US-AUSTRALIAN ACADEMIES JOINT WORKSHOP
US-AUSTRALIAN ACADEMIES JOINT WORKSHOP ON VERTEBRATE COMPARATIVE GENOMICS
Beckman Conference Centre, Irvine, California, 23-25 May 2007
Smile at the crocodile: a valuable contribution to vertebrate comparative genomics
by Chris Moran
Dr Chris Moran received his PhD in genetics from the Australian National University, Canberra, in 1978. He has been employed in the Faculty of Veterinary Science, University of Sydney since 1980, with sabbaticals in CSIRO laboratories and the National Institute for Medical Research London. He has been Professor of Animal Genetics since 2005. His interests include gene and QTL mapping in pigs, mice and most recently crocodiles, comparative genomics and endogenous retroviruses. He has recently been appointed editor-in-chief of Animal Genetics.
The saltwater crocodile, Crocodylus porosus, is farmed in tropical regions of Australia for skins for high value luxury products, comprising about 80% of their value, as well as meat and by-products. Unlike other species of crocodilians, which are mainly ranched using fertile eggs collected from nests in the wild, C. porosus can be bred in captivity and thus is amenable to controlled genetic studies.
Commencing in 2000, genetic and phenotypic parameters have been estimated for farmed C. porosus in order to develop an economic selection index designed to genetically improve the profitability of crocodile production. Subsequently about 600 microsatellite markers, mainly tetra- and tri-nucleotides, have been developed and are in the process of being added to a comprehensive linkage map. This linkage map will be physically anchored by FISH using fosmid clones containing linkage mapped microsatellites and will be used for QTL mapping.
Preliminary mapping results show that female crocodiles have higher recombination than males, similar to the elevated female recombination observed in humans and many mammals. However, since sex is determined by the temperature of incubation in crocodiles, any explanation for sex specific differences in recombination rate invoking sex chromosomes is clearly not valid.
Crocodiles and alligators diverged from a common ancestor about 140 million years before present (BP) and the Crocodylia from birds an estimated 254 million years BP, bracketing the marsupial divergence about 170 million year BP. Genome sequences from both a crocodile and an alligator would be very informative from a comparative perspective to complement the single reptile, the anole lizard (Anolis carolinensis), and two bird, chicken and the zebrafinch, sequences.
Contact details:
Centre for Advanced Technologies in Animal Genetics and Reproduction
Faculty of Veterinary Science, University of Sydney NSW 2006
Tel: (+61) 2 9351 3553
Fax: (+61) 2 9351 2114
E-mail: Chris.Moran@vetsci.usyd.edu.au
Web: www.vetsci.usyd.edu.au/
