Minvielle Francis, Kayang Boniface B, Inoue-Murayama Miho, Miwa Mitsuru, Vignal Alain, Gourichon David, Neau André, Monvoisin Jean-Louis, Ito Shin' ichi
Génétique et Diversité Animales, Institut National de la Recherche Agronomique, Centre de Jouy, 78352 Jouy-en-Josas, France.
BMC Genet. 2006 May 5;7:26. doi: 10.1186/1471-2156-7-26.
Egg production is of critical importance in birds not only for their reproduction but also for human consumption as the egg is a highly nutritive and balanced food. Consequently, laying in poultry has been improved through selection to increase the total number of eggs laid per hen. This number is the cumulative result of the oviposition, a cyclic and repeated process which leads to a pattern over time (the egg laying curve) which can be modelled and described individually. Unlike the total egg number which compounds all variations, the shape of the curve gives information on the different phases of egg laying, and its genetic analysis using molecular markers might contribute to understand better the underlying mechanisms. The purpose of this study was to perform the first QTL search for traits involved in shaping the egg laying curve, in an F2 experiment with 359 female Japanese quail.
Eight QTL were found on five autosomes, and six of them could be directly associated with egg production traits, although none was significant at the genome-wide level. One of them (on CJA13) had an effect on the first part of the laying curve, before the production peak. Another one (on CJA06) was related to the central part of the curve when laying is maintained at a high level, and the four others (on CJA05, CJA10 and CJA14) acted on the last part of the curve where persistency is determinant. The QTL for the central part of the curve was mapped at the same position on CJA06 than a genome-wide significant QTL for total egg number detected previously in the same F2.
Despite its limited scope (number of microsatellites, size of the phenotypic data set), this work has shown that it was possible to use the individual egg laying data collected daily to find new QTL which affect the shape of the egg laying curve. Beyond the present results, this new approach could also be applied to longitudinal traits in other species, like growth and lactation in ruminants, for which good marker coverage of the genome and theoretical models with a biological significance are available.
产蛋在鸟类中至关重要，不仅关乎其繁殖，而且对于人类消费来说，鸡蛋是一种营养丰富且均衡的食物。因此，通过选育提高了家禽的产蛋量，以增加每只母鸡的总产蛋数。这个数字是产卵的累积结果，产卵是一个周期性且重复的过程，随着时间推移会形成一种模式（产蛋曲线），该曲线可以进行建模并单独描述。与综合了所有变异的总蛋数不同，曲线的形状能提供有关产蛋不同阶段的信息，利用分子标记对其进行遗传分析可能有助于更好地理解潜在机制。本研究的目的是在一个有359只雌性日本鹌鹑的F2实验中，首次对影响产蛋曲线形状的性状进行QTL搜索。
在五条常染色体上发现了8个QTL，其中6个可直接与产蛋性状相关，尽管在全基因组水平上均不显著。其中一个（位于CJA13上）对产蛋高峰前产蛋曲线的第一部分有影响。另一个（位于CJA06上）与产蛋维持在高水平时曲线的中间部分有关，另外四个（位于CJA05、CJA10和CJA14上）作用于曲线的最后一部分，此时持续性是决定性的。曲线中间部分的QTL在CJA06上的定位与之前在同一F2中检测到的全基因组显著的总蛋数QTL位于同一位置。
尽管本研究范围有限（微卫星数量、表型数据集大小），但这项工作表明，利用每天收集的个体产蛋数据来寻找影响产蛋曲线形状的新QTL是可行的。除了目前的结果外，这种新方法还可应用于其他物种的纵向性状，如反刍动物的生长和泌乳，对于这些性状，基因组有良好的标记覆盖且有具有生物学意义的理论模型。
