Highlights in DD
Article first published online: 17 AUG 2007
Copyright © 2007 Wiley-Liss, Inc.
Volume 236, Issue 9, page fvi, September 2007
How to Cite
Kiefer, J. (2007), Highlights in DD. Dev. Dyn., 236: fvi. doi: 10.1002/dvdy.21277
- Issue published online: 17 AUG 2007
- Article first published online: 17 AUG 2007
“Highlights” is a new feature that calls attention to exciting advances in developmental biology that have recently been reported in Developmental Dynamics. Development is a broad field encompassing many important areas. To reflect this fact, the section will spotlight significant discoveries that occur across the entire spectrum of developmental events and problems: from new experimental approaches, to novel interpretations of results, to noteworthy findings utilizing different developmental organisms.
Clinicians and Basic Scientists Unite (Dev Dyn236:1456–1474) When pipeting into Eppendorf tubes all day long, it can be easy to forget that results obtained at the bench can impact the human condition. In one of several enlightening Segmentation Focus Special Issue reviews, Dunwoodie and colleagues make this relationship abundantly clear. Proper somite segmentation is central to the development and organization of axial skeleton and musculature, and dermis. Understandably, defects in genes that regulate any one of the many steps that governs segmentation can have profound affects on human health. Here, the authors detail various abnormal vertebral segmentation (AVS) syndromes: their phenotypes, and when known, their genetic bases. Significantly, several genes that basic researchers have identified as crucial to segmentation are affected in AVS patients. Taken together, this information has been used to build standardized guidelines to classify congenital spinal malformations. The authors emphasize that continued efforts to share information between molecular biologists and clinicians will be pivotal to implementing accurate diagnoses and appropriate courses of treatment.
Designed by Mother Nature (Dev Dyn236:1495–1508) Mother Nature creates intricate patterns by painstakingly arranging biological parameters just so. During segmentation, somites bud with periodic regularity from the anterior presomitic mesoderm (PSM). Segmentation gene expression patterns presage somite boundaries, and are activated by retinoic acid (RA) signaling and inhibited by FGF8. Developmental biologist Olivier Pourquié teamed with mathematicians led by Albert Goldbeter to determine how the two pathways, which are mutually antagonistic, pattern the PSM. An FGF gradient originates at the posterior PSM, and an RA gradient at the anterior. Mathematical models show that somewhere in between, inhibition exerted by both pathways creates a window of “bistability.” Cells residing within this window are equally likely to receive instructions from either pathway. The authors postulate that an output of the segmentation clock alternately tips the balance to favor one pathway over the other, thus generating characteristic allor-none expression patterns. Models further show that anterior degradation of fgf8 mRNA progressively ratchets the bistability window posteriorward, allowing for successive segmentation domains. The authors discuss how bistability may also forge other embryonic patterns.
NO Means No Metamorphosis (Dev Dyn236:1535–1546) What looks to be a writhing alien in this paper's supplementary video actually documents a newly discovered sea urchin behavior that precedes metamorphosis. The animal settles on bacterial biofilm and uses its cilia to direct water flow over its ventral surface. The findings in this paper reveal why this behavior is so important. Previous research showed that the gaseous molecule, nitric oxide (NO) inhibits metamorphosis. Here, the authors trace the NO pathway, and find that NO synthase (NOS) resides in a set of neurons within the post-oral ciliary band (POCB). When the POCB is excised, animals fail to linger on biofilm, and initiation of subsequent behavioral and morphogenetic events associated with metamorphosis is drastically reduced. Based on these data, it is postulated that the authors postulate that the behavior described above wafts soluble chemicals secreted by biofilm over the POCB, a chemosensory organ. In response, NO signaling is inhibited. The authors discuss how different cell types that contain cGMP, which they confirm is an NO effector during metamorphosis, may regulate specific metamorphosis-associated morphogenetic events.