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This Week in Science: Mar 11, 2011

In Science this week, a team led by investigators at the University of Massachusetts Medical School reports its use of yeast genetic engineering, chemical biology techniques, and multi-wavelength fluorescence microscopy to "follow assembly of single spliceosomes in real time in whole-cell extracts." In its investigations, the team found that spliceosomal subcomplexes sequentially associate with pre-mRNA, such that they produce functional spliceosomes and that each subcomplex is reversible. "Early subcomplex binding events do not fully commit a pre-mRNA to splicing," the authors say. Rather, they report, as assembly proceeds, commitment increases. The team suggests its experimental approach could "prove widely useful for mechanistic analysis of other macromolecular machines."

An international team led by researchers at Imperial College London shows that de-catenation between sister chromatids by DNA topoisomerase II in eukaryotes is driven by positive supercoiling of mitotic DNA. In yeast, the team found that the topology of centromeric plasmids changes as positive supercoiling takes place. "However, when positive supercoiling takes place in catenated plasmid, topoisomerase II activity is directed toward de-catenation of the molecules before relaxation," the authors write in this week's Science.

In a letter that appears in this week's issue, the University of Virginia's Anne Milles and Patti Tereskerz suggest there is "a lack of empirical evidence about the numbers of human DNA patents," given that they're often subject to merger and acquisition activities, among other variables that may confound their quantification. "Our hope is that future study will give decisions-makers a more complete and accurate picture of the genetics industry," Milles and Tereskerz write.

And in Science Translational Medicine, researchers at the University of Texas M.D. Anderson Cancer Center demonstrate that "neutrophils activate plasmacytoid dendritic cells by releasing self-DNA-peptide complexes in systemic lupus erythematosus." More specifically, the team reports its identification of previously unknown links between neutrophils, plasmacytoid dendritic cell activation via TLR9, and autoimmunity in systemic lupus erythematosus.