Bacon L D, Smith E, Crittenden L B, Havenstein G B
US Department of Agriculture, Agricultural Research Service, East Lansing, Michigan 48823.
Poult Sci. 1988 Feb;67(2):191-7. doi: 10.3382/ps.0670191.
A dominant sex-linked gene, K, regulates slow feathering (SF), whereas a recessive allele, k+, determines rapid feathering (RF) in chickens. This trait provides a convenient and inexpensive approach to gender identification of White Leghorn (WL) chicks at hatch, i.e., in a sex-linked mating using k+/k+ males mated with K/- females, the K/k+ male chicks are SF, and the k+/- females are RF. However, in many WL strains, female progeny of SF dams produce fewer eggs and have higher mortality than progeny of RF dams. This loss in productivity has been attributed to higher infection and shedding rates for leukosis viruses (ALV) in SF than in RF dam lines. Because infectious endogenous viruses (EV) can induce immunological tolerance to ALV, we examined the expression and distribution of ev genes in SF and RF siblings from heterozygous K/k+ sires and k+/- dams. Infectious ALV and EV were detected by cocultivation of frozen heparinized blood cells on selected chick embryo fibroblasts and culture supernatants were tested for viral antigen by enzyme-linked immunosorbent assay tests. Specific ev genes were identified as restriction fragment length polymorphisms after hybridization with a recombinant plasmid containing the complete genome of a Rous-associated virus. It was concluded that ev21 and K genes are tightly linked because, in different WL crosses, all SF chicks inherited ev21 but RF siblings uniformly lacked ev21. Alternatively, the K gene in WL may be a mutation resulting from the insertion of ev21 in the k+ gene. The SF chicks which harbor ev21 expressed infectious EV21; evidence that EV21 may influence susceptibility to ALV is presented.
一个显性性连锁基因K调控鸡的慢羽（SF），而隐性等位基因k⁺决定快羽（RF）。这一性状为白来航（WL）雏鸡出壳时的性别鉴定提供了一种便捷且经济的方法，即在一个性连锁交配中，用k⁺/k⁺雄性与K/-雌性交配，K/k⁺雄性雏鸡为慢羽，k⁺/-雌性雏鸡为快羽。然而，在许多WL品系中，慢羽母鸡的雌性后代产蛋量比快羽母鸡的后代少，死亡率也更高。这种生产力的损失归因于慢羽品系中白血病病毒（ALV）的感染率和排毒率高于快羽品系。由于感染性内源性病毒（EV）可诱导对ALV的免疫耐受，我们检测了来自杂合K/k⁺父本和k⁺/-母本的慢羽和快羽同胞中ev基因的表达和分布。通过在选定的鸡胚成纤维细胞上共培养冷冻的肝素化血细胞来检测感染性ALV和EV，并通过酶联免疫吸附试验检测培养上清液中的病毒抗原。与含有劳斯相关病毒完整基因组的重组质粒杂交后，将特定的ev基因鉴定为限制性片段长度多态性。得出的结论是，ev21和K基因紧密连锁，因为在不同的WL杂交中，所有慢羽雏鸡都继承了ev21，而快羽同胞均未携带ev21。或者，WL中的K基因可能是ev21插入k⁺基因导致的突变。携带ev21的慢羽雏鸡表达感染性EV21；文中提供了EV21可能影响对ALV易感性的证据。
