“#IAmScience because during their journey all graduate students deserve expertise, care and advocacy from graduate coordinators.”
As Coordinator of Graduate Life Science Initiatives, Debbie Allen facilitates several activities supporting graduate recruitment, training, mentoring and career services. In other words, she’s been the “mama bear” to many life sciences graduate students over the years, and is passionate about student advocacy. To Debbie, while understanding the hard science her students study is important, supporting those students through their challenges and triumphs, and guiding them closer to their goals motivates her every day.
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.
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
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.”
What if you could have pork without the pig? Nicholas Genovese’s cultured meat could provide a more environmentally friendly meat By Eleanor C. Hasenbeck | MU Bond Life Sciences Center
Scientists are one step closer to that reality. For the first time, researchers in the Roberts’ lab at Bond Life Sciences Center at MU were able to create a framework to make pig skeletal muscle cells from cell cultures.
In vitro meat, also known as cultured meat or cell-cultured meat, is made up of muscle cells created from cultured stem cells.
As a visiting scholar at the University of Missouri, Nicholas Genovese mapped out pathways to successfully create the first batch of in vitro pork. Genovese also said it was the first time it was done without an animal serum, a growth agent made from animal blood.
According to Genovese, his research in the Roberts Lab was also the first time the field of in vitro meats was studied at an American university.
“I feel it’s a very meaningful way to create more environmentally sustainable meats, which is going to use fewer resources, with fewer environmental impacts and reduce need for animal suffering and slaughter while providing meats for everyone who loves meat,” Genovese said.
The research could have environmental impacts. According to the United Nation’s Food and Agriculture Organization, livestock produce 14.5 percent of all human-produced greenhouse gas emissions. Livestock grazing and feed production takes up 59 percent of the earth’s un-iced landscape. Cultured meat takes up only as much land as the laboratory or kitchen (or carnery, the term some members of the industry have coined for their facilities) it is produced in. It uses energy more efficiently. According to Genovese, three calories of energy can produce one calorie of consumable meat. The conversion factor in meat produced by an animal is much higher. According to the FAO, a cow must consume 11 calories to produce one calorie of beef for human consumption.
And while Michael Roberts, the lab’s principal investigator, is skeptical of how successful in vitro meat will be, he said the results could yield other benefits. Researchers might be able to use a similar technique as they used to create skeletal muscle tissue to make cardiac muscle tissue. Pork muscles are anatomically similar to a human’s and can be used to model treatments for regenerative muscle therapies, like replacing tissue damaged by injury or heart attacks.
“I was interested in using these cells to show that we could differentiate them into a tissue. It’d been done with human and mouse, but we’re not going to eat human and mouse,” Roberts said. “The pig is so similar in many respects to humans, that if you’re going to test out technology and regenerative medicine, the pig is really an ideal animal for doing this, particularly for heart muscle,” he added.
“#IAmScience because through my research, I can expand the bubble of human knowledge and I think that’s a pretty amazing thing. We don’t have a volcano, so we make our own.”
Imagine stirring rock. Sounds impossible? Not to Arianna Soldati, a volcanology expert conducting #MizzouResearch on the viscosity of rock. By heating and then stirring rocky material in a machine that acts like a miniature volcano, she identifies its viscosity, or thickness. As someone who has always been interested in volcanos, she is passionate about saving people from dangerous eruptions. “By knowing the signs, people are more likely to get to safety in time.”
Scientists prove parasite mimics key plant peptide to feed off roots By Roger Meissen | Bond LSC
When it comes to nematodes, unraveling the root of the issue is complicated.
These tiny parasites siphon off the nutrients from the roots of important crops like soybeans, and scientists keep uncovering more about how they accomplish this task.
Research from the lab of Bond LSC’s Melissa Mitchum recently pinpointed a new way nematodes take over root cells.
“In a normal plant, the plant sends different chemical signals to form different types of structures for a plant. One of those structures is the xylem for nutrient flow,” said Mitchum, an associate professor in the Division of Plant Sciences at MU. “Plant researchers discovered a peptide signal for vascular stem cells several years ago, but this is the first time anyone has proven that a nematode is also secreting chemical mimics to keep these stem cells from changing into the plant structures they normally would.”
Stem cells? Xylem? Chemical mimics?
Let’s unpack what’s going on.
First, all plants contain stem cells. These are cells with unbridled potential and are at the growth centers in a plant. Think the tips of shoots and roots. With the right urging, plant stem cells can turn into many different types of cells.
That influence often comes in the form of chemicals. These chemicals are typically made inside the plant and when stem cells are exposed to them at the right time, they turn certain genes either on or off that in turn start a transformation of these cells into more specialized organs.
Want a leaf? Expose a stem cell to a particular combination of chemicals. Need a root? Flood it with a different concoction of peptides. The xylem — the dead cells that pipe water and nutrients up and down the plant — requires a particular type of peptide that connects with just the right receptor to start the process.
But for a nematode, the plan is to hijack the plant’s plan and make plant cells feed it. This microscopic worm attaches itself to a root and uses a needle-like mouthpiece to inject spit into a single root cell. That spit contains chemical signals of its own engineered to look like plant signals. In this case, these chemicals — B-type CLE peptides — and their purpose are just being discovered by Mitchum’s lab.
“Now a nematode doesn’t want to turn its feeding site into xylem because these are dead cells it can’t use, so they may be tapping into part of the pathway required to maintain the stems cells while suppressing xylem differentiation to form a structure that serves as a nutrient sink,” Mitchum said. “To me that’s really cool.”
This means these cells are free to serve the nematode. Many of their cell walls dissolve to create a large nutrient storage container for the nematode and some create finger-like cell wall ingrowths that increase the take up of food being piped through the roots. For a nematode, that’s a lifetime of meals for it while it sits immobile, just eating.
But how did scientists figure out and test that this nematode’s chemical was the cause?
Using next generation sequencing technologies that were previously unavailable, Michael Gardner, a graduate research assistant, and Jianying Wang, a senior research associate in Mitchum’s lab, compared the pieces of the plant and nematode genome and found nearly identical peptides in both — B-type CLE peptides.
“Everything is faster, more sensitive and we can detect things that had gone undetected through these technological advances that didn’t exist 10 years ago,” Mitchum said.
To test their theory, Xiaoli Guo, postdoctoral researcher and first author of the study in Mitchum’s lab synthesized the B-type CLE nematode peptide and applied it to vascular stem cells of the model plant Arabidopsis. They found that the nematode peptides triggered a growth response in much the same way as the plants own peptides affected development.
They used mutant Arabidopsis plants engineered to not be affected as much by this peptide to confirm their findings.
“We knocked out genes in the plant to turn off this pathway, and that caused the nematode’s feeding cell to be compromised. That’s why you see reduced development of the nematode on the plants.”
This all matters because these tiny nematodes cost U.S. farmers billions every year in lost yields from soybeans, and similar nematodes affect sugar beets, potatoes, corn and other crops.
While this discovery is just a piece of a puzzle, these pieces hopefully will come together to build better crops.
“You have to know what is happening before you can intervene,” Mitchum said. “Now our biggest hurdle is to figure out how to not compromise plant growth while blocking only the nematode’s version of this peptide.”
Nga Nguyen hopes to apply her research to increase nutrient contents in crop plants
By Eleanor C. Hasenbeck | Bond LSC
Plants smell better than animals, at least to Nga Nguyen. That’s one reason why she decided to study them.
“In my undergrad, I studied horticulture,” Nguyen said. “For that you don’t really learn the inside mechanisms of plants, so I decided besides knowing the cultivation techniques, I’d like to also learn about the molecular biology.”
As a fifth year doctoral candidate in the Mendoza-Cózatl lab at Bond Life Sciences Center, she hopes to combine her undergraduate background with her present research in the microbiology of plants to improve the crops of the future.
Nguyen studies how transporter proteins move micronutrients like iron through plants. By understanding how plants move these nutrients in model plants, researchers hope to apply the same understanding and techniques to crops like soy and common beans. Increasing the micronutrient content of these crops could be a useful tool in combatting nutrient deficiencies in areas where people don’t have access to meat and dairy.
But Nguyen says the benefits of studying plants don’t end there. “I hope people pay attention to plant research and study,” Nguyen said. “If you think about it, it’s not just our food, but our clothing and the materials we use.”
Nick Dietz was not certain where to start his research journey this time last year.
But the atmosphere during a recruitment weekend nearly a year ago convinced him to pick MU over three other offers of admission. He is now a first-year plant sciences Ph.D. graduate student and life sciences fellow at MU.
“It is crucially important for [prospective] graduate students to feel they are going to feel like home, and Mizzou just knocked out that part with the recruitment weekend,” said Dietz.
The Graduate Life Sciences Joint Recruitment Weekend, an annual event since 2010, builds a two-way street between MU faculties and prospective graduate students and helps them to determine whether MU is the place for them to continue their education.
This year, about 35 prospective students with different academic backgrounds participated in the recruitment event.
“Up to this point, the departments only know these [prospective] students on paper,” said Debbie Allen, coordinator of Graduate Initiatives. “But this is an chance for the faculty and staff to meet them in person to get a feel that whether they are going to be a good fit for our program.”
Conversely, the prospective students also gain deeper understanding of MU via tours around the campus and the laboratories, one-on-one interviews with potential advisors and interdisciplinary poster sessions. The event combines recruiting efforts from the division of Biochemistry, Plant Sciences, Molecular Pathogenesis and Therapeutics graduate program, Genetics Area program, MU Information Institute, the Interdisciplinary Plant Group and Life Sciences Fellowship Program.
More than 100 faculty, graduate students and post-doctoral fellows joined the recruitment weekend. They play a valuable role in interacting with the prospective students, as they are the ones who are in the midst of MU life.
Dietz joined that effort as a student ambassador. He toured Matthew Murphy, an Illinois College graduate, around the campus and shuttled him to different interviews.
Murphy drove from St. Louis for the recruitment weekend. With a major in biology and a minor in mathematics, he wishes to submerge himself into plant sciences.
During his gap year at the Donald Danforth Plant Science Center after graduation, Murphy learned about the division of Plant Sciences, which is one of the MU’s strongest programs. That eventually got him pumped up to apply for MU.
The recruitment weekend energized him further.
“Every graduate student I have talked to is really helpful and honest,” said Murphy. “They are all saying… how thankful they are to pick Mizzou.”
Lloyd Sumner, an MU professor of biochemistry, is expecting new students to join his lab. He had lunch and one-on-one meetings with the 11 prospective students invited by the biochemistry department, and toured them around his lab to showcase the instrumental resources.
“These are educated young adults with often very grand ideas. It is inspiring to visit with them and to be part of their future goals and careers,” Sumner said.
After six months rotating between different labs, Dietz has not yet decided which research route he will take yet. Nevertheless, he remains certain of one thing: he is enjoying the life here.
“It is a really warm atmosphere,” said Dietz. “I don’t feel I am being used as a labor. Professors actually want me to do well and get a good education.”