The simultaneous expression of the hunchback gene in the numerous nuclei of the developing fly embryo gives us a unique opportunity to study how transcription is regulated in living organisms. A recently developed MS2-MCP technique for imaging nascent messenger RNA in living Drosophila embryos allows us to quantify the dynamics of the developmental transcription process. The initial measurement...

The simultaneous expression of the hunchback gene in the multiple nuclei of the developing fly embryo gives us a unique opportunity to study how transcription is regulated in functional organisms. A recently developed MS2-MCP technique for imaging transcription in living Drosophila embryos allows us to quantify the dynamics of the developmental transcription process. The initial measurement of ...

Anterior terminal development is controlled by several zygotic genes that are positively regulated at the anterior pole of Drosophila blastoderm embryos by the anterior (bicoid) and the terminal (torso) maternal determinants. Most Bicoid target genes, however, are first expressed at syncitial blastoderm as anterior caps, which retract from the anterior pole upon activation of Torso. To better u...

Axial patterning is a fundamental event in early development, and molecules involved in determining the body axes provide a coordinate system for subsequent patterning. While orthologs of Drosophila bicoid and nanos play a conserved role in anteroposterior (AP) patterning within at least a subset of Diptera, conservation of this process has not yet been demonstrated outside of the flies. Indeed...

—We captured 1,055 Nelson’s (Ammodramus nelsoni) and Saltmarsh (Ammodramus caudacutus) sparrows during the winter season (2006–2014) within the outer Coastal Plain of Virginia to determine the composition of subspecies. Birds were captured using mist nets in 24 tidal salt marshes and identified to subspecies using a plumage-based, syntopic key. Contrary to previous assessments, both species of ...

Sparrows in the nine-primaried oscine family Passerellidae represent an attractive model for studying avian diversification across North and South America. However, the lack of phylogenetic resolution at the base of the New World sparrow tree has hampered the use of the existing sparrow phylogeny to test questions about the evolution of sparrow traits. We generated phylogenomic data from 1,063 ...

During cerebral cortex development, a series of projection neuron types is generated in a fixed temporal order. In Drosophila neuroblasts, the transcription factor hunchback encodes first-born identity within neural lineages. One of its mammalian homologs, Ikaros, was recently reported to play an equivalent role in retinal progenitor cells, raising the question as to whether Ikaros/Hunchback pr...

The Drosophila Nanos protein is a localized repressor of hunchback mRNA translation in the early embryo, and is required for the establishment of the anterior-posterior body axis. Analysis of nanos mutants reveals that a small, evolutionarily conserved, C-terminal region is essential for Nanos function in vivo, while no other single portion of the Nanos protein is absolutely required. Within th...

The renal anatomy of three species of sparrows, two from mesic areas, the House Sparrow (Passer domesticus) and Song Sparrow (Melospiza melodia), and one salt marsh species, the Savannah Sparrow (Passerculus sandwichensis) was examined. Electron microscopy was used to describe the ultrastructure of the nephron. In addition, stereology was used to quantify the volumes of cortex, medulla, and maj...