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animal models

Collegen

Credit: David Sleboda and Thomas Roberts, Brown University, Providence, RI

Over the past few years, my blog has highlighted winners from the annual BioArt contest sponsored by the Federation of American Societies for Experimental Biology (FASEB). So, let’s keep a good thing going with one of the amazing scientific images that captured top honors in FASEB’s latest competition: a scanning electron micrograph of the hamstring muscle of a bullfrog.

That’s right, a bullfrog, For decades, researchers have used the American bullfrog, Rana catesbeiana, as a model for studying the physiology and biomechanics of skeletal muscles. My own early work with electron microscopy, as a student at Yale in the 1970s, was devoted to producing images from this very tissue. Thanks to its disproportionately large skeletal muscles, this common amphibian has played a critical role in helping to build the knowledge base for understanding how these muscles work in other organisms, including humans.

Revealed in this picture is the intricate matrix of connective tissue that holds together the frog’s hamstring muscle, with the muscle fibers themselves having been digested away with chemicals. And running diagonally, from lower left to upper right, you can see a band of fibrils made up of a key structural protein called collagen.

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Posted In: Health, Science

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This Fourth of July, many of you will spread out a blanket and enjoy an evening display of fireworks with their dramatic, colorful bursts. But here’s one pyrotechnic pattern that you’ve probably never seen. In this real-time video, researchers set off some fluorescent fireworks under their microscope lens while making an important basic discovery about how microtubules, the hollow filaments that act as the supportive skeleton of the cell, dynamically assemble during cell division.

The video starts with a few individual microtubule filaments (red) growing linearly at one end (green). Notice the green “comets” that quickly appear, followed by a red trail. Those are new microtubules branching off. This continuous branching is interesting because microtubules were generally thought to grow linearly in animal cells (although branching had been observed a few years earlier in fission yeast and plant cells). The researchers, led by Sabine Petry, now at Princeton University, Princeton, NJ, showed for the first time that not only do new microtubules branch during cell division, but they do so very rapidly, going from a few branches to hundreds in a matter of minutes [1].

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Black bear

Credit: Karen Laubenstein (Big Game Alaska)/U.S. Fish and Wildlife Service

When bears, bats, and other animals prepare to hibernate, they pack on fat at an impressive pace to almost double their weight. As they drift off into their winter slumber, their heart rates, breathing, and metabolism slow dramatically. Hibernating mammals can survive in this state of torpor for a period of weeks or even months without eating or drinking anything at all!

It’s a fascinating and still rather mysterious process—and one that William Israelsen of The University of Texas Southwestern Medical Center, Dallas, thinks may yield intriguing insights with implications for human health. A recipient of a 2015 NIH Director’s Early Independence Award, Israelsen plans to use a little-known mouse species to study hibernation in the laboratory at a level of detail that’s not possible in the wild. He especially wants to learn how hibernating animals shift their metabolic gears over the course of the year, and what those findings might reveal about human obesity, cancer, and other health conditions.

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Ferret

Ferret in a Colorado conservation center, U.S. Fish and Wildlife Service

Not only is the ferret (Mustela putorius furo) adept at navigating a dirt field or threading electrical cables through piping (in New Zealand, ferrets can be registered as electrician assistants), this furry 5-pounder ranks as a real heavyweight for studying respiratory diseases. In fact, much of our current thinking about influenza is influenced by research with ferrets.

Now, the ferret will stand out even more. As reported online in Nature Biotechnology, NIH-funded researchers recently sequenced the genome of the sable ferret, the type that is bred in the United States as a pet. By studying this genetic blueprint like an explorer would a map, scientists can perform experiments to learn more systematically how the ferret copes biologically with common or emerging respiratory pathogens, pointing the way to improved strategies to preserve the health and well being of humans and ferrets alike.

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Healthy and mutated zebrafish

Caption: Healthy zebrafish (top) compared to zebrafish with arrhythmia-causing mutation (bottom). Their hearts are shown to the right, with enlargement indicating a weaker heart. The heart’s outflow tract is marked OFT; atrium, a; and ventricle, v.
Credit: Asimaki et al. Science Translational Medicine

Arrhythmia is a condition in which the heart loses its regular rhythm, beating either too rapidly or too slowly. Occasional irregular heartbeats are harmless, but if sustained they can cause dizziness, fainting, and even sudden death. There are a number of drugs available that can prevent arrhythmias, but none are perfect. Implanted devices can help—pacemakers can keep the heart from beating too slowly, and defibrillators can reset the heart’s rhythm with an electrical shock if a dangerously rapid rhythm develops.

But new treatments are needed. Now, an NIH-funded research team has created an animal model that is advancing efforts to find new drugs to prevent arrhythmia.  Led by Jeffrey Saffitz at Beth Israel Deaconess Medical Center, Boston, researchers used genetic engineering techniques to produce zebrafish with genetic mutations identical to those in some people who suffer from a rare inherited disease called arrhythmogenic cardiomyopathy (ACM). In humans, ACM leads to dangerous arrhythmias that can cause sudden cardiac death, usually in people under the age of 35.

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