Iridescent Beauty: Development, function and evolution of plant nanostructures that influence animal behavior

Iridescent wings of a Morpho butterfly

Iridescent wings of a Morpho butterfly

Creatures like the Morpho butterfly on the leaf above appear to be covered in shimmering blue and green metallic colors. This phenomenon is called “iridescence,” meaning that color appears to change as the angle changes, much like soap bubbles and sea shells.

Iridescent behavior of a soap bubble

Iridescent behavior of a soap bubble

In animals, the physical mechanisms and function of structural color have been studied significantly as a signal for recognition or mate choice.

On the other hand, Beverley Glover believes that such shimmering in plants can actually influence animal behavior by attracting pollinators better than their non-iridescent counterparts. Glover,Director of Cambridge University Botanic Garden,  presented her study during the Biology Seminar Series in the French Family Science Center on Monday earlier this week.

Hibiscus Trionum

Hibiscus Trionum

The metallic property of flowers like the Hibiscus Trionum above are generated by diffraction grating – similar to the way CD shines – to create color from transparent material.

In order to observe the effects of the iridescence on pollinators like bees, Glover created artificial materials with a surface structure of nanoscale ridges, similar to the microscopic view of a petal’s epidermal surface below.

Nanoscale ridges on a petal's epidermal surface.

Nanoscale ridges on a petal’s epidermal surface.

In the first set of experiments, Glover and her team marked bees with paint to follow their behavior as they set the insects to explore iridescent flowers. Some were covered in a red grating – containing a sweet solution as a reward – and others with a blue iridescent grating – containing a sour solution as deterrent. The experiment demonstrated that the bees were able to detect the iridescent signal produced by the petal’s nanoridges, and – as a result – correctly identified the rewarding flowers.

Bees pollinating iridescent "flowers"

Bees pollinating iridescent “flowers”

With the evidence that the bees were able to see iridescence, Glover set out for the second experiment: once the bees find a specific type of flower, how long does it take them to find the same flower in a different location? Using the triangular arrangement of shimmering surfaces as shown below, Glover observed that iridescence produced by a diffraction grating leads to significant increase in foraging speed as compared to non-iridescent flowers.

Triangular formation of iridescent disks used for experimentation on bees

Triangular formation of iridescent disks used for experimentation on bees

While iridescence in plants is difficult to spot by a casual stroll through the garden, pollinators such as bees definitely can see it, and scientists have recently realized that insect vision and flower colors have co-evolved.

In order to ensure that pollen is transferred between flowers of the same species, these flowers have developed a unique structure of iridescence. As scientists work on understanding which plants produce these beautiful colors and how the nanoscale structure is passed down through reproduction, we can only look at our gardens in wonder at the vast amount of nature that still remains to be explored and learned.

Wonder of nature

Wonders of nature in an everyday garden



Beverley Glover is the Director of Cambridge University Botanic Garden and is currently accepting applications for PhD students






Post written by Anika Radiya-Dixit


Pinpointing the Cause of Coughs and Sneezes

Duke students are trying to help doctors find a faster way to pinpoint the cause of their patients’ coughs, sore throats and sniffles.

The goal is to better determine if and when to give antibiotics in order to stem the rise of drug-resistant superbugs, said senior Kelsey Sumner.

For ten weeks this summer, Sumner and fellow Duke student Christopher Hong teamed up with researchers at Duke Medicine to identify blood markers that could be used to tell whether what’s making someone sick is a bacteria, or a virus.

More than half of children who go to the doctor for a sore throat, ear infection, bronchitis or other respiratory illness leave with a prescription for antibiotics, even though the majority of these infections — more than 70% — turn out to be caused by viruses, which antibiotics can’t kill.

The end result is that antibiotics are prescribed roughly twice as often as they should be, to the tune of 11.4 million unnecessary prescriptions a year.

“It’s a big problem,” said Emily Ray Ko, MD, PhD, a physician at Duke Regional Hospital who worked with Sumner and Hong on the project, alongside biostatistician Ashlee Valente and infectious disease researcher Ephraim Tsalik of Duke’s Center for Applied Genomics and Precision Medicine.

Prescribing antibiotics when they aren’t needed can make other infections trickier to treat.

Fast, accurate genetic tests may soon help doctors tell if you really need antibiotics. Photo from the Centers for Disease Control and Prevention.

Fast, accurate genetic tests may soon help doctors tell if you really need antibiotics. Photo from the Centers for Disease Control and Prevention.

That’s because antibiotics wipe out susceptible bacteria, but a few bacteria that are naturally resistant to the drugs survive, which allows them to multiply without other bacteria to keep them in check.

More than two million people develop drug-resistant bacterial infections each year.

A single superbug known as methicillin-resistant Staphylococcus aureus, or MRSA, kills more Americans every year than emphysema, HIV/ AIDS, Parkinson’s disease and homicide combined.

Using antibiotics only when necessary can help, Ko said, but doctors need a quick and easy test that can be performed while the patient is still in the clinic or the emergency room.

“Most doctors need to know within an hour or two whether someone should get antibiotics or not,” Ko said. “Delaying treatment in someone with a bacterial infection could have serious and potentially life threatening consequences, which is one of the main reasons why antibiotics are over-prescribed.”

With help from Sumner and Hong, the team has identified differences in patients’ bloodwork they hope could eventually be detected within a few hours, whereas current tests can take days.

The researchers made use of the fact that bacteria and viruses trigger different responses in the immune system.

They focused on the genetic signature generated by tiny snippets of genetic material called microRNAs, or miRNAs, which play a role in controlling the activity of other genes within the cell.

Using blood samples from 31 people, ten with bacterial pneumonia and 21 with flu virus, they used a technique called RNA sequencing to compare miRNA levels in bacterial versus viral infections.

So far, the researchers have identified several snippets of miRNA that differ between bacterial and viral infections, and could be used to discriminate between the two.

“Hopefully it could be used for a blood test,” Sumner said.

“One goal of these types of assays could be to identify infections before symptoms even appear,” Ko said. “Think early detection of viral infections like Ebola, for example, where it would be helpful to screen people so you know who to quarantine.”

Sumner and Hong were among 40 students selected for a summer research program at Duke called Data+. They presented their work at the Data+ Final Symposium on July 23 in Gross Hall.

Data+ is sponsored by the Information Initiative at Duke, the Social Sciences Research Institute and Bass Connections. Additional funding was provided by the National Science Foundation via a grant to the departments of mathematics and statistical science.



Writing by Robin Smith; photos and video by Christine Delp and Hannah McCracken



Undergrads Share Results, and Lack Thereof

ashby and grundwald

Arts & Sciences Dean Valerie Ashby and Associate Dean for Undergraduate Research Ron Grunwald got the big picture of the poster session from an LSRC landing.

Dozens of Duke undergrads spent the summer working in labs, in part to learn why science is called “research” not “finding.”

“About a third of these students ended up without any data,” said Ron Grunwald, associate dean for undergraduate research, during a Friday poster session in the atrium of the LSRC building for three of the summer research programs.

Biology junior Eric Song gets it now. He spent the summer trying to culture one specific kind of bacteria taken from the abdomens of an ant called Camponotus chromaiodes, which he collected in the Duke Forest. All he got was

Eric Song

Eric Song’s poster featured a photo of the ant and the mysterious white stuff.

“this white stuff showing up and we don’t even know what that is.” His faculty mentor in the Genomics Summer Fellows Program, Jennifer Wernegreen, was hoping to do some genetic sequences on the bacteria, but the 10-week project never made it that far. “We’re only interested in the genome basically,” Song said good-naturedly.

Christine Zhou did get what she set out for, mastering the art of arranging E.coli bacteria in orderly rows of tight little dots, using a specially adapted ink jet printer. Working with graduate student Hannah Meredith and faculty mentor Linchong You, she was able to lay the bugs down at a rate of 500 dots per minute, which might lead to some massive studies. “In the future, we’re hoping to use the different colored cartridges to print multiple kinds of bacteria at the same time,” she said.

Sean Sweat

Sean Sweat (left) discusses her mouse study.

Neuroscience senior Sean Sweat also got good results, finding in her research with faculty mentor Staci Bilbo, that opiate addiction can be lessened in mice by handling them more, and identifying some of the patterns of gene expression that may lie behind that effect.

Neuroscience senior Obia Muoneke wanted to know if adolescents are more likely than children or adults to engage in risky behaviors. Muoneke, who worked with mentor Scott Huettel, said her results showed the influence of peers. “Adolescents are driven to seek rewards while with a peer,” said Muoneke. “Adults are more motivated to avoid losing rewards when they are by themselves.”

The new dean of Trinity College, chemist Valerie Ashby, worked the room asking questions before addressing everyone from a landing overlooking the atrium. “How many of you wake up thinking ‘I want nothing to happen today that I am uncertain about?’” she asked. Well, Ashby continued, scientists need to become comfortable with the unexpected and the unexplainable – such as not having any data after weeks of work.

“We need you to be scientists,” Ashby said, and a liberal arts education is a good start. “If all you took was science classes, you would not be well-educated,” she said.

_ post by Shakira Warren and Karl Leif Bates


Karl Leif Bates

Students Brief Senate, FDA, & Personalized Medicine Coalition

By Nonie Arora

Duke students and faculty brief Senate staffers, Pictured left to right: Allison Dorogi, Nonie Arora, Robert Cook-Deegan, Samantha Phillips, Jenny Zhao, Elisa Berson. Credit: Robert Cook-Deegan

Duke students and faculty brief Senate staffers, Pictured left to right: Allison Dorogi, Nonie Arora, Robert Cook-Deegan, Samantha Phillips, Jenny Zhao, Elisa Berson. Credit: Robert Cook-Deegan

The week of April 13, at the height of cherry blossom season, Duke students traveled to Washington, D.C. to brief senior staff members of the Senate, Food and Drug Administration (FDA), and the Personalized Medicine Coalition (PMC). Over the spring semester, five students in the Genome Sciences & Policy Capstone course (including myself) studied the regulatory framework of laboratory developed tests (LDTs).

LDTs are tests developed for use in a single laboratory. The clinical laboratories that develop LDTs are considered to be medical device manufacturers and are therefore subject to FDA jurisdiction. The FDA exercises “enforcement discretion” over LDTs, which means they choose when to regulate these tests.

Duke students in Washington, D.C. Credit: Robert Cook-Deegan

Duke students in Washington, D.C. Credit: Robert Cook-Deegan

Under the supervision of Duke professor Robert Cook-Deegan, we dove into five case studies regarding different types of LDT tests.

The case study that I focused on was the differential regulation of two tests used for breast cancer patients. The two tests, MammaPrint and Oncotype Dx are regulated differently even though both aim to help doctors understand when patients should have follow-up chemotherapy after surgery. The company that markets MammaPrint, Agendia, chose to obtain FDA clearance for their test, but the company behind Oncotype Dx, Genomic Health, chose against it. Surprisingly, this decision did not substantially increase the number of patients who receive Oncotype Dx relative to MammaPrint.

Furthermore, the two tests do not always produce the same result, according to a research study. Several key question remain, such as:

  1. Is the FDA-regulated test more accurate?
  2. Does the more accurate test get more market share? Does FDA approval make a difference?
  3. How should these tests, and ones like them, be regulated to reduce harm to patients?

The students hope that their case studies will serve as illuminating examples for stakeholders and help guide the conversation regarding federal regulation of LDTs.


Joining the Team: Anika Ayyar

By Anika Ayyar

Hi! My name is Anika Ayyar and I am currently a Duke freshman. I grew up in warm, lovely Saratoga, California, where I picked up my love for long distance running, organic farming, and the ocean. When I was 14, I moved to across the country to Exeter, New Hampshire to attend a boarding high school, and here I developed a deep interest in biology and medicine. Exeter’s frost and snow were far from the Cali weather I was used to, but my fascinating classes, caring teachers, and wonderful friends more than made up for the cold.

My sophomore semester abroad program at The Island School, on an island called Eleuthera in the Bahamas, certainly provided a welcome change to East coast weather as well. At the Island School I studied marine biology and environmental conservation, earned my SCUBA certification, and spent time with the local middle schoolers refurbishing a library and stocking it with books. I was also part of a research team that studied species richness and diversity on patch reefs off the coast of the island.

Dissecting fruit fly larvae under the microscope at the Seung Kim Lab at Stanford.

Dissecting fruit fly larvae under the microscope at the Seung Kim Lab at Stanford.

My marine research stint in the Bahamas drove me to join a molecular biology lab the summer after I returned; a decision that transformed my passion for science. At the Seung Kim Lab for Pancreas Development at Stanford University, I worked on a project that used binary systems to study the expression of specific genes related to insulin production and diabetes in fruit flies. I soon grew so immersed in my work that I wanted to share the project with others in the scientific community at Exeter, and my research mentors, biology professors, and I worked to create a novel course where other students could take part in the project as well. This unique research collaboration, called the “StanEx” project, proved to be a huge success, allowing other students to experience the trials and joys of real-world research while also generating Drosophila fly strains that were useful to the larger scientific community. If you are interested in reading more, check out my website about the StanEx project!

While my current interests lie more at the intersection of technology and medicine, I hope to be involved in equally compelling and fulfilling research here at Duke. Hearing about the various projects my professors are working on, and reading about the discoveries made in labs on campus, I have no doubt that this will be the case.

Outside of classes and research, I enjoy being part of the Duke Debate team, and Lady Blue, one of Duke’s all-female a cappella groups. You can often find me on the trails on a long run, or trying out a new dessert recipe I found on Pinterest. I am beyond excited to be a part of the research blogging team, and can’t wait to start attending talks and interviewing research personalities whose stories I can share with our readers!

Is the “Wizarding Gene” Dominant or Recessive?

By Nonie Arora

Dr. Spana explains the wizarding gene to eager students. Credit: Arnab Chatterjee

Dr. Spana explains the wizarding gene to eager students. Credit: Arnab Chatterjee

How do recessive alleles and the world of Harry Potter connect? Some students found out last week from Dr. Eric Spana, a faculty member in the Biology department.

He started off by explaining how a mutation in the MC1R (melanocortin 1 receptor) gene causes red hair in humans because of the way it affects a pigment called eumelanin. He added that MC1R is a recessive gene, and showed a pedigree of the Weasley family tree. Professor Spana pointed out that J. K. Rowling had gotten the genetics right. The Weasley clan has red hair and so does Harry’s daughter Lily. This makes sense because Harry must have a recessive allele for red hair since his mother, also Lily, had red hair. Whether this is intentional or just fortuitous casting, who can really say?

He then explained some potential retroactive genetic “crosses” that could be done to determine whether the “wizarding gene” was dominant or recessive. As a quick refresher, recessive alleles require both the mom and dad to pass on the same genetic sequence to the child for the condition to occur, while dominant alleles require only one copy.

According to Professor Spana, Step 1 was to check whether a witch and a muggle who mated ould produce a wizard. Indeed, this is possible, and the evidence is Seamus Finnigan, a half-blood wizard. Due to these results, the gene could still be dominant or recessive.

In Step 2, he explained, you mate a wizard to someone who could not have the wizarding gene. Fridwulfa, the giantess, married Mr. Hagrid, a wizard, to produce our beloved Rubeus Hagrid, who was a wizard. Since giants cannot have the wizarding gene, but Hagrid is still a wizard, the wizarding gene must be dominant!

Crowd of students ask provocative questions about squibs and recessive vs. dominant inheritance. Credit: Arnab Chatterjee

Crowd of students ask provocative questions about squibs and recessive vs. dominant inheritance. Credit: Arnab Chatterjee

You’ll have to stop by Dr. Spana’s office to ask him more about where muggle-borns and squibs come from. There’s a few different genetic explanations, and I encourage you to do some thinking and exploration.

Outside of his work on the genetics of Harry Potter, Dr. Spana also researches and teaches Genetics & Developmental Biology at Duke.