February 25, 2010

Networks of actin filaments can provide force within a cell to generate movement, but the mechanism of how this occurs isn’t completely understood. A group recently created a computer model to simulate and predict motility caused by actin polymerization, and tested new predictions experimentally. The figure above shows how an actin network uniformly coating a bead will break its symmetry to result in movement of the bead (top). The computer simulation (middle) and a 3D view of the simulation (bottom) are also shown.

Reference:

Mark J. Dayel, Orkun Akin, Mark Landeryou, Viviana Risca, Alex Mogilner, R. Dyche Mullins. Article found here.

February 22, 2010

A group recently developed a new method for studying retinal development in chick embryos, using in ovo electroporation at embryonic day 3 or 4 (E3-E4). This method has allowed the visualization of the dynamic morphologies of differentiating retinal cells, which previously was difficult with standard injection and electroporation techniques. Image above shows GFP expression in a ganglion cell at E18, with its characteristic morphology and location within the developing retina.

Reference: Sung Tae Doh, Hailing Hao, Stephanie C Loh, Tapan Patel, Haim Y Tawil, David K Chen, Anna Pashkova, Andy Shen, Huimin Wang and Li Cai. Analysis of retinal cell development in chick embryo by immunohistochemistry and in ovo electroporation techniques. BMC Developmental Biology 2010, 10:8. doi:10.1186/1471-213X-10-8. Article can be found here.

February 18, 2010

Cardiac muscle cell contractions require calcium intake into the cell through L-type calcium channels (Cav1.2) located on tubular membrane invaginations called T-tubules. BIN1, a member of the BAR domain superfamily, can generate membrane invaginations, and was recently reported to tether microtubules to the membrane scaffolding of cardiac T-tubules. These microtubules are used for transport of the Cav1.2 calcium channels to T-tubules. Images above are of a HeLa cell expressing α-tubulin:GFP (black) and BIN1:mCherry (red), showing microtubules tethered to BIN1. Panel on the right shows the travel path of three microtubules (green).

Reference: Ting-Ting Hong, James W. Smyth, Danchen Gao, Kevin Y. Chu, Jacob M. Vogan, Tina S. Fong, Brian C. Jensen, Henry M. Colecraft, Robin M. Shaw. BIN1 Localizes the L-Type Calcium Channel to Cardiac T-Tubules. PLoS Biology 2010, 8(2): e1000312. Article can be found here.

Great synopsis of this work can be found here.

February 15, 2010

Tight junctions are structures that serve as barriers on epithelial cells—separating fluids from either side of the epithelial sheet and preventing the diffusion of membrane proteins to different domains of the cell’s plasma membrane. Image is of epithelial cells (Caco-2, a human colon adenocarcinoma cell line) immunostained for MarvelD3 and occludin, colocalizing at tight junctions. MarvelD3 is a novel member of the occludin family of tight junction transmembrane proteins. Although MarvelD3 is not necessary for the formation of tight junctions, its function is important in regulating ion permeability of the cell.

Reference: Emily Steed, Nelio TL Rodrigues, Maria S Balda and Karl Matter. Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family. BMC Cell Biology 2009, 10:95

http://www.biomedcentral.com/1471-2121/10/95