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| Exploring the principles of lichen combinations and the evolution of lichens, which can survive even in harsh environments |
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Prof. Tsuyoshi Naganuma has been active in diverse fields, with a great interest in various lifeforms. We asked him to explain the three research themes on which he is currently working.
One of the research subjects that attract his interest is lichens―extremely tough organisms whose distribution area is the largest among terrestrial lifeforms. Prof. Naganuma is investigating these organisms, which are not only found around us in the usual sphere of human living, but also in harsh environments, such as the polar regions, highlands, and deserts. In addition, they are actually two types of organisms in one, according to the professor.
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He explains: “A lichen is a composite organism made up of a fungus and an alga. The fungus provides the alga with a kind of house to protect the alga from the harsh environment. The alga photosynthesizes to produce nutrients, and gives the surplus nutrients to the fungus. They are in a so-called symbiotic relationship, which makes one plus one equal three. Thanks to this symbiosis, lichens can greatly flourish even under harsh environments.”
His interest is centered on whether the combinations between fungi and algae have some principles or not.
Prof. Naganuma points out: “Conventionally, scientists have thought that there is a kind of inevitability about lichen combinations. However, viewed at the genetic level, we have found that these combinations depend on contingency, to a considerable extent. Lichen combinations formed by a chance encounter between a fungus and alga have been gradually selected for better traits, while facing environmental pressures. I think this process serves as a miniaturized model for the evolution of organisms.”
He hopes to clarify this mystery, and says with great enthusiasm: “I want to travel around the globe to see in person various lichens. I also wish to collect lichens surviving in various places around the world.” According to Prof. Naganuma, another new mystery is that lichens are found in the Arctic and Antarctic regions as well. He is particularly fond of organisms living in harsh environments, such as the polar regions, and is always pursuing these organisms. |
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| Persistently continuing to search for strange organisms, sometimes making a great discovery by sheer chance |
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The second theme that interests him is strange organisms. “I am looking for microorganisms, which themselves are extraordinarily strange,” says the professor. One example is microorganisms related to right-handed amino acids.
Amino acids are one of the ingredients that form a human body. However, there are only 21 types of amino acids that string together to create proteins. Moreover, 20 of them have a property called “chirality,” meaning that their molecules have a non-superimposable mirror image of one another―just like the human hand, although they share the same quality and elements.
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He points out: “If artificially synthesized, a half of the resultant amino acids are right-handed, and the other half are left-handed. However, right-handed amino acids are hardly found in organisms. This poses a mystery.”
The reason for the overwhelming dominance of left-handed amino acids is not yet known. However, Prof. Naganuma has formulated a hypothesis that there may be organisms that prefer right-handed amino acids or organisms whose body comprises right-handed amino acids. Based on this hypothesis, he is looking for such organisms.
“Scientists have believed that all the organisms living on Earth share the same family tree. This belief is probably correct. Nevertheless, we will take on the challenge to find a different answer. If we can discover an organism comprising right-handed amino acids, it will be put on a different family tree. Such a discovery will be equivalent to the discovery of a lifeform in outer space. We aim to accomplish such a feat,” he says. In fact, a recent study has revealed that a certain organism is more vigorous when eating right-handed amino acids than in other cases. While striving to resolve the mystery of why this phenomenon occurs, he continues to search for strange organisms. Taking this approach, Prof. Naganuma enjoys his current position, which is very pleasant for him. |
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This article presents the three themes that arouse his interest. The first is strange organisms residing in strange environments, and the second is strange organisms that may live in an ordinary environment. Let’s move on to the third theme―a strange organism that was discovered though a strange method of isolation.
“We can discover truly strange organisms by devising various ideas for obtaining them. For example, when cultivating a pure culture of a microbe from the natural environment, we grow bacteria under various conditions. Usually, we isolate the microbes soon after they are cultivated. In a research project, however, we discarded all of them, and instead we isolated microbes that were generated slowly, after waiting for a considerably long time. We then conducted detailed analysis, whose results showed that they were new microbes that we had never seen before.”
Also worthy of special note is that the discovery was on a high level in terms of biological classification, which uses taxonomic ranks, including, among others, species, genus, family, order, and class (in order from least inclusive to most inclusive). His team discovered a new “class” of microbes.
With a smile on his face, he says: “In the 21st century, it is rather unusual to be able to make a discovery at such a high level. I myself was greatly surprised.”
Prof. Naganuma realized that even in this present age, there was an opportunity to find out exceptionally rare organisms by exercising our ingenuity. “I will continue to work to discover new organisms by doing something different from others,” says the professor, with a sparkle in his eye. |
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| Hiroshima University provides an environment that allows you to enjoy interesting experiences. We invite young people to join us! |
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Prof. Naganuma says that he feels an attraction to something exceptionally novel, interesting and strange. As a researcher, he aims to “do something extremely interesting!”
He explains: “I have a great dream. As my life work, I wish to make the ‘discovery of an extraterrestrial lifeform.’ However, I cannot pursue this theme in an ordinary laboratory. As such, I am working on various research activities toward this ultimate goal. I strive to demonstrate how strange organisms on Earth can really be. In other words, I explore the possibilities of life on Earth. By accumulating data showing these possibilities, I believe that I can approach the possibility of existence of life in a harsh environment, like outer space.”
Asked about the research environment offered by Hiroshima University, he greatly admires it, mentioning that “the environment is truly nice.” He says that “Hiroshima University is a comprehensive institution well developed in terms of academic disciplines and equipment as well as facilities.” “Our university therefore provides an optimal environment for education and research activities,” he adds, expressing his high regard for it.
“Here the stage has been fully set. What matters is how you play the game.”
He sends the following message to young people:
“One of the educational goals of Hiroshima University is to foster well-educated cosmopolitans who are committed to the pursuit of peace. If you want to become such a person, why not join our university. We of the faculty will firmly support you in realizing your hopes. However, although we can provide you with knowledge, techniques and skills that help you live better, the ʻpower to live’ itself should be developed by yourself. When you feel weak and have some problem, please do not hesitate to consult us. In such a case, we are willing to help you and give you a supportive push. Our faculty members hope to become your supporters, just like your close friends and family members. Hiroshima University aims to be an institution that supports the growth of its students. We sincerely look forward to welcoming you to our university and faculty!” |
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| Takeshi Naganuma |
Professor
Laboratory of Marine Ecosystem Dynamics
April 1, 1989 – August 31, 2004 Research Scientist, Deep Sea Research Department, Japan Marine Science and Technology Center (JAMSTEC, now Japan Agency for Marine-Earth Science and Technology)
March 1, 1991 – March 31, 1993 Visiting Researcher, University of California, Santa Barbara (UCSB)
September 1, 1994 – March 31, 2002 Associate Professor, School of Applied Biological Science, Hiroshima University
April 1, 2002 – September 30, 2015 Associate Professor, School of Applied Biological Science, Hiroshima University
October 1, 2015 – present Professor, School of Applied Biological Science, Hiroshima University
Posted on Jan 12, 2016
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