Image via Wikimedia Commons
The advent of microarrays and advanced genomic technologies is making it easier for scientists to take a (much) closer look at some of the world's most confounding problems. Marine biologists have long wondered which pathogens are to blame for the multitude of diseases that have weakened and, in some cases, killed large tracts of coral reefs around the world. PhyloChip, a new DNA microarray developed by a team of scientists from the Lawrence Berkeley National Laboratory and UC Merced, could help shed lights on this vexing question.
A DNA microarray is a tool used by molecular biologists to analyze gene expression in a variety of organisms; it typically takes the form of a glass slide with tens of thousands of gene samples arranged in a regular pattern. Microarrays come in handy for comparing gene expression in two different cell types or tissues--healthy tissue versus diseased tissue, for example. It can also be used to examine the microbes present in a small sample of air, water, blood or tissue. (For a much more comprehensive overview of microarrays, read the National Center for Biotechnology Information's factsheet.)
The scientists are using PhyloChip to study the microbial flora living among corals off the coast of Puerto Rico. They are trying to understand whether the apparent growth in microbial diversity is the cause, or result, of the corals' diseases.
Research presented at a microbiology conference last year suggested that global warming is weakening corals, making them more susceptible to attack by the microbes that live in and around them. According to John Bythell of Newcastle University, many of the most recent mass coral deaths could be due to slight variations in microbial communities. At the time, Bythell said that future research needed to look at the causes of disease and bleaching in corals.
Image via Lawrence Berkeley National Laboratory
This is part of what Todd DeSantis and his colleagues hope to accomplish with their innovative credit card-sized chip, which can identify up to 9,000 different species of microbes. With it, the researchers will conduct a thorough assessment of the reefs' microbial community to determine which are associated with ailing corals.
Image via ARC Centre of Excellence
"We need to determine what comes first: the disease or the microbial population change. We don't know if the disease-associated microbial population kills the coral, or if the microbes are simply feeding on dead coral tissue," DeSantis said. So far, the chip has already helped them detect new species and has overturned some of their early assumptions. The technology, which is available for licensing, could eventually be used to identify reef microbiota around the world.