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This Week in PNAS: May 28, 2013

In the early, online edition of the Proceedings of the National Academy of Sciences, a Johns Hopkins University- and University of Iowa-led team describes a genome engineering scheme centered on a modified version of the piggyBac transposase enzyme and its corresponding transposon, which were used in combination with zinc finger proteins in the proof-of-principle study. Because the system makes it possible to insert and remove a sequence without altering the original sequence, study authors note, the piggyBac approach may hold promise for targeted genome engineering in general and for related applications such as reversible transgenesis or modified insertion targeting.

A combination of linkage analyses and exome sequencing helped researchers from Radboud University and elsewhere track down mutations in a zinc finger protein-coding gene called ZNF408 in a family affected by a retinal condition called familial exudative vitreoretinopathy, or FEVR. The team found suspicious mutations in ZNF408 and in a second gene when they did linkage analyses on eight individuals from a large Dutch family affected by FEVR, along with exome sequencing on two members of the family. The same ZNF408 alteration subsequently turned up in another Dutch family. Targeted testing on 132 more individuals uncovered a distinct change in the gene in a FEVR-affected family from Japan, study authors note, while their model organism experiments linked a lack of the ZNF408 gene product to unusual retinal vascular development.

Maternal exposure to bisphenol A during pregnancy appears to coincide with sex-specific changes to expression and epigenetic patterns in the fetal mouse brain, according to another study slated to appear online in PNAS this week. After exposing pregnant mice to various BPA doses, Columbia University researchers tested multiple regions of fetal mouse brains, identifying changes in the expression and/or methylation profiles of sex-related genes — shifts that corresponded with levels of exposure to the purported endocrine disruptor. "[W]e demonstrate that low-dose prenatal BPA exposure induces lasting epigenetic disruption in the brain that possibly underlie enduring effects on BPA on brain function and behavior," the team writes, "especially regarding sexually dimorphic phenotypes."