In a study that could benefit medical and food-safety research, scientists have used comparative genomics tools to find clues about why some strains of the bacterium Campylobacter – which each year cause more than 400 million cases of gastrointestinal disease – are more virulent than others.
The study, which appears in the January 2005 issue of PLoS Biology, compares the complete genome sequences of two strains of Campylobacter jejuni – the species most often associated with human illness – and supplements that analysis by contrasting those with the mostly-finished sequences of three other Campylobacters, including one species that may be an emerging pathogen in Africa.
In their analysis, the researchers found a set of genes that may be closely associated with the virulence of some Campylobacter strains as human pathogens. They also found sequence variations among the four Campylobacter isolates, including major structural differences related to the insertion of new stretches of DNA in the genome sequences. Those "insertions" and other gene variations may help scientists understand why there are major differences in the biology of various Campylobacter strains.
"The comparative genome sequences give scientists some new ideas to better control and detect these organisms," says TIGR’s Nelson, the study’s senior author. She and Fouts also say the study has helped scientists better understand the evolutionary relationships among Campylobacter species. In addition, the phage and megaplasmids discovered by the genome analysis may yield clues to the intra- and inter-species lateral transfer of DNA among Campylobacter strains.
Campylobacter are the leading cause of bacterial gastrointestinal illness in the United States, where about 15 out of every 100,000 people are diagnosed with campylobacteriosis every year. Many other cases go unreported due to the sporadic nature of the disease. The illness lasts for a week to 10 days, with symptoms that include diarrhea, cramps, abdominal pain and fever. Infrequently, the infection can be more serious or even fatal when victims develop Guillain-Barré syndrome, which involves damage to the nerves that link the spinal cord and brain to the rest of the body.
Campylobacteriosis is usually caused by C. jejuni, a microbe normally found in cattle, swine and birds, where it causes no problems. But the illness can also be caused by C. coli (also found in cattle, swine and birds), C. upsaliensis (found in cats and dogs), and C. lari (present in seabirds in particular). People are often exposed to the disease-causing bacteria when they eat contaminated food – in many cases, undercooked or poorly handled poultry.
While C. jejuni colonizes the gastrointestinal tracts of many animals, it appears to be especially adapted to the enteric tracts of birds, including chickens and turkeys. That is why poultry is considered to be a source of human campylobacteriosis. The disease can also be transmitted via human contact with contaminated water, livestock or household pets.
USDA’s Mandrell says the new Campylobacter sequence data has allowed the PSMRU group in California to develop more comprehensive detection methods, including microarrays, for analyzing human and environmental isolates of the bacteria. The goal is to be able to "fingerprint" strains, an important aspect of determining their source, fitness and epidemiology.
By identifying similar housekeeping genes among the non-jejuni species sequence data, the group has expanded its original fingerprinting method and initiated a study at several ARS locations to characterize differences among C. coli strains isolated from different animal and clinical sources.
Robert Koenig | EurekAlert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences