Our People: Newly Elected NAS Members

The ASCB congratulates two ASCB members who were recently elected to the National Academy of Sciences: Stephen M. Beverley, Washington University in St. Louis, and Robert H. Singer, Albert Einstein College of Medicine.

Robert H. Singer, Albert Einstein College of Medicine

Stephen M. Beverley, Washington University in St. Louis

CellTweets #10   Cells Steer by an Internal Compass Box

Many kinds of cells can move—from single-celled amoeba such as Dictyostelium to highly specialized cells in multi-cellular organisms such as white blood cells—in the human body. In recent decades, cell motility has become a hot research field. We’ve learned much about the mechanisms underlying cell movements and applied some of that knowledge to understanding complex functions in the body such as wound healing, as well as pathological conditions such as cancer metastasis in which cell movements are abnormal.

Yet certain elements of cell movement have remained a mystery. One perplexing question is the effect of electric fields on cell motility. The differential movement of ions across the plasma membrane by channels and pumps can establish small electric fields in a tissue or organism, and these electric fields are key to many functions, including proper patterning during vertebrate development. In addition, disruptions to the trans-epithelial potential in a wound cause local electric fields that are important during healing. An electric field alone does not make most cells move, but it does seem to steer them—and it can steer different cell types in different directions. When placed in a direct current (DC) electric field, some cell types move toward the anode (positive electrode) and others move toward the cathode (negative electrode).

This process called “galvanotaxis” has been known for years, but the actual mechanism of steering by the electric field has been elusive, in part because most research has focused on steering by other signals, such as chemical gradients (i.e., chemotaxis). Now, two labs, Julie Theriot’s at Stanford University, and "Alex Mogilner’s at the University of California, Davis, have published a pair of related papers in Current Biology that get at the mechanism of galvanotaxis.

Working with fish epidermal keratocytes, the researchers found that when cells are placed in an electric field, charged components on the surface of the cell, like membrane proteins, migrate toward the anode or cathode via electrophoresis—much as DNA or proteins are drawn through an electrophoresis gel in the lab. The researchers hypothesize that the movement of these components to one side of the cell or the other acts like a cellular compass to define the front and back. The charge and mobility of the surface components determine whether they can move, and whether they move toward the anode or cathode. And since different cell types express different surface proteins, the compass might be oriented in one way for one cell type and the opposite for another cell type, which could explain why some cells move toward the anode and others move toward the cathode. This cell surface compass then interfaces with the pathways that turn on the engine and drive cell motility. In this way, galvanotaxis is remarkably similar to chemotaxis in which the activation of receptors on one side of the cell (where the chemical signal is strongest) sets up the compass to define the front and rear, and then signals to the motility engine. Galvanotaxis and chemotaxis seem to share an engine, but have different steering mechanisms.

Although the galvanotaxis of cells has not been well understood before now, it is clear that electric fields are essential in the developing embryo, as well as during processes such as wound healing in the mature organism, so the ability of cells to orient and migrate with respect to these electric fields may well be very important.

—Lee Ligon

Created on Friday, April 19, 2013

King for a Day, President All Year

Grand strategy or wish list? The President makes a big move in the chess game of DC budgeting. Photo by John Fleischman

Even in a good year, the document commonly called “the President’s budget” is really just a detailed outline of what programs the President would support if he were king and not president.

This year is not a good year. President Obama’s FY14 budget proposal was delivered to Congress Wednesday (April 10), almost two months late. Tired of waiting, the House of Representatives and the Senate have already begun constructing their own budgets. Because of cuts connected with sequestration, it is also difficult to find easy points for comparison for his FY14 proposals.

On paper, President Obama’s FY14 budget calls for a significant increase in federal spending in the “R” in federal Research & Development. The President has asked for $31.3 billion for the U.S. National Institutes of Health (NIH) for FY14, which he says is $472 million (1.5%) more than FY12. Despite the increase in the overall NIH budget, it appears that shifting priorities, for example, at the National Institute for General Medical Sciences (NIGMS) resulted in a slight decrease in its budget.

The President’s proposal says that the budget for the National Science Foundation (NSF) would increase by 8.4% more than FY12. The BIO Directorate at NSF sees a similarly sized budget request from the president.

The President rounds out his commitment to R&D and science by increasing the budgets for a number of other science agencies. The White House Office of Science and Technology Policy touts significant increases for the following agencies:

• National Aeronautics & Space Administration (NASA) – a 2.6% increase
• National Oceanic & Atmospheric Administration (NOAA) – a 28% increase
• National Institute of Standards & Technology (NIST) – a 21% increase

The difference between being king (for a day) and president (for four years) becomes slightly more understandable when you look at what is not in the President’s budget. If the President were king, the sequester over which politicians fought throughout 2012 and is now beginning to be felt in research labs all over the nation would disappear. As it says in the “Economic and Budget Analysis” section of the budget proposal, “This economic forecast, as always, is based on the assumption….that the sequester that took effect on March 1st of this year is avoided and the harmful, across-the-board cuts are reversed.” In other words, Merlin would make it disappear.

Since the chances of Merlin appearing inside the Beltway are slim, it’s probably better to view the budget proposals in a more pragmatic light. Instead of a $470 million increase for the NIH, the President’s budget is unable to undo the damage done by the $1.5 billion sequestration cut, leaving the agency $1 billion short of its FY12 budget. The NSF budget would see a $303 million increase instead of a $592 million increase.

—Kevin M. Wilson

Created on Friday, April 12, 2013