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BPA rewires the sex of turtle brains

By Jinghong Chen | Bond Life Sciences Center

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Painted turtle eggs were brought from a hatchery in Louisiana, candled to ensure embryo viability and then incubated at male-permissive temperatures in a bed of vermiculite. Those exposed to BPA developed deformities to testes that held female characteristics.Photo by Roger Meissen | © 2015 – MU Bond Life Sciences Center

Cool dudes, hot mommas. This is the underlying concept behind sex development in painted turtles, a species that lacks sex chromosomes.

A painted turtle’s sex is determined by temperature at which the eggs are incubated at critical stages during early development. Eggs incubated at lower temperatures produce male turtles, while those incubated at higher temperatures results in females.

However, early exposure to certain environmental chemicals that mimic hormones naturally produced in individuals can override incubation temperature. Scientists at the Bond Life Sciences Center have teamed up to study how endocrine disrupting chemicals (EDCs), namely bisphenol A (BPA) and ethinyl estradiol (EE), result in irreversible sexual programming of the brain in painted turtles.

“Turtles do not have sex chromosomes. Instead, they demonstrate temperature sex determination. But if they are exposed to EDCs prior to when certain organs form, such chemicals can cause partial to full sex reversal to female both in terms of the gonad and brain,” said Cheryl Rosenfeld, a Bond Life Sciences Center investigator and an associate professor of biomedical sciences at the University of Missouri. “The males will essentially act like females in terms of their behavioral responses.”

The hormones Rosenfeld refers to are BPA and EE, two widely used EDCs. BPA is present in many commonly used household, such as plastic food storage containers, store receipts, and dental fillings. The EE is present in birth control pills and can accumulate in many aquatic environments. These chemicals have been identified in all aquatic environments tested to date, including rivers and streams. Thus, exposure of turtles and other species that inhabit such environments can potentially lead to irreversible effects.

Previously, Rosenfeld and colleagues had studied how these chemicals change behavior of painted turtles after treating the eggs with BPA and EE under male-promoting temperatures. They discovered that male turtles that are early exposed to chemicals exhibit greater spatial navigational ability and improved memory, which are considered female-typical behaviors.

Rosenfeld and colleagues postulated that if the behavioral patterns differ between those exposed to BPA and those who were not, the different behaviors may be due to underlying and persistent differences in the neural circuitry between these two groups.

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Cheryl Rosenfeld is a Bond Life Sciences Center investigator and an associate professor of biomedical sciences at the University of Missouri. | photo by Jinghong Chen, Bond LSC

A gene map for turtle

In order to address this possibility, Rosenfeld teamed up with Scott Givan, associate director of the Informatics Research Core Facility, to study the gene expression profiles of the turtles and potentially identify patterns of gene expression associated with the altered behaviors.

After Rosenfeld’s team tested the behavior of the turtles, they collected RNA from the turtle brains to perform a technique called RNAseq that isolates all of the transcripts expressed in this organ. RNA is a nucleic acid that carries genetic information and is indicative of the expression level of every gene in the turtle genome. Once these sequencing results were obtained, Givan had to align the results to the painted turtle genome that has been previously sequenced and annotated. He then determined the transcripts that were differentially expressed in turtles developmentally exposed to BPA or EE versus those unexposed individuals.

There are no existing turtle gene pathway profiles. Therefore, Givan had to analyze the turtle gene expression profiles based on those previously identified in human samples.

“[One] of the most important things in this paper is the linkage of the gene expression profile to behavior difference,” Givan said. “But the gene and metabolic pathway data don’t exist for turtles. We had to basically infer pathway modeling based on the human metabolic pathway maps.”

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Scott Givan is the associate director of Informatics Research Core Facility and research assistant professor of molecular microbiology and immunology. | photo by Jinghong Chen, Bond LSC

The results suggest that BPA and, to a much lesser extent, EE exposure overridden incubation temperature and altered the gene expression profile in the brain to potentially reprogram brain to the female rather than male pathway. Specifically, BPA exposure was associated with metabolic pathway alterations involving mitochondria, such as oxidative phosphorylation and influenced ribosomal function.

Mitochondrial activity provides energy. Up-regulation of metabolic pathways in mitochondria can lead to more energy in brain cells, which may have permitted BPA-exposed turtles to demonstrate faster responses and greater cognitive flexibility, including enhanced spatial navigational ability that was previously identified in this group.

The other changes — oxidative phosphorylation and ribosomal function — play key roles in protein synthesis. Specifically, oxidative phosphorylation generates is one of main pathways involved in generating ATP, which is considered an energy source. Ribosome functions to assemble amino acids together for the synthesis of proteins, including enzymes that may facilitate metabolic reactions.

Less appealing males

The possibility for shifting brain sex has a real impact in the wild.

In the beginning, a turtle’s brain is neutral, as it is requires hormones to sculpt and direct it to be male or female. However EDCs, such as BPA and EE, can usurp these normal pathways and cause the brain of otherwise male turtles to develop more feminine characteristics.

“There are certain programmed behaviors [male turtles] have to do to entice the female to select them as their reproductive partner, but if he is not demonstrating these male-typical behaviors, she will likely reject him,” Rosenfeld said. “Even if such chemicals reprogram the brain and subsequent adult behaviors without affecting the gonad, it could have individual and population consequences by reducing a male’s likelihood of breeding.”

Combined with possible shrinking and already inbred population, declines in male turtles or skewing of sex ratio to females that could originate due to EDC-exposure, could push turtle species that exhibit temperature-dependent sex determination (TSD) to the brink of extinction.

“The concern also with turtle species that exhibit TSD, climate change and exposure to EDCs can lead to detrimental and irreversible imbalances in sex ratio favoring females over males, and thereby compromising genetic diversity of the population as a whole,” Rosenfeld said.

Future studies in Rosenfeld’s lab plan to extend the research to female turtles to learn whether the chemicals have any effects on females derived based on TSD rather than those due to exposure to environmental chemicals that are similar to estrogen. She also hopes to look into individual brain regions, such as the forebrain and hippocampus that are essential for cognitive abilities.

 

Cheryl Rosenfeld is a Bond LSC investigator,associate professor of biomedical sciences, and research faculty member in the Thompson Center for Autism and Neurobehavioral Disorders. Scott Givan is the associate director of Informatics Research Core Facility and research assistant professor of molecular microbiology and immunology.

This research was funded by the Mizzou Advantage Program, the Bond Life Sciences Center and the University of Missouri Office of Research.

National Cancer Institute researcher to speak at Life Sciences Week

By Jinghong Chen | Bond Life Sciences Center

“Living things are too beautiful for there not to be a mathematics that describes them.”

Thomas D. Schneider will speak Tuesday, April 11 in Bond LSC’s Monsanto Auditorium. | Photo by National Institutes of Health

Thomas D. Schneider will speak Tuesday, April 11 in Bond LSC’s Monsanto Auditorium. | Photo by National Institutes of Health

This is Thomas Schneider’s motto.

Schneider, a research biologist at the National Cancer Institute, spent most of his career understanding math and its relation with fundamental biology. His lab focuses on the DNA and RNA patterns that characterize genetic control systems; they invented the widely-used sequence logos.

“In the first place, I am doing this because I am curious,” Schneider said. “Let’s go find the math and who knows what would come out of that.”

Schneider will speak during the 33rd annual Missouri Life Sciences Week, a celebration of MU’s science research and collaboration across disciplines.

Claude Shannon’s information theory lays the foundation of Schneider’s study. In the landmark paper published in 1948, Shannon defined the quantity of information and how it transmits amid interference of noise. When people communicate via a phone call, the heat of the telephone line is one type of noise. As noise contaminates information, the highest rate at which information can be reliably transmitted over a noisy communication channel is defined as the channel capacity.

A similar concept emerges in Schneider’s Molecular Information Theory. It leads to a theoretical measure of the efficiency of molecules.

“I thought [Shannon’s] theory was screaming as I dragged it into biology. The stunning thing is that it fits biology really, really well,” Schneider said.

He looked at the DNA binding protein EcoRI, a restriction enzyme that binds DNA. When it binds, there is an inequality relationship between information and the information gained for the dissipated energy. The efficiency of DNA binding sites on nucleic acids is about 70 percent.

This mysterious number has appeared widely in his research and it also describes ecological evenness. In an even ecosystem with all species being equally represented, the evenness is close to 100 percent, but when only one species dominates the environment, its evenness dwindles to 0 percent.

Schneider found that fish species diversity in a Georgia estuary is near 70 percent and the evenness of plant species in different divisions of 8-square-meter plots in California is also around 70 percent.

When Schneider turns from ecological system to biological systems, this number still stands out. Caenorhabditis elegans (C. elegans), a free-living tiny worm, has been extensively studied and has had its entire cell lineage traced. On the basis of previous studies, Schneider calculated the efficiency of its lineage and found that the number fits the ubiquitous 70 percent, when excluding the dead cells of a C. elegans.

With this established case, one of his colleagues suggested looking into one of human’s biggest enemy – cancer. Cancer occurs when a cell develops mutations and grows out of control. Schneider hypothesized that if you have more of a certain type of cell, then you have a larger chance for that cell type to get a mutation that might lead to cancer.

The International Agency for Research on Cancer (IARC) publishes a report on all different types of cancers observed each five or six years. Based on the data collected by IARC and the hypothesis, Schneider found that for adults whose ages are above 14 years old, the cancer type evenness always remains around 70 percent.

“The thing that is interesting is that when you understand things fundamentally, it inevitably leads to practical results,” Schneider said.

Schneider’s speech on “Three Principles of Biological States: Ecology and Cancer” will be held at 1:15 p.m. April 11 in the Monsanto Auditorium at Bond Life Sciences Center.

Missouri Life Sciences Week is a university-wide event that brings together research across scientific disciplines at Mizzou. This year will highlight more than 300 student, faculty and staff research presentations and four topical lectures by accomplished researchers in addition to career development workshops and scientific service and supply exhibits.

Check out the full schedule of events here.

 

Why self-defense turns self-attack

By Jinghong Chen | Bond Life Sciences Center

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Mahmoud Khalafalla, a Ph.D. student at Weisman’s lab, is isolating RNA from salivary glands of Sjögren’s syndrome mouse model to look for the expression of pro-inflammatory genes. | photo by Jinghong Chen, Bond LSC

Our immune system is often the key to our health. Everyday, it works to protect us from foreign invaders such as bacteria and virus, but what happens when it attacks our own tissues?

Gary Weisman, a Curator’s Distinguished Professor of Biochemistry at the Bond Life Sciences Center, is working to advance our understanding of the mechanisms behind immune system function and autoimmune diseases such as Sjögren’s syndrome.

In our immune system, B cells are responsible for producing antibodies to recognize foreign invaders. However, in many autoimmune diseases, B cells produce autoantibodies that recognize our own proteins, causing inflammation and tissue damage. In Sjögren’s syndrome (SS), they attack the glands that produce saliva and tears.

Patients with SS often suffer chronic dry eyes and dry mouth, which might lead to bacterial infection, difficulties in swallowing and speech.

“The symptoms decrease the quality of life rather than the length of life,” said Lucas Woods, research lab manager in Weisman’s lab.

Although SS patients are at higher risk of developing lymphoma cancers and other concurrent autoimmune diseases that may increase mortality, Woods further explained.

According to the Sjögren’s Syndrome Foundation, there are an estimated four million people living with the disease in the U.S. For unknown reasons, 90 percent of them are female.

Yet, current clinical treatments only reduce symptoms by using artificial saliva and tears or cholinergic agents to promote fluid secretion, but there is no approved treatment to reduce the inflammation of the glands themselves. This is the focus of Weisman’s lab.

Sensor of danger

There are 15 different types of nucleotide receptors in humans that regulate numerous cell processes from inflammatory responses to tissue regeneration. Those receptors are stimulated by nucleotides such as ATP. In the past three and a half years, Mahmoud Khalafalla, a Ph.D. student in Weisman’s lab, has focused on one of them in particular – the P2X7 receptor.

Previous studies show increased P2X7 expression in salivary glands from SS patients, as compared to healthy individuals. To understand the reasons behind this, Weisman’s lab used genetically modified mice that develop disease traits similar to SS patients.

In this mouse model, Sjögren’s-like disease occurs when the immune cells invade salivary glands and damage the tissue, leading to decreased saliva production. The invasion of immune cells is triggered by proinflammatory cytokines, a type of signaling molecule that promotes the recruitment of immune cells to the inflamed areas.

But what induces those cytokines?

Weisman’s lab tries to piece together the answer. For the first time, they found that the P2X7 receptor is responsible for the release of these proinflammatory molecules from salivary gland epithelial cells.

To function, most cell-surface receptors require ligands that bind to the receptor to induce cellular responses. The ligand for the P2X7 receptor is ATP – the “energy currency inside of cells.” P2X7 receptors are activated when high concentrations of ATP are released to the outside of the cells, which typically occurs when the cells are injured during inflammation.

“P2X7 receptors [act like] the sensor of danger,” Khalafalla said.

After identifying the role of the P2X7 receptor, the lab then asked: if we stop its activation, what would happen?

Using a drug that inhibits P2X7 receptor activation, they blocked the receptor in their SS mouse model to determine its effect on the development of autoimmune disease. Interestingly, saliva secretion was restored when the P2X7 receptor is blocked while the levels of invading immune cells in salivary glands were dramatically reduced.

“This gives us the thought that [blockade of the] P2X7 receptor is really a promising strategy to reduce salivary inflammation. This may not only relate to Sjögren’s syndrome, but to other autoimmune diseases as well,” Khalafalla said.

Our receptor

Another similar receptor that plays a role in autoimmune diseases is the P2Y2 receptor, which has been referred to as “our receptor” by Weisman’s lab.

As one of the researchers who proved the existence of this receptor, Weisman has spent most of his career studying it.

One of his research projects investigating P2Y2 receptors in human disease recently gained a grant extension for another five years from the National Institutes of Health. The lab found that in a mouse model of SS, similar to the P2X7 receptor, the expression of P2Y2 receptors was increased in both the salivary gland epithelial cells and immune cells.

Furthermore, after they knocked out the P2Y2 receptor in the SS mouse model by breeding them with genetically-modified P2Y2 receptor knockout mice, the inflammation of salivary glands was dramatically reduced.

“The very next step is that we are going to isolate these immune cells out of the diseased mouse salivary glands, and characterize what kinds of cells they are. We want to know exactly which ones are controlling the development of autoimmune diseases, and how P2Y2 receptors and nucleotides like ATP in general are contributing to the diseases,” Woods said.

 

Gary Weisman is a Curator’s Distinguished Professor of Biochemistry at the Bond Life Sciences Center. His research focuses on the relationship between inflammatory diseases and nucleotide receptors. He currently works on a collaborative research project with Dr. Carisa Petris, an eye surgeon at the MU Hospital, to understand the mechanism of how Sjögren’s syndrome damages the tear-secreting lacrimal glands in mice.

 

Planting a seed for sciences

Jinghong Chen | Bond Life Sciences Center

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Plants on the left grow with rhizobia bacteria, one type of fixing nitrogen bacteria, in the greenhouse, while the plants on the right grow without the bacteria. | photo by Jinghong Chen, Bond LSC

Since eight years old, Beverly Agtuca knew she wanted to be a scientist.

A trip to Philippines changed Agtuca, an American-born Filipino, and inspired her passion on plants.

“My grandma always told me to work in the field all day so that they can have enough food for us to eat,” Agtuca said. “The life [in Philippines] is so different from here…I want to not just provide food but be that scientist trying to figuring something out, and hopefully saving the world.”

Agtuca is on her way to her dream. She is now a third year doctoral student in Gary Stacey’s lab at Bond Life Sciences Center with a focus on nitrogen-fixing bacteria.

Although she has been involved in research since high school, Agtuca recently faced a new challenge of telling people about her work. The Preparing Tomorrow’s Leaders of Science class tasked her with making a 90-second video to explain her two-year study to the general public.

Her team, “The A Team,” chose to go with the benefits of having nitrogen-fixing bacteria.

For decades, people have been adding nitrogen fertilizers to plants to improve yields, but this can lead to pollution in water systems and ecosystems. Scientists need to enhance plant productivity to meet a huge food demand by the year of 2050.

One little bacteria might make this possible and save the world. Rhizobia, a type of natural bacteria in soil, are able to fix nitrogen via biological nitrogen fixation. These bacteria can convert nitrogen gas into ammonia as a plant nutrient source, while the plants give all the carbon sources back to the bacteria.

“It is like a walky-talky,” Agtuca said. “They are communicating with each other.”

Yet before speaking to the public, Agtuca needs to explain the plant-bacteria interaction to her teammates. Students less well versed in science like Jessica Kaiser, a strategic communication student, thinks of science differently.

“The biggest issue we ran into is jargon, like basic science words that [my teammates] are so comfortable with,” Kaiser said. “We need to focus on what people care about instead of the technical sides, to focus on why it matters to anybody rather than just to a science person.”

Within two weeks, they produced the video “Good Microbes: reducing pollution one farm at a time.” Along with two other teams, their videos will be commented and judged by representatives from Monsanto.

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“The A Team” stands together at Bond Life Sciences Center. From left to right: Jessica Kaiser, Sven Nelson, Anna Glowinski, Eleni Galata and Beverly Agtuca. | photo by Jinghong Chen, Bond LSC

The 90-second video is just a glimpse of Agtuca’s study. In the last two years she has been focusing on the use of a new technique — laser ablation electrospray ionization mass spectrometry (LAESI-MS) — that does in situ metabolic profiling of tissues. The lab is using LAESI-MS to investigate the metabolites in a well-characterized model plant-rhizobium system, specifically nitrogen-fixing soybean nodules resulting from root infection by the symbiotic bacterium Bradyrhizobium japonicum.

This work includes a huge collaboration that was developed through a Department of Energy (DOE) grant involving the George Washington University, Washington D.C. and the Environmental Molecular Science Laboratory (EMSL), Pacific Northwest National Laboratory, Richland, WA.

LAESI-MS works like a superhero’s laser-like beams. You first aim the laser on the sample, which then heats it and causes neutral particles to be released into the air. This plume of neutrals is then captured and ionized by the electrospray, and finally analyzed by the spectrometer to figure out the exactly what metabolites in nodules are involved in biological nitrogen fixation.

“It takes about three seconds to analyze one sample using this LAESI-MS technique,” Agtuca said. Other metabolic techniques require extensive pre-treatment of the sample before analysis.

By analyzing the data collected via LAESI-MS, the lab is able to confirm that future plant studies could apply this new approach to understand the interactions between plant and bacteria.

Agtuca’s research is a long way from her first experiences with plants. She still remembers the moment she found her plants in her own garden died. She was less than 10 years old, yet devoted to taking care of her plants with water and fertilizers.

“I was really sad. I could not get my tomatoes, peppers and eggplants to live.…That makes me think that I want to answer why they didn’t grow,” Agtuca said.

More than ever, her future is helping her answer those question for herself.

 

Gary Stacey is a Bond LSC investigator and MU curators’ professor of plant science and MSMC endowed professor of soybean biotechnology. Read more here about Stacey lab.

Sven Nelson is a USDA/ARS postdoctoral research scientist at the University of Missouri. Anna Glowinski is a Ph.D. student in the USDA/ARS lab. Jessica Kaiser is a graduate student in strategic communication. Eleni Galata works as the team mentor and she is a Ph.D. student in agricultural and applied economics at MU.

Art of balance

Jinghong Chen | Bond Life Sciences Center

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Vinit Shanbhag mixes the CRISPR plasmid DNA with cells. The lab will test whether the gene of interest has been knocked out of the cells later. | photo by Jinghong Chen, Bond LSC

It might be strange to say, but in a way the Australian soil led scientist Michael Petris to where he is now.

In certain areas of Australia, soils suffer from extremely low level of copper bioavailability, resulting in poor growth and neurological problems on sheep.

Petris, a Bond LSC investigator and professor of biochemistry who was born in Australia, now spends his time studying how copper, an essential mineral in human body, works in cells to build and maintain essential functions.

Recently published work from his lab focuses on how the ATP7A protein, one of the major proteins, cycles within the cell.

“Copper is solely acquired from diet. The absorption of copper from the intestine in the blood needs ATP7A,” Vinit Shanbhag, a Ph.D. biochemistry student at Petris’ lab and an author of the study, said. “It transports copper to different copper dependent enzymes and exports free copper from the cell to the outside.”

After exporting copper at the cell membrane, ATP7A needs to come back to its steady-state location within the Golgi apparatus of cells – via a process called retrograde trafficking. But one question baffled scientists: what are the key elements that lead ATP7A coming back?

Back in the late 90s, Petris discovered the importance of one single di-leucine in retrograde trafficking of ATP7A. For those of you wondering, leucine is an amino acid that forms the building blocks of proteins like ATP7A, while di-leucine consists of two of them connected via a peptide bond.

His team wished to identify other signals for retrograde trafficking, but one technical hurdle stood in the way— the ATP7A gene is unstable when grown in bacterial plasmids, the traditional way of amplifying genes in the lab.

Commercial DNA synthesis was the answer. This method could create artificial genes in the laboratory.

“We reasoned that if we introduced enough silent mutations into a DNA sequence, we could avoid or change the region of instability in the native sequence without affecting the encoded protein,” Petris said.

To stabilize the gene, they changed more than 1,000 nucleotides within a 3,000 nucleotides segment, and thus solving the problem of instability of the ATP7A gene. In doing so, they subsequently found that in fact multiple di-leucines that are required for retrograde trafficking of ATP7A. This approach could be used by other laboratories whose gene of interest is also unstable.

An overlooked mineral

“If you ask [people], is it important to understand iron nutrition? Is it important to understand calcium nutrition? Most people would say of course! … But, perhaps you would not get the same answer for copper, despite the fact there is a little dispute that copper is important,” Petris said.

As an essential micronutrient, copper performs central functions to develop and maintain human skin, bones, brains and other organs.

“If you don’t have enough copper in your body, you cannot use oxygen to make energy,” Petris said. “If you don’t have copper, you would not survive.”

Pregnant women who carry a mutated ATP7A gene on their X chromosome can pass it on to their children in the form of Menkes disease.

Menkes disease is a genetic disorder that results in poor uptake and distribution of copper to cells. The incidence of this disease is estimated to be one in 100,000 newborns, according to U.S. National Library of Medicine.

Infants with Menkes disease typically begin to develop symptoms during infancy and rarely live past the first few years of life. Abnormally high accumulation of copper in kidneys and low-level accumulation in the liver and brain, cause visible symptoms like sparse hair, loose skin and failure to grow.

Despite copper’s importance, it also can be a potentially toxic nutrient.

“Copper deficiency can be a problem but too much copper is also a problem. There should be a balance,” Shanbhag explained.

The liver normally stores excessive copper and excretes it into bile to release it out of the body. Yet people with genetic disorders that preventing copper excretion might suffer Wilson’s disease, leading to life-threatening organ damage.

Shanbhag said people with Wilson’s disease accumulate toxic amounts of copper in liver and other organs, causing Kayser–Fleischer rings that encircle the pigmented regions of the eye, a hue caused by copper deposits in the cornea.

Its clinical consequences differ from chornic liver failure to neurological sysmptoms like tremors, dystonia, ataxia and cognitive deteriortation.

About one in 30,000 people have Wilson disease, according to National Institute of Diabetes and Digestive and Kidney Diseases.

Starving tumors

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Vinit Shanbhag mixes the CRISPR DNA with mammalian cells to specifically delete a gene in these cells in lab hood. | photo by Jinghong Chen, Bond LSC

In 2013, Petris’ lab published the first direct evidence suggesting ATP7A is essential for the dietary absorption of copper. Since then they have dug deeper into this copper transporter, and his lab now sets their sights on a greater enemy of human health — cancer.

Tumor growth requires access to large amounts of nutrients. Without an adequate supply of oxygen and nutrients, tumors fail to grow and survive. Scientists have identified that by preventing access to nutrients—for example by blocking the growth of new blood vessels—they could starve the tumor of nutrients.

Copper is a key nutrient for tumor growth. With the new-introduced system CRISPR-Cas9 — a genome editing tool to knock out specfic genes — his lab has explored how to exploit understanding of copper metabolic pathways to withhold copper from cancer cells.

“Copper starvation might be a good approach as an anti-cancer strategy,” Petris said.

Weapon of the immune system

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Michael Petris, a professor of biochemistry at MU, stands with his lab. From left to right: Vinit Shanbhag, Nikita Gudekar, Michael Petris, Kimberly Jasmer-McDonald, Aslam Khan. | photo by Jinghong Chen, Bond LSC

Currently, four members study in Petris’ lab to tackle the relationship between copper and various diseases. Petris plans to expand his research to another area: the role of copper in innate immunity against bacterial pathogens.

This is the topic of Petris’ next grant. Nutritional immunity, which describes how the mammalian host withholds nutrients from the invading bacteria during infection, is very well-described for iron and zinc.

Yet copper performs differently.

During infection, the level of copper in blood actually goes up instead of going down. The immune system concentrates copper at sites of infection and within regions where the bacteria are engulfed.

“We speculate that copper is being used as weapon by the host to kill the bacteria,” Petris said. “That is the area we are trying to develop further.”

 

Michael Petris is a Bond LSC investigator and a professor of biochemistry. The study “Multiple di-leucines in the ATP7A copper transporter are required for retrograde trafficking to the trans-Golgi network” was published by The Royal Society of Chemistry in September 2016.