Detail from the 1871 painting "The Somnambulist" by John Everett Millais.
In the 1830s, a 16-year-old girl became famous as a sleepwalker and an experimental patient of the early asylum movement. The curious case is one of many unearthed by Emory English professor Benjamin Reiss, the author of “Theaters of Madness: Insane Asylums and Nineteenth-Century American Culture.”
Reiss was recently interviewed about the case on the public radio show “BackStory with the American History Guys.”
Jane C. Rider, from Brattleboro, Vermont, was a servant to a wealthy family who became a medical curiosity when she started to do her chores while sleep walking.
“Some of the things that she would do included setting the table, perfectly, during the middle of the night,” Reis told “BackStory.” She’d wake up in the morning and wonder why someone else had done her job for her while she was sleeping.
A doctor seeking to cure Rider of her condition coaxed her into entering one of the newly opened lunatic asylums, which was mainly populated by the criminally insane.
“She was given everything from opium to ether to medications that would make her vomit,” Reiss said. “Leeches were applied, she was bled profusely. She was blistered, also. Puss would ooze out of her. Some thought it would draw out whatever fluids that would not harmonize with her body and were causing her to behave this way.”
Click here to listen to the “BackStory” podcast.
Reiss’ current research focuses on a cultural history of sleep, from the industrial revolution in the 19th century to the present. “I’m interested in how sleep has become such a ‘problem’ in contemporary culture,” he says, “something in need of micro-management, medical advice and pervasive worry.”
Related:
Shedding light on a pre-electric sleep culture
Some eye-opening thoughts on sleep
Wednesday, June 5, 2013
Monday, June 3, 2013
Helping everyone see the light of evolution
"If we don’t help everyone understand what constitutes science and what constitutes faith, we’re bound to run into more problems," says evolutionary biologist Jaap de Roode.
By Carol Clark
Jaap de Roode likes to tell his Evolutionary Biology students: “I don’t believe in evolution.”
It gets their attention. Then he explains: “Evolution isn’t a belief, it’s a theory. You may believe in God and have faith in a religion, but when it comes to science, you look at the evidence for a theory and then decide whether to accept it.”
Any perceived conflict between science and religious beliefs often comes down to semantics, says de Roode, assistant professor of biology at Emory. “I want all of my students to understand the meaning of ‘scientific theory’ and why science is different from faith, but doesn’t have to be in conflict with it,” he says.
Adding to the confusion is the popular use of the word “theory” to describe a hunch or a guess. In science, a hypothesis is more akin to a hunch or a guess, while a theory refers to a body of knowledge supported by considerable evidence, such as gravitational theory or cell theory.
Despite his efforts, at the end of 16 weeks of teaching evolution theory, de Roode sometimes has one or two students complain on their class evaluation forms that he should include opposing views.
“It’s shocking to me that even some seniors, after taking many science courses, still don’t understand that scientifically, there is no alternative to evolution theory,” de Roode says. “They don’t want to fail the class, so they give me the answers they know that I want to see, but they remain skeptical. That bugs me as a scientist, and as a teacher.”
Forty-six percent of Americans responding to a Gallup poll in 2012 said that they believe God created humans in their present form within the past 10,000 years or so, a belief sometimes referred to as “creationism.”
While only a tiny fraction of Emory students report feeling that way to de Roode, even one is too many for him.
“Part of the reason that some of these students don’t want to accept evolution is fear,” he says. “They see and understand the evidence, but they are afraid that it means they will have to give up their faith. I feel strongly that it is my role to help students resolve this conflict.”
The issue came to a head last year, when Emory tapped Ben Carson for its 2012 commencement speaker. In addition to being a renowned neurosurgeon, Carson is a 7th Day Adventist and an advocate of creationism.
A student in de Roode’s class brought Carson’s views on evolution to his attention. De Roode joined with several other faculty to write a letter, published by the Emory Wheel, aimed not at disinviting Carson, but to call attention to Carson’s denial of evolution, and a statement he made implying that accepting evolution was akin to dismissing ethics.
The Emory faculty countered that evolution and the scientific method are not at odds with being moral or religious. “Dr. Carson insists on not seeing a difference between science, which is predictable and falsifiable, and religious belief systems, which by their very nature cannot be falsified,” they wrote. “This is especially troubling since his great achievements in medicine allow him to be viewed as someone who ‘understands science.’”
"Science doesn't invent nature. Science reveals nature," says Joel Martin, author of "The Prism and the Rainbow: A Christian Explains Why Evolution is Not a Threat."
Four hundred others from across the Emory community signed in support of the letter. De Roode points out that he is a great admirer of Carson as a physician. “But it’s important to pay attention to this issue of anti-scientific views,” de Roode says, “because it is standing in the way of scientific progress and the future of this nation. As a university, we are training the country’s future leaders.”
De Roode and other Emory faculty, including biologist Arri Eisen, biophysicist Ilya Nemenman and chemist David Lynn got together with Emory President James Wagner to discuss how to help students struggling to resolve any perceived conflict between scientific evidence and their religious beliefs. They launched a series of small, informal dinners and speaker seminars called “The Nature of Knowledge.”
Five students turned up to discuss evolution and faith at the first dinner, hosted by de Roode and Lynn, and including representatives from Campus Life and the Dean of the Chapel and Religious Life.
“I grew up in a fundamentalist Christian family,” said a freshman majoring in neuroscience and behavioral biology, explaining why he attended the dinner. “I asked my youth counselor in church about the science of evolution that I was learning in high school and he just said, ‘Don’t pay any attention to that.’ But as you grow older, you have to make your own decisions.”
The student added that he has long been a fan of Bill Nye “the science guy,” and a recent video by Nye called “Creationism is Not Appropriate for Children,” prompted him to think more deeply about the topic.
While he accepts evolutionary theory, he finds it odd that, “when high school teachers talk about it, they feel like they have to say, ‘I don’t want to offend anyone’s religious beliefs.’”
In the above video, Bill Nye "the science guy" gives his views on teaching evolution.
The first “Nature of Knowledge” seminar speaker, Joel Martin, drew a standing-room-only audience to Emory’s Harland Cinema last fall. Martin is both an evolutionary biologist at the Natural History Museum of Los Angeles County and an ordained elder in the Presbyterian Church USA, where he works with high school youth ministry. He published a book in 2010 called “The Prism and the Rainbow: A Christian Explains Why Evolution is Not a Threat.”
“When light hits a drop of water, it refracts. It’s a stunning natural spectacle,” Martin told the Emory audience, adding that knowing how a rainbow works does not have to remove God from the picture. “Science does not invent nature. Science reveals nature,” he said. “If this is God’s world, science can only reveal God’s world.”
Martin described a growing disconnect between youth, science and faith. He noted that most major Christian denominations in the United States officially accept the science of evolution, even though some of the members may not.
“The most respected theologians that we have need to come forward and be much more vocal on this issue,” Martin said.
Kyle Niezgoda, a junior majoring in environmental studies, found Martin’s talk beneficial, although he has never doubted evolution.
“I think it’s important to understand how others think and feel, so you can work towards a common goal instead of just arguing,” said Niezgoda, who plans to go to graduate school to study atmospheric science. “The more I get involved in science, the more I realize the importance of being able to translate what I learn to the public, especially when it comes to things like climate change.”
In the spring, a second “Nature of Knowledge” seminar featured Emory primatologist Frans de Waal, who talked about his new book, “The Bonobo and the Atheist: In Search of Humanism Among the Primates.” He described the growing scientific evidence that morality predates religion.
“The Nature of Knowledge” program will continue the series in the fall, with plans to expand some of its events to involve resident life in the dorms.
“We don’t want to stage useless debates between evolution proponents and opponents,” de Roode said. “We’re trying to educate students about the wonderful world around us, rather than have fireworks. If we don’t help everyone understand what constitutes science and what constitutes faith, we’re bound to run into more problems and our children will suffer for it.”
Photos by iStockphoto.com
Related:
Teaching evolution enters new era
Brain trumps hand in Stone Age tool study
A brainy time traveler
By Carol Clark
Jaap de Roode likes to tell his Evolutionary Biology students: “I don’t believe in evolution.”
It gets their attention. Then he explains: “Evolution isn’t a belief, it’s a theory. You may believe in God and have faith in a religion, but when it comes to science, you look at the evidence for a theory and then decide whether to accept it.”
Any perceived conflict between science and religious beliefs often comes down to semantics, says de Roode, assistant professor of biology at Emory. “I want all of my students to understand the meaning of ‘scientific theory’ and why science is different from faith, but doesn’t have to be in conflict with it,” he says.
Adding to the confusion is the popular use of the word “theory” to describe a hunch or a guess. In science, a hypothesis is more akin to a hunch or a guess, while a theory refers to a body of knowledge supported by considerable evidence, such as gravitational theory or cell theory.
Despite his efforts, at the end of 16 weeks of teaching evolution theory, de Roode sometimes has one or two students complain on their class evaluation forms that he should include opposing views.
“It’s shocking to me that even some seniors, after taking many science courses, still don’t understand that scientifically, there is no alternative to evolution theory,” de Roode says. “They don’t want to fail the class, so they give me the answers they know that I want to see, but they remain skeptical. That bugs me as a scientist, and as a teacher.”
Forty-six percent of Americans responding to a Gallup poll in 2012 said that they believe God created humans in their present form within the past 10,000 years or so, a belief sometimes referred to as “creationism.”
While only a tiny fraction of Emory students report feeling that way to de Roode, even one is too many for him.
“Part of the reason that some of these students don’t want to accept evolution is fear,” he says. “They see and understand the evidence, but they are afraid that it means they will have to give up their faith. I feel strongly that it is my role to help students resolve this conflict.”
The issue came to a head last year, when Emory tapped Ben Carson for its 2012 commencement speaker. In addition to being a renowned neurosurgeon, Carson is a 7th Day Adventist and an advocate of creationism.
A student in de Roode’s class brought Carson’s views on evolution to his attention. De Roode joined with several other faculty to write a letter, published by the Emory Wheel, aimed not at disinviting Carson, but to call attention to Carson’s denial of evolution, and a statement he made implying that accepting evolution was akin to dismissing ethics.
The Emory faculty countered that evolution and the scientific method are not at odds with being moral or religious. “Dr. Carson insists on not seeing a difference between science, which is predictable and falsifiable, and religious belief systems, which by their very nature cannot be falsified,” they wrote. “This is especially troubling since his great achievements in medicine allow him to be viewed as someone who ‘understands science.’”
"Science doesn't invent nature. Science reveals nature," says Joel Martin, author of "The Prism and the Rainbow: A Christian Explains Why Evolution is Not a Threat."
Four hundred others from across the Emory community signed in support of the letter. De Roode points out that he is a great admirer of Carson as a physician. “But it’s important to pay attention to this issue of anti-scientific views,” de Roode says, “because it is standing in the way of scientific progress and the future of this nation. As a university, we are training the country’s future leaders.”
De Roode and other Emory faculty, including biologist Arri Eisen, biophysicist Ilya Nemenman and chemist David Lynn got together with Emory President James Wagner to discuss how to help students struggling to resolve any perceived conflict between scientific evidence and their religious beliefs. They launched a series of small, informal dinners and speaker seminars called “The Nature of Knowledge.”
Five students turned up to discuss evolution and faith at the first dinner, hosted by de Roode and Lynn, and including representatives from Campus Life and the Dean of the Chapel and Religious Life.
“I grew up in a fundamentalist Christian family,” said a freshman majoring in neuroscience and behavioral biology, explaining why he attended the dinner. “I asked my youth counselor in church about the science of evolution that I was learning in high school and he just said, ‘Don’t pay any attention to that.’ But as you grow older, you have to make your own decisions.”
The student added that he has long been a fan of Bill Nye “the science guy,” and a recent video by Nye called “Creationism is Not Appropriate for Children,” prompted him to think more deeply about the topic.
While he accepts evolutionary theory, he finds it odd that, “when high school teachers talk about it, they feel like they have to say, ‘I don’t want to offend anyone’s religious beliefs.’”
In the above video, Bill Nye "the science guy" gives his views on teaching evolution.
The first “Nature of Knowledge” seminar speaker, Joel Martin, drew a standing-room-only audience to Emory’s Harland Cinema last fall. Martin is both an evolutionary biologist at the Natural History Museum of Los Angeles County and an ordained elder in the Presbyterian Church USA, where he works with high school youth ministry. He published a book in 2010 called “The Prism and the Rainbow: A Christian Explains Why Evolution is Not a Threat.”
“When light hits a drop of water, it refracts. It’s a stunning natural spectacle,” Martin told the Emory audience, adding that knowing how a rainbow works does not have to remove God from the picture. “Science does not invent nature. Science reveals nature,” he said. “If this is God’s world, science can only reveal God’s world.”
Martin described a growing disconnect between youth, science and faith. He noted that most major Christian denominations in the United States officially accept the science of evolution, even though some of the members may not.
“The most respected theologians that we have need to come forward and be much more vocal on this issue,” Martin said.
Kyle Niezgoda, a junior majoring in environmental studies, found Martin’s talk beneficial, although he has never doubted evolution.
“I think it’s important to understand how others think and feel, so you can work towards a common goal instead of just arguing,” said Niezgoda, who plans to go to graduate school to study atmospheric science. “The more I get involved in science, the more I realize the importance of being able to translate what I learn to the public, especially when it comes to things like climate change.”
In the spring, a second “Nature of Knowledge” seminar featured Emory primatologist Frans de Waal, who talked about his new book, “The Bonobo and the Atheist: In Search of Humanism Among the Primates.” He described the growing scientific evidence that morality predates religion.
“The Nature of Knowledge” program will continue the series in the fall, with plans to expand some of its events to involve resident life in the dorms.
“We don’t want to stage useless debates between evolution proponents and opponents,” de Roode said. “We’re trying to educate students about the wonderful world around us, rather than have fireworks. If we don’t help everyone understand what constitutes science and what constitutes faith, we’re bound to run into more problems and our children will suffer for it.”
Photos by iStockphoto.com
Related:
Teaching evolution enters new era
Brain trumps hand in Stone Age tool study
A brainy time traveler
Wednesday, May 29, 2013
A healthy business is in his cards
Eddie Kovel just graduated from Emory with the unusual combination of a business major and a predictive health minor, fashioned with the support of the Center for the Study of Human Health. One of the fastest growing sectors in the economy, the human health field is creating new opportunities in medicine, business, law, public policy, the arts and elsewhere.
“There’s definitely an emerging need for business-minded health professionals and health-minded business professionals,” Kovel says.
Kovel has developed a card game called “Playout” which aims to motivate people to exercise. He’s now working to spread the word about the product, and its philosophy of having fun while getting fit.
Related:
Predictive health: A call to reinvent medicine
Friday, May 24, 2013
A medical exhibit that won't put you to sleep
"Medical Treasures at Emory" is an exhibit of historical artifacts that serve as reminders of the days when doctors had a rudimentary understanding of human anatomy, performed surgery without antiseptic and used primitive forms of anesthesia for operations and dental work.
The above video gives a peek at some of the objects on display through October at the Woodruff Health Sciences Center Library. Notable artifacts include one of the earliest stethoscopes from the 19th century, and a kit of Civil War surgeon's instruments, primarily used for amputation.
Among the historical books on display are volumes about Civil War field surgery practices, an 1881 book that incorporates early medical photography to show the ravages of syphilis, a copy of "Notes on Nursing: What It is, and What It Is Not" (1865) by Florence Nightingale, and an 1849 obstetrics book by Charles D. Meigs, an obstetrician who opposed anesthesia and the introduction of sanitary practices during childbirth on the theory that "doctors are gentlemen and a gentleman's hands are clean."
Also on display is a rare copy of "One the Workings of the Human Body," or "de Humani corporis fabrica," a 1543 book containing the first accurate representations of human anatomy.
Read more about the exhibit.
Related:
The rare book that changed medicine
Objects of our afflictions
The above video gives a peek at some of the objects on display through October at the Woodruff Health Sciences Center Library. Notable artifacts include one of the earliest stethoscopes from the 19th century, and a kit of Civil War surgeon's instruments, primarily used for amputation.
Among the historical books on display are volumes about Civil War field surgery practices, an 1881 book that incorporates early medical photography to show the ravages of syphilis, a copy of "Notes on Nursing: What It is, and What It Is Not" (1865) by Florence Nightingale, and an 1849 obstetrics book by Charles D. Meigs, an obstetrician who opposed anesthesia and the introduction of sanitary practices during childbirth on the theory that "doctors are gentlemen and a gentleman's hands are clean."
Also on display is a rare copy of "One the Workings of the Human Body," or "de Humani corporis fabrica," a 1543 book containing the first accurate representations of human anatomy.
Read more about the exhibit.
Related:
The rare book that changed medicine
Objects of our afflictions
Monday, May 20, 2013
Parasitic wasps use calcium pump to block fruit-fly immunity
A parasitic wasp on the prowl for fruit fly larva to inject with her eggs.
By Carol Clark
Parasitic wasps switch off the immune systems of fruit flies by draining calcium from the flies’ blood cells, a finding that offers new insight into how pathogens break through a host’s defenses.
“We believe that we have discovered an important component of cellular immunity, one that parasites have learned to take advantage of,” says Emory University biologist Todd Schlenke, whose lab led the research.
The Proceedings of the National Academy of Sciences (PNAS) published the results, showing how a wasp version of a conserved protein called SERCA, which normally functions to pump calcium from the cell cytoplasm to the endoplasmic reticulum, can block a host’s cellular immune response.
“Before our study, there were hints that calcium signaling was important for blood cell activation following infection, but the fact that a parasite actively suppresses this signaling shows how important it is, Schlenke says. He adds that the insects can serve as a model for more complex human immune systems.
“It’s incredible the way the wasps use a protein in their venom to control the flies at a molecular level,” says Nathan Mortimer, a post-doctoral fellow in the Schlenke lab who conducted the experiments. “Instead of killing the fly immune cells, the wasps actually take over blood-cell signaling, manipulating the host’s cellular behavior from the bottom up.”
The research team also included Emory biologist Balint Kacsoh; Jeremy Goecks and James Taylor, from Emory’s departments of biology and mathematics and computer science; and James Mobley and Gregory Bowersock of the University of Alabama, Birmingham.
Fruit fly wins: A wasp egg has turned black and died (see arrow) inside the larva of a fruit fly that has mounted a successful immune response.
Fruit flies and the tiny wasps that parasitize them have co-evolved complex strategies of attack and defense. The wasps inject their eggs into the body cavities of fruit fly larvae, along with venom that aims to suppress the flies’ cellular immunity. If the flies fail to kill the wasp egg, a wasp larva hatches inside the fruit fly larva and begins to eat its host from the inside out.
“The wasp larvae have these sharp appendages, like the fingers of Edward Scissorhands, that they use to stick into the fly tissue and start eating,” Mortimer says. “It’s a brutal process.”
In previous research, the Schlenke lab has shown how fruit flies sometimes use alcohol in rotting fruit as a drug to kill the wasps.
In the current study, the researchers focused on the molecular attack strategies of the wasps. After sequencing the transcriptome of the newly described wasp species Ganaspis sp.1, they took a proteomic approach to identify peptide sequences out of the wasp’s venom gland, which they could then link back to full-length transcript sequences.
“We found that the venom of Ganaspis sp.1 is a toxic cocktail of 170 different proteins,” Schlenke says, “but the most prominent component was the SERCA calcium pump protein. That really surprised us.”
Wasps win: Arrows point to wasp larvae that have successfully blocked the fruit-fly immune response and are eating the tissue of the fruit fly.
Calcium pumps are found in the membranes of every living cell of every animal, and are needed to maintain ionic homeostasis and cellular stability. One type of pump moves calcium ions out of the endoplasmic reticulum and into the cytoplasm where they transmit signals that activate other proteins. The SERCA calcium pump operates in the opposite direction, sucking calcium ions out of the cytoplasm and back into storage.
“We wondered why the wasps would inject the flies with a protein that the flies already have, and that every cell needs to function,” Schlenke says. “How could that be an infection strategy?”
The researchers knew of studies suggesting that a calcium burst in cytoplasm is associated with the activation of human blood cells. They wondered if something similar was happening with the flies.
Mortimer conducted experiments on a transgenic fly strain with cells that fluoresce in the presence of calcium. He found that the fly blood cells release a burst of calcium into their cytoplasm, and that this activates the blood cells to start homing in on the wasp eggs. Genetically increasing or decreasing blood-cell calcium levels makes the flies more or less resistant to the parasite infection.
“The wasp venom prevents this calcium burst, and it’s like the fly blood cells don’t realize they’re supposed to be responding to infection,” Mortimer says. “The venom essentially sucks the calcium out of the fly’s blood cells.”
The experiments showed that the wasp venom is specifically targeted to the fly blood cells, and has no effect on other cells.
An unresolved question is how a SERCA protein, which is hydrophobic and normally resides in an oily membrane, moves out of a wasp venom cell and makes its way into a fly blood cell.
“We have no idea how it works,” Schlenke says, “but somehow this calcium pump moves through all these environments and finds its way into its target cells.”
The researchers hypothesize that virus-like particles in the wasp’s venom may be involved. “If they aren’t really viruses, they seem to be some virus-like thing that the wasp has invented,” Schlenke says. “It’s pure speculation, but we think maybe the wasps use these particles as delivery vehicles for the calcium pumps.”
Previous research has established that fruit fly immune signaling pathways have homologues in humans, making fruit flies a valuable model for learning about human immunity. That work led to the award of the 2011 Nobel Prize in physiology or medicine to Jules Hoffmann, a fruit fly immunologist.
Studying the wasp-fly battle for survival at the molecular level provides a powerful new tool for unlocking more secrets of immunity that could apply to human health, Mortimer says.
“I’m also interested in using the flies to understand more about the immune systems of mosquitos and other insect vectors of human disease,” he says. “If we could somehow boost vector insect immunity, it could decrease transmission of human disease like malaria.”
Related:
Fruit flies use alcohol as a drug to kill parasites
Fruit flies force their young to drink alcohol -- for their own good
What aphids can teach us about immunity
By Carol Clark
Parasitic wasps switch off the immune systems of fruit flies by draining calcium from the flies’ blood cells, a finding that offers new insight into how pathogens break through a host’s defenses.
“We believe that we have discovered an important component of cellular immunity, one that parasites have learned to take advantage of,” says Emory University biologist Todd Schlenke, whose lab led the research.
The Proceedings of the National Academy of Sciences (PNAS) published the results, showing how a wasp version of a conserved protein called SERCA, which normally functions to pump calcium from the cell cytoplasm to the endoplasmic reticulum, can block a host’s cellular immune response.
“Before our study, there were hints that calcium signaling was important for blood cell activation following infection, but the fact that a parasite actively suppresses this signaling shows how important it is, Schlenke says. He adds that the insects can serve as a model for more complex human immune systems.
“It’s incredible the way the wasps use a protein in their venom to control the flies at a molecular level,” says Nathan Mortimer, a post-doctoral fellow in the Schlenke lab who conducted the experiments. “Instead of killing the fly immune cells, the wasps actually take over blood-cell signaling, manipulating the host’s cellular behavior from the bottom up.”
The research team also included Emory biologist Balint Kacsoh; Jeremy Goecks and James Taylor, from Emory’s departments of biology and mathematics and computer science; and James Mobley and Gregory Bowersock of the University of Alabama, Birmingham.
Fruit flies and the tiny wasps that parasitize them have co-evolved complex strategies of attack and defense. The wasps inject their eggs into the body cavities of fruit fly larvae, along with venom that aims to suppress the flies’ cellular immunity. If the flies fail to kill the wasp egg, a wasp larva hatches inside the fruit fly larva and begins to eat its host from the inside out.
“The wasp larvae have these sharp appendages, like the fingers of Edward Scissorhands, that they use to stick into the fly tissue and start eating,” Mortimer says. “It’s a brutal process.”
In previous research, the Schlenke lab has shown how fruit flies sometimes use alcohol in rotting fruit as a drug to kill the wasps.
In the current study, the researchers focused on the molecular attack strategies of the wasps. After sequencing the transcriptome of the newly described wasp species Ganaspis sp.1, they took a proteomic approach to identify peptide sequences out of the wasp’s venom gland, which they could then link back to full-length transcript sequences.
“We found that the venom of Ganaspis sp.1 is a toxic cocktail of 170 different proteins,” Schlenke says, “but the most prominent component was the SERCA calcium pump protein. That really surprised us.”
Wasps win: Arrows point to wasp larvae that have successfully blocked the fruit-fly immune response and are eating the tissue of the fruit fly.
Calcium pumps are found in the membranes of every living cell of every animal, and are needed to maintain ionic homeostasis and cellular stability. One type of pump moves calcium ions out of the endoplasmic reticulum and into the cytoplasm where they transmit signals that activate other proteins. The SERCA calcium pump operates in the opposite direction, sucking calcium ions out of the cytoplasm and back into storage.
“We wondered why the wasps would inject the flies with a protein that the flies already have, and that every cell needs to function,” Schlenke says. “How could that be an infection strategy?”
The researchers knew of studies suggesting that a calcium burst in cytoplasm is associated with the activation of human blood cells. They wondered if something similar was happening with the flies.
Mortimer conducted experiments on a transgenic fly strain with cells that fluoresce in the presence of calcium. He found that the fly blood cells release a burst of calcium into their cytoplasm, and that this activates the blood cells to start homing in on the wasp eggs. Genetically increasing or decreasing blood-cell calcium levels makes the flies more or less resistant to the parasite infection.
“The wasp venom prevents this calcium burst, and it’s like the fly blood cells don’t realize they’re supposed to be responding to infection,” Mortimer says. “The venom essentially sucks the calcium out of the fly’s blood cells.”
The experiments showed that the wasp venom is specifically targeted to the fly blood cells, and has no effect on other cells.
An unresolved question is how a SERCA protein, which is hydrophobic and normally resides in an oily membrane, moves out of a wasp venom cell and makes its way into a fly blood cell.
“We have no idea how it works,” Schlenke says, “but somehow this calcium pump moves through all these environments and finds its way into its target cells.”
The researchers hypothesize that virus-like particles in the wasp’s venom may be involved. “If they aren’t really viruses, they seem to be some virus-like thing that the wasp has invented,” Schlenke says. “It’s pure speculation, but we think maybe the wasps use these particles as delivery vehicles for the calcium pumps.”
Previous research has established that fruit fly immune signaling pathways have homologues in humans, making fruit flies a valuable model for learning about human immunity. That work led to the award of the 2011 Nobel Prize in physiology or medicine to Jules Hoffmann, a fruit fly immunologist.
Studying the wasp-fly battle for survival at the molecular level provides a powerful new tool for unlocking more secrets of immunity that could apply to human health, Mortimer says.
“I’m also interested in using the flies to understand more about the immune systems of mosquitos and other insect vectors of human disease,” he says. “If we could somehow boost vector insect immunity, it could decrease transmission of human disease like malaria.”
Related:
Fruit flies use alcohol as a drug to kill parasites
Fruit flies force their young to drink alcohol -- for their own good
What aphids can teach us about immunity
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Environmental Studies,
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