Daily Archives: January 11, 2017

Research: Some Bats Develop Resistance to Devastating Fungal Disease

Some bat populations in North America appear to have developed resistance to the deadly fungal disease known as white-nose syndrome. Researchers from the University of New Hampshire analyzed infection data and population trends of the little brown bat in the eastern United States and found that persisting populations long exposed to the disease had much lower fungal infection levels at the end of winter than bat populations that were still declining and only recently exposed.

The little brown bat was previously one of the most abundant bat species in the eastern United States, but was reduced to less than 10 percent of its former population with the arrival of white-nose syndrome.

The little brown bat was previously one of the most abundant bat species in the eastern United States, but was reduced to less than 10 percent of its former population with the arrival of white-nose syndrome. The fungus was introduced to New York in 2006, and continues to spread across the U.S. and Canada.

Bats play an important role in controlling insect pests called insectivorous. They feast on insects each night, adding up to more than $3.7 billion worth of pest control each year in the U.S., according to the National Park Service. When bats are around to eat insects, there are fewer insect pests causing damage to crops, and farmers don’t have to invest as much in pesticides.

UNH researchers Jeffrey Foster and Katy Parise collaborated with scientists at the University of California Santa Cruz to sample hibernating bats at nine sites in New York, Illinois, and Virginia using a standardized sampling technique to detect and quantify the amount of white-nose fungus on each bat. They then used mathematical modeling techniques to examine disease dynamics between persisting and declining bat populations. Their findings were published recently in the journal Philosophical Transactions of the Royal Society: Biological Sciences.

“Populations of little brown bats have declined dramatically across their range,” said first author Kate Langwig, who worked on the study as a graduate student at UC Santa Cruz and is now a postdoctoral researcher at Harvard University. “There have been several reports that populations in New York, where the disease was first introduced, are no longer declining, but no one understood why. It now appears that at least some populations have developed resistance to the disease.”

The researchers considered several possible hypotheses for the ability of some bats to persist with the fungus: host resistance, host tolerance, and lower transmission. Their results pointed toward host resistance causing lower growth rates of the fungus during late winter. The results did not support the other hypotheses, Langwig said.

How disease resistance has developed in little brown bats remains unknown. “It could be changes in arousal behavior, differences in skin microbes, or an activation of the immune response by bats after infection has reached a moderate level,” Foster said. One key next step is to determine which specific mechanisms enable resistance to white-nose syndrome.

The authors emphasized that they have only examined populations of a single bat species. “For other species, like the northern long-eared bat, we don’t have evidence to suggest populations are persisting inside hibernacula,” Langwig said. “While this study is good news for some colonies of little brown bats, other species show little sign of being able to persist with the disease.”

Source: University of New Hampshire


Secret New Weapon of Insect-Transmitted Viruses Exposed

Findings by a team of scientists, including two from the University of California, Riverside, could provide critical knowledge to attack deadly viruses transmitted by arthropods such as mosquitoes and aphids.

The scientists uncovered molecular mechanisms that the cucumber mosaic virus uses to manipulate plants to make them release odors that attract aphids, which transmit the virus. The work was published Jan. 6 in the journal Cell Research.

Spinach plant infected with cucumber mosaic virus.

The cucumber mosaic virus, which is found worldwide, spreads rapidly and causes irreversible damage to plants, including many used in landscaping, and vegetable crops, such as tomatoes, peppers, lettuce, and cucumbers. The research could lead to more disease resistant vegetables and larger crop yields for farmers.

Shou-Wei Ding, a professor of plant pathology and microbiology at UC Riverside, has studied RNA viruses, such as cucumber mosaic virus, for more than 20 years. Much of that work has focused on understanding virus-host interactions.

Many important diseases in plants and humans are caused by pathogens, such as cucumber mosaic virus and Zika virus, which are transmitted by disease-carrying arthropods. The emergence and success of these pathogens are shaped by their molecular interactions with both the host and the arthropods.

The primary defense for plants against cucumber mosaic virus and other viruses is directed by RNA interference (RNAi). As a common counter-defense strategy, Ding previously found that a protein (known as the 2b protein) in the cucumber mosaic virus blocks a plant from launching antiviral RNA interference.

The current Cell Research paper builds on Ding’s previous work and other studies that have found some pathogens can manipulate plants and animals to cause them to release odors that are attractive to the mosquitos and aphids that transmit the pathogen.

While that broader concept is understood, the molecular mechanism underlying this host manipulation has been unknown. In particular, the specific effectors the pathogens employ, and the pathways within the hosts they target, had been unknown.

The research outlined in the Cell Research paper provides answers to those questions.

The scientists found that the aphid-borne cucumber mosaic virus employs its 2b protein to suppress a specific hormone pathway in the plant, thus making aphid vectors more attracted to the infected plant. The hormone is known as jasmonic acid and is studied extensively by Daoxin Xie, a professor of Tsinghua University in China.

The findings represent the first time that a viral effector protein has been seen as attracting insect vectors to feed on plants through odor. The findings also represent the first time that a plant hormone has been uncovered as the major host factor to mediate the attraction of insect vectors to the infected plants.

These findings provide a novel strategy to control viral diseases by targeting either the viral effector protein or the host hormone required for attracting disease vectors to the infected host for virus transmission.

The paper is called “Viral effector protein manipulates host hormone signaling to attract insect vectors.”

In addition to Ding and Xie, the authors are: Wan-Xiang Li, a staff research associate working with Ding; Dewei Wu, Tiancong Qi, Hua Gao, Jiaojiao Wang, Ruifeng Yao, Haixia Tian, Chunmei Ren, Yule Liu, and Xian-Bing Wang working with Xie; and Jin Ge working with Le Kang of the Chinese Academy of Sciences.

Source: UC Riverside

Brain impairments in premature infants may begin in the womb

Even before they are born, premature babies may display alterations in the circuitry of their developing brains, according to a first-of-its kind research study by Yale School of Medicine researchers and their colleagues at the National Institutes of Health (NIH) and Wayne State University.

The findings are published in the journal Scientific Reports, a Nature Publishing Group Journal.

According to the authors, 10% to 11% percent of American babies are born prematurely. This new study suggest that factors contributing to early birth might also impact the brain’s development in the womb, leading to significant neurodevelopmental disorders, such as autism, attention deficit hyperactivity disorder, and cerebral palsy.

In the study, Yale School of Medicine researchers Dr. Laura Ment, Dustin Scheinost, and R. Todd Constable collaborated closely with principal investigator Moriah Thomason of Wayne State University, and Dr. Roberto Romero, chief of the Perinatology Research Branch and Program Director for Obstetrics and Maternal-Fetal Medicine of NICHD/NIH.

The research team used fetal resting-state functional magnetic resonance imaging to measure brain connectivity in uteroin 32 human fetuses with normal brain anatomy, 14 of which were subsequently delivered preterm (between 24 and 35 weeks).

Patients were studied at Wayne State and Scheinost, assistant professor in the Magnetic Resonance Research Center at Yale School of Medicine, spearheaded the analysis using novel functional magnetic resonance imaging strategies to detect differences in neural networks between study groups.

The team found that systems-level neural connectivity was weaker in fetuses that would subsequently be born preterm. The findings were localized in left-hemisphere, pre-language regions of the brain.

“It was striking to see brain differences associated with preterm birth many weeks before the infants were prematurely-born,” said Scheinost. “Preterm infants are known to have brain changes in language regions, and we were particularly surprised that the fetal differences we detected were in these same language regions.”

Co-author Ment said these findings suggest that some prematurely born infants show changes in neural systems prior to birth. “Impaired connectivity in language regions in infants born long before their due dates needs further study, but is important for future research into both the causes and outcomes of preterm birth,” said Ment, professor of pediatrics and neurology at Yale School of Medicine.

The team’s future research will focus on potential causes of prematurity, such as infection and inflammation, to determine whether and how those conditions influence brain development in utero. They also will follow the study participants’ children to establish long-term outcomes.

Other authors on the study include Janessa H. Manning, Lauren E. Grove, Jasmine Hect, Narcis Marshall, Edgar Hernandez-Andrade, Susan Berman, Athina Pappas, Lami Yeo, and Sonia S. Hassan.

This project was supported by grants from the National Institutes of Health (MH110793 and ES026022), by a National Alliance for Research on Schizophrenia and Depression Young Investigator Award and, in part, by NIH contract HHSN 275201300006C.

Source: Yale University

Bilingualism may save brain resources as you age

New research findings show that bilingual people are great at saving brain power, that is. To do a task, the brain recruits different networks, or the highways on which different types of information flow, depending on the task to be done. The team of Ana Inés Ansaldo, PhD, a researcher at the Centre de recherche de l’Institut universitaire de gériatrie de Montréal and a professor at Université de Montréal, compared what are known as functional brain connections between seniors who are monolingual and seniors who are bilingual. Her team established that years of bilingualism change how the brain carries out tasks that require concentrating on one piece of information without becoming distracted by other information. This makes the brain more efficient and economical with its resources.

To arrive at this finding, Dr. Ansaldo’s team asked two groups of seniors (one of monolinguals and one of bilinguals) to perform a task that involved focusing on visual information while ignoring spatial information. The researchers compared the networks between different brain areas as people did the task. They found that monolinguals recruited a larger circuit with multiple connections, whereas bilinguals recruited a smaller circuit that was more appropriate for the required information. These findings were published in the Journal of Neurolinguistics.

Two different ways of doing the same task

Researchers Shed Light on the Roundworm’s Curious Swimming Behavior

The round worm Caenorhabditis elegans, a nematode, is a puzzling creature.

A previous study at the University of Pennsylvania established that, in some cases, these nematodes are actually counter-current and swim upstream rather than with the flow of liquid as a result of hydrodynamic forces. Another study indicated that they tend to accumulate next to surfaces.

Now, a new study published in the Journal of the Royal Society Interface finds that, rather than settling to the bottom of a pool of water as one would expect for an animal heavier than water, the nematodes seem to “swim happily” through the liquid.

Using two microscopes, one that observed from above and the other from the side, the researchers found that, despite their slow pace and inability to develop lift, the nematodes manage to remain essentially suspended above the bottom of the vessel through constant collisions with it. By continuously bouncing against the bottom, they can maintain their swimming gait.

Nematodes are broadly used in medical science to study the relationship between genotype and phenotype, to study simple neural circuits of behavior and to study the aging process, among other uses. The results of this current study could give researchers a means to sort nematodes based on their ability to swim, which depends on their genes, nerve cells, age, reaction to drugs, environmental conditions and many other factors.

Being able to sort these animals by certain traits allows researchers to screen hundreds or thousands of them for a specific behavior or trait in order to determine which genes are responsible for it.

The research was led by Haim Bau, professor in the Department of Mechanical Engineering Applied Mechanics in the School of Engineering and Applied Science; alumnus Jinzhou Yuan; and graduate student Huang Ko. David Raizen, associate professor in the Department of Neurology in Penn’s Perelman School of Medicine, also contributed to the study.

The findings led to the idea that, since the nematodes interact closely with the bottom of the vessel and if the vessel has some kind of a topology or pattern, the animal will have to follow that pattern.

“This is somewhat unusual for swimmers,” Bau said. “You can imagine if you’re swimming in the ocean and there is a trench, you won’t dip into the trench and come out; you’ll simply glide over it. But the same is not true for C. elegans. They will actually go to the bottom of the trench and try to climb upwards.”

To investigate this, the researchers used an inclined conduit to direct the animal to stay in the direction of steepest ascent or descent. They found that the velocity of the animal decreased when it was going uphill and increased when it was going downhill. Since the gravitational force is known, this provides a relatively easy way to estimate the swimming thrust of the animal.

The researchers could also modify the animals to fluoresce, enabling them to monitor the nematodes’ swimming to get some idea about the topology, or structure of the surface.

The researchers then attempted to sort the nematodes based on their ability to negotiate an inclined conduit and overcome gravity. They constructed a device containing a holding chamber where they put a large population of nematodes. The nematodes would attempt to climb the inclines. The ones able to negotiate the incline would fall into a collection chamber, while the weaker ones would remain in the holding chamber.

By repeating this process and isolating the abler nematodes, the researchers are able to enrich a particular population with a desired property, in this case thrust, and then subject them to genetic analysis to identify the genes that are responsible for their exceptional ability.

This could have applications in identifying drug resistance. The nematodes that are more susceptible to drugs are weaker and therefore less likely to escape the holding chamber. By collecting the drug-resistant ones, researchers can subject them to genetic analysis to try to identify which genes instill the drug resistance.

The researchers also realized that they would be able to force the animal to move in a desired direction.

“To demonstrate that, we fabricated a ratchet, which included a sequence of inclined planes arranged in a torus,” Bau said. “The teeth of the ratchet had two different inclination angles: one relatively mild and the other quite steep.”

The animals would go up the mild incline, drop to the pit between two teeth and then climb the next mild incline. This gave the researchers a sort of “toy” that allowed them to force the animals to move in one particular direction.

The ratchet, Bau said, “goes a little bit more into the science-fiction category.”

If researchers can force the animals to move in the way they would like rather than randomly, the nematodes may be able to carry cargo or generate work or convert energy. For instance, if the scientists designed a ratchet that rotates, the nematodes would be able to push the ratchet instead of climbing over the inclines.

This research is part of a bigger sequence of studies that focus on the swimming behavior of nematodes. The next steps are to investigate a question that arose throughout the course of this research: whether nematodes can sense the direction of gravity.

“We would like to identify whether they sense gravity, and, if so, what is the mechanism that allows them to do this,” Bau said. “This is a very fundamental question and, as far as I know, nobody has the answer.”

This research was supported, in part, by the National Institutes of Health’s National Institute on Aging.

Source: University of Pennsylvania