapsae has been widely used for the biological control of insect pests. It shares a symbiotic relationship with the bacterium Xenorhabdus nematophila, and is emerging as a genetic model to study symbiosis and pathogenesis. We obtained a high-quality draft of the nematode’s genome comprising 84,613,633 bp in 347 scaffolds, with an N50 of 1.24 Mb. To improve annotation, we sequenced both short and long RNA and conducted shotgun proteomic analyses. S. carpocapsae shares orthologous genes with other parasitic nematodes that are absent in the free-living nematode C. elegans, it has ncRNA families that are enriched in parasites, and expresses proteins putatively associated with parasitism and pathogenesis, suggesting an active role for the nematode during the pathogenic process. Host and parasites might engage in a co-evolutionary arms-race dynamic with genes participating in their interaction showing signatures of positive selection. Our analyses indicate that the consequence of this arms race is better characterized by positive selection altering specific functions instead of just increasing the number of positively selected genes, adding a new perspective to these co-evolutionary theories. We identified a protein, ATAD-3, that suggests a relevant role for mitochondrial function in the evolution and mechanisms of nematode parasitism

Multi-Party Elections in the Arab World: Institutional Engineering and Oppositional Strategies

Recent moves toward multi-party competition for elected legislatures in numerous Arab countries constitute a significant departure from earlier practices there, and create the basis for democratic activists to gradually chip away at persistent authoritarian rule. This article explores the institutional mechanisms by which incumbent authoritarian executives seek to engineer these elections. It documents examples of rulers changing electoral systems to ensure compliant legislatures, and demonstrates the prevalent use of winner-takes-all electoral systems, which generally work to the regimes\u27 advantage. I then review various strategies of opposition forces--boycotts, non-competition agreements, election monitoring, and struggles over election rules--and the dilemmas that these entail. Surmounting differences in terms of ideologies, as well as short-term political goals and prospects, is a central challenge. The future should see greater electoral participation among opposition activists, along with cleaner elections. As vote coercion and ballot box stuffing is restricted by opposition pressures, electoral institutions will take on greater importance, and struggles for proportional representation are likely to increase