Researchers map DNA of platypus

Mon, 05 May 2008 04:15:00 -0500

Photo: New genome research proves platypus DNA is an equally cobbled-together array of avian, reptilian and mammalian lineages that may hold clues for human disease prevention. The male platypus has venomous spurs on his hind feet with poison very similar to that of reptiles. The female lays eggs like birds and lactates to feed their young just like mammals. -- Zina Deretsky, National Science Foundation

The mapping of the platypus genome has important implications for researchers in several fields including evolution and human disease.

A female platypus named “Glennie” was sequenced by scientists at the Genome Sequencing Centre of Washington University School of Medicine in St. Louis as part of an international research collaboration including scientists from the UK, Australia Germany, Israel, Japan, New Zealand and Spain. The analysis is published in the May 8 issue of Nature.

It’s thought that the platypus evolved from a common ancestor shared with humans about 170 million years ago. The platypus (Ornithorhynchus anatinus) is a monotreme with many features both similar to and distinct from other mammals. While it has fur and nurses its offspring on milk (but through glands instead of nipples), it also has characteristics of a reptile. The females lay eggs and the males produce venom. It uses ‘electro-reception,’ a specialized system in its bill that uses electricity to detect food under water. It has 10 sex chromosomes instead of two.

The platypus's unique features are reflected in what researchers call a “patchwork of genes” resembling those from reptiles, birds and other mammals. “The platypus looks like such a strange blend of mammalian, bird-like and reptilian features and now we know that the genome is an equally bizarre mix of all of these,” said Ewan Birney, who led the genome analysis performed at the European Bioinformatics Institute. “It’s much more of a mélange than anyone expected.”

A 'missing link' in evolution studies

“The platypus genome is extremely important because it is the missing link in our understanding of how we and other mammals first evolved,” said lead researcher Chris Ponting of the Medical Research Council Functional Genomics Unit at Oxford University. “This is our ticket back in time to when all mammals laid eggs while suckling their young on milk. It also provides an essential background to future advances in understanding mammalian biology and evolution.”

Importantance for medical research

"This is a huge genetic step,” said Mark Batzer of Louisiana State University who was part of the team that completed the first draft sequence and analysis of the platypus genome.“We're learning a lot about mammalian gene regulation and immune systems, which has huge implications for disease susceptibility research. We hope to, in time, identify the underlying causes and methods of disease prevention in humans."

The platypus genome sequence, along with those for other organisms and animals including the mouse, dog, cow, and others can be accessed at NIH's GenBank.

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Comment: It's exciting to see the complex platypus getting some long overdue respect.

The Platypus

I like the duck-billed platypus

Because it is anomalous.

I like the way it raises its family

Partly birdly, partly mammaly.

I like its independent attitude.

Let no one call it a duck-billed platitude.

by Ogden Nash

Flesh and Stone

Researchers map DNA of platypus