Laboratory of Animal Breeding and Genetics, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8528, Japan.
Yamaguchi Prefectural Agriculture and Forestry General Technology Center, Mine, Yamaguchi 759-2221, Japan.
Poult Sci. 2018 Feb 1;97(2):403-411. doi: 10.3382/ps/pex345.
The late-feathering (LF) gene K on the Z chromosome is an important gene in the chicken industry, which is frequently utilized for the feather sexing, a type of autosexing, of neonatal chicks. The K gene is closely associated with the endogenous ev21 gene from an avian leukosis virus and the incomplete duplication (ID) of prolactin receptor (PRLR) and sperm flagellar protein 2 (SPEF2) genes, and ev21 has been used as a molecular marker to detect LF birds. In the present study, a comprehensive survey for the presence or absence of ev21 and ID across 1,994 birds from 52 chicken breeds, three commercial hybrid groups, and the Red Jungle Fowl revealed that almost all LF breeds have both ev21 and ID. However, only one LF breed (Ingie) has only ID and no ev21. Moreover, this study revealed that almost all early (normal)-feathering (EF) breeds lack both ev21 and ID, but only one breed (White Plymouth Rock) included EF birds with ev21 but no ID. Therefore, regarding LF expression, the results indicated that ID is responsible, but ev21 is not required. Henceforth, ID should be used as a molecular marker to detect LF birds instead of ev21. Because ev21 contains the full genome of an avian leukosis virus, there is a risk of disease development in breeds with this gene. Therefore, the Ingie breed, which has no ev21 at the K locus, represents excellent material for the establishment of new LF stocks.
Z 染色体上的迟羽（LF）基因 K 是家禽业的一个重要基因，常用于新生雏鸡的性别鉴定（一种自动性别鉴定）。K 基因与禽白血病病毒的内源性 ev21 基因以及催乳素受体（PRLR）和精子鞭毛蛋白 2（SPEF2）基因的不完全重复（ID）密切相关，ev21 已被用作检测 LF 鸟类的分子标记。在本研究中，对来自 52 个鸡品种、3 个商业杂交群和红原鸡的 1994 只鸟类进行了 ev21 和 ID 存在或缺失的综合调查，结果表明几乎所有 LF 品种都同时具有 ev21 和 ID。然而，只有一个 LF 品种（Ingie）只有 ID 而没有 ev21。此外，本研究还表明，几乎所有早期（正常）羽（EF）品种都缺乏 ev21 和 ID，但只有一个品种（白普利茅斯岩鸡）包括具有 ev21 但没有 ID 的 EF 鸟类。因此，关于 LF 的表达，结果表明 ID 是负责的，但 ev21 不是必需的。因此，ID 应该用作检测 LF 鸟类的分子标记，而不是 ev21。由于 ev21 包含禽白血病病毒的完整基因组，因此具有该基因的品种存在疾病发展的风险。因此，Ingie 品种在 K 位点没有 ev21，代表了建立新 LF 种群的优秀材料。
