Breaking the Diffraction Barrier
In the past few years, a flurry of technical advancements have improved the resolving power of fluorescence microscopy by quantum leaps. Collectively known as “super-resolution” imaging, these methods are poised to provide biologists with unprecedented images of fine cellular structures and their dynamics inside the cell.
Image: Mouse C2C12 cells in prophase imaged with 3D structured illumination microscopy (SIM). Condensed chromosomes are stained with DAPI (red), the nuclear lamina and microtubuli are immunolabeled with an anti-lamin B (blue) and an anti-tubulin antibody (green), respectively.
Findings Point to Clues for Regenerative Therapies
June 25, 2009 - In a new study, published this week in Science, researchers investigated a trio of cell-signaling pathways that work simultaneously, converging to direct pancreas and liver progenitor cells to mature into their final state. They looked at how BMP, TGF-beta, and FGF signaling pathways turn on genes that guide cells to ultimately become pancreas or liver tissue.
The Science paper addresses how chemical signals from neighboring cells in the embryo tell early progenitor cells to activate genes encoding the regulatory proteins. The regulatory proteins, in turn, guide the cells to become a liver cell or a pancreas cell. “In the current study we mapped the signaling pathways being turned on before they connected with the target genes,” explains Zaret. “We monitored these cues before the cell displayed any overt signs of differentiation. While my lab and others had previously looked at individual signals that influence development, in this paper we simultaneously mapped three signal paths that converge to induce liver and pancreas cells. We’re starting to construct a network of the common signals that govern development of these specific cell types. The complexity of this system is somewhat like our 26-letter alphabet being able to encode Shakespeare or a menu at a restaurant.” (found on Penn Medicine)
Picture : Distribution of the genetic regulatory protein, Smad4, in a mouse embryo at 8.5 days gestation. The green stain in the center is Smad4 expressed in the liver and pancreas progenitor cells. The green on the periphery is Smad4 in the extraembryonic yolk sac tissue.
Credit: Ken Zaret, PhD; Ewa Wandzioch, PhD, University of Pennsylvania School of Medicine
Fractals, Parasites and 3-D Reconstructions: 18 Startling Science Images is a Scientific American gallery of winners of the Czech “Science Is Beautiful” contest. Check it out to see more startlingly beautiful images like these.
A Fruit Fly Embryo Montage
These brilliant photos, taken by the lab of Dr. Stephen W. Paddock from the University of Wisconsin, are various stages of embryonic development in Drosophila (fruit flies). Fruit flies are extremely useful (and popular) model organisms for studying developmental biology, basic biological processes, population genetics and other basic genetic processes (like mutation and disease).
Captions From the Stephen Paddock Digital Image Gallery
1 and 2- Triple-labeled Drosophila embryo at the cellular blastoderm stage. The specimen was immunofluorescently tagged with antibodies to the hairy protein in red, Kruppel repressor in green and the giant protein in blue.
3- The central nervous system of a Drosophila (fruit fly) embryo captured in a serial optical section by confocal laser scanning microscopy. This double-labeled fluorescent specimen reveals peripheral neurons in green and glial cells in red.
4- Presented below is a color mapped image of a Drosophila embryo, featuring stripes of the engrailed gene, which circle the embryo. The engrailed gene helps to direct fruit fly wing development, and mutations in this gene can affect how the wings appear in adult flies.
5- A tripled labeled fruit fly imaginal disc (developmental tissues from which many adult structures, such as eyes, wings, and halteres, are formed)
6- Triple-labeled Drosophila eye imaginal disc recovered from the third instar larval developmental stage.
These images are some of my favorites. Visit the gallery to see more amazing microscopy from this lab!