H. William Detrich, PhD is Professor Emeritus, Marine Molecular Biology and Biochemistry, Department of Biology, Northeastern University. For the bulk of his career, Dr. Detrich traveled every two years to the far end of the Earth to study the Antarctic icefish, which not only have evolved unique “antifreeze” properties that enable them to survive the extreme cold of the Southern Ocean (temperatures of –1.8 to +1°C), but also discarded red blood cells and hemoglobin altogether, which are essential to all other known vertebrates. In 2016, a piece of land in the Antarctica was named Detrich Island in honor of his discoveries, within a mile of Palmer Station, the U.S. research base in Antarctica that served as Detrich’s home away from home.
In this podcast, Dr. Bill Detrich talks with Helen Osborne about:
- Doing research in such a remote location
- Biomedical factors of these fishes with implications to better understand human biology
- What’s now and next in terms of climate change
Music by Skilsel from Pixabay.
Producer and audio editor: Kip Clark
HELEN: Welcome to talking about blood. I’m Helen Osbourne, host of this podcast series and a member of the advisory board for the Blood project. I also produce and host my own podcast series about many aspects of health communication and that is called Health Literacy Out Loud. The Blood Project’s website includes a lot of important science information along with medical best practices. It also provides a fascinating glimpse about the people side of science and medicine. One of these fascinating people is William (or Bill) Dietrich, who is Professor Emeritus of Biochemistry and Marine Biology in the Department of Marine and Environmental Sciences at Northeastern University. He also is a scientific research associate in medicine in the division of Hematology Oncology at Children’s Hospital in Boston, Massachusetts. Professor Dietrich researches the remarkable evolutionary adaptations that have enabled Antarctic fishes to live in the freezing Southern Ocean, yet now are susceptible to oceanic warming. Bill, welcome to Talking About Blood.
BILL: Well, thank you very much, Helen. I’m very pleased to be here.
HELEN: Well, you are the only researcher I’ve ever spoken to who looks at fishes in the Antarctic. I’m excited to keep learning more, but I guess from starters I’m just so curious. How did your scientific work get you to the bottom of our Earth to be learning about science and medicine?
BILL: That’s a very good example of serendipity in career choice. I was working as a postdoctoral fellow in California at the University of California, Santa Barbara when I received an invitation to join a research expedition that was going to McMurdo Station in Antarctica. And when I got there in 1981, I realized there was this incredible amount of biology available to study and there was a relatively small number of scientists actually doing it. So it really opened my eyes and provided research opportunities. And here we are now.
HELEN: From warm, sunny California to freezing cold McMurdo Station. Quite a change. What kind of history and discovery were you hoping to find down there and what did you find?
BILL: Humankind has known about Antarctica for a relatively short period of time and biological investigation of the organisms that live in the ocean and on the continent has only systematically begun about the late 1800s. So we haven’t had a lot of time to learn about the organisms that are there. And the organisms are remarkable, as you’ve mentioned.
HELEN: Like what?
Well, let me tell you a little history that will introduce our subject here. In the late 1920s, Norway sent an expedition to Bouvay Island in the South Atlantic – it borders on the Antarctic. And on board the expedition was a biologist ___ who was charged with finding out what kind of organisms were living in these extremely cold waters. And one day – the day after Christmas 1927 – he pulled up a very strange fish that had clear blood, no indication of red blood cells, whatsoever. And that’s the beginning of the story of investigation of these remarkable creatures.
HELEN: So as you know, I’m not a scientist myself. How would somebody know that a fish has clear blood? Do you look at it or do you cut it open? How, in 1927, did that Norwegian researcher even figure this out right away?
BILL: Well, he, in fact, bled the fish and found that he had a relatively transparent fluid and it wasn’t red. There was no indication of red blood cells being present. So this was strange because red blood cells were at the time considered to be a common feature of all vertebrates. We estimate about 75,000 vertebrates in the world. We now know that the 16 species of ice fish are the only vertebrates that don’t produce red blood cells. Yeah, this is pretty remarkable. How do they live?
HELEN: Yeah, that’s what I’m wondering. This is your research, right, is on these fishes. And it is plural. When we say fishes, right, fishes.
BILL: We speak of multiple species, we speak in terms of fishes. Within a species, we can use the term fish.
HELEN: Okay. This has been your life’s work, this discovery, correct?
BILL: Yes. I’ve spent my career working on various aspects of their biology. And one of the most important is the absence of red blood cells because this has major biomedical implications. The absence of red blood cells is a very severe anemia. And by studying this process, how this occurred, we may discover proteins that are important in actually making red blood.
HELEN: So you have been studying them. These fish have severe anemia. How do they thrive down there? And also, when you say it’s cold, I have my image of what cold is, how cold is really cold down there.
BILL: The ocean is at the freezing point of natural seawater. Because of the salts in seawater, the freezing point is actually -1.9 degrees Celsius, or about 28 degrees Fahrenheit.
HELEN: And are you surprised, were scientists surprised 100 years ago that so many fish are living in that environment that I assume is somewhat hostile?
BILL: Yes. Full of questions about how they were able to live. And one of the unique features of Antarctic fish is not work that I have done, but work of others, is the revelation that they actually make antifreeze proteins to prevent their blood and bodies from freezing.
HELEN: Antifreeze? Protein like. Antifreeze like I know from putting in my car.
BILL: It’s a different kind of antifreeze. Not the ethylene glycol that we use in our automobiles. It’s actually a protein and it functions differently. But back to the subject of how the Antarctic fishes, the icefishes, are able to live without red blood cells, that’s a very interesting story. How do you go from making blood to not making blood and still get enough oxygen to your tissues? The key to this story here is that the red-blooded relatives of the icefishes closely related, except they’re making red blood cells. They don’t necessarily need to use their red blood cells. And we know this because we can poison their hemoglobin with carbon monoxide and the fish still live. If we had our hemoglobin poisoned, we die. Carbon monoxide kills humans. That’s why we have carbon monoxide detectors in our homes. But here are red-blooded fish with their hemoglobin poisoned so it can’t transport oxygen, and they still live. So that tells us that there’s enough oxygen in the fluid part of the blood, physically dissolved. There’s enough oxygen to support life in the red-blooded species. Therefore, it’s not terribly surprising that the evolutionary endpoint of this would be the loss of red blood cells.
HELEN: Explain that some more, please. What’s happening, physiologically? Scientists are somewhat surprised because that wouldn’t happen with all this adaptation. But what is happening? How are they thriving and existing?
BILL: The answer is that there’s been a relaxation of the need for red blood cells, and that’s because the Southern Ocean is saturated with oxygen.
BILL: Yeah. So the environment is such that you don’t necessarily need red blood cells, and one lineage of the fish there got rid of it. I mean, it’s not a purposeful thing, but they evolved so they lost the capacity to make red blood cells.
HELEN: I’m getting two schools of thought, if I may do that. One is about all that’s happening over time to this species of fish to be able to exist there and what the implications are, I guess, for what we’re learning about humans and all of us who do have red blood cells. And the other part I’m hearing from you as you describe that is the adaptation and the interplay between the environment and our biology. When you talked about the fact that the ocean is so saturated with oxygen, it can make up for this deficit. If we can divide those two, there’s something that’s happening within that species. And the other part is the interplay with the species in their environment. Is that correct?
BILL: Yes, that’s well phrased. And to address the second part, evolutionary biologists know that a trait is beneficial or disadvantageous depending upon the environment in which the trait exists. So an example of that is that many of the Antarctic fishes have very poorly mineralized bones. That’s an advantage in their context because it makes it easier for them to swim in the water column and catch food. Well, for us, low bone mineralization is osteopenia and it predisposes to osteoporosis. Our environment, we’re faced with one g gravity and that puts stress on bones. Their environment, they don’t need to have strong bones. So the benefit or disadvantage of a trait is always contingent upon the environment.
HELEN: Fascinating. And the environment, our world, our planet is certainly changing. I don’t know if you are studying or others are studying how that is changing this species of fish.
BILL: That’s another aspect of the work that we’ve taken on in the lab in the last ten years or so. And that’s asking the question how is a changing environment in the southern ocean – warming environment – how is that going to affect the fish? In fact, can the fish evolve traits that will allow them to handle warmer water. Studies in process… I’ll tell you what we’ve been actually doing in that area – about ten years ago I thought an important aspect of the biology of climate change that wasn’t being addressed was the development of early embryos. And so we chose to study fish embryos and we raised the embryos over the Antarctic winter. They breed in April and the eggs actually hatch in November. That’s the wintertime in the southern hemisphere. And we’ve decided to look at how embryonic development was affected by warmer water temperatures. We chose some fairly realistic scenarios, for instance taking embryos and raising them at zero degrees as our control embryos and raising others at plus four centigrade. And so we raised these embryos and we sampled them for various kinds of studies and that work is ongoing right now. So we are going to be learning how a realistic change in oceanic temperature over the next 200 years will impact the development of fish. That in turn has important implications for the food web because if fish don’t develop well at warm temperature then that component of the food web – fish are eaten by seals and so on and killer whales – that aspect might collapse.
HELEN: Oh my goodness. Thank you for putting that into context. I’m fascinated in this. Our listeners, Bill, are people who are somehow interested in human biology and especially blood… might be people at all levels of their career and interest, whether they’re seasoned hematologists or those entering in the sciences or those just simply curious about it. I wonder if you could somehow share with us about all these lessons you’ve learned by doing your research in the Antarctic about the implications for understanding human biology.
BILL: YYs. So for instance, the work on the icefishes and their severe anemia allowed us to identify a protein that is very important in the maturation of red blood cells.
BILL: The protein is called hemogen and it’s involved in the later stages of blood cell development. Here’s the interesting thing about Antarctic ice fishes. They actually have red blood cell precursors in their bone marrow. Those are cells that are called proerythroblasts. They are poised to differentiate into red blood cells. What they’re missing is several proteins, like hemogen, that push the process forward to make red blood cells. So that’s the critical breakpoint in the process of taking a stem cell, making a proerythroblast, and ultimately converting those proerythroblasts into erythrocytes or red blood cells. That’s where the process is stuck in the icefish. And so we were able to discover an important protein, hemogen, that participates in this process. And other people had discovered this protein independently. And now we have the option or the opportunity to intervene in human anemias, perhaps by influencing the production of hemogen.
HELEN: That seems to bring it full circle. Isn’t it referred to as translational research when what you learn in one place, you’re translating to another environment?
BILL: Yes. Translational research is often taking things that have been discovered and applying them to humans. And this could be an example of translational research. Yes.
HELEN: Thank you. I could keep listening to all of this. I once got as close as going to southern New Zealand, and that’s as close as I came to the environment that you’re talking about, other than watching movies and films. And in fact, you have several resources where people can learn more. And I watched a video that includes you about the work you’re doing. We’ll have that link on your Talking About Blood webpage. Is there an easy link you could tell listeners about? Because I learned so much. It’s not just the words I’m hearing, but it was actually seeing it. Is there a way people can be learning more and putting themselves in this experience a little bit?
BILL: Yes, there are. The videos that you referred to is called The Birth and Death of Genes, and it’s available on the Howard Hughes Medical Institute site for educational purposes. In addition, there’s a set of three videos that my research team produced called Expedition Antarctica. These are available on YouTube. If you look up Expedition Antarctica and my last name, Dietrich, these should come right up.
HELEN: Words can only capture so much. Those images were so useful. As we’re bringing this conversation to a close, I want to ask you three questions that I ask all guests on Talking About Blood about your tips or recommendations for listeners, no matter where they are in their interest and knowledge about blood. So that starts with the seasoned professionals, with the people at the early stages of their careers, and those who just want to keep learning. From all your incredible work you’ve been doing, what would you want to share with everyone at these different levels?
BILL: For the seasoned professional, I would like to suggest that comparative biology is a fascinating and extremely valuable resource for learning, actually, about humans, how humans work, be open to information from other kinds of systems. For the individual who’s developing their career and research medicine, or both, be open to different kinds of biology and be ready to take a risk. The worst thing can happen is that it doesn’t work and you lose a little time. But being willing to reach out and touch something that’s unusual and work with it.
HELEN: You sure did that when you chose to go to this part of the world that very few people have ever been. So you exemplify that.
BILL: And for the person who is curious and wants to just keep learning, there are a number of videographers who are producing videos that cover biological topics. It’s easy to find these online and just look up videos on unusual organisms. You’re going to find some fascinating material through the Internet.
HELEN: Thank you. Bill, it has been an honor and a pleasure and so interesting to meet you and to talk with you on Talking About Blood. And I’m thanking you on behalf of all the folks involved in the Blood Project and all our many listeners of this podcast. Thank you, thank you.
BILL: Thank you you very much, Helen. I hope that I have conveyed some of my enthusiasm for the subject and will help the Blood Project and Talking About Blood moving forward.
HELEN: As we just heard from Professor Bill Dietrich, there’s so much to learn about all the species in the whole wide world. To help learn more about the Blood Project and explore its many resources for professionals, trainees and patients, go to thebloodproject.com. I also invite you to listen to my other podcast series about health communication. It’s at healthliteracyoutloud.com. Please help spread the word about this podcast series and The Blood Project. Thank you for listening. Until next time, I’m Helen Osborne.