YOU鈥橠 struggle to tell them apart. Human head and body lice look similar, appear to share the same genome and are believed to be the same species. But they鈥檝e never been seen to interbreed outside of the lab.
What鈥檚 more, while head lice (Pediculus humanus capitis) are known to be harmless, body lice (P. humanus corporis) transmit bacteria that cause typhus and trench fever.
鈥淪omething has to be different between them,鈥� says of the University of Bath, UK.
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Now Urrutia and her team have evidence that, although their genes seem to be the same, the two lice read them differently. They do so through a process called alternative splicing.
Many genes are split into segments of coding and non-coding DNA. When these genes are expressed to make proteins, they are first copied into RNA. At this point the non-coding segments are spliced out and the important pieces of information are stitched together.
But sometimes non-coding segments are left in, or seemingly important regions are spliced out. By varying what RNA regions are stitched together, the same gene can provide multiple templates for slightly altered proteins.
聯By varying what RNA regions are stitched, the same gene can provide multiple templates聰
Urrutia鈥檚 team identified more than 3500 examples where genes were spliced differently in the two types of lice (Molecular Biology and Evolution, ). This might provide an explanation for the difference between them, says of the University of Toronto, Canada.
The salivary gland and feeding tract genes that body lice splice differently might have helped them adapt to living in clothes, which we most likely started wearing less than half a million years ago.
鈥淏ody lice have to adapt to a different feeding pattern, because they are not necessarily in 24-hour contact with their host,鈥� says Urrutia.
This article appeared in print under the headline 鈥淗ead and body lice splice genes to be different鈥�