Sex control in cod

水产养殖业是世界上增长最快的食品生产部门。在加拿大，捕捞渔业从20世纪80年代末的历史高位下降，水产养殖产量在过去十年中增长了十倍以上。加拿大水产养殖业的大部分产量来自不列颠哥伦比亚省和新不伦瑞克省养殖的三文鱼。然而，三文鱼不太适合大西洋加拿大大部分地区的水产养殖，三文鱼水产养殖作为一个整体在加拿大很难保持盈利。因此，行业和政府共同努力，使大西洋加拿大的水产养殖多样化。大西洋鳕鱼被视为该地区主要的替代水产养殖物种，也是大西洋加拿大最大的水产养殖公司(Cooke Aquaculture Inc.)最近对鳕鱼水产养殖进行了重大投资。他们的初步生产试验强调，生产鱼的过早成熟是商业生存能力的关键制约因素，因为成熟鱼停止生长，肉质降低，死亡率高。鳕鱼很容易在笼子里产卵，因此有可能将大量受精卵释放到野外，这一事实使这个问题变得更加复杂。我们建议开发生产单性鳕鱼种群的实用方法，以便利用成熟时年龄和大小的性别差异，并与目前正在进行的关于生产三倍体(不育)鳕鱼的平行研究计划相联系。我们的研究将确定大西洋鳕鱼性别决定的遗传基础，并将导致开发该物种功能性性别逆转的治疗方案。性别决定的遗传机制将由雌核发育决定，借此阻止父系基因组在可存活胚胎中的表达，并复制母体基因组。检查雌核发育种群后代的性别比有助于确定性别决定的遗传基础，并为决定生产单性种群的最佳方法提供信息。然后，内分泌性逆转将被用来创造能够产生单性后代的亲代。将资助两名研究生进行这项研究。

Aquaculture is the world's fastest growing food production sector. In Canada, where capture fisheries have declined from historic highs in the late 1980s, aquaculture production has increased more than ten-fold in the last decade. Most of Canada's aquaculture production comes from salmon farmed in British Columbia and New Brunswick. However, salmon are not well suited for aquaculture in most of Atlantic Canada and salmon aquaculture as a whole has had difficulty remaining profitable in Canada. As a result, there is a concerted effort by industry and government to diversify aquaculture in Atlantic Canada. Atlantic cod is seen as a prime alternative aquaculture species for the region, and Atlantic Canada's largest aquaculture company (Cooke Aquaculture Inc.) has recently made significant investments into cod aquaculture. Their preliminary production trials have highlighted early maturation of production fish as a key constraint to commercial viability, because mature fish cease growing, have reduced flesh quality and have high mortality rates. This problem is compounded by the fact that cod will eadily spawn in cages, thereby potentially releasing large numbers of fertilized eggs into the wild. We propose to develop practical approaches for the production of single-sex populations of cod, in order to take advantage of sex-related differences in age and size at maturity, and to link into a parallel research program currently underway on the production of triploid (sterile) cod. Our research will determine the genetic basis to sex determination in Atlantic cod and will lead to the development of treatment regimes for functional sex reversal in this species. The genetic mechanism of sex determination will be determined y gynogenesis, whereby expression of the paternal genome in viable embryos is prevented and the maternal genome is duplicated. Examining sex ratios of the offspring from gynogenetic populations helps to identify the genetic basis of sex determination and informs the decision on best approaches for producing single-sex populations. Endocrine sex reversal will then be used to create broodstock capable of generating single-sex progeny. Two graduate students will be funded to conduct this research.