A personal note

This will be my last HighMag post for a while, as I await the August arrival of my second daughter.  While I love looking at beautiful images of cells and reading exciting new papers, I am currently obsessed with insane nesting projects…as if the baby will be interested in our how organized our garage is.  After Baby arrives and my sleep deprivation eases up a bit (ha!), I look forward to posting again on HighMag.

To make sure you don’t miss future HighMag posts, be sure to “Like” the HighMag Facebook page.  All of the cool kids are doing it, so you should too.

If you need to contact me for anything, feel free to email me at highmagblog@gmail.com.  

Until I’m back in the HighMag saddle, check out these HighMag Greatest Hits I've compiled for you.  The following are links to posts that were either your favorite images and papers (lots of traffic!) or my own personal favorites.  Enjoy!





July 17, 2013

We don’t need to reinvent the wheel (even if someone tried to in 2001...click here).  We use the wheel for so many things ranging from transport to energy.  Cells have proven clever at co-opting machinery for multiple processes, as the paper from today’s image describes.  This recent paper shows the use of specific machinery in both cytokinesis and neuronal migration.

When neurons migrate, there is a leading process in the front of the cell body and a trailing process.  The leading process contains actin filaments that enable the cell body of the neuron to move forward.  A recent paper describes how the microtubule-based motor kinesin-6 plays an important role in neuronal migration.  Kinesin-6 is best known for its role in cytokinesis, the physical division of a cell after mitosis.  Falnikar and colleagues found that kinesin-6 concentrates in the same region as actin filaments in the leading process of a migrating neuron.  Without kinesin-6, neurons lose their bipolar leading-trailing process morphology, concentrate actin filaments in more than one process, and either remain stationary or continually change the direction of migration.  In addition, Falnikar and colleagues found that kinesin-6 signals through the GTPase activating protein MgcRacGAP to regulate the actin cytoskeleton, as it does during cytokinesis.  In the images above, control neurons (top time-lapse series) moved in a single direction, while neurons depleted of kinesin-6 bottom) frequently changed directions.

BONUS!!  Check out a movie of a wandering, migrating kinesin-6-depleted neuron below.

ResearchBlogging.orgAditi Falnikar, Shubha Tole, Mei Liu, Judy S. Liu, & Peter W. Baas (2013). Polarity in Migrating Neurons Is Related to a Mechanism Analogous to Cytokinesis Current Biology, 23 (13), 1215-1220 DOI: 10.1016/j.cub.2013.05.027 Copyright ©2013 Elsevier Ltd. All rights reserved.

July 10, 2013

The grace of a migrating cell is as deceiving as a pair of Spanx on an English Bulldog… there is a lot going underneath.  Today’s image is from a paper showing the importance of the protein vinculin at the leading edge of a migrating cell.

Cell migration is driven by actin filament polymerization that pushes the leading edge of the cell forward, as well as F-actin retrograde flow.  Focal adhesions (FAs) adhere the crawling cell to the underlying extracellular matrix (ECM), and are assembled and disassembled near the leading edge of the cell.  Proteins of these FAs are believed to make up a “molecular clutch” that engages the retrograde F-actin flow, and a recent paper identifies the protein vinculin, an actin-binding protein, as a molecular clutch.  Thievessen and colleagues investigated the effects of vinculin gene disruption in migrating fibroblasts, and found that vinculin is important in regulating F-actin organization and FA dynamics.  Specifically, vinculin generates the ECM traction forces necessary for migration, and promotes FA formation and turnover.  In the images above, a normal fibroblast (top) and a fibroblast lacking vinculin (bottom) show F-actin (green) and the lamellipodial protein cortactin (purple).  Normal crawling fibroblasts have a sharply defined band of cortactin colocalized with F-actin at the leading edge, while vinculin mutants have a wider, less defined region of cortactin at the leading edge, suggesting the importance of vinculin in leading edge organization.

BONUS!  Check out some cool movies from this paper here.

ResearchBlogging.orgThievessen I, Thompson PM, Berlemont S, Plevock KM, Plotnikov SV, Zemljic-Harpf A, Ross RS, Davidson MW, Danuser G, Campbell SL, & Waterman CM (2013). Vinculin-actin interaction couples actin retrograde flow to focal adhesions, but is dispensable for focal adhesion growth. originally published in the Journal of Cell Biology, 202 (1), 163-77 PMID: 23836933

July 2, 2013

Timing is everything….from the fluke encounter in a romantic comedy, to your rush to make the bus/train/plane this morning, to the development of an organism. Today’s image is from a paper describing the temporal patterning involved in the development of the fruit fly optic lobe.

In the fruit fly optic lobe, the medulla processes visual information using 40,000 neurons of over 70 different cell types. The medulla develops from a crescent-shaped tissue from which the neuronal progenitors divide, requiring several different transcription factors. A recent paper describes the sequential patterning of five transcription factors as the medulla neuroblasts age. Li and colleagues found that this temporal patterning of transcription factors is necessary for the diversity of cell types found in the medulla. The images of the developing medulla above show the sequential expression of these five transcription factors—Homothorax (Hth), Eyeless (Ey), Sloppy paired 1 and 2 (Slp), Dichaete (D), and Tailless (Tll)—in five consecutive stripes. Hth is found in the youngest neuroblasts. Ey, Slp, and D are required for turning on the next transcription factor in the cascade. Slp and D are also required for turning off the preceding transcription factor.

ResearchBlogging.orgLi X, Erclik T, Bertet C, Chen Z, Voutev R, Venkatesh S, Morante J, Celik A, & Desplan C (2013). Temporal patterning of Drosophila medulla neuroblasts controls neural fates. Nature, 498 (7455), 456-62 PMID: 23783517 
Adapted by permission from Macmillan Publishers Ltd, copyright ©2013