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Sheep Genomic Advances The sheep genome has finally made it on to the international genome sequencing research agenda. Traditionally, the small size of the international market for sheep products has limited investment in sheep genetic and genomic resources. Commercial sheep genomic resources have developed at a slower pace and to lower specifications than for other species of domesticated livestock. However, the formation of the International Sheep Genomics Consortium (ISGC) heralds a new era in sheep genomic research, says Dr Orla Keane in TResearch, Teagasc’s Research and Innovation magazine. Thanks to DNA Chip technology much progress has already been made. “The ISGC has used a newly developed chip to genotype approximately 3,000 sheep of 74 breeds from around the world in the Sheep HapMap and breed diversity project. The sheep genotyped included approximately 50 each of the Galway and Suffolk breeds sourced from Teagasc and University College Dublin flocks” explains Dr Keane. “The technology also makes mapping the gene responsible for a single gene recessive trait relatively straightforward. Since the chip was released, the technology has been successfully used to map and identify the gene responsible for microphthalmia (a recessive disorder causing blindness) and chondroplasia (a disease resulting in dwarfism and deformity of the limbs) in the Texel breed, yellow fat in the Perendale breed, and the gene responsible for polledness. As part of the EU Seventh Framework Programme 3SR project (Sustainable Solutions for Small Ruminants), the technology is currently being utilised by Teagasc researchers, in collaboration with the ISGC, to map the gene responsible for increased ovulation rate in the highly prolific Cambridge flock at the Teagasc Animal & Grassland Research and Innovation Centre, Athenry” says Dr Keane. Such examples of gene identification can have an immediate impact on the sheep breeding industry by allowing sheep breeders to screen animals for the genes and select replacement stock, cull or avoid at-risk matings based on the results. The technology is also currently being utilised by Teagasc and collaborators to identify genes underpinning polygenic traits, such as production traits and parasite resistance. Furthermore, the technology is a fundamental tool required for genomic selection, where animals are selected on genomic rather than phenotypic characteristics.
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Dul Chun Cinn na Géanómaíochta Caorach Ar deireadh thiar, d’éirigh leis an ngéanómaíocht chaorach clár taighde idirnáisiúnta seicheamhú géanómaíochta a bhaint amach. Go stairiúil, tá ag méid bheag an mhargaidh idirnáisiúnta le haghaidh táirgí caorach infheistíocht theoranta in acmhainní géiniteacha agus géanómaíocht chaorach. Tá forbairt tagtha ar acmhainní tráchtála géanómaíocht chaorach ag luas níos moille agus ag sonraíocht níos ísle ná speicis eile de bheostoc dúchasaithe. Ar a shon sin, tá ré nua arna cruthú ag an gCuibhreannas Idirnáisiúnta Géanómaíocht Chaorach (ISGC) sa taighde ar ghéanómaíocht chaorach, a dúirt an Dr Orla Keane in TReasearch, irisleabhar Taighde agus Nuálaíochta Theagasc. Tá go leor dul chun cinn déanta cheana féin, a bhuí le teicneolaíocht Slis DNA. “D’úsáid an ISGC slis atá forbartha le déanaí d’fhonn géinitíopáil a dhéanamh ar thart ar 3,000 caora de 74 pór ó áiteanna ar fud an domhain sa tionscadal HapMap Caorach agus sa tionscadal éagsúlacht phórtha. I measc na gcaorach ar a ndearnadh géinitíopáil bhí thart ar 50 caora de phórtha na Gaillimhe agus Suffolk a chuir Teagasc agus Ollscoil na hÉireann, Baile Átha Cliath ar fáil óna gcuid tréad", a mhíníonn an Dr Keane. “Is féidir mapáil a dhéanamh ar an ngéin is cúis le tréith chúlaitheach ghéine single gan mórán stró, a bhuíochas leis an teicneolaíocht. Ó bhí an tslis ann, d'éirigh leo leas a bhaint as an teicneolaíocht chun mapáil a dhéanamh agus leis an ngéin is cúis le micrea-oftailme (neamhord cúlaitheach is cúis le daille) agus chondroplasia (galar ar a mbíonn abhcacht agus míchuma ghéag mar thoradh) sa phór Texel, saill bhuí sa phór Perendale, agus an ghéin is cúis le hainmhithe maola. Mar chuid de thionscadal 3SR Sheachtú Creatchlár an AE (Réitigh Inbhuanaithe le haghaidh Athchogantaigh Bheaga) [‘EU Seventh Framework Programme 3SR project (Sustainable Solutions for Small Ruminants)’], tá taighdeoirí Theagasc ag baint leasa as an teicneolaíocht faoi láthair, i gcomhar leis an ISGC, chun an ghéin is cúis le ráta méadaithe ubhsceite i dtréad torthúil Cambridge a mhapáil ag an Ionad Taighde agus Nuálaíocht Ainmhithe agus Féarach Theagasc i mBaile Átha an Rí", a deir an Dr Keane. Is féidir lena leithéid de shamplaí d’aithint ghéine tionchar láithreach bheith ar an tionscadal póraithe caorach trí ligeann don lucht póraithe caorach scagthástáil a dhéanamh ar ainmhithe i leith na géine agus le stoc ionaid a roghnú, cúplálacha atá i mbaol a dhealú nó a sheachaint, bunaithe ar na torthaí. Sa mhullach air sin, tá an teicneolaíocht á húsáid ag Teagasc agus ag comhoibrithe faoi láthair d’fhonn géin a aithint is cúis le tréithe ilghéineacha, ar nós tréithe táirgthe agus frithsheasmhachta i leith seadán. Ina theannta sin uile, bunuirlis atá sa teicneolaíocht a theastaíonn le haghaidh roghnú géanómaíochta, sa chás go roghnaítear ainmhithe de bharr géanómaíochta seachas tréithe feinitíopacha.