In a paper published online in advance in Science this week, researchers at the University of Cambridge and at the Babraham Institute in the UK present oxidative bisulfite sequencing, or oxBS-seq, which they note is "the first method for quantitative mapping of 5hmC in genomic DNA at single-nucleotide resolution." The team says the results of its work to quantify 5hmC at CpG islands in murine embryonic stem cells "open new questions on 5hmC dynamics and sequence-specific targeting by TET [enzymes]."
Investigators at the University of Limoges in France show that the 3' cis-regulatory region of the immunoglobulin heavy chain locus is "is transcribed and undergoes AID [activation-induced deaminase]-mediated mutation and recombination around phylogenetically conserved switch-like DNA repeats." Such recombination, the authors write, "deletes the whole constant region gene cluster and thus stops expression of the immunoglobulin of the B cell surface, which is critical for B cell survival." Further, the team suggests that the "frequency of this event is approaching that of class switching and makes it a potential regulator of B cell homeostasis."
Elsewhere in Science Express, Nicole Schirle and Ian MacRae at the Scripps Research Institute report a 2.3-angstrom-resolution crystal structure of human Argonaute2. The structure "reveals a bi-lobed molecule with a central cleft for binding guide and target RNAs," they add.
Over in Science Translational Medicine, University of Chicago's Joel Collier discusses the potential of siRNA as both carrier and therapeutic in the context of work published by MIT's Jong Bum Lee et al. in Nature Methods. "Lee and co-workers describe microparticle carriers for siRNA that, once delivered to cells, transform directly from the carrier into the siRNA therapeutic itself," Collier writes.