Genome-wide mapping reveals single-origin chromosome replication in Leishmania, a eukaryotic microbe

Background DNA replication initiates on defined genome sites, termed origins. Origin usage appears to follow common rules in the eukaryotic organisms examined to date: all chromosomes are replicated from multiple origins, which display variations in firing efficiency and are selected from a larger pool of potential origins. To ask if these features of DNA replication are true of all eukaryotes, we describe genome-wide origin mapping in the parasite Leishmania. Results Origin mapping in Leishmania suggests a striking divergence in origin usage relative to characterized eukaryotes, since each chromosome appears to be replicated from a single origin. By comparing two species of Leishmania, we find evidence that such origin singularity is maintained in the face of chromosome fusion or fission events during evolution. Mapping Leishmania origins suggests that all origins fire with equal efficiency, and that the genomic sites occupied by origins differ from related non-origins sites. Finally, we provide evidence that origin location in Leishmania displays striking conservation with Trypanosoma brucei, despite the latter parasite replicating its chromosomes from multiple, variable strength origins. Conclusions The demonstration of chromosome replication for a single origin in Leishmania, a microbial eukaryote, has implications for the evolution of origin multiplicity and associated controls, and may explain the pervasive aneuploidy that characterizes Leishmania chromosome architecture

A unifying representation for a class of dependent random measures

We present a general construction for dependent random measures based on thinning Poisson processes on an augmented space. The framework is not restricted to dependent versions of a specific nonparametric model, but can be applied to all models that can be represented using completely random measures. Several existing dependent random measures can be seen as specific cases of this framework. Interesting properties of the resulting measures are derived and the efficacy of the framework is demonstrated by constructing a covariate-dependent latent feature model and topic model that obtain superior predictive performance

A National Veterans Strategy: The Economic, Social and Security Imperative

This publication details the foundational logic supporting a call to action, related to a broad-based effort to articulate and institutionalize a National Veterans Strategy. We argue that coordinated, "whole-of-government" action toward this end is essential to meet the nation's most important economic, social, and security obligations. Furthermore, we contend that the second Obama administration, working in close collaboration with executive agencies, Congress, and the private sector, is well-positioned to act on what we perceive to be a historic opportunity -- capitalizing on both the foundations of veteran-focused policy and progress enacted over the past decade and the overwhelming public support for returning veterans and military families -- to craft and institutionalize a National Veterans Strategy.Our purpose is to provide a researched and logically-developed case for action that is grounded in this nation's social and cultural traditions and attuned to the practical realities of our contemporary economic and political climate