Pigozzi M I, Solari A J
Centro de Investigaciones en Reproduccion, Facultad de Medicina, Buenos Aires, Argentina.
Chromosome Res. 1999;7(7):541-51. doi: 10.1023/a:1009241528994.
Pachytene oocytes from the two presumably most primitive orders (Paleognathae) among living birds were used to study the pairing behaviour and location of recombination nodules (RNs) in the sex pair. In the ratite Pterocnemia pennata (Rheiformes), the 42 analyzed ZW pairs show an average of 2.2 RNs distributed along 80% of the synaptonemal complex (SC) that covers the long arm of the acrocentric Z and W chromosomes in this homomorphic sex pair. In the tinamid Rynchotus rufescens (Tinamiformes), the 60 analyzed ZW pairs show an average of 1.35 RNs distributed along 66% of the SC covering most of the long arms of this visibly heteromorphic ZW pair. RNs are non-randomly distributed and show interference in both species, but in the tinamou they are restricted to a significantly smaller stretch. The discovery of an intermediate degree in the restriction of RN location, between the extremes of free recombination along most of the W in ratites and strict localization of a single RN in Neognath birds, suggests its relationship with the mechanism of sex chromosome differentiation among Aves.
来自现存鸟类中可能最原始的两个目（古颚总目）的粗线期卵母细胞被用于研究性染色体对中配对行为和重组结节（RNs）的位置。在平胸鸟类的彭纳氏凤冠雉（美洲鸵鸟目）中，所分析的42个ZW对平均显示有2.2个RNs，沿着覆盖该同形性染色体对中近端着丝粒Z和W染色体长臂的80%的联会复合体（SC）分布。在䳍形目的棕喉䳍中，所分析的60个ZW对平均显示有1.35个RNs，沿着覆盖该明显异形ZW对大部分长臂的SC的66%分布。RNs在两个物种中均呈非随机分布且存在干涉现象，但在䳍中它们被限制在明显更小的区段。在平胸鸟类中W染色体大部分区域自由重组以及新颚类鸟类单个RN严格定位这两个极端情况之间，发现了RN位置限制的中间程度，这表明其与鸟类性染色体分化机制有关。
