In a Science paper published online in advance, an international research team describes "a unifying genetic model for facioscapulohumeral muscular dystrophy," which suggests that "FSHD arises through a toxic gain of function attributable to the stabilized distal DUX4 transcript." They show that patients with FSHD carry specific SNPs, and that this "predisposing configuration creates a canonical polyadenylation signal for transcripts derived from DUX4." In their subsequent transfection studies, the team found the DUX4 transcripts are "more stable when expressed from permissive chromosomes." The New York Times' Gina Kolata adds that "the culprit gene is part of what has been called junk DNA," whose function is largely unknown and that this study suggests that those "junk" genes "can rise from the dead like zombies, waking up to cause one of the most common forms of muscular dystrophy."
A trio of researchers led by Brian Green at the Johns Hopkins University School of Medicine this week suggest that "re-replication may be a contributor to gene copy number changes" in Saccharomyces cerevisiae. Amplicons produced as a result of re-replication are "mediated by non-allelic homologous recombination between the repetitive elements," Green et al. write, adding that their study may have implications for the study of cancer biology, evolution, and human genetics.
In an accompanying editorial, researchers at the University of Arizona write that "the yeast study provides a solid example of another curious and perhaps relevant feature of DNA structure. Because of its propensity to undergo re-replication (at least in mutants), the ARS317 region can be considered a 'hot spot' ... in human tumors, there also appear to be 'hot spots' of gene amplification," although it's unknown whether these are the results of re-replication events. "The extent to which re-replication–driven instability explains other unusual DNA structures common in cancer cells ... also remains to be clarified," the authors write.
Investigators at Macquarie University in Australia report in Science this week that female finches use extra-pair copulations and a genetically loaded process of sperm competition "to target genes that are optimally compatible with their own to ensure fertility and optimize offspring viability." These behaviors, the team writes, suggest an "adaptive function of female infidelity in socially monogamous animals."