Inside the Kueltz Lab at UC Davis

Original article on the Coastal and Marine Sciences Institute website.

Dr. Kueltz’s background

Dr. Dietmar Kueltz describes himself as  “...a comparative biologist and most interested in mechanisms of stress-induced evolution. My lab studies how fish and marine invertebrates counteract environmental stress.” Originally from Berlin, Germany, he grew up interested in aquatic life. “I was diving and swimming a lot,” he said, “and I am interested in watersports and just about everything aquatic.” Dr. Kueltz attributes this early love of aquatics to his interest in studying stress and evolution in aquatic organisms.

German roots run strong in Dr. Kueltz. It is where he was born and raised, and also where he completed his undergraduate degree and PhD in marine ecology and physiology. For his postdoc, Dr. Kueltz was offered a fellowship by the DAAD (German Academic Exchange Service) to go abroad and study at Oregon State University. He said, “I worked on fish and marine invertebrates looking mostly at Goby fish and how they respond to changes in their environment.” 

Oregon has so far been Dr. Kueltz’s favorite place to live, as it was his first experience abroad and held so many exciting things. He said, “Corvallis was similar to Davis. But when you’re a postdoc, you can do whatever you want; no administrative responsibilities!” Additionally, “[The biggest culture shock] was that everybody was saying ‘hi’ on the streets. In Berlin, people are--I don’t want to say less friendly,” he said with a laugh, “but you only say hello to people you are close with; on a superficial basis, you don’t say hi or anything. We thought [the Americans] were making fun of us, initially.”

After his time in Oregon, Dr. Kueltz traveled across the country to begin research at the National Institutes of Health in Maryland. “There I spent another three years and did similar research to my postdoc, but this time on kidney cells looking at cellular mechanisms. I was basically studying the same phenomena in a different model,” said Dr. Kueltz. Florida called next. Dr. Kueltz said, “I got a position as an assistant professor at the University of Florida and worked mostly at the Whitney Marine Lab for four years until 2002. Then, I joined the ANS department here at Davis.” Dr. Kueltz has been a prized faculty member of UC Davis and its Department of Animal Science ever since then.

The Kueltz Lab at UC Davis

Here at UC Davis, Dr. Kueltz has made amazing strides in discovering evolutionary mechanisms regulated by stress. He said, “What we are interested in is stress-induced evolution. What effect does environmental stress have on fish and marine invertebrates?”

Most of Dr. Kueltz’s research centers around a different view of evolution than most people consider. He said, “The traditional view of evolution says it occurs gradually and generally takes a long time. But lately, there have been other thoughts on how evolution can occur on a much more rapid scale, which is important for understanding diseases like cancer.”

Dr. Kueltz’s research has proved that cells evolve very quickly, especially when exposed to stress. In the marine environment, these changes could be in salinity, pH, and other stressors, and it can lead to cell evolution which converts organisms into something totally different than their original state. Some of these acquired changes can be mutations or inherited in forms other than DNA sequence changes. Kueltz said,

“That’s what happens with cancer, so we are interested in how does this happen, how does stress change the genome? Are there particular constraints on how genomes change during stress or are changes random? Do they lead to organisms that are better adapted to stressful environments?”  

Furthermore, the Kueltz lab is changing the dynamic view of cellular evolution through the work he has already done. Dr. Kueltz said, “We’re trying to go beyond the gene-centric thinking of evolution. We are looking at evolution as a result of environments changing and affecting genomes and proteomes as integrated systems, rather than genes mutating in certain positions. We are trying to promote this viewpoint of thinking about evolution from a network/systems level perspective in contrast to the gene-centric view, particularly for stress-induced evolution.” 

This research is an exciting new perspective on evolutionary mechanisms, and it is full of new revelations. As for Dr. Kueltz’s favorite discovery, he said, “We did a tilapia cell experimental evolution [...] study because tilapia cells are highly stress-tolerant and, for this reason, have invaded many ecosystems.” In the study, the lab increased the typical level of salinity that tilapia cells are normally exposed to by three times the normal value. This resulted in cells that had completely changed, both in phenotype and in molecular network topology. Dr. Kueltz explained, “Their protein complement (proteome) was very different, which indicated a dramatic shift on how they operate. Just seeing what kind of changes occur at the molecular level is exciting because it sheds light on underlying mechanisms.”

This is not the only significant accomplishment of Dr. Kueltz. He considers his greatest achievement to be his discovery that salinity stress causes DNA damage and reduces the fidelity of DNA repair. He said, “[My discovery] is the first time someone had seen that in any organism. It explains why stress-induced evolution occurs. There’s an increased amount of mutations happening, which increases the rate of evolution, and that happens much more rapidly during stress.”

 Human implications of the research

The Kueltz Lab is currently collaborating with several clinical labs which work on mammalian models, such as humans, in the hopes of applying their research to human illnesses and diseases. According to Dr. Kueltz, “The cellular effects of evolution [in aquatic organisms] are similar to humans and mammals on that level. We generated several cell line models for the fish we work with and are trying to also make cell lines for marine invertebrates.” Cell lines are experimental tools which are useful for mechanistic studies, but also for the production of pharmaceuticals and the development of vaccines. Invertebrates such as sponges and corals metabolize unique compounds that are important for fighting human diseases, but to extract enough of these compounds, it requires the destruction of the animals. Dr. Kueltz said, “It’s a tough balance, ethically, which can be addressed by generating cell lines that synthesize these compounds [instead of] the animals.” This spares the animals since the compounds are created artificially via cell lines.

Aquaculture

Aquacultural economics is also impacted by research done by Dr. Kueltz revolving around commonly farmed and caught fish, such as tilapia. Dr. Kueltz shared his advice on how to choose fish at the grocery store. He said, “Some things to look for at the store are the product tags that have a lot of information on them.” 

Some things to consider:

• Is it always better to eat wild-caught fish? Probably not, because aquaculture relieves the pressure of harvesting the natural populations of fish. 
• From fisheries, you should consider the method of capture. Kueltz adds, “I would absolutely not recommend bottom trawling caught fish because it is so destructive in so many ways.” 
• Take into account what type of aquaculture you are purchasing from. Some methods of aquaculture have minimal footprints on ecosystems, but some do not. Salmon aquaculture in open water has a much larger ecological footprint than trout aquaculture in a contained system. 
• The key to choosing is information. In Dr. Kueltz’s opinion, “aquaculture is better [than wild-caught fish], but within that, there are some types that are better than others. “Responsible methods of capture for open water fish may be better than aquaculture that creates a lot of waste, which is released into natural habitat without any kind of treatment.”

Why is this an issue? According to Dr. Kueltz,

“The problem is that aquaculture of the future needs to adjust to operating under unideal conditions where the farms are prone to salinization, they become more brackish, they experience temperature and pH changes and have limited water supply. Recirculating systems that [filter matter efficiently] are key for future aquaculture. In addition, we are trying to generate genetically better-adapted fish that grow well on a smaller ecological footprint.”

This is because many commonly farmed aquaculture animals are invasive species. Therefore, understanding why they tolerate stressful conditions allows Kueltz to mitigate their invasiveness, which in turn helps to manage them better in captivity and the wild.

Future endeavors and opportunities

The Kueltz lab is no stranger to mentoring undergraduate students, and many have worked as interns doing husbandry for the fish facilities. Dr. Kueltz said, “They can learn about how to care for the fish, how aquaculture works, and shadow graduate students. [While shadowing], the undergrads can learn lab techniques, cell cultures, cloning techniques, etc.” Usually, interns stay for multiple quarters and develop a small spin-off project on their own. Email is the best way to get in touch for those interested in internships, but many interns also join through taking Dr. Kueltz’s aquaculture class, ANS18.

ANS18 is a GE class taught in the fall which does not require prerequisites and aims to offer a sustainability-minded approach to aquaculture. Kueltz said, “[The class] is very diverse. It is focused on ecological aquaculture, from sponges to corals, mollusks, crustaceans, and fish.”

The class considers things such as: 

• How to make aquaculture more sustainable.
• Farming methods that are ecologically most sustainable and most environmentally destructive
• Students develop team presentations on what they think aquaculture should be and what they like or dislike about it.

Dr. Kueltz’s mastery of subject matter is so acute that he is writing a textbook for the class called Ecological Aquaculture, which is set to be published by Oxford University Press in the near future. He said, “It took me about two years, and I’m almost finished. It’s a fun project, it just takes some time.” It is written to feel like a companion and guide for [ANS18]. Dr. Kueltz also presents a unique perspective, one that emphasizes the ecological perspective rather than just the production perspective. He discusses how practices can be improved without sacrificing productivity too much.

Dr. Kueltz is nowhere near slowing down. In fact, he is in “probably one of the most exciting stages of [his] research that [he’s] done.” In regards to what he sees in the future, Kueltz said, 

“I want to try to go from a level of individual components to more of a systems and holistic level of understanding how cells and organisms respond to selective pressures such as stress as a whole and put together a holistic framework.” He hopes to answer questions like: How can we manipulate the response of evolving cells and organisms using pharmaceuticals or genetic engineering to alter stress tolerance? 

He also hopes to provide tools and knowledge to understand how anthropogenic stressors affect fish and marine invertebrates. “Thoroughly understanding how organisms cope with environmental stress represents the first step for minimizing its impacts. This first step is critical for the likelihood of success of the second step, i.e. managing such effects. It is important to not reverse the order in which we take those steps.” 

To contact Dr. Dietmar Kueltz, email him at dkueltz@ucdavis.edu.