When you think of a coral reef, what do you picture? Perhaps you imagine colorful branching structures jutting out of rock and the sea floor, with flourishing communities of fish swimming about. Or if you’ve been paying attention to news about global warming for the past decade or two, maybe you picture desolate expanses of bleached corals, their bone-like structures eerily reminiscent of a mass graveyard.
What you might not picture is a zoomed-in view of the coral ecosystem: the multitude of bacteria, fungi, viruses, and algae that occupy the intricate crevices of every coral. While corals are indeed animals in their own right, they belong to a complex symbiotic relationship with these microorganisms: the algae, which are more specifically dinoflagellates, provide energy to the coral through the process of photosynthesis. Bacteria occupying the mucus layers cycle nutrients and play a role in defense against pathogen invasion through the production of antimicrobial peptides.
One lesser-known member of this community, or the coral ‘holobiont’ as it is called, are the viruses. It’s probable that, like other members of the holobiont, they contribute to the health of the coral in some way, but this role is as of yet unclear. Our guest this week is Emily Schmeltzer, a fifth year PhD student in the Vega Thurber lab in the Department of Microbiology, and these elusive viruses are exactly what she is trying to uncover.
Emily Schmeltzer, PhD candidate in Rebecca Vega-Thurber’s lab, takes a sample of a coral
“We don’t know a ton about viruses on coral reefs,” says Schmeltzer. “ We know that some probably cause disease or mortality through infections, but we don’t really know exactly what a lot of them are doing, because marine viral ecology is such a relatively new field,” she explains.
It’s not surprising: viruses, while the most abundant and diverse entity on earth, are incredibly tiny and difficult to detect in environments where other organisms also thrive. Part of the challenge is that they have no universally conserved genes: that is, no easy way to tell the genes from viruses apart from the genes of other organisms. When studying bacteria, a gene called the 16S rRNA gene can be used as a sort of ‘name tag’ – every bacteria has this gene, whereas other organisms do not. There’s no such thing for viruses, making them difficult to study if you don’t already know what you’re looking for.
Schmeltzer is studying the viruses that live on corals and their response to climate change. To do this, her PhD research has involved a massive spatiotemporal study (spatio = across different locations, temporal = across multiple time points) looking at nearly 400 individual coral colonies of three different species over 3 years. All of these colonies are off the coast of the Moorea, a small island in French Polynesia in the South Pacific. The ultimate goal of the project is to contribute to the ongoing data collection for the Moorea Coral Reef Long Term Ecological Research project, and to characterize virus community diversity and potential function in the health of these corals.
Studying coral reefs is a big leap for Schmeltzer, who hails from the land-locked deserts of New Mexico. She was always interested in biology, which she attributes to her dad bringing home dead scorpions to look at together when she was a child. Arthropods ultimately ended up becoming her first research subjects: as an undergraduate at the University of New Mexico, she worked in an insect and spider taxonomy lab, before pivoting to working on West Nile virus.
So how did this insect-loving desert-dweller end up studying viruses that live on corals in the ocean? To learn more about Schmeltzer’s career trajectory, her love of corals, and the challenges of viral research, tune in to Inspiration Dissemination this Sunday, April 2nd at 7 PM. Listen live at 88.7 FM or on the live stream, or catch the episode after the show wherever you get your podcasts!
We eat food to keep ourselves happy and healthy. While the foods we eat are degraded in our gut, it’s actually little microbes that do most of the work to break down our food. Many many microbes. It is well known that our diet controls our health. But until recently, we have not appreciated the intermediate step that relies on microbes in our gut, and their influence on our health. What if our gut microbes are just as important for human health as the food we eat? The so-called gut microbiome, the unique community of microbes living in our digestive tract that influences how we break down food, is the quickly evolving research area that our guest is interested in. Michael Sieler is a 3rd year Ph.D. student in the Microbiology Department and is interested in better understanding how environmental factors, like rising temperatures and pathogens to name just a few, influence our gut microbiome and thus our health.
Michael Sieler is a 3rd year PhD student in the department of Microbiology at Oregon State University
There are hundreds of different microbial species living in human guts. These microbes work together to support human health by helping us digest our food and fight off pathogenic microbes. Because humans eat a multitude of diets, it can be tricky to figure out how human health is influenced by our gut microbes if the things we eat are not consistent. Instead of forcing humans to undergo rigorous eating and environmental trials – that may even be unethical given how much we’d need to control a human life – researchers like Michael use different organisms that are similar to humans to help understand some of the fundamental drivers of health. While you may be thinking of mice trials to see how toxic a substance is, or if we’ve successfully created a non-hallucinogenic version of psilocybin for therapeutic purposes, mice still have plenty of limitations.
Instead of using mice to run experiments, researchers are increasingly using zebrafish because they’re well studied, easy to grow and maintain, fast to reproduce, and 70% of their genes overlap with human genes so we can generally use these little fish as models of larger humans. For example, we’ve interviewed previous guests like Grace Deitzler researching how the gut microbiome can influence anxiety disorders and the connections to autism spectrum disorder. We’ve also interviewed Sarah Alto who researched how different levels of oxygen and carbon dioxide are connected to stress responses. Finally, Delia Shelton is actively researching how cadmium, a toxic heavy metal, is influencing behavioral patterns. You can imagine these studies would be tricky to perform on humans, that’s why all of these researchers use zebrafish as their model organism.
Michael’s research uses the zebrafish model organism to answer questions about how the gut microbiome influences the health of its host.
Michael’s work focuses on how environmental factors impact our gut microbiome to influence our health. For example, exposure to antibiotics or pathogens can dramatically affect the microbes living in our guts, but so can our diet. Surprisingly, unlike other model organisms such as mice, zebrafish are not fed a consistent diet across research studies and facilities. Given the importance of the gut microbiome to digest food and support our health, inconsistent use of diets in zebrafish microbiome studies could lead to inconsistency in study results. It’s like trying to compare race times for a five-mile race, except some people get to use cars and bikes and unicycles. Without a standard way to compare people, how comparable are the race results? Michael’s current work seeks to address this conundrum by feeding zebrafish one of three commonly used research diets and comparing their microbiomes. He finds that type of diet has an overwhelming effect on their gut microbiome, and these effects may overwhelm the effects of other environmental factors, like pathogen exposure.
What does this mean for the mountain of research built on zebrafish? We’ll answer that, and so much more with our guest Michael Sieler. We’ll also discuss his non-traditional route to graduate school, his love of travel, a side project using a tamagotchi-style video game to teach students about fish health, and how a year in the Guatemalan countryside helped him rethink his relationship to food and how he could have a greater impact in our world. Tune in live on Sunday at 7pm PT on 88.7FM, or check out the podcast if you missed the interview.
In the summer of 2012, the seeds for Michael’s interest in science were planted while working alongside Guatemalan community members and agronomists
Puffy snout syndrome: though it has a cute-sounding name, this debilitating condition causes masses on the face of Scombridae fish (a group of fish that includes mackerel and tuna.) Fish afflicted with puffy snout syndrome (PSS) develop excessive collagenous tumor-like growths around the eyes, snout, and mouth. This ultimately leads to visual impairment, difficulty feeding, and eventual death. PSS is surprisingly confined to just fish raised in captivity – those in aquaculture farms or aquariums, for example. Unfortunately, when PSS is identified in aquaculture, the only option is to cull the entire tank — no treatments or cures currently exist.
Left: a mackerel with puffy snout syndrome. Collagenous growths cover the snout and eye. Right: a healthy mackerel. Photos Emily Miller
PSS was first identified in the 1950s, in a fish research center in Honolulu, Hawaii. Since then, there have only been 9 publications in the scientific literature documenting the condition and possible causes, although the fish community has come to the conclusion that PSS is likely a transmittable condition with an infectious agent as the cause. But despite this conclusion, there’s been no success so far in identifying such a cause – tests for parasites, bacterial growth, and viruses have come up empty-handed. That was until a 2021 paper, using high-resolution electron microscopy, found evidence of viral particles in facial tissues taken from Pacific mackerel. Suddenly, there was a lead: could PSS be caused by a virus that we just don’t have a test for yet?
Electron microscopy images showing viral-like particles (red arrows) in facial tissue from Pacific mackerel (Miller et al 2022).
Putting Together the Pieces
To investigate this hypothesis, this week’s guest Savanah Leidholt (a co-author of the 2021 microscopy study) is using an approach for viral detection known as metatranscriptomics. Leidholt, a fourth year PhD candidate in the Microbiology department, sees this complex approach as a sort of puzzle: “Your sample of RNA has, say, 10 giant jigsaw puzzles in it. But the individual puzzles might not be complete, and the pieces might fit into multiple places, so your job is to reassemble the pieces into the puzzles in a way that gives you a better picture of your story.”
Savanah Leidholt, PhD candidate in Rebecca Vega-Thurber’s lab, is looking for evidence of viruses in the tissues of fish with puffy snout syndrome.
RNA, or ribonucleic acid, is a nucleic acid similar to DNA found in all living organisms, But where DNA is like a blueprint – providing the code that makes you, you; RNA is more like the assembly manual. When a gene is expressed (meaning the corresponding protein is manufactured), the double-stranded DNA is unwound and the information is transcribed into a molecule called messenger RNA. This single-stranded mRNA is now a copy of the gene that can be translated into protein. The process of writing an mRNA copy of the DNA blueprint is called transcription, and these mRNA molecules are the target of this metatranscriptomics approach, with the prefix “meta” meaning all of the RNA in a sample (both the fish RNA and the potential viral RNA, in this case) and the suffix “omics” just referring to the fact that this approach happens on a large scale (ALL of the RNA, not just a single gene, is sequenced here!) When mRNA is sequenced in this manner, the researchers can then conclude that the gene it corresponds to was being expressed in the fish at the time the sample was collected.
The process of transcription: making messenger RNA from DNA. Image from Nature Education.
So far, Leidholt has identified some specific genes in fish that tend to be much more abundant in fish from captive settings versus those found in the wild. Could these genes be related to why PSS is only seen in fish in captivity? It’s likely – the genes identified are immune markers, and the upregulation of immune markers is well-known to be associated with chronic stress. Think about a college student during finals week – stress is high after a long semester, maybe they’ve been studying until late in the night and not eating or sleeping well, consuming more alcohol than is recommended. And then suddenly, on the day of the test, they’re stuck in bed with the flu or a cold. The same thing can happen to fish (well, maybe not the part where they take a test!,) especially in captivity – Pacific mackerel, tuna, and other scombrid species susceptible to PSS are fairly large, sometimes swimming hundreds of miles in a single day in the ocean. But in captivity, they are often in very small tanks, constantly swimming in constrained circles. They’re not exposed to the same diversity of other fish, plankton, prey, and landscape as they would be in the wild. “Captivity is a great place to be if you’re a pathogen, but not great if you’re a fish”, says Leidholt.
The results of Leidholt’s study are an exciting step forward in the field of PSS research, as one of the biggest challenges currently facing aquaculture farms and aquariums is that there is no way to screen for PSS in healthy fish before symptoms begin to show. Finding these marker genes that appear in fish that could later on develop PSS means that in the future a test could be developed. If vulnerable fish could be identified and removed from the population before they begin to show symptoms and spread the condition, then it would mean fish farmers no longer have to cull the entire tank when PSS is noticed.
The elusive virus
One of the challenges that remains is going beyond the identification of genes in the fish and beginning to identify viruses in the samples. Viruses, which are small entities made up of a DNA or RNA core and a protective protein coating, are thought to be the most abundant biological entities on the planet Earth – and the smallest in terms of size. They usually get a bit of a bad reputation due to their association with diseases in humans and other animals, but there are also viruses that play important positive roles in their ecosystems – bacteriophages, for example, are viruses that infect bacteria. In humans, bacteriophages can attack and invade pathogenic or antibiotic-resistance bacteria like E. coli or S. aureus (for more information on phages and how they are actually studied as a potential therapy for infections, check out this November 2021 interview with Miriam Lipton!) Across the entire planet there are estimated to be between 10^7 to 10^9 distinct viral species – that’s between 10 million and 10 billion different species. And fish are thought to host more viruses than any other vertebrate species. Because of technological advancements, these viral species have only really been identified very recently, and identification still poses a significant challenge.
As a group, viruses are very diverse, so one of the challenges is finding a reliable way to identify them in a given sample. For bacteria, researchers can use a marker gene called the 16S rRNA gene – this gene is found in every single bacterial cell, making it universal, but it also has a region of variability. This region of variability allows for identification of different strains of bacteria. “Nothing like 16S exists for viruses,” Leidholt says. “Intense sequencing methods have to be used to capture them in a given sample.” The metatranscriptomic methods that Leidholt is using should allow her to capture elusive viruses by taking a scorched earth approach – targeting and sequencing any little bit of RNA in the sample at all, and trying to match up that RNA to a virus.
To learn more about Savanah’s research on puffy snout syndrome, her journey to Oregon State, and the amazing outreach she’s doing with high school students in the Microbiology Department, tune in to Inspiration Dissemination on Sunday, November 20th at 7 PM Pacific!
Coral reef ecosystems offer a multitude of benefits, ranging from coastline protection from storms and erosion to a source of food through fishing or harvest. In fact, it is estimated that over half a billion people depend on reefs for food, income, and/or protection. However, coral reefs face many threats in our rapidly changing world. Climate change and nutrient input due to run-off from land are two stressors that can affect coral health. How exactly do these stressors impact corals? This week’s guest Alex Vompe is trying to figure that out!
Alex is a 4th year PhD candidate in the Department of Microbiology at OSU, where he is co-advised by Dr. Becky Vega-Thurber and Dr. Tom Sharpton. The goal of Alex’s research is to understand how coral microbe communities change over time and across various sources of stress. While the microbial communities of different coral species can differ, typically under normal, non-stressed conditions, they look quite similar. However, once exposed to a stressor, changes start to arise in the microbial community between different coral species, which can have different outcomes for the coral host. This pattern has been coined the ‘Anna Karenina principle’ whereby all happy corals are alike, however as soon as things start to go wrong, corals suffer differently.
Alex is testing how this Anna Karenina principle plays out for three different coral species (Acropora retusa, Pocillopora verrucosa [also known as cauliflower coral], Porites lobata [also known as lobe coral]) in the tropical Pacific Ocean. The stressors that Alex is investigating are reduction in herbivory and introduction of fertilizer. A big source of stress for reefs is when fish populations are low, which results in a lack of grazing by fish on macroalgae. In extreme situations, macroalgae can overgrow a coral reef completely and outcompete it for light and resources. Fertilizers contain a whole host of nutrients with the intent of increasing plant growth and production on land. However, these fertilizers run-off from land into aquatic ecosystems which can often be problematic for aquatic flora and fauna.
How is Alex testing the effects of these stressors on the corals? He is achieving this both in-situ and in the lab. Alex and his lab conduct field work on coral reefs off the island of Moorea in French Polynesia. Here, they have set up experimental apparatus in the ocean on coral reefs (via scuba diving!) to simulate the effects of reduced herbivory and fertilizer introduction. This field work is conducted three times a year. When not under the water surface, Alex sets up aquaria experiments on land in Moorea using coral fragments, which he has been able to grow in order to investigate the microbial communities more closely. These samples then get processed in the lab at OSU for genomic analysis and Alex uses bioinformatics to investigate the coral microbiome dynamics.
Alex underwater in Moorea
Curious to know more about Alex’s research? Listen live on Sunday, October 23, 2022 at 7 PM on KBVR 88.7FM. Missed the live show? You can download the episode on our Podcast Pages! Also, feel free to follow Alex on Twitter (@AVompe) and Instagram (@vompedomp) to learn more about him and his research.
Improvements in DNA sequencing technology have allowed scientists to dig deeper than ever before into the intricacies of the microbes that inhabit our gut, also called the gut microbiome. Massive amounts of data – on the scale of pentabytes – have been accumulated as labs and institutes across the globe sequence the gut microbiome in an effort to learn more about its inhabitants and how they contribute to human health. But now that we have all of this data (and more accumulating all the time), the challenge becomes making sense of it.
This is a challenge that Christine Tataru, a rising fifth year PhD student in the Department of Microbiology, is tackling head-on. “My research is trying to understand what a ‘healthy’ gut microbiome actually looks like, how it ‘should’ look, and to do so in a way that is integrative,” she explains.
Christine Tataru, fifth year PhD student in Maude David’s lab.
An integrative approach looks at all of the processes and relationships that are occurring between all of the trillions of microorganisms in our gut, and the cells within our body. Previous microbiology dogma focused on the behavior and impact of singular species such as pathogens, but as we learn more about microbiomes, this approach becomes limiting. There are a vast number of relationships that can occur between microbes and human cells. And there are many different lenses through which we can look at this system: taking a census of what microbes are present; tracking the genes that are present rather than just the microbes (this tells us about the functions that might be carried out); and what proteins or metabolites are actually present, whether those are created by the bacteria or the host. Each piece of the puzzle allows us a glimpse of the massively complex system that is the gut microbiome.
“It’s difficult for a human brain to keep track of these relationships and sources of variations, so I use computer algorithms to try to get a picture of what is happening, and what that might mean for health.”
It’s an approach that makes sense for the Stanford-trained computer-scientist-turned-biologist. Christine recalls a deep learning class in college in which a natural language processing algorithm on the whiteboard struck her with inspiration: what if instead of being applied to words, this algorithm could be applied to gut microbiomes? The thought stuck with her and when she came to OSU to pursue her PhD, she already had a clear goal in mind for what she wanted to do.
The natural language processing and interpretation algorithm treats words in a document as discrete entities, and looks for patterns and relationships between words to gain context and “understand” the contents. A computer can’t really understand what words mean linguistically and with the complex nuances that natural language presents, but they are really good at looking for patterns. It can look at what words occur together frequently, what words never occur together, and what words share a ‘social network’ — words that don’t appear together, but appear with the same other words. Christine has developed a way to apply this algorithm to large gut microbiome datasets: using this approach to identify what microbes frequently appear together, which don’t, and which share ‘social networks’. This produces clusters of microbes, or what she refers to as ‘topics’, which can then be interpreted by humans to try to understand how these clusters relate to certain aspects of health. You can read more about this method in her recent PLOS Computational Biology publicationhere.
It’s quite the challenging undertaking: no one has done this type of approach before, and even when the clusters are generated, we still need to be able to interpret what it means – why is it interesting or important that these microbes occur with each other and also correlate with these genes or metabolites? Biologically, what does it actually mean?
The question of biological meaning prompted Christine to pivot to a more traditional ‘wet lab’ biology approach. “Who gave this computer scientist a pipette,” she jokes. But to be perfectly honest, it makes a lot of sense: who better to investigate the hypotheses that can be generated by computers than the scientist who wrote the code?
Taking the ‘integrative approach’ to the next level, she now works on recapitulating the environment of the gut microbiome on a chip in the lab. The organ-on-a-chip system is a fairly new approach to studying biological mechanisms in a way that better mimics the naturally occurring environment. In Christine’s case, she is using a ‘gut on a chip’, which is made of a thin piece of silicone with input and output channels. The silicone is split by a microporous membrane in such a way that two different kinds of cells can be grown, one on the top layer and one on the bottom. What makes this system unique as compared to traditional cell culture is that the channels and membrane allow for constant flow of growth media, which physically simulates the flow of blood over the cells. It can also mimic peristalsis, which is the stretching and relaxing of intestinal cells that helps push food and nutrients through the digestive tract. It’s a sophisticated system, and one that allows her a high degree of control over the environment. She can use this system to mimic Inflammatory Bowel Disease, and then add in specific microbes or combinations of microbes to see how the gut cells respond, using findings from her algorithm results to inform what kinds of additions might have anti-inflammatory effects.
Christine in a biosafety hood, preparing gut-chips for experiments.
This innovative approach provides Christine another lens through which to view the relationship between the gut microbiome and health. Though she will be finishing her doctorate at the end of the year, the curiosity doesn’t end there – “Broadly, my life goal to some extent has always been to make ways for people to help people.” Whether that’s pipeline and methods development or building the infrastructure to study complex biological relationships, Christine’s innovation-driven approach is sure to lead to huge strides in our understanding of how the tiny living things in our gut influence our health, behavior, and mood.
Tune in at 7 PM this Sunday evening on KBVR 88.7 or stream online to hear more about her research and how she ended up here at OSU!
Have you ever considered that a virus that eats bacteria could potentially have an effect on global carbon cycling? No? Me neither. Yet, our guest this week, Dr. Holger Buchholz, a postdoctoral researcher at OSU, taught me just that! Holger, who works with Drs. Kimberly Halsey and Stephen Giovannoni in OSU’s Department of Microbiology, is trying to understand how a bacteriophage (a bacteria-eating virus), called Venkman, impacts the metabolism of marine bacterial strains in a clade called OM43.
Bacteria that are part of the OM43 clade are methylotrophs, in other words, these bacteria eat methanol, a type of volatile organic compound. It is thought that the methanol that the OM43 bacteria consume are a by-product of photosynthesis by algae. In fact, OM43 bacteria are more abundant in coastal waters and are particularly associated with phytoplankton (algae) blooms. While this relationship has been shown in the marine environment before, there are still a lot of unknowns surrounding the exact dynamics. For example, how much methanol do the algae produce and how much of this methanol do the OM43 bacteria in turn consume? Is methanol in the ocean a sink or a source for methanol in the atmosphere? Given that methanol is a carbon compound, these processes likely affect global carbon cycles in some way. We just do not know how much yet. And methanol is just one of many different Volatile Organic Carbon (VOC) compounds that scientists think are important in the marine ecosystem, and they are probably consumed by bacteria too!
Depiction of the carbon cycle within the marine food web. DOM means Dissolved Organic Material, POM stands for Particulate Organic Material. This refers to all the things that are bound within cells that gets released when for example viruses destroy cells.
All of this gets even more complicated by the fact that a bacteriophage, by the name of Venkman, infects the OM43 bacteria. If you are a fan of Ghostbusters and your mind is conjuring the image of Bill Murray in tan coveralls at the sound of the name Venkman, then you are actually not at all wrong. During his PhD, which he conducted at the University of Exeter, part of Holger’s research was to isolate the bacteriophage that consumes OM43 bacteria (which he successfully did). As a result, Holger and his advisor (Dr. Ben Temperton, who is a big Ghostbusters fan) were able to name the bacteriophage and called it Venkman. Holger’s current work at OSU is to try and figure out how the Venkman bacteriophage affects the metabolism of methanol in OM43 bacteria and the viral influence on methanol production in algae. Does the virus increase the bacteria’s methanol metabolism? Decrease it? Or does nothing happen at all? At this point, Holger is not entirely sure what he is going to find, but whatever the answer, there would be an effect on the amount of carbon in the oceans, which is why this work is being conducted.
A bacteriophageHolger & PhD advisor BenInfected OM43 cells, every little black dot is a virus!
Holger is currently in the process of setting up experiments to answer these questions. He has been at OSU since February 2022 and has funding to conduct this work for three years from the Simons Foundation. Join us live on Sunday at 7 pm PST on 88.7 KBVR FM or https://kbvrfm.orangemedianetwork.com/ to hear more about Holger’s research and how a chance encounter with a marine biologist in Australia set him on his current career path! Can’t make it live, catch the podcast after the episode on your preferred podcast platform!
Much like Oregon’s forests experience wildfire seasons, the waters off the Oregon coast experience what are called “hypoxia seasons”. During these periods, which occur in the summer, northern winds bring nutrient-rich water to the Eastern Current Boundary off the Oregon Coast. While that might sound like a good thing, the upwells bring a bloom of microscopic organisms such as phytoplankton that consume these nutrients and then die off. As they die off, they sink and are then decomposed by marine microorganisms. This process of decomposition removes oxygen from the water, creating what’s called an oxygen minimum zone, or OMZs. These OMZs can span thousands of square miles. While mobile organisms such as fish can escape these areas and relocate, place-bound creatures such as crabs and bottom-dwelling fish can perish in these low oxygen zones. While these hypoxia seasons can occur due to natural phenomena, stratification of the water column due to other factors such as climate change can increase the frequency or severity of these seasons.
2021 was one of the worst years on record for hypoxic waters off the Western coast of the United States. A major contributing factor was the extremely early start to the upwelling triggered by strong winds. Measurements of dissolved oxygen and ocean acidity were high enough to be consistent with conditions that can lead to dead zones, and this is exactly what happened. Massive die-offs of crabs are concerning as the harvesting of Dungeness crab is one of the most lucrative fishing industries in the state. Other species and organisms move into shallower waters, disturbing the delicate balance of the coastal ecosystems. From the smallest microbe to the largest whale, almost every part of the coast can be affected by hypoxia season.
Our guest this week is Sarah Wolf, a fourth year PhD candidate in the Department of Microbiology here at Oregon State. Sarah, who is co-advised by Dr. Steve Giovannoni and Dr. Francis Chan, studies how microbes operate in these OMZs. Her work centers around microbial physiology and enzyme kinetics, and how these things change over time and in varying oxygen concentrations. To do this, she spent her second year developing a mesocosm, which is a closed environment that allows for the study of a natural environment, which replicates conditions found in low oxygen environments.
Sarah Wolf, a fourth year PhD Candidate in the department of Microbiology, in her lab
Her experiments involve hauling hundreds of liters of ocean water from the Oregon coast back to her lab in Nash Hall, where she filters and portions it into different jugs hooked up to a controlled gas delivery system which allows her to precisely control the concentration of oxygen in the mesocosm. Over a period of four months Sarah samples the water in these jugs to look at the microbial composition, carbon levels, oxygen respiration rates, cell counts, and other measures of the biological and chemical dynamics occurring in low oxygen. Organic matter can get transformed by different microorganisms that “eat” different pieces through the use of enzymes, but many enzymes which can break down large, complex molecules require oxygen, and in low oxygen conditions, this can be a problem for the breakdown and accumulation of organic matter. This is the kind of phenomenon that Sarah is studying in these mesocosms, which her lab affectionately refers to as the “Data Machine”.
Sarah’s journey into science has been a little nontraditional. A first generation college student, she started out her education as a political science major at Montana State before moving to the University of the Virgin Islands for a semester abroad. At the time she wasn’t really sure how to get into research or science as a career. During this semester her interest in microbiology was sparked during an environmental science course which led to her first research experience, studying water quality in St. Thomas. This experience resulted in an award-winning poster at a conference, and prompted Sarah to change her major to Microbiology and transfer to California State University Los Angeles. Her second research experience was very different – an internship at NASA’s Jet Propulsion Laboratory studying cleanroom microbiology, which resulted in a publication identifying two novel species of Bacillus isolated from the Kennedy Space Center. Ultimately Sarah’s journey brought her here to Oregon State, which she was drawn to because of its strong marine microbiology research program.
Sarah works on the “Data Machine”
But Sarah’s passion for science doesn’t stop at the lab: during the Covid-19 pandemic, she began creating and teaching lessons for children stuck at home. During this time she taught over 60 kids remotely, with lessons about microbes ranging from marine microbiology to astrobiology and even how to create your own sourdough starter at home. Eventually she compiled these lessons onto her website where parents and teachers alike can download them for use in classrooms and at home. She also began reviewing children’s science books on her Instagram page (@scientist.sarahwolf), and inviting experts in different fields to participate in livestreams about books relating to their topics. A practicing Catholic, she also shares thoughts and resources about religion and science, especially topics surrounding climate science. With around 12k followers, Sarah’s outreach on Instagram has certainly found its audience, and will only continue to grow.
If you’re curious about microbes in low oxygen conditions, what it’s like to be a science educator and social media influencer, or want to hear more about Sarah’s journey in her own words, tune in at 7 PM on March 13th to catch the live episode at 7 PM PST on 88.7 FM Corvallis, online at https://kbvrfm.orangemedianetwork.com – or you can catch this episode after the show airs wherever you get your podcasts!
It might sound like science fiction, but you’ve probably heard the phrase ‘gut-brain axis’ used in recent years to describe this phenomenon. What we call the “gut” actually refers to the small and large intestines, where a collection of microorganisms known as the gut microbiome reside. In addition to the microbes that inhabit it, your gut contains around 500 million neurons, which connect to your brain through bidirectional nerves – the biggest of which is the vagus nerve. Bacteria might be able to interact with specialized sensory cells within the gut lining and trigger neuronal firing from the gut to the brain.
Our guest this week is Caroline Hernández, a PhD student in the Maude David Lab in the Department of Microbiology, and she is studying exactly this phenomenon. While the idea that the gut and the brain are connected is not exactly new (ever heard the phrase “a gut feeling” or felt “butterflies” in your gut when you’re nervous?), there still isn’t much known about how exactly this works on a molecular level. This is what Caroline’s work aims to untangle, using an in vitro(which means outside of a living organism – in this case, cells in a petri dish) approach: if you could grow both the sensory gut cells and neurons in the same petri dish, and then expose them to gut bacteria, what could you observe about their interactions?
Caroline Hernández in her lab at Oregon State, using a stereo microscope to identify anatomical structures in a mouse before dissecting out a nerve bundle
The answer to this question could tell us a lot about how the gut-brain axis works on a molecular level, and could help researchers understand the mechanisms by which the gut microbiome can possibly modulate behavior, mood, learning, and cognition. This could have important implications down the line for how we conceptualize and potentially treat mood and behavioral disorders. Some mouse studies have already shown that mice treated with the probiotic Lactobacillus rhamnosus display reduced anxiety-like and depressive behaviors, for example – but exactly how this works isn’t really clear.
The challenges of in vitro research
Before these mechanisms can really be untangled, there are several challenges that Caroline is working on solving. The biggest one is just getting the cells to grow at all: Caroline and her team must first carefully extract specific gut sensory tissue and a specific ganglion (which is a blob of neurons) from mice, a delicate process that requires the use of specialized tools and equipment. Once they’ve verified that they have the correct anatomy, the tissues are moved into media, a liquid that contains specialized nutrients to help provide the cells with the growth factors they need to stay alive. Because this is very cutting-edge research, Caroline’s team is among the first in the world to attempt this technique – meaning there is a lot of trial and error and not a great amount of resources out there to help. There have been a number of hurdles along the way, but Caroline is no stranger to meeting challenges head-on and overcoming them with incredible resilience.
From art interactions to microbial interactions
Her journey into science started in a somewhat unexpected way: Caroline began her undergraduate career as a studio art major in community college. Her art was focused on interactivity and she was especially interested in how the person perceiving the art could interact with and explore it. Eventually she decided that while she was quite skilled at it, art was not the career path she wanted to pursue, so she switched into science, where she began her Bachelors of Science in molecular and cellular biology at the University of Illinois in Urbana Champaign.
During her undergraduate degree, a mental health crisis prompted Caroline to file for a medical withdrawal from her program. The break was much needed and allowed her to focus on taking care of herself and her health before returning to the rigorous and intense program three years later. Caroline is now a strong supporter of mental health resource awareness – in this episode of Inspiration Dissemination she will describe some of the challenges and barriers she faced when returning to finish her degree, and some of the pushback she faced when deciding to pursue a PhD.
“Not everyone was supportive,” she says. “I didn’t receive great encouragement from some of my advisors.”
Where she did find support and community was in her undergraduate research lab. Her work in this lab on the effects of diet and the microbiome on human health gave her the confidence to pursue graduate school, demonstrating that she was more than capable of engaging in independent research. In particular Caroline recalls her mentor Leila Shinn, a PhD student at the time in that lab, who had a profound impact on her decision to apply to graduate programs.
Tune in on Feb 27th to hear the rest of Caroline’s story and what brought her to Oregon State in particular. You can listen live at 7 PM PST on 88.7 FM Corvallis, online at https://kbvrfm.orangemedianetwork.com, or you can catch the episode after the show airs wherever you get your podcasts.
If you are an undergraduate student or graduate student at Oregon State University and are experiencing mental health struggles, you’re not alone and there are resources to help. CAPS offers crisis counseling services as well as individual therapy and support and skill-building groups.
Amidst the challenges of a global pandemic, the Inspiration Dissemination podcast will strive to be an avenue of human connection and inspiration during a more isolated time. This week, we sit down with Joaquin Rodriquez for the first podcast of a special series covering the COVID-10 outbreak and its impact on the research and lives of our OSU community.
Joaquin Rodriguez; Undergraduate student and researcher in the Barbar lab at Oregon State University.
Joaquin is an undergraduate (soon to be graduate) researcher in the Barbar lab at OSU studying how viruses hijack their hosts. Joaquin’s research allows him to view the coronavirus from a biological perspective that yields him clarity and patience.
Although his studies and research are conducted at Oregon State University, Joaquin calls Lima, Peru home. During an unprecedented time where students are leaving campus to be home with their families, travel restrictions render Joaquin unable to leave Corvallis. Despite the challenges Joaquin faces, he emanates a sense of calm and understanding of the coronavirus and shares with us his experience.
Joaquin explains how misinformation is easy to spread and clear answers are hard to discern during times of fear and uncertainty. Even for those that may have the scientific literacy to understand what a virus is, there can be a great difficulty in comprehending just how a virus works within our bodies. In simplified terms, a virus can be thought of as a piece of genetic material (usually RNA) encapsulated by a protein. Debate on whether or not a virus can even be considered a living thing stems from the fact that viruses themselves do not code for the biological machinery needed for replication, but rather use their host as a means to thrive and reproduce. Upon entering the body, the coronavirus binds to respiratory cells at sites called receptors. Receptors are like doors that only viruses have the keys to, and once binded, they are able to enter the cell and replicate before finally causing the respiratory cell to die. This particular coronavirus eventually causes the disease COVID-19.
Simplified Viral Structure– By domdomegg [CC BY 4.0 (https://creativecommons.org/licenses/by/4.0)], from Wikimedia Commons
The death of respiratory cells as the virus multiplies is inarguably harmful to the body, however, the symptoms we experience from COVID-19 are actually an expression of our immune system response rather than the virus itself. This in part explains why some of those infected by the virus appear to be minimally impacted, while others may develop flu-like symptoms or pneumonia. In fact, the range and lack of predictability of symptoms contribute to the high rate of transmission and success of the virus.
There are many evolutionary trade-offs involved in the overall success of a virus. Aggressive replication within a host may cause the virus to be too deadly and thus lower transmissibility between hosts; the virus is unlikely to become widespread. For this reason, the deadly virus causing Ebola is not likely to become a global pandemic, whereas the new coronavirus is impacting countries around the world.
Viral success and transmissibility also relies on mutation rate. At first glance it may seem intuitive that a high rate of mutation would be evolutionarily advantageous. Afterall, a small mutation in the genome of the coronavirus lended its ability to jump hosts from bat to human. However, not all mutations are advantageous. Mutations are random, and the potential of a mutation to be detrimental to the virus’s ability to infect and replicate is high. A high mutation rate is a risk to the success of a virus, but a low mutation rate would yield a stagnation allowing for hosts to more easily adapt immunity.
Joaquin explains that the coronavirus is successful because it has a relatively low mutation rate compared to other RNA viruses, as well as a high transmissibility owing to a relatively low rate of host death, varying host symptoms, and the utilization of airborne avenues of transmission. He tells us that through a global research effort we are continuously learning about the biology of the coronavirus and using this knowledge to explore treatment options and vaccines.
While many research labs around the world, including Joaquin’s lab at OSU, are shifting their efforts to contribute to the study of the coronavirus, many researcher’s work has been put on hold. Joaquin now finds himself with extra time to connect with family in Lima or take trips to the coast where he finds comfort surfing. He urges us to stay informed, mindful, and calm, and to find that thing that brings up happiness as we all experience an unusual time united in our isolation.
If you are interested in hearing the full interview with Joaquin, want to keep up with new episodes and our special Covid-19 series, or want to check out past interviews, you can find us on iTunes under Inspiration Dissemination.
Even though seagrasses occupy less than 0.2% of the world’s oceans, they account for more than 10% of all carbon trapped in the sea. In a world and time where we are producing more carbon than we should be and can manage, making sure that seagrasses are healthy and abundant is extremely pertinent. Winni Wang is one such seagrass scientist working to understand the biology of seagrasses and what threatens them.
Winni is a 5th year PhD candidate in the Department of Microbiology working with Dr. Ryan Mueller. Winni specializes in studying the microbiome of different plants, which for her PhD happens to be seagrasses. The microbiome is the community of microorganisms in a particular environment, and therefore it is found on all living things. By studying the microbiome on different seagrasses, Winni hopes to determine how anthropogenic (human-induced) stressors affect seagrass plants as a whole through changes in the microbiome.
If you’re like me and you love marine megafauna, then when thinking about seagrass beds you most likely are picturing a big manatee slowly grazing on seagrass in tropical, warm waters. Well, then you might be surprised to know that seagrasses don’t only occur in warm, tropical waters. In fact, there are over 60 species of seagrass worldwide and they occur in all kinds of habitats and climates. As a matter of fact, there is a species of seagrass right off of our coast here in Oregon, in Yaquina Bay, which is one of Winni’s study sites for her thesis research.
Eelgrass at Yaquina Bay.
Winni with the experimental tanks at HMSC.
Her work in Yaquina Bay relates to understanding how seagrasses are affected by eutrophication. Eutrophication occurs when an excessive amount of nutrients enters an aquatic environment, often due to land run-off, which in extreme cases can lead to severe oxygen depletion in those habitats resulting in death of plant and animal life. Winni hypothesized that with increased nutrients in a seagrass habitat, the microbiome of the seagrass would change in a way that would have an effect on the overall plant. In order to test this hypothesis, Winni had to carry out controlled lab experiments but not without collecting her test species first. She collected over 200 seagrass individuals as well as buckets of mud from Yaquina Bay, which she took back to Hatfield Marine Science Center where she set up tanks for her experiment. The tanks housed seagrasses and the collected mud. Half of the tanks included added fertilizer to test the effects of nutrient addition, and the other half were left as controls. Over the course of the experiment, Winni tracked plant growth metrics and nitrogen concentrations of the tanks, as well as collecting root and leaf samples to look at the microbiomes on both of those parts of the seagrass.
The mud buckets.
Winni found that the fertilizer affected the roots in such a way that it changed the microbiome community found there. This change resulted in enrichment for microbes that could cycle sulfur, which could potentially have quite detrimental effects on seagrasses. This is because seagrasses grow in anoxic, or oxygen-low, environments where sulfur is found in its reduced form, hydrogen sulfide. Usually, in environments without excessive nutrient input, seagrasses are able to deal with sulfide, which is typically toxic to plants and animals. However, with increased nutrients, the seagrasses may become overwhelmed by the amount of sulfur in the water as it gets converted into hydrogen sulfide. At certain thresholds, the sulfide ends up becoming toxic to seagrasses. Thus, Winni’s research shows that excessive fertilization to seagrass environments, potentially from land run-off, could have detrimental impacts on seagrasses.
Another chapter of her PhD takes Winni half way across the world to the Mediterranean. Well, it is not so much that it takes Winni to the Mediterranean, it is more that the Mediterranean comes to her! Through her advisor, Winni was able to obtain seagrass samples from the Mediterranean. What makes these samples unique is that they were taken from a site near a naturally occurring underwater volcano. You may be wondering how this is relevant to Winni’s research since she is trying to figure out how human-induced stressors impact seagrasses. Well, the underwater volcano spews carbon dioxide into the water, which makes the water more acidic. This phenomenon is essentially a natural experiment because it mimics the effects of human-induced ocean acidification, which is becoming a problem around the world’s oceans. The results are still underway but they will help fill some of the knowledge gaps concerning the effects of ocean acidification on organisms.
This blog started by emphasizing how important seagrasses are in sequestering carbon, however it is not the only thing that makes these small, unassuming plants so vital to our lives and the lives of many other organisms. Coastal waters with seagrass beds have been found to contain relatively less human pathogens than areas without seagrasses. This is because seagrasses filter the water and are able to remove a lot of pathogens. Furthermore, they are important in preventing coastal erosion and often make coastlines more resilient to storms. Not only are they also important habitats to some beloved marine megafauna (manatees, sharks, turtles) but they are also important for many smaller, but equally ecologically and economically important, species. For example, in Oregon, seagrass beds may actually be helping mitigate ocean acidification which is having a negative impact on oysters as it affects the strength of their shells.
Winni’s life, both at Oregon State and before her arrival here, has not been all about seagrass science though. To hear more about her background and some of the struggles and lessons that she has had during her tenure here, tune in on Sunday, March 8 at 7 PM on KBVR Corvallis 88.7 FM or stream live. To follow Winni and her research, be sure to follow her on Twitter @ramenmicrobiome. Something that we weren’t able to cover on the blog but covered on the show, is that Winni is one of the founders of the Women of Color Caucus (WoCC) at OSU. Read about the origin story of WoCC here, follow their Instagram and Twitter pages and join their listserv here.
