Duplicate DNA a Hallmark of Tick Genome

Researchers have sequenced the genome of one of the most prolific pathogen-transmitting agents on the planet - the Lyme-disease-spreading tick (Ixodes scapularis) that bites humans. The findings could lead to advances not only in disrupting the tick's capacity to spread diseases, but also in eradicating the pest. The large tick genome - smaller than, but similar in complexity to, the human genome - supports redundancy, said R. Michael Roe, Ph.D., the William Neal Reynolds Distinguished Professor of Entomology at North Carolina State University and a co-author of a paper published in Nature Communications that describes the tick genome. The open-access article is titled “Genomic Insights into the Ixodes scapularis Tick Vector of Lyme Disease.” Dr. Roe said that the size and complexity of the genome - combined with its repetitive elements - were problematic for tick researchers. "Repetition makes assembly more challenging," Dr. Roe said. Dr. Roe focused his work on the processes that help ticks find each other and mate; how ticks produce eggs and the hormones that regulate egg production; what makes ticks bite; and how ticks feed and process their blood meals. "We identified the hormones used for development, the process of how ticks utilize the blood that they eat, and how they convert that blood into eggs," Dr. Roe said. Besides repetitive elements, Roe noted important differences between the tick genome and insect genomes. "We know from previous work that, at the genome level, ticks do not control their development like insects," Dr. Roe said. "For example, ticks don't have a juvenile hormone that insects have. That hormone is responsible for color, molt patterns, migration activity, and many other functions in insects. That's important because some of the safer insecticides are based on upsetting the juvenile hormone balance."
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