In a paper published online in advance in Nature this week, an international research team led by investigators at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, shows that gene expression divergence in Drosophila "recapitulates the developmental hourglass model," and confirms that the "genes that conform most to the hourglass pattern are involved in key developmental processes." Using species-specific microarrays, the team quantified divergence throughout embryonic development; "by fitting different evolutionary models to each gene," the researchers found that "natural selection acts to conserve patterns of gene expression during mid-embryogenesis."
The Max Planck Institute for Evolutionary Biology's Tomislav Domazet-Lošo and Diethard Tautz at the Ruđer Bošković Institute in Zagreb, Croatia, used a "combination of phylostratigraphy and stage-specific gene expression data to generate a cumulative index that reflects the evolutionary age of the transcriptome at given ontogenetic stages" in zebrafish, which they found mirrors the hourglass model of morphological divergence. More specifically, the authors report in Nature that "reproductively active animals show the youngest transcriptome" and that "aging animals express increasingly older genes." Domazet-Lošo and Tautz used published data from flies and nematodes to show that the pattern they observed "occurs across phyla."
In a paper published online in advance in Nature Genetics this week, an international research team reports that loss-of-function mutations in the human ortholog of the canine gene CCDC39 "underlie a substantial fraction of [primary ciliary dyskinesia] cases with axonemal disorganization and abnormal ciliary beating." First, the team "exploited the unique properties of dog populations to positionally clone ... CCDC39." From there, the investigators performed functional analyses of the gene, through which they found that "CCDC39 localizes to ciliary axonemes and is essential for assembly of inner dynein arms and the dynein regulatory complex."
Researchers at institutions across Europe report online in Nature Genetics this week that "mutations in genes encoding subunits of RNA polymerases I and III cause Treacher Collins syndrome," a craniofacial development disorder. After having identified a deletion of POLR1D — a gene that codes for a subunit of Pol I and Pol II — in an affected individual, the team interrogated mutations of the gene in 252 additional cases. In three individuals, the team "discovered mutations in both alleles of POLR1C." The authors report that they've also identified additional candidate mutations and say that their study supports "the hypothesis that TCS is a ribosomopathy."