The Sheep Gene Map

Thomas E. Broad, B.V.Sc. (Hons), M.Sc, Ph.D., is Senior Scientist in the AgResearch Molecular Biology Unit; Grant W. Montgomery, B.Ag.Sc. (Hons), Ph.D., is Program Leader of the AgResearch Molecular Biology Unit; Diana F. Hill, B.Sc, Ph.D., is Director of the Molecular Biology Unit and Associate Professor in the Department of Biochemistry, University of Otago, Dunedin, New Zealand. Jillian F. Maddox, B.V.Sc, Ph.D., G.Dip.Inf.Sci., is Senior Research Fellow of the Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Australia; and Frank W. Nicholas, B.Ag.Sc, Ph.D., is Associate Professor in the Department of Animal Science, University of Sydney, Camperdown, Australia. Thomas E. Broad, B.V.Sc. (Hons), M.Sc, Ph.D., is Senior Scientist in the AgResearch Molecular Biology Unit; Grant W. Montgomery, B.Ag.Sc. (Hons), Ph.D., is Program Leader of the AgResearch Molecular Biology Unit; Diana F. Hill, B.Sc, Ph.D., is Director of the Molecular Biology Unit and Associate Professor in the Department of Biochemistry, University of Otago, Dunedin, New Zealand. Jillian F. Maddox, B.V.Sc, Ph.D., G.Dip.Inf.Sci., is Senior Research Fellow of the Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Australia; and Frank W. Nicholas, B.Ag.Sc, Ph.D., is Associate Professor in the Department of Animal Science, University of Sydney, Camperdown, Australia. Thomas E. Broad, B.V.Sc. (Hons), M.Sc, Ph.D., is Senior Scientist in the AgResearch Molecular Biology Unit; Grant W. Montgomery, B.Ag.Sc. (Hons), Ph.D., is Program Leader of the AgResearch Molecular Biology Unit; Diana F. Hill, B.Sc, Ph.D., is Director of the Molecular Biology Unit and Associate Professor in the Department of Biochemistry, University of Otago, Dunedin, New Zealand. Jillian F. Maddox, B.V.Sc, Ph.D., G.Dip.Inf.Sci., is Senior Research Fellow of the Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Australia; and Frank W. Nicholas, B.Ag.Sc, Ph.D., is Associate Professor in the Department of Animal Science, University of Sydney, Camperdown, Australia. Thomas E. Broad, B.V.Sc. (Hons), M.Sc, Ph.D., is Senior Scientist in the AgResearch Molecular Biology Unit; Grant W. Montgomery, B.Ag.Sc. (Hons), Ph.D., is Program Leader of the AgResearch Molecular Biology Unit; Diana F. Hill, B.Sc, Ph.D., is Director of the Molecular Biology Unit and Associate Professor in the Department of Biochemistry, University of Otago, Dunedin, New Zealand. Jillian F. Maddox, B.V.Sc, Ph.D., G.Dip.Inf.Sci., is Senior Research Fellow of the Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Australia; and Frank W. Nicholas, B.Ag.Sc, Ph.D., is Associate Professor in the Department of Animal Science, University of Sydney, Camperdown, Australia. Thomas E. Broad, B.V.Sc. (Hons), M.Sc, Ph.D., is Senior Scientist in the AgResearch Molecular Biology Unit; Grant W. Montgomery, B.Ag.Sc. (Hons), Ph.D., is Program Leader of the AgResearch Molecular Biology Unit; Diana F. Hill, B.Sc, Ph.D., is Director of the Molecular Biology Unit and Associate Professor in the Department of Biochemistry, University of Otago, Dunedin, New Zealand. Jillian F. Maddox, B.V.Sc, Ph.D., G.Dip.Inf.Sci., is Senior Research Fellow of the Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Australia; and Frank W. Nicholas, B.Ag.Sc, Ph.D., is Associate Professor in the Department of Animal Science, University of Sydney, Camperdown, Australia. Since their domestication around 7000 to 9000 BC, sheep have significantly influenced the economic, social, and cultural fabric of human society. The volume entitled “The Genetics of Sheep,” edited by Piper and Ruvinsky (1997), contains comprehensive reviews of several aspects outlined in the following brief discussion of the sheep gene map. Only summary details of these aspects are included below. The genus Ovis ( Figure 1 ) comprises several wild and domesticated species ( Maijala 1997 ). This taxonomical usage is controversial since all of these so-called “species” can interbreed ( Franklin 1997 ). However, based on chromosome number, 4 cytogenetic groupings of at least 8 species of sheep are recognized at the time of this writing: Three medium-wool sheep of the New Zealand Romney breed of the domestic sheep (Ovis aries) . Farmed for both wool and meat production, this breed makes up the majority of the national flock in New Zealand. Ovis aries is I of several species of sheep, which diverged from goats about 5 million yr ago and from cattle about 25 million yr ago. At the time of this writing, the sheep gene map is being constructed to identity genes of economic and medical importance and to understand--through comparisons with their bovid cousins and more distantly related mammals--how subtle rearrangements in genome organization result in widely different biological functions. Photograph reproduced with kind permission from Wools of New Zealand. 2n=52 Ovis nivicola (snow sheep or Siberian bighorn) 2n=54 Ovis aries (domestic sheep) Ovis canadensis (bighorn) Ovis dalli (thinhorn or Dall's sheep) Ovis musimon (European mouflon) Ovis orientalis (Asiatic mouflon, Urial) 2n=56 Ovis ammon (Arkhar-Argali, giant wild sheep) Ovis ammon severtzovi (Severtzov wild sheep) ( Lyapunova and others 1997 ) 2n=58 Ovis vignei (Oriental steppe sheep) The name Ovis aries, which has been given to the domestic sheep apparently to distinguish it from the wild sheep, is thought to be derived from Ovis orientalis (the Asiatic mouflon, which may also be the ancestor of the European mouflon [ Maijala 1997 ]). Of the wild sheep, the thinhorn, bighorn, and snow sheep have never been domesticated ( Maijala 1997 ). Most if not all of the gene mapping work has been, and continues to be, done on various breeds of the domestic sheep, Ovis aries . For details of these breeds, see Maijala (1997 ). The genus Ovis is one of the 10 genera usually included in the subfamily Caprinae. A variety of evidence suggests that Ovis diverged contemporaneously from the goats (Capra) and chamois (Rupicapra) approximately 5 million yr ago ( Franklin 1997 ). The subfamily Caprinae is one of the 9 subfamilies that comprise the family Bovidae, which includes the subfamily Bovinae and comprises the bison, buffalo, and wild and domestic cattle. The Caprinae are believed to have diverged from the Bovinae and other bovid species approximately 17 to 25 million yr ago ( Franklin 1997 ). Robertsonian translocations appear to be common in many of the bovid lineages and result in the differences in chromosome number between them. Thus, 3 centric fusion events account for the differences in chromosome number of sheep compared with goats and cattle (2n=60). Apart from a few other minor chromosomal rearrangements, there is a very high level of banding similarity between the chromosomes of sheep, goats, and cattle. This similarity has enabled the nomenclature of the karyotypes of these species to be correlated ( Popescu and others 1996 ), a development that together with their close evolutionary relatedness, has been particularly important for the mapping of the genomes of all 3 genera. The family Bovidae (cattle, sheep, and goats) is a member of the suborder Ruminantia. The deer also comprise a large grouping (family Cervidae) of this suborder. These groupings also have important implications for the mapping of the sheep genome, as discussed below. (The true ruminants, with 3-chambered stomachs, are classified into the Pecoran infraorder.) The suborders Ruminantia (deer, cattle, goats, and sheep), Tylopoda (camelids), and Suiformes (pigs, peccaries, and hippopotamus) are members of the order Artiodactyla ( Franklin 1997 ). Thus, a relatively close evolutionary relationship can be seen to exist between sheep, goats, cattle, deer, and pigs. Following the recommendations of the International Society for Animal Genetics, mapped loci on sheep and other farmed animal genomes are named using human nomenclature guidelines. These human guidelines are designed to facilitate the identification of orthologues in sheep, reflecting the extensive past and current use made of heterologous (particularly human) gene probes and nucleotide sequence data in the mapping of these genomes. The names and symbols of human genes can be obtained on the World Wide Web (Web 1 ) from the Genome Database ( http://gdbwww.gdb.org/gdb/gdbtop.html ) and the Human Genome Organization (HUGO) Genome Database Nomenclature Committee ( http://www.gene.ucl.ac.uk/nomenclature/ ). Condensed guidelines containing rules for homologies with other species have recently been published by White and others (1997 ). For all other loci, or those for which no human equivalent was available at the time of preparation, the naming of sheep loci followed the recommendations of the Committee on Genetic Nomenclature of Selected Animal Genera (COGNOSAG 1 ). Recommendations of COGNOSAG are published in reports of the COGNOSAG Ad Hoc Committee (1995 ), Lauvergne and others (1996 ), and Dolling (1997 ). In these guidelines, the nomenclature for the keratins---especially the wool keratins and associated proteins--are from Powell and Rogers (1994 ). As is the case for most species, gene mapping of the sheep is being performed mainly for the following purposes: to enhance the quality and diversity of sheep and their products by positive or negative marker-assisted selection; to improve animal health and welfare by marker-assisted selection to eliminate diseases and to protect the environment by reducing the need for widespread use of agrochemicals; to investigate aspects of speciation and evolution; to establish models for elucidating the etiology and treatment of human genetic disease; and to protect genetic diversity and rare breeds and species. Maps and associated sheep genome mapping data in the public domain are compiled and available on the Web in SheepBase ( http://zaphod.invermay.cri.nz/ ). As of December 3, 1997, 627 loci, of which 245 are known genes, have been mapped in sheep. These loci are graphically displayed in 2 linkage maps and 1 cytogenetic on the of their The linkage maps are which is a linkage map of and others (1995 ) constructed using the International 1 ) and a sheep linkage using I as a containing published in is a map of the chromosome based on the of ancestor of the European and others (1996 ). The cytogenetic map contains mainly mapped that have been to a are in the of The linkage map of and others (1995 ) has been by a linkage map based on the and Department of 1 ) Animal Research ( and others ). This map has of which have also been mapped in cattle, and a of is to it in SheepBase it be displayed together with the map of and others (1995 ). A linkage map with of is at the time of this Maddox, Centre for Animal University of Melbourne, on and the maps the map is A of that are included in the map and map is on the Web at . data on the of of the in the and maps and the of mapped on are also available at this The map of between on the sheep genome for from of chromosomes as from comparisons cattle and sheep maps ( ) and of the sheep map with as from comparisons cattle and sheep maps ( 2 ). of the map at the of sheep chromosomes of the sheep genome in the map and genetic mapping the mapping for sheep. have been ( and others 1997 and 1997 ). have been made since to a for the sheep ( and others ). was in in for a sheep that was correlated with the cattle on the of banding and gene loci ( and others 1997 ). The and of and others (1996 ), derived from to and to are with the sheep These karyotypes constructed by cytogenetic from sheep with 3 different Robertsonian chromosomes that as chromosomes as At the level of loci may be mapped to chromosomes by of A of the sheep genome has been for this ( and others ). mapping to have been to can be performed using the of by and ( and others ). The of sheep chromosomes ( and others ) these as for loci to sheep At a level of loci may be to by in using or probes in and others 1997 ). the level of by in 1 ) on or chromosomes is recognized to be about of the of the genome, between and can be obtained using ( and others 1997 ). this chromosomal level of mapping is performed by using a sheep chromosome with of approximately ( and ), and a sheep chromosomal with of University of and of the sheep genome have been constructed in as and various AgResearch in New and Research Organization and in Australia; and for in may be available on from in New and the have to the sheep linkage map using a common of The linkage map was published in using the AgResearch International and others ). The map with of between ( and others ). This map approximately of the sheep The on which this map was comprises 9 with from these has been to by the at ( and others ). These of from 4 to The of was for the linkage map ( and others ). This map containing the of the map by approximately and all of the linkage into 1 A of sheep mapping has been by and comprises of by 2 Romney the 1 and 2 Robertsonian translocations with 9 the The of these has with the other this is the of the map of important of the sheep linkage map has been the extensive use of cattle which the of the and of in sheep ( and others 1997 of the in the sheep map are and in the map are in The and maps extensive of order linkage with is sheep chromosome 9 to have been from the of cattle chromosome 9 to with cattle chromosome which has linkage with the of sheep chromosome 9 ( and others ). equivalent is in goats ( and others 1996 ). In to the for the several are mapping in as of to loci or for A map of sheep chromosome was using the together with for the gene ( and others 1996 ). A map of the sheep chromosome with and genes was by and others (1996 ). A map of the of sheep chromosome which the has been by and others (1996 ). the large majority of are other of are and ( and 1997 ). have been and mapped by and others (1996 and more have also been mapped in sheep AgResearch Molecular Biology Dunedin, New Three have been for mapping 9 of 3 ( and others the mapping flock of and the Animal Research flock ( and others ). from these is available on for mapping The widespread use of these (particularly the by the sheep genome mapping has been in the development of a map for the species. The of in both and loci selection for genetic may also be of in genetic in other species. of the of this and this below. However, it be that this is not of sheep have been in New Zealand and and to ). In New gene mapping have on of Romney sheep that have diverged by a of by between these have been to and the that in their to to are being using a ( and others ). is to a selection flock between of Melbourne, and of is a by the of the by the which on in Since and of Romney sheep have been being by the of the of the The have diverged by ( and others ). The selection in and 4 to Romney The are being using both a gene and ( and others ). 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At the time of this writing, 3 from these are being to at AgResearch New to a flock in which the gene is that a gene in a in of sheep ( and others 1996 ) in of and to At the time of this writing, a flock the gene is being for gene and obtained from at least 3 have been by to be of is for gene are being of sheep the following Robertsonian 1 ( 2 ( 3 ( and 5 ( ( and others and others ). with the 3 of these centric are derived from those by and others ) in New Zealand Romney sheep. the are in a and a flock translocations has been in which the chromosome number of several is in high and of sheep at based on the for In and 2 yr of and diverged and in from the to and in between the with the and and compared with for the ( and others 1997 ). In the and with both selection in and 1996 ( and others ). At the time of this writing, from these are being to gene and selection of sheep also in ( and others ), these have been the of A is being of a flock of sheep that on the of the of a of was no of the selection with the a level the and the the The the and more at the the ( and others ). The which in sheep (particularly of the has been mapped to the of sheep chromosome Only the of to be ( and others 1996 ). The gene was in a in a flock in and was to the to containing the gene have been in the and is to the gene by The which the of the in sheep, has been in the of derived from the ( and others ). The maps to a of sheep chromosome as the is to the of the in flock of sheep ( and others 1997 ) and to it is to In and at the University of the of a flock for and meat by with are being for the of are being for all the important and a are being for and meat quality and all are being for a of breed and are also being to a genome with in with high Romney to that 2 yr with to A of was performed with Romney to are being performed to linkage with the following wool and ( and others ). A genome is in using a selection flock from derived from with and that to to large family containing at least ( and others ). gene are at the time of this for wool and wool quality in of the mapping flock in from this flock is available on from Australia. A gene to be a of the gene has been in the derived from a to and to ( and others 1997 ). The gene to have in the flock in which the in to it was as a and it is known to by 1 gene to on The gene has been mapped to sheep chromosome using a genome in and others ), and work is to more and to the gene by The gene was in in a family of Romney sheep that from 1 of from to the of the gene on the of the gene by about and by about However, in it was that with 2 of the gene have and are in the gene was in a flock of Romney sheep ( and others ). is to to the gene ( and others 1996 ). Genetic maps and are being in sheep to of and mapping genes production, and of have been to the of ( and others ) and to the of by ( and others 1996 ). The number of loci with that have been mapped to is ( 3 ). those production, wool and These have been mapped using a of gene and genome gene and loci for sheep chromosome not at the time of this not published at the time of this writing, a has been ( and others ) in the 3 gene for which in the development of to ( Lauvergne and others 1996 ). of this genetic and of the to these is to to the development of marker-assisted selection to the genetic of sheep. This has been by and (1997 ). The of known genes on the sheep genome have been compared with their in cattle, and ( 1997 ). of these data in the of of chromosomal organization these with cattle and least with Thus, there is a between chromosomes and chromosomal of the sheep and cattle genomes compared with human and A of chromosomal have been to between sheep and and between sheep and is also a high level of between the sheep and deer genomes comparisons of sheep with human and this to to that the order of loci these is also ( and others 1996 ). the deer map may be in the sheep and other or genomes. deer mapping has been from deer ( deer ( ) from deer deer ( and others ). At the time of this writing, the deer map contains mapped loci, of which are mapped in in sheep, and in cattle. of the order of these loci in the different species has very few rearrangements between sheep, cattle, and However, of the deer and human maps evidence not Thus, for ruminants, the of the deer mapping for mapping and loci a of species ( and others ). be both and if the deer map the map for as sheep, goats, and cattle. for it are for the order of loci of and for mapping I loci genes and sequence from other species the In the of this the has since the of the deer mapping 2 important mapping and of mapping data with and linkage mapping In the deer can be in most time and In using mapping most can be to other at into of This the of mapping from human and and other species into the and the of animal on and genetic similarity to the human sheep have several and other as models for the of human diseases and sheep are in to human the development of and the of sheep are more related to are and other cultural and there are to using sheep pigs. In as New Zealand and the of sheep is in and many other These have to the development of models for several human (1997 ) has and in sheep that may be models for human have been to evolutionary between sheep breeds ( and others ) and in wild as ( and others ) and ( and others ). The sheep genome map and associated can be to in the of sheep has been that breeds of sheep have in the yr 1997 ). The of genetic is for sheep as as for all other For a comprehensive of this as it sheep, see (1997 ). For on the and Organization for of animal genetic see the Web ( ). As of this is recommendations for a of to in sheep breeds at of by the diversity of the At the time of this writing, the large Animal of Web has from the to the ( ). As the of gene mapping in sheep and in other species, evolutionary may be that the events associated with The of may also be and may in or of chromosome this on chromosome and organization may to a more of gene which may in result in the development of to of and SheepBase is a of mapping and associated data that are on the Web ( http://zaphod.invermay.cri.nz/ ). The of SheepBase is AgResearch New are available at the ( ), and at the ( ). The for SheepBase is the as that for and This the map and the Web by and of the and of the SheepBase the by has been designed as a genome is that by number of species mapping establish a common that facilitate In the the includes chromosomal and of loci, and details of and The of to other is A of sheep genome data and by Frank and of Sydney, is available on the Web at the Genome ( ). on of human entitled in ( ), has of at the Web more and are together with a of of this has been published ( 1997 ). at the are the COGNOSAG of loci, which have been published the in ( Lauvergne and others 1996 ). In the entitled of has also made available a of sheep and other animal At the Web ( ), Jillian has made available of mapping data of sheep and other in to reports of linkage mapping genome is being in many around the at the time of this no to this Research are widely in a of and at and other In a national sheep mapping entitled has been in New Zealand. For on and . In the the sheep genome is by Professor the Department of Animal Research relatively compared with cattle and genome the sheep genome mapping has to of the organization and of the genome and has for a of the genetic of the of the sheep. As more in the of those of the sheep genome that are to be important to the sheep or to human there be for comparisons with the genomes of other species. These mapped of the sheep genome of be in about the and other loci and of the organization and between these as these the the of genome For this are all and of the for the available to and for their in The work of E. F. and W. was as of a to AgResearch from the New Zealand for and work was as of a for the Research and