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Parker Named 2020 Pew Scholar in Biomedical Sciences

August 3, 2023 by micro

Benjamin Parker, an assistant professor in the Department of Microbiology, is a member of the 2020 Pew Scholars Program in the Biomedical Sciences. Parker was selected from among 191 nominations submitted by leading US academic and research institutions to receive four years of funding to invest in exploratory research.

The 2020 Pew Scholars are undertaking groundbreaking research projects aimed at advancing human health, from development and aging to better detection, prevention, and defense against cancer.

Parker’s research uses an insect (the pea aphid) and the beneficial and harmful microbes that inhabit it as a model system to study host-microbe interactions, and his lab uses genomic, molecular, and experimental techniques.

“This work will contribute to a broader understanding of how immune systems evolve and how natural selection shapes relationships between animals and beneficial microbes,” said Parker. “It will inform more applied research exploring the effects of microbial communities on human health and disease.”

The Pew Scholars Program in the Biomedical Sciences provides funding to young investigators of outstanding promise in science relevant to the advancement of human health. The program makes grants to selected academic institutions to support the independent research of outstanding individuals who are in their first few years of their appointment at the assistant professor level.

-By Kelly Alley

Wilhelm Receives John H. Martin Award for Research

August 3, 2023 by newframe

The Association for the Sciences of Limnology and Oceanography (ASLO) presents the John H. Martin Award to one paper each year that has led to fundamental shifts in research focus and interpretation of a large body of previous observations.

The 2021 John H. Martin Award is for “Viruses and nutrient cycles in the sea,” by Steven Wilhelm (University of Tennessee) and Curtis Suttle (University of British Columbia). The award will be presented at the 2021 ASLO Aquatic Sciences Virtual Meeting in June.

Wilhelm and Suttle’s foundational 1999 paper originated the concept of the ‘viral shunt,’ the phenomenon in which viral infection of marine microbes redirects flow of organic matter away from higher trophic levels and through the microbial loop. Drawing on early estimates of viral production in the water column, Wilhelm and Suttle shined a light on the considerable role viruses play in ocean biogeochemical cycles at a time when much of the research was focused on describing viral diversity and distribution. Their calculations showed that a staggering 25% of all photosynthetically fixed carbon, and associated nutrients, in the ocean may be recycled through the viral shunt.

Additionally, Wilhelm and Suttle made some of the first estimates of the total carbon stored in the viral pool and made eye-opening comparisons to the carbon stored in other types of marine organisms (including whales). Today, the concept of the viral shunt continues to influence our understanding of ocean ecosystem functioning and nutrient cycles. With >1000 citations, and more than 300 in the last five years, the legacy of “Viruses and nutrient cycles in the sea” and the viral shunt concept is still strongly felt in the field today.

“Every so often a novel concept is described which truly transforms a scientific field for decades,” says ASLO President Roxane Maranger. “Wilhelm and Suttle’s conception of the ‘viral shunt’ as a major pathway of oceanic carbon and nutrient flow in their 1999 paper is a stunning example of such a transformation.”

Full Citation: Wilhelm, S.W. and C.A. Suttle. 1999. Viruses and nutrient cycles in the sea, BioScience 49(10): 781-788. doi.org/10.2307/1313569.

ASLO is an international aquatic science society that was founded in 1948. For more than 60 years, it has been the leading professional organization for researchers and educators in the field of aquatic science. The purpose of ASLO is to foster a diverse, international scientific community that creates, integrates and communicates knowledge across the full spectrum of aquatic sciences, advances public awareness and education about aquatic resources and research, and promotes scientific stewardship of aquatic resources for the public interest. Its products and activities are directed toward these ends. With more than 3,800 members worldwide, the society has earned an outstanding reputation and is best known for its journals, interdisciplinary meetings, and special symposia. For more information about ASLO, please visit our website at www.ASLO.org.  

Faculty Spotlight – Ben Parker and the Parker Lab

March 4, 2023 by newframe

Walking into Ben Parker’s lab, you are greeted by rows upon rows of small plants, each in their own enclosed container with a complex handwritten label. What initially looks like a greenhouse operation changes quickly when you look closely at the plants: each is covered by hundreds of tiny bugs, or pea aphids. 

Parker’s lab utilizes the pea aphid as a model organism to study its life history traits and genetics and uses the findings to further understand larger questions in biology, evolutionary biology, and microbiology. The pea aphid system offers two main advantages: the insects give live birth to genetically identical offspring in just 10 days, and their bodies contain a simple microbial community, allowing Parker and his researchers to easily add or remove microbes in the systems and complete various mechanistic studies. 

Bacteria are one microbe that inhabit aphids. They are vertically transmitted, which means they are passed from parents to offspring, and can form important symbiotic relationships with their hosts. 

“The bacteria Regiella insectcola makes aphids resistant to the fungal pathogen Pandora neoaphidis,” Parker elaborates. “Not all aphids harbor Regiella, but those that do are more resistant to fungal infections.” 

However, the bacteria are not entirely beneficial. 

“One big question we are interested in is how the aphid’s immune system evolves to accommodate these beneficial bacteria in ways that still allow it to fight off bacterial pathogens,” Parker says. 

For example, the lab has been focusing on the phenoloxidase mechanism, which is an enzyme aphids use in melanization (a method insects use to fight pathogenic microbes). Aphids harboring Regiella have reduced gene expression of the phenoloxidase enzyme producing genes. 

The lab theorizes that this occurs because the bacteria are attempting to maximize their abundance, despite compromising the aphid’s ability to fight off other bacteria, but this finding is just a first glimpse into the mechanism. 

“We want to understand that in a broader context,” Parker states. “We want to know what effects that has on interactions with pathogenic bacteria and how those mechanisms are evolving in natural populations.” 

Viral genes are also vertically transmitted between aphid parents and their offspring. One such gene has interesting morphological effects on the host wherein in two genetically identical offspring, one can be winged while the other is wingless.  

This occurrence is an example of a phenotypically plastic traits, or a morphological trait influenced by the environment. In this case, the environmental trait influencing gene expression is plant crowdedness, which aphids have evolved to sense. The viral gene triggers the production of winged offspring by making aphids more sensitive to crowding.

 “When it is too crowded, they produce winged offspring, so they can fly to another plant and start over,” Parker explains. 

Currently, the Parker lab is focusing their studies on the genome and microbiome of the Pandora neoaphidis fungal pathogen. Additionally, they are working to understand aphid immune systems and how different aphid genotypes interact with bacteria. This talented group undoubtedly has a promising future.

-By Taylor Mattioli

Bikash Bogati – Graduate Student Spotlight

February 4, 2023 by newframe

Hailing from Nepal, Bikash Bogati has traveled far to pursue his doctoral degree at the University of Tennessee. In Nepal, he obtained his undergraduate degree in medical microbiology and worked in a diagnostic microbiology lab. He now works with Elizabeth Fozo, associate professor of microbiology, studying how bacteria survive different stress conditions. 

Specifically, he focuses on enterohemorrhagic E. coli, or EHEC, which is a food-borne pathogen. EHEC produces the Shiga toxin, which causes damage to the intestinal wall and severe illness in humans. 

“I’m looking into a gene segment that codes for a type I toxin protein, called ZorO, to see how it helps the bacteria to survive in different stress conditions,” Bogati said.   

Not much is known about this small protein or its specific function; however, when ZorO is artificially overproduced, cell growth stasis and death ensue. 

“My dissertation work mostly focuses on what we overproduce as toxic [in the lab] might be helpful for the bacteria,” Bogati explains. “This protein can help the bacteria survive antibiotics that we have been testing in the lab.” 

Understanding this system is important, as antibiotic resistance is a growing concern. 

“It is really challenging to have antibiotics synthesized compared to how fast the bacteria are gaining resistance,” Bogati elaborates. 

During his time at UT, Bogati has contributed to more than just the understanding of E. coli. In 2018, he was inspired to seek community service opportunities when he was asked, “what would you do if you had an extra hour in your day?”  

“I said that I would do something for others, because whatever time I have, I’m using on myself,” he smiles. He now volunteers with Volunteer Assisted Transportation, which connects volunteer drivers to individuals in need of transportation. 

The organization has had a large impact on Bogati’s view of America, and he has learned much from those he drives. 

“As an international student, we are used to the school life, and we don’t have much interaction with people outside of school,” he laughs. “I started getting to know their lives. I now realize our lives are all pretty similar.” 

His eyes shine as he talks about the veterans, teachers, and other passengers he has connected with. “We can learn so much from their lives and experiences.” 

After he obtains his PhD, Bogati will continue to study infectious diseases and antibiotic resistance as a post-doctoral researcher at Emory University. He is eager to continue volunteering as well.

-By Taylor Mattioli

Andy Wagner – Graduate Student Spotlight

January 1, 2023 by newframe

Chances are, many have heard of the fungal pathogen Candida albicans without realizing it. The pathogen causes many diseases, including yeast infections, which cause significant issues for women worldwide, and thrush, which is a mouth yeast infection that is common in babies and AIDS sufferers. 

Andy Wagner, a doctoral researcher in Todd Reynolds’s lab, focuses his work on this pesky pathogen. Wagner explains that while yeast infections may be uncomfortable, they are generally mild and easily treated; however, Candida albicans can occasionally cause bloodstream infections. Although rare, these infections have a mortality rate of about 30-50 percent, and they can be especially problematic for people with compromised immune systems. 

Wagner’s work specifically focuses on the idea that microbiologists can alter how the disease is recognized by the patient’s immune system to create a more favorable outcome for the patient. To make these alterations, Wagner focuses on Candida albicans’ cell wall, which is composed of three main layers: a basal layer composed of chitin, a middle layer composed of beta glucans, and an outer protein coat. 

 “The host’s immune system recognizes the beta glucans layer of this cell wall,” Wagner explains. “The outer protein coat serves as a barrier that prevents it from being recognized by the host immune system.” 

Inducing the cell to expose its beta glucans layer is no easy task. 

“There are signal transduction pathways that sense an outside change and will transmit the signal into the fungus to make it change its structural organization,” Wagner explains. “We found that if we can disrupt these signal transduction pathways, we can get the fungus to inappropriately expose the beta glucans layer.” 

Essentially, by altering the signaling pathways, Wagner alters how the cell wall is made. Currently, he is seeing overproduction of the basal layer and underproduction of the outer protein layer. 

“The basal layer is definitely being affected, which prevents the cell wall from being put together correctly,” Wager states. That, in turn, is making the recognizable basal layer more visible to the host’s immune receptors. This process is aptly termed “unmasking.” 

Wagner’s results are promising. “If we infect mice with these mutant fungus cells, we find they are able to recognize and clear the infection and survive longer,” he smiles. 

In the future, Wagner wants to continue working on disease-causing fungi, and he is hopeful that unmasking can be applied to other fungi as well.

Juneau Icefield may be key to unlocking secrets of Jupiter ice moon

July 26, 2022 by newframe

For researchers looking to unravel the mysteries of Jupiter’s moon Europa, a resource has emerged as a potential key to unlocking if the moon is habitable — the Juneau Icefield.