A Structural Split in the Human Genome

Background: Promoter-associated CpG islands (PCIs) mediate methylation-dependent gene silencing, yet tend to co-locate to transcriptionally active genes. To address this paradox, we used data mining to assess the behavior of PCI-positive (PCI+) genes in the human genome. Results: PCI+ genes exhibit a bimodal distribution: (1) a 'housekeeping-like' subset characterized by higher GC content and lower intron length/number, and (2) a 'pseudogene paralog' subset characterized by lower GC content and higher intron length/number (p<0.001). These subsets are functionally distinguishable, with the former gene group characterized by higher expression levels and lower evolutionary rate (p<0.001). PCI-negative (PCI-) genes exhibit higher evolutionary rate and narrower expression breadth than PCI+ genes (p<0.001), consistent with more frequent tissue-specific inactivation. Conclusions: Adaptive evolution of the human genome appears driven in part by declining transcription of a subset of PCI+ genes, predisposing to both CpG→TpA mutation and intron insertion. We propose a model of evolving biological complexity in which environmentally-selected gains or losses of PCI methylation respectively favor positive or negative selection, thus polarizing PCI+ gene structures around a genomic core of ancestral PCI- genes. © 2007 Tang, Epstein.published_or_final_versio

International technology innovation to accelerate energy transitions:The case of the international energy agency technology collaboration programmes

International cooperation in technology innovation can help accelerate energy transitions globally. If they are to promote global systemic change, partnerships need to move beyond nurturing niches and increase their geographical reach. Moving beyond niches brings challenges for such international partnerships traditionally focused on technological-hardware innovation in advanced countries. Based on an analytical framework rooted in innovation and transition studies, this paper explores how international technology innovation partnerships can help accelerate transitions globally by conducting a unique empirical study of the almost five decades-old IEA Technology Collaboration Programmes (TCPs). Results suggest that well-established networks for knowledge diffusion, growing compatibility of activities with climate change mitigation goals, and increased global participation currently enable TCPs to contribute to the energy transition. Improving outreach to non-scientific audiences, knowledge diffusion beyond technical knowledge, and cross-sectoral coordination, as well as ensuring equal-footing participation of developing countries, remain challenges to be addressed, especially as the transition accelerates