Institute of Marine Research, Bergen, Norway.
Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
BMC Genom Data. 2024 Aug 30;25(1):78. doi: 10.1186/s12863-024-01263-5.
Increased knowledge of heritable traits in Atlantic Salmon (Salmo salar) is important to overcome bottlenecks in salmonid aquaculture. Atlantic salmonid populations, both landlocked and anadromous, represent an interesting model to gain insight into anadromy related traits, most notably, the probability to smoltify. While a previous study has identified several genomic regions diverging between anadromous and landlocked populations across the species range, the present study explores these data further with the aim to uncover if some of these genomic regions are linked to beneficial genetic traits associated with smoltification. In this study 17 of these loci were monitored in 669 anadromous salmon originating from 36 full-sibling families that had been reared under common garden conditions. The Smolt Index was calculated, using multiple visual markers, and provided a means of assessing smoltification stage. One SNP, located in Ssa04, showed a significant association with probability to smoltify, where individuals homozygous for the landlocked variant (LL) displayed a decrease in probability of smoltifying after one winter when compared with the homozygous for the anadromous variant (AA). This effect was independent of individual fish size. A separate common garden study comprising 200 individuals from either anadromous or landlocked strains showed that expression levels of ncor1, a thyroid mediator hormone located on the same chromosomal region (Ssa04), were significantly reduced in landlocked individuals post smoltification but remained constant in their anadromous counterparts. This study therefore suggests that while size is still the most important trigger for the induction of smoltification, there may also be an additional genetic component or trigger that has been 'lost' during the years deprived of SW transfer. In conclusion, the LL genotype identified here could potentially be used by the industry to delay smoltification and may also represent one of the first clues to the genetic regulation of smoltification in Atlantic salmon.
增加对大西洋鲑（Salmo salar）遗传特征的了解对于克服鲑鱼养殖业的瓶颈至关重要。无论是内陆洄游型还是溯河洄游型的大西洋鲑种群，都是研究与溯河洄游相关特征的有趣模型，尤其是变态为幼鱼的概率。虽然之前的一项研究已经确定了跨越物种范围的洄游型和内陆型种群之间存在几个基因组区域的差异，但本研究进一步探讨了这些数据，旨在揭示这些基因组区域中是否有一些与变态为幼鱼相关的有益遗传特征有关。在这项研究中，监测了 17 个这样的基因座，这些基因座位于 36 个全同胞家系的 669 条溯河洄游鲑鱼中，这些鲑鱼是在共同饲养条件下饲养的。使用多个视觉标记计算了变态指数，并提供了评估变态阶段的方法。一个位于 Ssa04 的 SNP 与变态为幼鱼的概率显著相关，与溯河洄游型变异（AA）个体相比，在经历一个冬季后，纯合内陆型变异（LL）个体的变态为幼鱼的概率降低。这种影响与个体鱼的大小无关。另一项包括来自溯河洄游或内陆型的 200 个个体的独立共同饲养研究表明，位于同一染色体区域（Ssa04）的甲状腺介体激素 ncor1 的表达水平在变态为幼鱼后的内陆型个体中显著降低，但在它们的溯河洄游型对应物中保持不变。因此，本研究表明，虽然大小仍然是诱导变态为幼鱼的最重要触发因素，但在失去 SW 转移的这些年中，可能也存在一个额外的遗传成分或触发因素。总之，这里鉴定的 LL 基因型可能被该行业用于延迟变态为幼鱼，并且也可能代表大西洋鲑变态为幼鱼的遗传调控的第一个线索之一。
