袋鼠基因组定序成功

Kangaroos form an important niche¹ in the tree of life, but until now their DNA² had never been sequenced. In an article newly published in BioMed Central's open access journal Genome Biology, an international consortium（财团，联合） of researchers present the first kangaroo genome sequence -- that of the tammar wallaby species -- and find hidden in their data the gene³ that may well be responsible for the kangaroo's characteristic hop⁴. "The tammar wallaby sequencing project has provided us with many possibilities for understanding how marsupials（有袋类） are so different to us," says Prof Marilyn Renfree of The University of Melbourne. Renfree was one of the lead researchers on the project, which was conducted by an international consortium of scientists from Australia, USA, Japan, England and Germany.

Tammar wallabies have many intriguing⁶（有趣的） biological characteristics. For example, the 12 month gestation⁷（酝酿，怀孕） includes an 11 month period of suspended animation⁸ in the womb. At birth, the young weigh only half a gram, and spend 9 months in the mother's pouch⁹, where the newborn babies reside for protection. Researchers hope that the genome sequence will offer clues as to how tammar wallaby genes¹⁰ regulate these fascinating features of kangaroo life.

In addition to zeroing in on the "hop" genes, other exciting discoveries from the genome include the 1,500 smell detector¹¹ genes responsible for the tammar wallaby's excellent sense of smell, and genes that make antibiotics¹² in the mother's milk in order to protect kangaroo newborns from E. coli and other harmful bacteria. As Prof Renfree explains, lessons to be learned from the tammar wallaby genome "may well be helpful in producing future treatments for human disease."

The first kangaroo genome is a key milestone¹³ in the study of mammalian evolution. As the ancestors of kangaroos separated from other mammals at least 130 million years ago, it is hoped that the DNA sequence is in some senses a living fossil of the early mammalian species from which humans evolved. To understand this evolutionary¹⁴ journey better, the genome sequence is complemented¹⁵ by the "transcriptome" sequence, which represents a catalogue of how strongly each gene is turned "on" or "off" at different stages of the tammar life cycle and in different parts of the body. Study of the transcriptome will allow many more interesting questions to be asked about how kangaroo genes compare to their counterparts in humans.

The Genome Biology article is accompanied by a series of articles in the journals BMC Genomics, EvoDevo, BMC Immunology, BMC Molecular¹⁶ Biology, BMC Genetics, BMC Developmental Biology and BMC Evolutionary Biology, which collectively examine some of the most appealing biological stories arising from the genome sequence.

The tammar wallaby is only the third marsupial⁵, and only the second Australian marsupial (after the Tasmanian devil), to have its genome sequenced. As the kangaroo is an icon¹⁷ of Australia, whose image appears on its coat of arms, currency and national airline symbol, the publication of its genome sequence in Genome Biology stands as a landmark¹⁸ day in Australian science.