UCLA researchers determine the structure of a toxin that kills malaria-carrying mosquitoes

Results pave the way for genetically engineering the toxin to be lethal to other mosquito species transmitting Zika virus and dengue fever

By Katherine Kornei

Figure showing BinA and BinB folds and carbohydrate-binding modules. BinA and BinB are structurally similar to each other. The most noticeable differences correspond to insertions in surface loops on the trefoil domains (purple). UCLA researchers used an X-ray laser to determine the arrangement of atoms.

An international team of scientists, including five UCLA researchers, has used X-rays to reveal the structure of a molecule toxic to disease-carrying mosquitoes.

Nearly half of the world’s population is at risk of contracting malaria, a life-threatening disease transmitted by mosquitoes. Chemical insecticides are often a first line of defense against mosquitoes, but their application can result in both environmental pollution and resistance to the pesticide. The research was published in the journal Nature.

Countries around the globe have recently begun killing mosquito larvae using a natural toxin derived from bacteria. Now UCLA scientists and their collaborators have used X-rays to determine the atomic structure of this larvicide, which is lethal to mosquitoes transmitting malaria and West Nile virus. These results reveal how the toxin functions, knowledge that will inform future efforts to genetically engineer it to also kill mosquitoes carrying Zika virus and dengue fever.

“This is a chance to have a positive effect on a lot of the world’s population,” said senior author David Eisenberg, UCLA’s Paul D. Boyer Professor of Molecular Biology and a Howard Hughes Medical Institute investigator.

Eisenberg and his colleagues studied the larvicide known as BinAB, which is produced by soil-dwelling bacteria. The bacteria pack BinAB into tiny crystals, thousands of which could be stacked across the head of a pin. When these crystals are scattered into the watery environments in which mosquitoes thrive, hungry mosquito larvae eat the crystals. But the meal turns out to be a deadly one.

As the crystals pass through the larvae’s digestive tract, the gut juices of the larvae trigger the crystals to dissolve. The BinAB toxin is released, and its component molecules — called BinA and BinB — play distinct roles in entering the cells of the larvae’s guts and killing the young mosquitoes within 48 hours.

BinAB is toxic to the Culex and Anopheles species of mosquitoes — carriers of West Nile virus and malaria, respectively — but at this point is harmless to the Aedes species, the carriers of Zika virus and dengue fever.

“The toxin is this complex shape, and it has to fit with another shape on the intestine of the larvae. If the shapes don’t match up precisely, the toxin cannot get in the cell. It’s like a lock and key,” said Michael Sawaya, a staff scientist at UCLA involved in the study, to explain BinAB’s specificity.

Genetically engineering an effective toxin

Researchers are interested in genetically engineering BinAB to also kill the larvae of Aedes mosquitoes, work that requires a detailed understanding of BinAB’s atomic structure. However, the small size of the crystals containing BinAB has made it difficult for scientists to hold them securely in laboratory instruments for analysis.

The UCLA researchers and their colleagues, including Dr. Jacques-Philippe Colletier, a former UCLA researcher now working in France, overcame this size limitation by harvesting crystals from a particular strain of soil-dwelling bacteria engineered to produce larger crystals. The scientists then studied the precise shape of the BinAB toxin within the crystals using an X-ray laser. Eisenberg and his colleagues bombarded the crystals with an X-ray laser invented by a UCLA physicist.

“When we shine X-rays on the crystals, the X-rays are scattered into thousands of X-ray beams,” said Eisenberg, who is also a professor of chemistry, biochemistry and biological chemistry and a member of UCLA’s California NanoSystems Institute. “These beams contain information about the arrangement of the atoms that make up BinA and BinB.”

 

“It would be hard to find a problem that could potentially affect the health of more people.” –  Senior author David Eisenberg

 

Novel use of X-ray laser

This type of X-ray laser has never before been used to study a sample with an unknown structure. “We can do entirely new types of experiments using these X-ray lasers,” said co-author Jose Rodriguez, a UCLA assistant professor of chemistry and biochemistry.

The researchers found that the BinA and BinB molecules making up BinAB were crossed in an “X” shape. “They’re hugging each other,” Eisenberg said of the BinA and BinB molecules. This geometry helps ensure that the BinA and BinB molecules exist in equal numbers, which contributes to BinAB’s toxicity.

The scientists also isolated four special sites on the BinAB toxin that were most likely to be involved in the larvicide splitting into BinA and BinB, a transformation critical to the lethal nature of the toxin.

“You can think of the molecule as…having four latches,” Rodriguez said. “When these latches open, the molecule can change its shape. These crystals have to go through a lot of transformations before they actually reach the target location.”

The scientific world is now one step closer to genetically engineering BinAB to be lethal to the mosquitoes that carry Zika virus and dengue fever.

Eisenberg is optimistic. “It would be hard to find a problem that could potentially affect the health of more people,” he said.

Funding sources for the research include the Howard Hughes Medical Institute, W.M. Keck Foundation, National Science Foundation, National Institutes of Health, and the U.S. Department of Energy Office of Science and Office of Basic Energy Sciences.

David Eisenberg, UCLA’s Paul D. Boyer Professor of Molecular Biology

‘Jump-starting’ the brain of a patient recovering from a coma

Image: Representation of ultrasonic stimulation of the brain’s thalamus in a post-comatose patient.

New noninvasive technique could result in low-cost therapy for patients with severe brain injury

By Stuart Wolpert

A 25-year-old man recovering from a coma has made remarkable progress following a treatment to “restart” his brain using ultrasounds, a team of UCLA scientists reported in a letter published in the journal Brain Stimulation. This is the first time such an approach to severe brain injury has been tried.

“Our technique uses sonic stimulation to excite the neurons in the thalamus – almost as if we were jump-starting them back into function,” said lead author Martin Monti, associate professor of psychology and neurosurgery. “Until now, the only way of achieving this was for a patient to undergo brain surgery and have electrodes implanted directly inside the thalamus – an egg-shaped structure which serves as the bustling central hub for information flow within the brain – a risky procedure known as deep brain stimulation. Our approach directly targets the thalamus, but is noninvasive.”

This new technique, called low intensity focused ultrasound pulsation (LIFUP), has been pioneered by co-author Alexander Bystritsky, professor of psychiatry and biobehavioral sciences in the Semel Institute for Neuroscience and Human Behavior and founder of Brainsonix, which provided the experimental device for this research. In this approach, a small device, about the size of a coffee cup saucer, is placed by the side of a patient’s head. The device creates a small sphere of acoustic energy that can be aimed at different regions of the brain to excite or inhibit brain tissue. Monti said the technique is quite safe, partly because the amount of energy from each stimulation is small. The researchers repeated it 10 times over 10 minutes.

The changes in the patient’s brain were remarkable, Monti said. Before sonic stimulation, the patient could show only minimal signs of being conscious and of understanding speech. By the day after the sonic stimulation, he was able to show greater responses and started vocalizing responses. Three days later, the patient was fully conscious, had regained full language comprehension, could reliably communicate by gesturing “yes” or “no” with his head, and even gave a fist-bump.

“This result is exactly what we expected,” Monti said.

However, he cautioned that this is only one patient. “It is possible that we were just very lucky and happened to have stimulated the patient just as he

was spontaneously recovering,” Monti said. “This is why it is so crucial, before we get too excited, that we repeat this procedure in more patients.”

Joining with Ronald Reagan UCLA Medical Center

Monti and his colleagues, under the direction of UCLA professor Paul Vespa, are planning to perform this procedure in several more patients at the Ronald Reagan UCLA Medical Center, working with UCLA’s Brain Injury Research Center, and with funding from the Dana Foundation and the Tiny Blue Dot Foundation.

If the researchers are able to demonstrate that the recovery in this patient was linked to the ultrasound stimulation, the potential for this technique could be very large. There are currently few effective treatment options for patients in a coma, Monti said.

Monti’s long-term goal is to one day be able to build a small portable device, perhaps a helmet, that could be brought to the bedside of a patient who is in a coma and, with no surgery, help the brain return to normal levels of function, leading to the return of cognitive functions and consciousness.

Hope for an entirely new treatment

Monti said he hopes his technique could be the beginning of a new noninvasive, low-cost therapy to help wake up patients in a coma — perhaps even patients in a vegetative state and in a minimally conscious state, for whom there is almost no effective treatment.

The idea behind this new approach is that when patients fail to fully recover from a coma, and awaken to a state of deeply impaired mental function, this is due partly to an impairment in the functioning of the thalamus. Pharmacological treatment targets the thalamus only indirectly.

Co-authors are Vespa, who holds UCLA’s Gary L. Brinderson Family Chair in Neurocritical Care, and is a professor of neurology and neurosurgery at the UCLA David Geffen School of Medicine, and director of neurocritical care at the Ronald Reagan UCLA Medical Center; Caroline Schnakers, a UCLA researcher in neurosurgery; Bystritsky; and Alexander Korb, a researcher in the Semel Institute.

 

Meet the Professor- In his own words

By Martin Monti

In my laboratory we focus on two of the most fundamental aspects of being human:
1. What is the relationship between language and thought?
Does language make us special? One of the most striking features of human cognition is the ability to generate an infinite number of ideas by combining a finite set of elements according to structure-dependent principles. This ability is most clearly displayed in language, but also characterizes other aspects of our cognition such as drawing inferences, performing mental arithmetic or music cognition. Does language enable other types of structure-dependent cognition? Does the structure of natural language provide a scaffolding on which to build other forms of high-level cognition? In my research I employ behavioral and fMRI tools in healthy volunteers and patients to address these questions.
2. How is consciousness lost and recovered after severe brain injury?
How do we ever know that someone, other than ourselves, is conscious? Philosophical considerations aside, this issue is at the heart of one of the most challenging and least understood conditions of the human brain: the Vegetative State. This is a condition in which, after severe brain injury, patients are awake but not aware. In my research I focus on brain processing and consciousness in these patients, to try to ameliorate diagnostic procedures and to develop new interventions that may help recovery.

 

Watch it here Professor Monti on “The Mystery of Consciousness and the Vegetative State” at TEDx Claremont Colleges

 

 

Digital humanities students shine a light on the history of African American filmmakers

By Jessica Wolf

While the #OscarsSoWhite controversy raged over the dearth of people of color nominated for Academy Awards this past year, a group of digital humanities students at UCLA channeled their frustration into meticulously building the little-known history of silent films made for and by African Americans in the early 20th century.

 

Photo from Within Our Gates (1919), the oldest known surviving film made by an African American director.

What they found, and sought to highlight, is that African American artists are deeply entwined in the history of filmmaking,  and can be traced back to the medium’s beginnings.

The result of their efforts is “Early African American Film: Reconstructing the History of Silent Race Films, 1909-1930,” an informational website and searchable database that tracks the African American actors, crew members, writers, producers and other artists who were making films during the silent era.

“We were venturing into pretty unknown territory and I really wanted to be a part of telling the stories of this generation of African American people and their contributions,” said Shayna Norman, who graduated last spring. “The fact that the #OscarsSoWhite controversy blew up at the same time we worked on it made this project feel even more relevant and important.”

Hands-on research

Students worked closely with UCLA Library Special Collections, combing through old journals, production notes, posters and fliers to reconstruct what was once a thriving and collaborative network of African American writers, directors, actors and producers who were making what were known as “race films.”

Relying partially on the work of historians who have unearthed documentation of these forgotten filmmakers, the UCLA student team set its parameters to include films from 1909 to 1930 that featured African American cast members, were produced by an independent production company and discussed or advertised as a race film in the African American press.

While the community was vibrant, it struggled to gain mainstream traction. In the silent-film era, productions that fit the “race films”description, like those produced by the Hampton and Tuskegee Institutes, A Trip to Tuskegee (1909), John Henry at Hampton (1913) and A Day at Tuskegee (1913), could be shown only in certain theaters, or often in African American churches, and were played to segregated audiences. Most of these films, therefore, received scant mainstream media attention. The actual film reels were not preserved in any systematic way or protected in hermetically sealed vaults, which has led to physical degradation.

Motion picture director Oscar Micheaux (center) with an actor and a possible crew member appearing in an advertisement for the Micheaux Film Corporation.

Finding forgotten films

Few films survive, though Miriam Posner, core faculty and program coordinator for the digital humanities at UCLA, was partially inspired to ignite the project thanks to the recent release of a compilation of films from Kino Lorber called Pioneers of African-American Cinema.

The scarcity drove the students.

Coming up empty on internet searches caught students particularly off guard, Norman said.

“We’re not used to that kind of obscurity, but so much of the data has been lost or damaged, is not in any history textbooks in our educational system, and is not easily searchable,” she said.

A centering figure in the students’ archival exploration was Oscar Micheaux, author, filmmaker and founder of the Micheaux Film Corporation, one of the most prominent producers of the era’s race films. He kept copious notes and records on the actors and crew members he worked with, providing much-needed fodder for the database. Micheaux’s Within Our Gates (1919) is one of the few examples of a race film that garnered some attention — and an audience — from the white press.

Making data accessible worldwide

The project exists as a perusable database on the code-sharing site GitHub that others may use, build upon and correct. The site maintains a trail of attribution to the UCLA project.

“Not everyone knows how to work with data like ours, so we also spent a lot of time building tutorials that show people exactly how to create their own network graphs, maps and other kinds of analysis using our data,” Posner said.

Capstone activities like this are extremely important in the digital humanities field because students have the best, most meaningful experiences while apprenticing on an active project, she said.

“We love the way that students and faculty come to rely on each other, developing mutual respect for each other’s skills and abilities,” Posner said. “In a lot of cases, the capstone projects like this are specifically designed to live on after the q

Poster for Black Gold, Richard E. Norman’s lost final feature. Norman was a pioneer in the development of films for African American audiences.

uarter has ended. In all cases, we ensure that we preserve a ‘snapshot’ of the work from the time the quarter ended, and that all students are credited for their work.”

Working on a project like this has made lasting impact on the students.

“We get to work on a project that leaves an important footprint,” Girma said. “That’s the amazing part of the digital humanities.” A World Arts and Cultures major, Girma said she added a digital humanities minor in her fourth year after she heard from a friend that the coursework was “life-changing.”

Norman said that she hopes to pursue a career that allows her to continue working at the intersection of entertainment and digital technology.

“I’m a media junkie and by being involved in digital humanities projects like this one, I can see how such digital research methods and skills are relevant and needed in this growing age of mass consumer media.”

LEARN MORE:
Explore the students’ research,
“Early African American Film: Reconstructing the History of Silent Race Films, 1909-1930,”on their website at http://ucla.in/2fhm3BQ

 

 

 

Watch race film Within Our Gates at https://youtu.be/h1E0NrcnwAE