Tuberculosis may call to mind Old West consumptives and early 20th-century sanatoriums, yet according to the World Health Organization, the disease took the lives of more than 1.5 million people worldwide in 2006.
In the United States alone, thousands of new cases are reported annually making TB an enduring menace. The need to better understand this disease is becoming critical, note researchers at Arizona State University, especially with the emergence of antibiotic-resistant strains and increasing globalization spurring pathogen migration.
Among those trying to decipher the origins and trajectory of Mycobacterium tuberculosis, the bacteria responsible for TB, are three researchers in ASU’s College of Liberal Arts and Sciences. Graduate student Luz-Andrea “Lucha” Pfister and associate professor Anne Stone in ASU’s School of Human Evolution and Social Change, and Michael Rosenberg, an assistant professor in the School of Life Sciences, are trying to establish a credible evolutionary timeline for TB.
Their research suggests that the disease migrated from humans to cattle – not the reverse, as has long been assumed. The research estimates that the evolutionary leap took place prior to the domestication of cows – more than 113,000 years ago – indicating M. tuberculosis is a much older pathogen than previously believed.
This outcome supports that of the French Pasteur Institute’s Cristina Gutierrez, an evolutionary mycobacteriologist whose work first cast doubt on the cattle-to-human TB link and its date range. Gutierrez calls the findings of Pfister’s team confirmation of TB’s ancient origins and human-cattle transmission.
This summer, Pfister presented the results of the group’s research at the annual meeting of the Society of Molecular Biology and Evolution, in Barcelona. She also presented during the April assembly of the American Association of Physical Anthropologists and subsequently saw the group’s research reported on in the journal Science.
With no fossil evidence to consult, studying the deep history of bacteria has only recently become possible. Genomics holds the key. Using DNA, Pfister, Stone and Rosenberg are making inroads into calibrating the watershed moments in TB’s development, such as when it expanded in the human population. Through their work, they also plan to address the biogeography of the disease and what types of TB ancient people had relative to modern strains.
Why are scientists interested in TB’s status thousands of years ago? Pfister puts the research into perspective: “An accurate timeframe can help us learn about the development between host and pathogen. It can aid in understanding the disease and the way it evolves, how it creates new strains to stay alive.”
As Stone is quick to point out, “The data we generate can be used by clinicians to study this disease and formulate appropriate treatments. Our work is historical, but the implications are far-reaching.”
One of the primary goals is to calculate a meaningful mutation rate. The established model for bacteria was developed in the 1980s in regard to E. coli. Pfister notes, “This mutation rate has been used as the universal standard, but that is not feasible. TB and E. coli are very different. Bacteria may evolve at different rates. We cannot say that one model applies to all.”
Pfister, Stone and Rosenberg worked with 108 genes, compared to just over 20 genes used in the E. coli formula. As a result, they were able to delve deeper than Gutierrez at the time she conducted her ground-breaking research. “The Pasteur Institute looked at a small piece of the genome; the full genome gives a much better idea,” says Stone, alluding to the team’s comprehensive approach and its possibilities.
“The work we have done so far is only one aspect of a bigger project,” explains Rosenberg. “There are different directions we want to go with it. Of course, the main target is to get a better estimate of the rate of mycobacterium evolution, but a lot of things branch off from that.”
Rosenberg, a computational evolutionary biologist who designed the program to analyze many of the sequences, says the project shows that “as we get more data and complete sequencing of full genomes, we find new ways of looking at issues, which can do away with assumptions. An example is the belief of cow-to-human transmission of TB. That was a long-held notion, but it was just an assumption.”
“It is the evolutionary way of thinking that has caused us to explore this issue from new and varied angles,” states Pfister. “An evolutionary perspective is also important in a contemporary sense because our species’ population is growing dramatically. Soon we will reach carrying capacity. We will start producing pathogens and opportunities for problems at escalating rates.”
Pfister was born and raised in Chile where TB ran rampant before being subdued by aggressive government health programs. However, as in other parts of the world, Chile is presently facing a resurgence of tuberculosis. Still, Pfister is hopeful that someday the deadly pathogen will be rendered obsolete. She enthuses, “We now have lots of gene data. We can count mutations. There is so much evidence out there; we just need to link it all. If we start looking at the history and essence of TB in a holistic, transdisciplinary way, we can see the big picture and find solutions.”SOURCES:
Rebecca Howe | Newswise Science News
"Make two out of one" - Division of Artificial Cells
19.02.2020 | Max-Planck-Institut für Kolloid- und Grenzflächenforschung
Sweet beaks: What Galapagos finches and marine bacteria have in common
19.02.2020 | Max-Planck-Institut für Marine Mikrobiologie
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices
The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...
Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.
Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.
After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.
"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
19.02.2020 | Life Sciences
19.02.2020 | Information Technology
19.02.2020 | Power and Electrical Engineering