Scientists sequence genome of the human louse
Scientists have sequenced the genome
of the body louse, offering insights into human biology and insect
evolution that could help detach us from our inseparable, blood-sucking
companions
The study, published in the official journal of America’s National
Academy of Sciences, showed the louse had the smallest genome of any
insect and very few genes related to light reception, odours and tastes.
The body louse has “the smallest number of detoxification enzymes
observed in any insect,” researchers wrote, suggesting new repellants
could one day help rid us of the tiny mites that have been our
companions for millions of years.
“The ecology of lice is very, very simple. It either lives in your
hair or on your clothing and it has one type of meal and that’s blood,”
said University of Illinois entomology professor Barry Pittendrigh.
“So most of the genes that are responsible for sensing or responding
to the environment are very much reduced,” said Pittendrigh, who
coordinated the research of 28 institutions in the United States,
Europe, Australia and South Korea.
Known to experts as Pediculus humanus humanus, the body louse has
played its unsanitary part in history, blamed for spreading typhus and
trench fever to Napoleon’s retreating army in Russia in 1812.
“As an obligatory parasite of humans, the body louse is an important
vector for human diseases, including epidemic typhus, relapsing fever
and trench fever,” the study said.
“Thus, the body louse genome project offers unique information and
tools to use in advancing understanding of coevolution among vectors,
symbionts and pathogens.”
Completely dependent on humans for its survival, the louse will die
if separated from its host for very long.
In turn a tiny microbe, the bacterium Candidatus Riesia pediculicola,
lives inside it and produces pantothenate (Vitamin B5), an essential
nutrient for its host’s survival.
The study also sequenced the genome of the microbe and pointed out
that the research was key to understanding the co-evolution of
disease-carrying parasites and their bacterial co-conspirators.
“Lice have been used to understand human evolution and migration.
They’ve been used to estimate when we started wearing clothing,”
Pittendrigh said.
“The genome should also help us develop better methods of controlling
both head and body lice.”
AFP |