lunes, 3 de marzo de 2014

Ancient plaque reveals hidden window into the past

Calcified dental plaque (dental calculus) is known to preserve bacteria and microscopic particles of food on the surfaces of teeth, effectively creating a mineral tomb which an international team of researchers have now uncovered to a highly detailed level.
Directly datable and ubiquitous, the team have shown that locked in the dental calculus is evidence of pathogen activity, host immunity and diet, extending direct investigation of common diseases into the human evolutionary past.

Same bacteria

The research team discovered that the ancient human oral cavity carries numerous opportunistic pathogens and that periodontal disease is caused by the same bacteria today as in the past, despite major changes in human diet and hygiene.
The researchers discovered that the full collection of ancient human oral microorganisms already contained the basic genetic machinery for antibiotic resistance more than eight centuries before the invention of the first therapeutic antibiotics in the 1940s.
As well as health information, the scientists recovered dietary DNA from ancient dental calculus, allowing the identification of dietary components, such as vegetables, that leave few traces in the archaeological record.
Led by the University of Zürich, the University of Copenhagen, and the University of York, this pioneering analysis of ancient oral ecology saw contributions from 32 scientists at twelve institutions in seven countries.

Helping it to preserve biomolecules

The research published in the journal Nature Genetics reveals that unlike bone which rapidly loses much of its molecular information when buried, calculus grows slowly in the mouth and enters the soil in a much more stable state helping it to preserve biomolecules which enabled the researchers to analyse ancient DNA that was not compromised by the burial environment.
Analysing this vast data resource required overcoming the formidable challenge of sorting and identifying millions of genetic sequences in order to reconstruct the complex biology of the ancient oral microbial ecosystem. “Dental calculus is a window into the past and may well turn out to be one of the best-preserved records of human-associated microbes,” says Professor Christian von Mering, an author of the study and Group Director at the SIB Swiss Institute of Bioinformatics, which performed the bioinformatics analysis
Today, moderate to severe periodontal disease affects more than 10% of the world’s population and is linked to diverse systemic diseases, including cardiovascular disease, stroke, pulmonary disease, and type II diabetes.
“As we learn more about the evolution of this microbiome in response to migration and changes in diet, health and medicine, I can imagine a future in which most archaeologists regard calculus as more interesting than the teeth themselves,” says Professor Collins.

Source: Past Horizons:

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