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Building a 3D Map of the Genome

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3D Genome Map

Credit: Chen et al., 2018

Researchers have learned a lot in recent years about how six-plus feet of human DNA gets carefully packed into a tiny cell nucleus that measures less than .00024 of an inch. Under those cramped conditions, we’ve been learning more and more about how DNA twists, turns, and spatially orients its thousands of genes within the nucleus and what this positioning might mean for health and disease.

Thanks to a new technique developed by an NIH-funded research team, there is now an even more refined view [1]. The image above features the nucleus (blue) of a human leukemia cell. The diffuse orange-red clouds highlight chemically labeled DNA found in close proximity to the tiny nuclear speckles (green). You’ll need to look real carefully to see the nuclear speckles, but these structural landmarks in the nucleus have long been thought to serve as storage sites for important cellular machinery.


Cool Videos: A Biological Fireworks Display

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Let’s kick off the Fourth of July weekend with some biological fireworks! While we’ve added a few pyrotechnic sound effects just for fun, what you see in this video is the product of some serious research. Using a specialized microscope equipped with a time-lapse camera to image fluorescence-tagged proteins in real-time, an NIH-funded team has captured a critical step in the process of cell division, or mitosis: how filaments called microtubules (red) form new branches (green) and fan out to form mitotic spindles.

In this particular experimental system, the team led by Sabine Petry at Princeton University, Princeton, NJ, studies the dynamics of microtubules in a cell-free extract of cytoplasm taken from the egg of an African clawed frog (Xenopus laevis). Petry’s ultimate goal is to learn how to build mitotic spindles, molecule by molecule, in the lab. Such an achievement would mark a major step forward in understanding the complicated mechanics of cell division, which, when disrupted, can cause cancer and many other health problems.


“OMG” Microscope Lives Up To Its Name

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Photo of an epithelial cell in metaphase with microtubules stained red, kinetochores stained green, DNA stained blue

Courtesy of Indiana University

The scientists at the IU School of Medicine-Bloomington nicknamed their new microscope the “OMG” for good reason—the images it produces are showstoppers. The DeltaVision OMX imaging system (its official title) is a $1.2 million dollar microscope that can peek inside a cell and image fluorescent proteins in unprecedented detail.

Jane Stout, a researcher in the NIH-funded lab, used the OMG to create this spectacular image that won her first place in the high- and super-resolution microscopy category of the 2012 GE Healthcare Life Sciences Cell Imaging Competition.

What you’re looking at is a cell in the midst of dividing into two identical copies—a process called mitosis. Here, the chromosomes (in blue) are aligned at the cell’s equator. Microtubules (red) from opposite poles of the cell attach to the chromosomes using the kinetochores (green) and pull them to opposite ends of the cell, which then splits in half. But sometimes cells do not divide properly—a common problem in cancer. Understanding the mechanics of cell division could help us correct this process when it goes wrong.

Jane Stout’s prize: her mitosis image will light up a billboard in Times Square in New York City in April. That is a wonderful celebration of science!

NIH support: the National Institute of General Medical Sciences