School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK.
Laboratório de Citogenética e Evolução, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 91509-900, Rio Grande do Sul, Brazil.
Cells. 2020 Dec 22;10(1):4. doi: 10.3390/cells10010004.
Although cytogenetics studies in cuckoos (Aves, Cuculiformes) have demonstrated an interesting karyotype variation, such as variations in the chromosome morphology and diploid number, their chromosome organization and evolution, and relation with other birds are poorly understood. Hence, we combined conventional and molecular cytogenetic approaches to investigate chromosome homologies between chicken and the smooth-billed ani (). Our results demonstrate extensive chromosome reorganization in . , with interchromosomal rearrangements involving macro and microchromosomes. Intrachromosomal rearrangements were observed in some macrochromosomes, including the Z chromosome. The most evolutionary notable finding was a Robertsonian translocation between the microchromosome 17 and the Z chromosome, a rare event in birds. Additionally, the simple short repeats (SSRs) tested here were preferentially accumulated in the microchromosomes and in the Z and W chromosomes, showing no relationship with the constitutive heterochromatin regions, except in the W chromosome. Taken together, our results suggest that the avian sex chromosome is more complex than previously postulated and revealed the role of microchromosomes in the avian sex chromosome evolution, especially cuckoos.
尽管雀形目鸟类（Aves，Cuculiformes）的细胞遗传学研究已经证明了其具有有趣的染色体形态和二倍体数量变异，但它们的染色体组织和进化以及与其他鸟类的关系还知之甚少。因此，我们结合了常规和分子细胞遗传学方法来研究鸡和光滑胸蚁䴕（Crotophaga ani）之间的染色体同源性。我们的结果表明，光滑胸蚁䴕中存在广泛的染色体重排，涉及大染色体和小染色体之间的相互易位。在一些大染色体中观察到了染色体内部的重排，包括 Z 染色体。最显著的进化发现是小染色体 17 和 Z 染色体之间的罗伯逊易位，这在鸟类中是罕见的事件。此外，这里测试的简单短重复（SSRs）优先积累在小染色体和 Z 染色体和 W 染色体上，与常染色质区域没有关系，除了在 W 染色体上。总之，我们的结果表明，鸟类的性染色体比之前假设的更为复杂，并揭示了小染色体在鸟类性染色体进化中的作用，尤其是在杜鹃中。
