BioEssays

Molecular bioelectricity in developmental biology: New tools and recent discoveries. The cover image shows a section taken through a whole eye, formed outside of the head in a Xenopus embryo by targeted manipulation of transmembrane potential in key cells. The section stains with eye cell-specific markers such as cones (yellow), Mü ller glia (red/magenta), and amacrine cells (cyan), showing that bioelectric signals can drive cells to form complex organs with appropriate internal structure. On pages 205–217, Michael Levin reviews the state of the art in the interdisciplinary fi eld of molecular bioelectricity, and highlights recent advances in the molecular mechanisms by which voltage gradients regulate biological growth and form. The development of molecular-genetic tools for probing these biophysical signals has led to exciting discoveries of new roles for bioelectricity in morphogenesis during embryogenesis, regeneration, and cancer suppression. Endogenous voltage gradients within tissues provide instructive cues for anatomical polarity, organ identity, and positional information.

Cover by Vaibhav Pai

Eye genes expressed on wings. This image shows ommatidia containing red-reflecting screening pigments (photo courtesy of Doekela Stavenga) deployed on the wings of an Heliconius butterfly (photo courtesy of Chris Jiggins). On pages 181–186 of this issue Antónia Monteiro reviews recent discoveries that suggest that eye-like organs on the wings of Eohelea midges, and red patches on the wings of Heliconus butterflies, may have originated from redeployments of the eye gene regulatory network on the wings of these insects. Monteiro also develops an empirical framework to help recognize when such co-option events underlie the origin of novel traits. The doctored image conveys the concept of ectopic expression in the creation of novel traits.

Backcover by A. Monteiro

Squamates may be an attractive group in which to study the influence of sex chromosomes on speciation rates because of the repeated evolution of heterogamety (both XY and ZW), as well as an apparently large number of taxa with environmental sex-determination.

Current differentiation therapies for cancer may not be effective because it might not be enough to only use molecules targeting chromatin remodelers. It may also be necessary to stabilize the re-expressed genes to convert malignant cells into benign ones.

Polycomb proteins seem to help maintain silencing in pluripotent stem cells while establishing a chromatin environment that is permissive for priming by sequence-specific factors.

In the 1970s it was discovered that ATP could act as a neurotransmitter, and further research in this area has not only led to the cloning of the respective receptors, but also to the discovery that purinergic signalling is involved in pathophysiology, which might make it amenable to therapeutic strategies.

Parasites from the red algal lineage provide a unique and powerful model to investigate the genetic origins of a parasitic lifestyle, because they not only share a recent common ancestor with an extant free-living red algal species, but also because parasitism has independently arisen over 100 times within this group.

Many scientific problems (e.g. gene and drug discovery, metabolic engineering for the biotechnological improvement of organisms) can be viewed as a ‘landscape’ representing a large search space of possible solutions or experiments populated by a considerably smaller number of actual solutions that then emerge.

This biennial international workshop discusses the latest progress in non-bilaterian animal research.