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Environmental Factor, September 2012

Extramural papers of the month

By Nancy Lamontagne

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Whole genome sequencing reveals genetic basis for diversity and evolution

In one of the first population genomics studies to use high-coverage whole-genome sequencing, NIEHS-supported researchers analyzed the genomes of 15 Africans from three different hunter-gatherer groups. The work reveals new insight into human diversity and evolution and also shows the potential of new genome sequencing technology for uncovering the genetic basis of normal variations in humans and for identifying the genetic basis of disease risk.

The researchers sequenced the genomes of men from the Hadza and the Sandawe groups in Tanzania and the Western Pygmies in Cameroon. These three hunter-gather groups differ greatly from one another in appearance, language, culture, and the environments in which they live. The researchers used a high-coverage whole-genome sequencing approach that is highly accurate.

They found 13.4 million genetic variants, five million of which were new to science at the time of discovery. The results from the genome analysis provide evidence that the direct ancestors of modern humans might have interbred with members of an unknown ancestral group of hominins and that different groups evolved distinctly. The work also identifies new candidate genes that are likely involved in making Pygmies short in stature. The researchers say that these candidate genes would not have been found without comparing multiple genomic sequences from these isolated groups.

CitationLachance J, Vernot B, Elbers CC, Ferwerda B, Froment A, Bodo JM, Lema G, Fu W, Nyambo TB, Rebbeck TR, Zhang K, Akey JM, Tishkoff SA. (http://www.ncbi.nlm.nih.gov/pubmed/22840920)  2012. Evolutionary history and adaptation from high-coverage whole-genome sequences of diverse African hunter-gatherers. Cell 150(3):457-469.

Wearable sensor monitors personal exposure to VOCs

An NIEHS grantee and his colleagues developed a wearable sensor that measures personal exposure to volatile organic compounds (VOCs) and sends that information to a smart phone. The new device allows indoor and outdoor measurements, requires little training to use, and can provide important information about when, where, and how people experience exposure to contaminants.

The sensor can measure concentrations of aromatic, alkyl, and chlorinated hydrocarbons with a resolution as low as four parts per billion (ppb) and a detection range of four ppb to 1,000,000 ppb. It generates data every three minutes and sends this information to a smartphone, where an application processes the data and displays the results.

The researchers field-tested the sensor in several scenarios. They measured exposure to traffic-related pollutants in different cities, pollutants near the 2010 Deepwater Horizon oil spill, and indoor air quality during remodeling. The field tests validated the performance of the new technology and also showed that it could provide high temporal and spatial information on contaminant exposure.

CitationChen C, Campbell KD, Negi I, Iglesias RA, Owens P, Tao N, Tsow F, Forzani E. (http://www.ncbi.nlm.nih.gov/pubmed/22736952)  2012. A New Sensor for the Assessment of Personal Exposure to Volatile Organic Compounds. Atmos Environ 54:679-687. DERT Success story: Nongjian Tao

Biomarker predicts years of service for firefighters

An NIEHS-funded study shows that firefighters exposed to PAHs have epigenetic modifications that correlate with years of service and offer a potential biomarker for PAH exposure. Epigenetic modifications affect gene expression without changing the genetic code.

Firefighters are exposed to smoke and products of incomplete combustion, which often contain polycyclic aromatic hydrocarbons (PAHs). The researchers analyzed blood DNA from 18 firefighters and 20 non-firefighter controls, looking for a type of epigenetic change known as methylation in the promoters for four genes. They found that firefighters had a higher prevalence of promoter hypomethylation for the dual specificity phosphatase 22 (DUSP22) gene and that the extent of hypomethylation correlated with years of firefighting service but not with age. Cell studies confirmed that promotor methylation regulates DUSP22 expression.

This study’s findings indicate that gene expression of DUSP22 is modified epigenetically by environmental exposure. The researchers say that future studies need to examine whether hypomethylation of this gene can also predict later-life diseases, such as prostate cancer, that can result from long-term exposure to smoke.

CitationOuyang B, Baxter CS, Lam HM, Yeramaneni S, Levin L, Haynes E, Ho SM. (http://www.ncbi.nlm.nih.gov/pubmed/22796920)  2012. 2012. Hypomethylation of Dual Specificity Phosphatase 22 Promoter Correlates With Duration of Service in Firefighters and Is Inducible by Low-Dose Benzo[a]Pyrene. J Occup Environ Med 54(7):774-780. Story

Long-term air pollution exposure linked with heart problems

Studies have shown that short-term exposure to air pollution can trigger heart problems, and a new NIEHS-funded study provides evidence that long-term exposure can also have adverse health effects. The researchers report that mice exposed to air pollution for most of their lives showed heart problems that were consistent with developing heart failure.

The investigators exposed mice to environmentally-relevant levels of particulate air pollution (< 2.5 microns) or filtered air for six hours a day, five days a week, for nine months, which is a large portion of the animal’s lifespan. Echocardiography revealed that the mice exposed to air pollution developed heart dysfunction, which could also be seen at cellular and tissue levels. The researchers say that these findings have implications for air pollution as an independent risk factor for cardiovascular disease development.

CitationWold LE, Ying Z, Hutchinson KR, Velten M, Gorr MW, Velten C, Youtz DJ, Wang A, Lucchesi PA, Sun Q, Rajagopalan S. (http://www.ncbi.nlm.nih.gov/pubmed/22661498)  2012. Cardiovascular remodeling in response to long-term exposure to fine particulate matter air pollution. Circ Heart Fail 5(4):452-461.

(Nancy Lamontagne is a science writer with MDB, Inc., a contractor for the NIEHS Division of Extramural Research and Training, Superfund Research Program, and Worker Education and Training Program.)



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