Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

AN IMPROVED GENETIC PHYSICAL MAP IN RIVER BUFFALO (BUBALUS BUBALIS, 2N=50) CHROMOSOMES

IANNUZZI L., DI MEO G.P., PERUCATTI A., INCARNATO D.

National Research Council (CNR), IABBAM, Naples, Italy

L.Iannuzzi@iabbam.na.cnr.it

genetic map, river buffalo, fluorescence in situ hybridization, cytogenetics

Genomes of domestic animals are practically unknown when compared with those of both humans and mice. In cattle, the most studied species, only 3,804 loci are known with 1151 assigned genes (BovBase), mostly mapped on large chromosome regions. In other bovids, especially in the river buffalo (Bubalus bubalis, 2n=50), few loci, in particular those containing coding sequences, have been physically mapped to specific chromosome regions. Several studies have revealed numerous conserved syntenies between human and bovine genomes, as confirmed also by Zoo-FISH analysis using human specific chromosome painting probes. However, these studies did not establish the gene order within and between chromosome segments of different genomes. This problem can easily be resolved by comparative FISH-mapping, especially using type I loci which are highly conservative among mammalian species. Taking in account that the human genome has recently been sequenced, it is possible to noticeably increase our knowledge in the bovine genomes by using the human one as a point of reference. At the same time, considering the high degree of chromosome and locus homologies among bovids, is possible to use the bovine physical map as a template to extend the physical maps in related bovids as the river buffalo. Considering the great economical importance of river buffalo in the world (about 150 million of animals) and in Italy (especially in the south), our aim is to speed up our knowledge in its genome by FISH-mapping of both type I and type II loci.

Fluorescence in situ hybridisation (FISH) technique was applied on high-resolution R-banded chromosomes obtained from lymphocyte cell cultures treated for late incorporation of both 5-Bromodeoxyuridine and Hoechst 33258. Both R-banded metaphases and fluorescent FITC-signals were captured by a CCD-camera and processed by Image pro-plus software. As probes, we primarily use bovine and caprine BAC-clones containing both type I and type II loci. A summary of all mapped loci has been reported on R-banded ideogram. One-hundred-sixty-one loci, mostly of type I, were assigned to river buffalo chromosomes noticeably increasing the number of mapped loci when compared with the previous genetic physical map where only 54 loci were assigned (Iannuzzi 1998).

Direct comparisons between human and river buffalo physical maps allowed to reveal complex chromosome rearrangements (translocations and inversion) which differentiated human and bovid genomes.

Acknowledgements: the study has in part been supported by Structural Project FESR on Typical Products and in part by National Research Council of Rome, Special Project on the Biodiversity.