Interview With a Scientist: Joel Kralj, Electromicist

Every one of our thoughts, emotions, sensations, and movements arise from changes in the flow of electricity in the brain. Disruptions to the normal flow of electricity within and between cells is a hallmark of many diseases, especially neurological and cardiac diseases.

The source of electricity within nerve cells (i.e., neurons) is the separation of charge, referred to as voltage, across neuronal membranes. In the past, scientists weren’t able to identify all the molecules that control neuronal voltage. They simply lacked the tools. Now, University of Colorado biologist Joel Kralj Exit icon has developed a way to overcome this hurdle. His new technique—combining automated imaging tools and genetic manipulation of cells—is designed to measure the electrical contribution of every protein coded by every gene in the human genome. Kralj believes this technology will usher in a new field of “electromics” that will be of enormous benefit to both scientists studying biological processes and clinicians attempting to treat disease.

In 2017, Kralj won a New Innovator Award from the National Institutes of Health for his work on studying voltage in neurons. He is using the grant money to develop a new type of microscope that will be capable of measuring neuronal voltage from hundreds of cells simultaneously. He and his research team will then attempt to identify the genes that encode any of the 20,000 proteins in the human body that are involved in electrical signaling. This laborious process will involve collecting hundreds of nerve cells, genetically removing a single protein from each cell, and using the new microscope to see what happens. If the voltage within a cell is changed in any way when a specific protein is removed, the researchers can conclude that the protein is essential to electrical signaling.

In this video, Kralj discusses how he plans to use his electromics platform to study electricity-generating cells throughout the body, as well as in bacterial cells (see our companion blog post “Feeling Out Bacteria’s Sense of Touch” featuring Kralj’s research for more details).

Dr. Kralj’s work is funded in part by the NIH under grant 1DP2GM123458-01.

Zebrafish Scrapbook

Name: Danio rerio
Hometown: Freshwater ponds and rivers of India, Nepal, and neighboring countries
Occupation: Research
Long-term goal: Solving the basic mysteries of life
Work site: More than 600 science labs worldwide
Danio rerio
That’s me and some other zebrafish, swimming in a tank in one of the more than 600 labs around the world that use us to study embryo development, genetics, and all kinds of human diseases. Credit: Wikimedia Commons, Azul.

Apart from the tell-tale stripes that give me my nickname, zebrafish, I look a lot like your standard minnow swimming in the shallows of any pond, lake, or river. But I like to think I’m more important than that. In fact, researchers around the world have turned to me and my extended family to understand some of the most basic mysteries of life. From studying us, they’re learning about how embryos develop, how cancer works, and whether someday humans might be able to rebuild a heart, repair a spinal cord injury, or regrow a severed limb.

Why us? Because zebrafish are pretty special and researchers think we’re easy to work with. First, unlike your standard lab mouse or rat, we lay lots of eggs, producing baby fish that grow up fast. We develop outside our mothers and go from egg to embryo to free-swimming larva in just 3 days (check out this video Exit icon of how we grow, cell by cell, during the first 24 hours). Within 3 months, we’re fully mature.

Not only do zebrafish moms have many babies at the same time, and not only do these babies grow up quickly, but our eggs and embryos are see-through, so scientists can literally watch us grow one cell at a time. We stay mostly transparent for a few weeks after hatching. That makes it super easy for scientists to monitor us for both normal and abnormal development. In fact, scientists have learned how to turn off the genes that give our skin its color. These zebrafish, named casper, after the “friendly ghost” of cartoon fame, stay semi-transparent, or translucent, through adulthood.

And last, but certainly not least, did I mention that we can regenerate? If parts of my body are damaged, even to a significant degree, they can regrow. This holds true for my heart, fins, spinal cord, and even brain tissue. Our regenerative capacity is seemingly unlimited; my caudal fin, for example, can grow back dozens of times. Continue reading

“Selfish” Gene Enhances Own Transmission at Expense of Organism’s Fertility

These glowing images of yeast (Schizosaccharomyces kambucha) reproductive cells show an example of a selfish gene at work.
These glowing images of yeast (Schizosaccharomyces kambucha) reproductive cells show an example of a selfish gene at work. Here, the selfish gene boosts its chances of being passed to the next generation by producing both a toxin (stained cyan) and an antitoxin (stained magenta). Cells with a copy of the selfish gene are protected by the antitoxin, left and bottom ovals. Those without the selfish gene are destroyed by the toxin. Scientists suspect that selfish genes could be operating throughout many organisms’ genomes, possibly having a major impact on how genetic material is inherited over generations. Credit: Image courtesy of María Angélica Bravo Núñez and Nicole Nuckolls.

There’s an old saying that rules are meant to be broken. In the 1860s, Gregor Mendel found that each copy of a gene in an organism has an equal chance of being passed to the next generation. According to this simple rule, each version of a gene gets passed to offspring with the same frequency. The natural selection process can then operate efficiently, favoring the genes that produce an advantage for an organism’s survival or reproductive success and, over successive generations, eliminating genes from the gene pool that bring a disadvantage.

Of course, the way organisms inherit genes is not as straightforward as Mendel’s work predicted. In natural systems, inheritance often fails to follow the rules. One culprit scientists are identifying again and again are what are called “selfish genes”: one or more genes that have evolved a method of skewing inheritance in their favor.

Scientists refer to these selfish genes—which are often complexes of multiple genes working together—as “selfish” because they enhance their own transmission to the next generation, sometimes by killing off any of the organism’s reproductive cells that lack copies of those genes. Using a variety of techniques, the genes are effective at passing themselves on to future generations. However, their methods set up a conflict within the organism by damaging its fertility; overall, fewer reproductive cells or offspring survive to produce a new generation.

Selfish genes are a challenge for scientists to identify, but researchers say that knowing more about these genes could help explain a range of genetic mysteries, from causes of infertility to details on how species evolve. The methods these genes use could also be harnessed to help control the reproduction of certain populations such as mosquitos that spread disease.

One recently described selfish gene system is found in the yeast cells pictured above. Sarah Zanders Exit icon and her colleagues at the Stowers Institute for Medical Research in Kansas City, Missouri, and the Fred Hutchinson Cancer Research Center in Seattle, Washington, study selfish gene systems in yeast to understand how common they are and how they affect a species’ fertility and evolution. “Usually we think about infertility stemming from the good guys failing. For example, a gene that normally promotes fertility could be mutated so that it can no longer do its job,” says Zanders. “But selfish genes are another potential source of infertility. Learning general principles about selfish genes in simple models will guide future searches for selfish genes that could be contributing to human infertility.”

Recently, the scientists discovered a single selfish gene, wtf4, that encodes both a toxin and an antitoxin protein. When yeast produce their reproductive cells, called spores, the wtf4 toxin protein is released into the immediate vicinity, but the antitoxin remains inside spores that contain a copy of wtf4. The toxin destroys all the spores that don’t have the antitoxin protein. Although the yeast has fewer spores—and therefore reduced fertility—each spore carries wtf4, ensuring that the gene will be passed to the next generation of yeast. Continue reading

Fall 2017 Issue of Findings Magazine

It’s back! Check out the new issue of Findings magazine.

Findings presents cutting-edge research from scientists in diverse biomedical fields. The articles are aimed at high school students with the goal of making science—and the people who do it—interesting and exciting, and to inspire young readers to pursue careers in biomedical research. In addition to putting a face on science, Findings offers activities such as quizzes and crossword puzzles and, in its online version, video interviews with scientists.

The Fall 2017 issue profiles Yale University biologist Enrique De La Cruz, who studies how actin—a protein chain that supports cell structure—breaks so easily. Also profiled is University of California, Berkeley, biologist Rebecca Heald and her study of developmental factors that control an animal’s size.

This issue also features:

  • A virtual reality program designed to help burn patients manage pain
  • The promise of gene therapy for glaucoma
  • The many ways scientists categorize the biological world using “omics”
  • What researchers know—and don’t know—about how general anesthetics work
  • How animation helps researchers visualize interactions between biological molecules
  • How cells use sugary outer coatings to distinguish friend from foe
  • What makes our tissues stiff, squishy, solid, or see-through (hint: its initials are ECM)
  • How super-powerful microscopes are revealing views of biology never possible before

View Findings online, or order a print copy (classroom sets of up to 30 copies are available for educators).

 

Happy Birthday, BioBeat

This month, our blog that highlights NIGMS-funded research turns four years old! For each candle, we thought we’d illuminate an aspect of the blog to offer you, our reader, an insider’s view.

Who are we?

Over the years, the editorial team has included onsite science writers, office interns, staff scientists and guest authors from universities. Kathryn, who’s a regular contributor, writes entirely from her home office. Chris, who has a Ph.D. in neuroscience and now manages the blog, used to do research in a lab. Alisa has worked in NIGMS’ Bethesda-based office the longest: 22 years! She and I remember when we first launched Biomedical Beat as an e-newsletter in 2005. You can read more about each of the writers on the contributors page and if you know someone who’s considering a career in science communications, tell them to drop us a line.

How do we come up with the stories?

We get our story ideas from a range of sources. For instance, newspaper articles about an experimental pest control strategy in Florida and California prompted us to write about NIGMS-funded studies exploring the basic science of the technique. A beautiful visual from a grantee’s institution inspired a short post on tissue regeneration research. And an ongoing conversation with NIGMS scientific staff about the important role of research organisms in biological studies sparked the idea for a playful profile of one such science superstar.

A big change in our storytelling has been shifting the focus from a single finding to broader progress in a lab or field. So instead of reporting on a study just published in a scientific journal, we may write about the scientist’s career path or showcase a collection of recent findings in that particular field. These approaches help us demonstrate that scientific understanding usually progresses through the slow and steady work undertaken by many labs.

What are our favorite posts?

I polled the writers on posts they liked, and the list is really long! Here are the top picks.


Four Ways Inheritance Is More Complex Than Mendel Knew


The Endoplasmic Reticulum: Networking in the Cell


Interview With a Scientist: Janet Iwasa, Molecular Animator


From Basic Research to Bioelectric Medicine


An Insider’s Look at Life: Magnified, an Airport Exhibit of Stunning Microscopy Images

What are your favorite posts?

We regularly review data about the number of times a blog post has been viewed to identify the ones that interest readers the most. That information also helps guide our decisions about other topics to feature on the blog. The Cool Image posts are among the most popular! Below are some other chart-topping posts.


Our Complicated Relationship With Viruses


The Proteasome: The Cells Trash Processor in Action


Demystifying General Anesthetics


Meet Sarkis Mazmanian and the Bacteria That Keep Us Healthy


5 Reasons Biologists Love Math

We always like hearing from readers! If there’s a basic biomedical research topic you’d like us to write about, or if you have feedback on a story or the blog in general, please leave your suggestions in the comment field below or email me.

Flipping the Switch on Controlling Disease-Carrying Insects

Illustration of some of the jobs that the ER performs in the cell.

This image shows a mosquito egg. Wolbachia bacteria, which infect many species of insects including mosquitos, move from one generation to the next inside insect eggs. Credit: Wikimedia Commons, Mogana Das Murtey and Patchamuthu Ramasamy, Universiti Sains, Malaysia.

Suppressing insects that spread disease is an essential public health effort, and scientists are testing a possible new tool to use in this challenging arena. They’re harnessing a microbe capable of controlling insects’ reproductive processes.

The microbes, called Wolbachia, live inside the cells of about two-thirds of insect species worldwide, and they can manipulate the host’s reproductive cells in ways that boost their own survival. Scientists think they can use Wolbachia’s methods to reduce populations of insects that spread disease among humans.

A Switch to Control Fertility

Wolbachia have evolved complex ways to control insect reproduction so as to infect increasing numbers of an insect species—such as those prolific disease-spreaders, mosquitos. One method Wolbachia uses is called cytoplasmic incompatibility, or CI. The end result of CI, basically, is that the sperm of infected male insects cause sterility in uninfected females.

Wolbachia that have infected male insects can insert proteins that produce a kind of infertility switch into the host’s sperm. When the sperm later fuses with an egg from an uninfected female, the switch is triggered and renders the egg sterile. If the female is already infected, her eggs will contain Wolbachia, which can turn off the switch and allow the egg to develop. This trick ensures that more Wolbachia-infected insects will survive and continue to reproduce, while uninfected ones will be less successful.

Already, some states Exit icon and countries Exit icon are releasing Wolbachia-infected male mosquitoes into wild mosquito populations that carry disease-causing viruses to test this strategy for insect control. Males carrying a Wolbachia strain that strongly induces infertility in uninfected females should reduce the numbers of mosquito eggs that mature, leading to fewer mosquitos. Continue reading

Sea Urchin Regeneration May Help Us Understand Aging

Sea urchin

The variegated sea urchin typically lives for about 4 years in the wild. The close-up view shows the sea urchin’s spines and tube feet that regrew after being removed 15 days earlier. Credit: Helena Reinardy (left) and Andrea Bodnar (right), Bermuda Institute of Ocean Sciences.

If you’ve ever been to the beach and walked around the rocks during low tide, you’ve probably seen a sea urchin. You may not have known that sea urchins found along the Pacific shore can live for more than 100 years. What’s even cooler is that, as they age, they don’t seem to lose their abilities to reproduce or regenerate damaged body parts. While different species of sea urchins have varying life expectancies, they all seem to share fountain-of-youth characteristics. For these and other reasons, scientists study sea urchins to investigate aging and other basic life processes. Continue reading

Six Things to Know About DNA and DNA Repair

Deoxyribonucleic acid, better known as DNA, was first identified on a discarded surgical bandage almost 150 years ago. Increasingly sophisticated tools and techniques have allowed scientists to learn more about this chemical compound that includes all the instructions necessary for building a living organism. From among the dozens of fascinating things known about DNA, here are six items touching on the make up of DNA’s double helix, the vast amounts of DNA packed into every human’s cells, common DNA errors and a few ways DNA can repair itself.

1. DNA is in every living thing.

Nucleotide
DNA consists of two long, twisted chains made of nucleotides. Each nucleotide contains one base, one phosphate molecule and the sugar molecule deoxyribose. The bases in DNA nucleotides are adenine, cytosine, guanine and thymine. Credit: NIGMS.

The chemical instructions for building a person—and every other creature on Earth—are contained in DNA. DNA is shaped like a corkscrew-twisted ladder, called a double helix. The two ladder rails are referred to as backbones, made of alternating groups of sugar and phosphate. The ladder’s rungs are made from four different building blocks called bases, arranged in pairs: adenine (A) paired with thymine (T), and cytosine (C) paired with guanine (G). Humans have about 3 billion base pairs in each cell. The order of the base pairs determines the exact instructions encoded in that part of the DNA molecule. Also, the sequence of DNA base pairs in one person is about 99.9 percent identical to that of everyone else.

2. Humans have a lot of DNA.

Humans begin as a single fertilized cell containing (with some rare exceptions) the full complement of DNA—the genome—arranged into 46 discrete chromosomes (23 pairs, with mom and dad each contributing half of each pair) in the cell’s nucleus. There are about 5 feet of DNA coiled up tightly in that first cell. All the information in the DNA is replicated each time the cell divides. The amount of DNA packed into all of an adult’s cells is on the order of 100 trillion feet (about 19 billion miles)—so that if the DNA chain was stretched out, it would be long enough to reach back and forth between the Earth and the Sun more than 200 times. Continue reading

Birthdays, Nobel Prizes and Basic Research

James D. Watson
James D. Watson. Credit: Wikimedia Commons, Cold Spring Harbor Laboratory.

April 6 is the birthday of two Nobel Prize winners in physiology or medicine—James Watson and Edmond H. Fischer. They have also both been NIGMS-supported researchers.

Double helix model
In 1953, Watson and Crick created their historic model of the shape of DNA: the double helix. Credit: Cold Spring Harbor Laboratory archives.

James D. Watson, born on this day in 1928, was honored with the Nobel Prize in 1962. He shared it with Francis H. Compton Crick and Maurice Wilkins “for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material.” This laid the groundwork for future discoveries. In the early 1950s, Wilkins and another scientist, Rosalind Franklin, worked to determine DNA’s structure. In 1953, Watson and Crick discovered its shape as a double helix. This twisted ladder structure enabled other researchers to unlock the secret of how genetic information is stored, transferred and copied. Franklin is widely recognized as having played a significant role in revealing the physical structure of DNA; due to her death at age 37 in 1958, Franklin did not earn a share of the prize. Read more about DNA. Continue reading

Field Focus: High-Quality Genome Sequences Inform the Study of Human Evolution

Leafing through my favorite biology textbook from a handful of years ago, I was struck by the relative brevity of the chapter on human evolution. While other fields of biological research have enjoyed a steady gallop of productivity over the last few decades due in part to advances in computing power, imaging technology and experimental methods, the study of human evolution can be seen as having lagged behind until recently due to an almost complete dependence on fossil evidence.

Fortunately, contemporary biology textbook chapters on human evolution are being primed for a serious upgrade thanks to the recent availability of high-quality genome sequences from diverse modern human populations as well as from ancient humans and other non-human hominids, including the Neanderthals and Denisovans (but, for purposes of this story, not the Great Apes).

Modern human skull (left) and Neanderthal skull (right), shown to scale. There are not enough Denisovan bone fragments to reconstruct its skull. Credit: Wikimedia Commons, hairymuseummatt.

What are the new resources for studying human evolution?

The cost of DNA sequencing has dropped precipitously in the last decade. As a result, more complete human genome sequences become available for analysis with each passing year.

For example, the 1000 Genomes Project Exit icon includes more than 1,000 full human genome sequences of individuals from European, Asian, American and Sub-Saharan African populations. Earlier this year, the Simons Genome Diversity Project Exit icon further increased the number of available human genomes by adding 300 individuals representing 142 populations around the globe. Continue reading