Six million years ago, chimpanzees and humans diverged from a common ancestor and evolved into unique 1) ___. UCLA scientists have identified a new way to pinpoint the 2) ___ that separate us from our closest living relative — and make us uniquely human. We share more than 95% of our genetic blueprint with chimps. What sets us apart from chimps are our 3) ___: homo sapiens means ‘the knowing man. During evolution, changes in some genes alter how the human brain functions. Research has identified an entirely new way to identify these genes in the small portion of our DNA that differs from the chimpanzee’s. By evaluating the correlated activity of thousands of genes, a UCLA team identified not just individual genes, but entire networks of 4) ___ genes whose expression patterns, within the brains of humans, varied from those in the chimpanzee. Genes don’t operate in 5) ___ — each functions within a system of related genes. If we examine each gene individually, it would be similar to reading every fifth word in a paragraph — you don’t get to see how each word relates to the other. So instead we use a systems biology approach to study each gene within its context. The scientists identified networks of genes that correspond to specific brain regions. When they compared these 6) ___ between humans and chimps, they found that the gene networks differed the most widely in the cerebral cortex — the brain’s most highly evolved region, which is three times larger in humans than chimps. They also discovered that many of the genes that play a central role in cerebral cortex networks in humans, but not in the chimpanzee, also show significant changes at the 7) ___ level. When we see alterations in a gene network that correspond to functional changes in the genome, it implies that these differences are very meaningful. This finding supports the theory that variations in the DNA sequence contributed to human evolution. Relying on a new analytical approach the UCLA team used data from DNA microarrays — vast collections of tiny DNA spots — to map the activity of virtually every gene in the 8) ___ simultaneously. By comparing gene activity in different areas of the brain, the team identified gene networks that correlated to specific brain regions. Then they compared the strength of these correlations between humans and chimps. Many of the human-specific gene networks identified by the scientists related to 9) ___, brain cell activity and energy metabolism. If you view the brain as the body’s engine, findings suggest that the human brain fires like a 12-cylinder engine, while the chimp brain works more like a 6-cylinder engine. It’s possible that our genes adapted to allow our brains to increase in size, operate at different speeds, metabolize energy faster and enhance 10) ___ between brain cells across different brain regions. Adapted from materials provided by University of California – Los Angeles

ANSWERS: 1) species; 2) genes; 3) brains; 4) interconnected; 5) isolation; 6) networks; 7) DNA; 8) genome; 9) learning; 10) connections

Lead researcher Dr. Peter Mazzone and his team from the Cleveland Clinic have developed a breath test that can successfully pick up lung cancer with “moderate accuracy” even in the early stages. This breath test could revolutionize the way cancer is 1) ___ and potentially save lives. The test comprises a chemical 2) ___ sensor, which detects tiny changes in the unique 3) ___ signature of the breath of people with lung cancer. Metabolic changes in lung cancer cells cause changes in the production and processing of volatile organic 4) ___. Lung cancer cells give off chemicals, called volatile 5) ___ compounds or VOCs, which are then exhaled. The researchers used the color sensor to test the breath of 122 people with different types of 6) ___ disease, and 21 healthy people. Included in the group with respiratory illness were 49 people with small cell lung cancer at various stages of development. The research team used the sensor results from 70% of the study participants to develop a predictive model, the accuracy of which was then tested on the remaining 30%. The results showed that the test was able to predict, accurately, the presence of cancer in just under three out of four of those with lung cancer. The results were not affected by age, gender, or stage of disease. Other approaches to breath testing have been used, including, gas 7) ___ and mass spectrometry, both of which require a great deal of expertise to use, plus, both are very expensive. According to the authors, as cancer is often silent in its early stages and symptoms are often not specific, it is often difficult to pick up the disease at a stage when it could be treated effectively. Diagnosis is often, therefore, only made when the disease is 8) ___. Ultimately, this line of investigation could lead to an inexpensive, non-invasive screening or diagnostic test for lung cancer.

ANSWERS: 1) detected; 2) color; 3) chemical; 4) compounds; 5) organic; 6) respiratory; 7) chromatography; 8) advanced

More information: ChemSensing has designed systems with a customized colorimetric sensor array that uses metalloporphyrins that hold metal ions tightly, but with open sites. When exposed to volatile organic compounds, the metalloporphyrins produce measurable color changes. ChemSensing’s system was first developed to identify and measure levels of potentially deadly gas exposures, as might be encountered in the case of a bioterrorist attack or a major industrial accident. It has also been used to detect bacterial food spoilage. The system used by the Cleveland Clinic’s scientists contained 36 “chemically sensate spots,” each with different sensitivities to volatile organic compounds. The authors chose a broadly sensitive system, as the identity of the key volatiles that make the breath of patients with lung cancer unique has not been clearly established.