Silversides F G, Urrutia M S, Crawford R D
J Hered. 1982 Jul-Aug;73(4):295-6. doi: 10.1093/oxfordjournals.jhered.a109643.
A new condition affecting the facial structure of domestic fowl is described. It is controlled by an autosomal recessive gene having complete penetrance. The mutation has been named missing upper beak and the gene symbol mub is proposed. The condition is an obligate lethal. Mortality occurs on the twelfth day of incubation or during the hatching process. One chick hatched unaided and five were assisted from the shell; none of these survived beyond 11 days of age. They had partial vision and hearing, they could vocalize and had normal balance, but they were unable to eat. Major phenotypic effects of the mutation are absence of the upper beak and absence of eyelids. All or part of the upper eyelid is always missing; the lower eyelid and nictitating membrane may be present or absent. Premaxilla and nasal bones are greatly reduced causing the upper beak to be rudimentary. Other membranous bones of the head are reduced causing the face to be shortened. Cartilaginous bones appear not to be affected. It is postulated that the condition results from a defect in membrane formation during embryonic development.
本文描述了一种影响家禽面部结构的新病症。它由一个具有完全外显率的常染色体隐性基因控制。该突变被命名为“上喙缺失”，并提议用基因符号mub表示。这种病症是一种必然致死的情况。死亡发生在孵化的第12天或孵化过程中。有一只雏鸡自行破壳而出，五只雏鸡被辅助出壳；这些雏鸡无一存活超过11日龄。它们有部分视力和听力，能发声且平衡正常，但无法进食。该突变的主要表型效应是上喙缺失和眼睑缺失。上眼睑全部或部分总是缺失；下眼睑和瞬膜可能存在或不存在。前颌骨和鼻骨大幅缩小，导致上喙发育不全。头部的其他膜性骨缩小，致使面部缩短。软骨性骨似乎未受影响。据推测，这种病症是胚胎发育过程中膜形成缺陷所致。
