(photo credit: COURTESY PHOTO OF PROF. CHIPMAN)
An international team of 100 scientists that included one from the Hebrew University have for the first time sequenced the genome of the many-legged centipede. The achievement in understanding the DNA of the humble arthropod will, they say, help reveal how life evolved on Earth. Their work was published in the journal PLOS Biology on Tuesday evening.
Named for having “100 feet,” which in fact range from 20 to over 300, the centipede are insects with one pair per body segment. In fact, there are no centipedes that have exactly 100 feet. They are members of a biological group that includes spiders, insects and other creatures. Until now, the only class of arthropods not represented by a sequenced genome was the myriapods, which include centipedes and millipedes.
For this study, the researchers sequenced the genome of the centipede Strigamia maritima because its primitive features can help us understand more complex arthropods. All of the group have in common a pair of venom claws (forcipules) formed from a modified first appendage. Their drab colors usually range from brown to red, but some have no pigment at all. There are an estimate 8,000 species of centipedes, which live inside logs, under stones, in the soil and decomposing leaves.
Prof. Ariel Chipman, curator of the aquatic invertebrate collection at HU’s Alexander Silberman Institute of Life Sciences and senior co-author of the study, said that the newly discovered genetic data reveal how creatures made the transition from their original home in the sea to living on land.
“The use of different evolutionary solutions to similar problems shows that myriapods and insects adapted to dry land independently of each other,” said Chipman. “For example, comparing the centipede and insect genomes shows that they independently evolved different solutions to the same problem shared by all land-dwelling creatures — that of living in dry air.”
He added that despite being closely related to insects, the centipede lacks the olfactory (smell) gene used by insects to smell the air, and thus it developed its own air-sniffing ability by expanding other gene families lacking in insects.
In addition, Chipman said, this specific group of centipedes live underground and have no eyes, which they “lost” together with almost all vision genes and others involved in the body’s internal clock. They maintain enhanced sensory capabilities enabling them to recognize their environment and capture prey.
The cooperating scientists from 50 research institutions spent thousands of man-hours looking at specific genes in the centipede genome, with each researcher examining a limited set of genes or at specific structural characteristics to address specific questions. They included Dr. Stephen Richards of Baylor College of Medicine in Texas; Dr. David Ferrier, University of St. Andrews in Scotland; and Prof. Michael Akam of Cambridge University in the UK.
While early genomic studies focused on humans -- as sequencing equipment and expertise became more readily available -- researchers expanded into animals directly relevant to human well-being. In the latest research, genomic sequencing has become more broad-based, investigating the workings of the world around us.
“If we have a better understanding of the biological world around us, how it operates, and how it came to be as it is, we will ultimately have a better understanding of ourselves,” said Chipman, who added that the research will have applications for other researchers ranging from conservation to fighting crop pests.